RISC-V: Add support for rv32 userspace via COMPAT

The RISC-V port supports the rv32i and rv64i base ISAs, but provides no
mechanism to run 32-bit userspace on 64-bit systems.  This adds that
support, via the COMPAT framework.  As the RISC-V ISAs (and uABIs) were
developed concurrently, the resulting compat support is mostly generic.

This includes a handful of cleanups to the generic compat infrastructure
to more cleanly support RISC-V, followed by the RISC-V implementation.

* palmer/riscv-compat:
  riscv: compat: Add COMPAT Kbuild skeletal support
  riscv: compat: ptrace: Add compat_arch_ptrace implement
  riscv: compat: signal: Add rt_frame implementation
  riscv: compat: vdso: Add setup additional pages implementation
  riscv: compat: vdso: Add COMPAT_VDSO base code implementation
  riscv: compat: Add hw capability check for elf
  riscv: compat: Add elf.h implementation
  riscv: compat: process: Add UXL_32 support in start_thread
  riscv: compat: syscall: Add entry.S implementation
  riscv: compat: syscall: Add compat_sys_call_table implementation
  riscv: compat: Support TASK_SIZE for compat mode
  riscv: compat: Add basic compat data type implementation
  riscv: Fixup difference with defconfig
  syscalls: compat: Fix the missing part for __SYSCALL_COMPAT
  asm-generic: compat: Cleanup duplicate definitions
  fs: stat: compat: Add __ARCH_WANT_COMPAT_STAT
  arch: Add SYSVIPC_COMPAT for all architectures
  compat: consolidate the compat_flock{,64} definition
  uapi: always define F_GETLK64/F_SETLK64/F_SETLKW64 in fcntl.h
  uapi: simplify __ARCH_FLOCK{,64}_PAD a little

arch/arm64/Kconfig

@@ -2122,10 +2122,6 @@ config DMI
 
 endmenu
 
-config SYSVIPC_COMPAT
-	def_bool y
-	depends on COMPAT && SYSVIPC
-
 menu "Power management options"
 
 source "kernel/power/Kconfig"

arch/arm64/include/asm/compat.h

@@ -8,6 +8,15 @@
 #define compat_mode_t compat_mode_t
 typedef u16		compat_mode_t;
 
+#define __compat_uid_t	__compat_uid_t
+typedef u16		__compat_uid_t;
+typedef u16		__compat_gid_t;
+
+#define compat_ipc_pid_t compat_ipc_pid_t
+typedef u16		compat_ipc_pid_t;
+
+#define compat_statfs	compat_statfs
+
 #include <asm-generic/compat.h>
 
 #ifdef CONFIG_COMPAT
@@ -19,21 +28,15 @@ typedef u16		compat_mode_t;
 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
 
-#define COMPAT_USER_HZ		100
 #ifdef __AARCH64EB__
 #define COMPAT_UTS_MACHINE	"armv8b\0\0"
 #else
 #define COMPAT_UTS_MACHINE	"armv8l\0\0"
 #endif
 
-typedef u16		__compat_uid_t;
-typedef u16		__compat_gid_t;
 typedef u16		__compat_uid16_t;
 typedef u16		__compat_gid16_t;
-typedef u32		compat_dev_t;
 typedef s32		compat_nlink_t;
-typedef u16		compat_ipc_pid_t;
-typedef __kernel_fsid_t	compat_fsid_t;
 
 struct compat_stat {
 #ifdef __AARCH64EB__
@@ -65,26 +68,6 @@ struct compat_stat {
 	compat_ulong_t	__unused4[2];
 };
 
-struct compat_flock {
-	short		l_type;
-	short		l_whence;
-	compat_off_t	l_start;
-	compat_off_t	l_len;
-	compat_pid_t	l_pid;
-};
-
-#define F_GETLK64	12	/*  using 'struct flock64' */
-#define F_SETLK64	13
-#define F_SETLKW64	14
-
-struct compat_flock64 {
-	short		l_type;
-	short		l_whence;
-	compat_loff_t	l_start;
-	compat_loff_t	l_len;
-	compat_pid_t	l_pid;
-};
-
 struct compat_statfs {
 	int		f_type;
 	int		f_bsize;
@@ -107,64 +90,6 @@ struct compat_statfs {
 #define compat_user_stack_pointer() (user_stack_pointer(task_pt_regs(current)))
 #define COMPAT_MINSIGSTKSZ	2048
 
-struct compat_ipc64_perm {
-	compat_key_t key;
-	__compat_uid32_t uid;
-	__compat_gid32_t gid;
-	__compat_uid32_t cuid;
-	__compat_gid32_t cgid;
-	unsigned short mode;
-	unsigned short __pad1;
-	unsigned short seq;
-	unsigned short __pad2;
-	compat_ulong_t unused1;
-	compat_ulong_t unused2;
-};
-
-struct compat_semid64_ds {
-	struct compat_ipc64_perm sem_perm;
-	compat_ulong_t sem_otime;
-	compat_ulong_t sem_otime_high;
-	compat_ulong_t sem_ctime;
-	compat_ulong_t sem_ctime_high;
-	compat_ulong_t sem_nsems;
-	compat_ulong_t __unused3;
-	compat_ulong_t __unused4;
-};
-
-struct compat_msqid64_ds {
-	struct compat_ipc64_perm msg_perm;
-	compat_ulong_t msg_stime;
-	compat_ulong_t msg_stime_high;
-	compat_ulong_t msg_rtime;
-	compat_ulong_t msg_rtime_high;
-	compat_ulong_t msg_ctime;
-	compat_ulong_t msg_ctime_high;
-	compat_ulong_t msg_cbytes;
-	compat_ulong_t msg_qnum;
-	compat_ulong_t msg_qbytes;
-	compat_pid_t   msg_lspid;
-	compat_pid_t   msg_lrpid;
-	compat_ulong_t __unused4;
-	compat_ulong_t __unused5;
-};
-
-struct compat_shmid64_ds {
-	struct compat_ipc64_perm shm_perm;
-	compat_size_t  shm_segsz;
-	compat_ulong_t shm_atime;
-	compat_ulong_t shm_atime_high;
-	compat_ulong_t shm_dtime;
-	compat_ulong_t shm_dtime_high;
-	compat_ulong_t shm_ctime;
-	compat_ulong_t shm_ctime_high;
-	compat_pid_t   shm_cpid;
-	compat_pid_t   shm_lpid;
-	compat_ulong_t shm_nattch;
-	compat_ulong_t __unused4;
-	compat_ulong_t __unused5;
-};
-
 static inline int is_compat_task(void)
 {
 	return test_thread_flag(TIF_32BIT);

arch/arm64/include/asm/unistd.h

@@ -3,6 +3,7 @@
  * Copyright (C) 2012 ARM Ltd.
  */
 #ifdef CONFIG_COMPAT
+#define __ARCH_WANT_COMPAT_STAT
 #define __ARCH_WANT_COMPAT_STAT64
 #define __ARCH_WANT_SYS_GETHOSTNAME
 #define __ARCH_WANT_SYS_PAUSE

arch/mips/Kconfig

@@ -3198,16 +3198,12 @@ config MIPS32_COMPAT
 config COMPAT
 	bool
 
-config SYSVIPC_COMPAT
-	bool
-
 config MIPS32_O32
 	bool "Kernel support for o32 binaries"
 	depends on 64BIT
 	select ARCH_WANT_OLD_COMPAT_IPC
 	select COMPAT
 	select MIPS32_COMPAT
-	select SYSVIPC_COMPAT if SYSVIPC
 	help
 	  Select this option if you want to run o32 binaries.  These are pure
 	  32-bit binaries as used by the 32-bit Linux/MIPS port.  Most of
@@ -3221,7 +3217,6 @@ config MIPS32_N32
 	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 	select COMPAT
 	select MIPS32_COMPAT
-	select SYSVIPC_COMPAT if SYSVIPC
 	help
 	  Select this option if you want to run n32 binaries.  These are
 	  64-bit binaries using 32-bit quantities for addressing and certain

arch/mips/include/asm/compat.h

@@ -9,28 +9,28 @@
 #include <asm/page.h>
 #include <asm/ptrace.h>
 
+#define __compat_uid_t	__compat_uid_t
 typedef s32		__compat_uid_t;
 typedef s32		__compat_gid_t;
+
 typedef __compat_uid_t	__compat_uid32_t;
 typedef __compat_gid_t	__compat_gid32_t;
 #define __compat_uid32_t __compat_uid32_t
-#define __compat_gid32_t __compat_gid32_t
+
+#define compat_statfs		compat_statfs
+#define compat_ipc64_perm	compat_ipc64_perm
 
 #define _COMPAT_NSIG		128		/* Don't ask !$@#% ...	*/
 #define _COMPAT_NSIG_BPW	32
 typedef u32		compat_sigset_word;
 
+#define COMPAT_RLIM_INFINITY	0x7fffffffUL
+
 #include <asm-generic/compat.h>
 
-#define COMPAT_USER_HZ		100
 #define COMPAT_UTS_MACHINE	"mips\0\0\0"
 
-typedef u32		compat_dev_t;
 typedef u32		compat_nlink_t;
-typedef s32		compat_ipc_pid_t;
-typedef struct {
-	s32	val[2];
-} compat_fsid_t;
 
 struct compat_stat {
 	compat_dev_t	st_dev;
@@ -55,27 +55,8 @@ struct compat_stat {
 	s32		st_pad4[14];
 };
 
-struct compat_flock {
-	short		l_type;
-	short		l_whence;
-	compat_off_t	l_start;
-	compat_off_t	l_len;
-	s32		l_sysid;
-	compat_pid_t	l_pid;
-	s32		pad[4];
-};
-
-#define F_GETLK64	33
-#define F_SETLK64	34
-#define F_SETLKW64	35
-
-struct compat_flock64 {
-	short		l_type;
-	short		l_whence;
-	compat_loff_t	l_start;
-	compat_loff_t	l_len;
-	compat_pid_t	l_pid;
-};
+#define __ARCH_COMPAT_FLOCK_EXTRA_SYSID		s32 l_sysid;
+#define __ARCH_COMPAT_FLOCK_PAD			s32 pad[4];
 
 struct compat_statfs {
 	int		f_type;
@@ -92,10 +73,6 @@ struct compat_statfs {
 	int		f_spare[5];
 };
 
-#define COMPAT_RLIM_INFINITY	0x7fffffffUL
-
-#define COMPAT_OFF_T_MAX	0x7fffffff
-
 struct compat_ipc64_perm {
 	compat_key_t key;
 	__compat_uid32_t uid;

arch/mips/include/asm/unistd.h

@@ -50,6 +50,8 @@
 # ifdef CONFIG_32BIT
 #  define __ARCH_WANT_STAT64
 #  define __ARCH_WANT_SYS_TIME32
+# else
+#  define __ARCH_WANT_COMPAT_STAT
 # endif
 # ifdef CONFIG_MIPS32_O32
 #  define __ARCH_WANT_SYS_TIME32

arch/mips/include/uapi/asm/fcntl.h

@@ -44,36 +44,16 @@
 #define F_SETOWN	24	/*  for sockets. */
 #define F_GETOWN	23	/*  for sockets. */
 
-#ifndef __mips64
+#if __BITS_PER_LONG == 32 || defined(__KERNEL__)
 #define F_GETLK64	33	/*  using 'struct flock64' */
 #define F_SETLK64	34
 #define F_SETLKW64	35
-#endif
-
-/*
- * The flavours of struct flock.  "struct flock" is the ABI compliant
- * variant.  Finally struct flock64 is the LFS variant of struct flock.	 As
- * a historic accident and inconsistence with the ABI definition it doesn't
- * contain all the same fields as struct flock.
- */
+#endif /* __BITS_PER_LONG == 32 || defined(__KERNEL__) */
 
 #if _MIPS_SIM != _MIPS_SIM_ABI64
-
-#include <linux/types.h>
-
-struct flock {
-	short	l_type;
-	short	l_whence;
-	__kernel_off_t	l_start;
-	__kernel_off_t	l_len;
-	long	l_sysid;
-	__kernel_pid_t l_pid;
-	long	pad[4];
-};
-
-#define HAVE_ARCH_STRUCT_FLOCK
-
-#endif /* _MIPS_SIM == _MIPS_SIM_ABI32 */
+#define __ARCH_FLOCK_EXTRA_SYSID	long l_sysid;
+#define __ARCH_FLOCK_PAD		long pad[4];
+#endif
 
 #include <asm-generic/fcntl.h>
 

arch/parisc/Kconfig

@@ -331,10 +331,6 @@ config COMPAT
 	def_bool y
 	depends on 64BIT
 
-config SYSVIPC_COMPAT
-	def_bool y
-	depends on COMPAT && SYSVIPC
-
 config AUDIT_ARCH
 	def_bool y
 

arch/parisc/include/asm/compat.h

@@ -11,16 +11,16 @@
 #define compat_mode_t compat_mode_t
 typedef u16	compat_mode_t;
 
+#define compat_ipc_pid_t compat_ipc_pid_t
+typedef u16	compat_ipc_pid_t;
+
+#define compat_ipc64_perm compat_ipc64_perm
+
 #include <asm-generic/compat.h>
 
-#define COMPAT_USER_HZ 		100
 #define COMPAT_UTS_MACHINE	"parisc\0\0"
 
-typedef u32	__compat_uid_t;
-typedef u32	__compat_gid_t;
-typedef u32	compat_dev_t;
 typedef u16	compat_nlink_t;
-typedef u16	compat_ipc_pid_t;
 
 struct compat_stat {
 	compat_dev_t		st_dev;	/* dev_t is 32 bits on parisc */
@@ -53,37 +53,6 @@ struct compat_stat {
 	u32			st_spare4[3];
 };
 
-struct compat_flock {
-	short			l_type;
-	short			l_whence;
-	compat_off_t		l_start;
-	compat_off_t		l_len;
-	compat_pid_t		l_pid;
-};
-
-struct compat_flock64 {
-	short			l_type;
-	short			l_whence;
-	compat_loff_t		l_start;
-	compat_loff_t		l_len;
-	compat_pid_t		l_pid;
-};
-
-struct compat_statfs {
-	s32		f_type;
-	s32		f_bsize;
-	s32		f_blocks;
-	s32		f_bfree;
-	s32		f_bavail;
-	s32		f_files;
-	s32		f_ffree;
-	__kernel_fsid_t	f_fsid;
-	s32		f_namelen;
-	s32		f_frsize;
-	s32		f_flags;
-	s32		f_spare[4];
-};
-
 struct compat_sigcontext {
 	compat_int_t sc_flags;
 	compat_int_t sc_gr[32]; /* PSW in sc_gr[0] */
@@ -93,10 +62,6 @@ struct compat_sigcontext {
 	compat_int_t sc_sar; /* cr11 */
 };
 
-#define COMPAT_RLIM_INFINITY 0xffffffff
-
-#define COMPAT_OFF_T_MAX	0x7fffffff
-
 struct compat_ipc64_perm {
 	compat_key_t key;
 	__compat_uid_t uid;

arch/parisc/include/asm/unistd.h

@@ -164,6 +164,7 @@ type name(type1 arg1, type2 arg2, type3 arg3, type4 arg4, type5 arg5)	\
 #define __ARCH_WANT_SYS_CLONE
 #define __ARCH_WANT_SYS_CLONE3
 #define __ARCH_WANT_COMPAT_SYS_SENDFILE
+#define __ARCH_WANT_COMPAT_STAT
 
 #ifdef CONFIG_64BIT
 #define __ARCH_WANT_SYS_TIME

arch/powerpc/Kconfig

@@ -298,11 +298,6 @@ config COMPAT
 	select ARCH_WANT_OLD_COMPAT_IPC
 	select COMPAT_OLD_SIGACTION
 
-config SYSVIPC_COMPAT
-	bool
-	depends on COMPAT && SYSVIPC
-	default y
-
 config SCHED_OMIT_FRAME_POINTER
 	bool
 	default y

arch/powerpc/include/asm/compat.h

@@ -8,21 +8,20 @@
 #include <linux/types.h>
 #include <linux/sched.h>
 
+#define compat_ipc_pid_t compat_ipc_pid_t
+typedef u16		compat_ipc_pid_t;
+
+#define compat_ipc64_perm compat_ipc64_perm
+
 #include <asm-generic/compat.h>
 
-#define COMPAT_USER_HZ		100
 #ifdef __BIG_ENDIAN__
 #define COMPAT_UTS_MACHINE	"ppc\0\0"
 #else
 #define COMPAT_UTS_MACHINE	"ppcle\0\0"
 #endif
 
-typedef u32		__compat_uid_t;
-typedef u32		__compat_gid_t;
-typedef u32		compat_dev_t;
 typedef s16		compat_nlink_t;
-typedef u16		compat_ipc_pid_t;
-typedef __kernel_fsid_t	compat_fsid_t;
 
 struct compat_stat {
 	compat_dev_t	st_dev;
@@ -44,45 +43,6 @@ struct compat_stat {
 	u32		__unused4[2];
 };
 
-struct compat_flock {
-	short		l_type;
-	short		l_whence;
-	compat_off_t	l_start;
-	compat_off_t	l_len;
-	compat_pid_t	l_pid;
-};
-
-#define F_GETLK64	12	/*  using 'struct flock64' */
-#define F_SETLK64	13
-#define F_SETLKW64	14
-
-struct compat_flock64 {
-	short		l_type;
-	short		l_whence;
-	compat_loff_t	l_start;
-	compat_loff_t	l_len;
-	compat_pid_t	l_pid;
-};
-
-struct compat_statfs {
-	int		f_type;
-	int		f_bsize;
-	int		f_blocks;
-	int		f_bfree;
-	int		f_bavail;
-	int		f_files;
-	int		f_ffree;
-	compat_fsid_t	f_fsid;
-	int		f_namelen;	/* SunOS ignores this field. */
-	int		f_frsize;
-	int		f_flags;
-	int		f_spare[4];
-};
-
-#define COMPAT_RLIM_INFINITY		0xffffffff
-
-#define COMPAT_OFF_T_MAX	0x7fffffff
-
 /*
  * ipc64_perm is actually 32/64bit clean but since the compat layer refers to
  * it we may as well define it.

arch/powerpc/include/asm/unistd.h

@@ -44,6 +44,7 @@
 #define __ARCH_WANT_SYS_TIME
 #define __ARCH_WANT_SYS_UTIME
 #define __ARCH_WANT_SYS_NEWFSTATAT
+#define __ARCH_WANT_COMPAT_STAT
 #define __ARCH_WANT_COMPAT_SYS_SENDFILE
 #endif
 #define __ARCH_WANT_SYS_FORK

arch/riscv/Kconfig

@@ -76,6 +76,7 @@ config RISCV
 	select HAVE_ARCH_KGDB if !XIP_KERNEL
 	select HAVE_ARCH_KGDB_QXFER_PKT
 	select HAVE_ARCH_MMAP_RND_BITS if MMU
+	select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU
@@ -127,12 +128,18 @@ config ARCH_MMAP_RND_BITS_MIN
 	default 18 if 64BIT
 	default 8
 
+config ARCH_MMAP_RND_COMPAT_BITS_MIN
+	default 8
+
 # max bits determined by the following formula:
 #  VA_BITS - PAGE_SHIFT - 3
 config ARCH_MMAP_RND_BITS_MAX
 	default 24 if 64BIT # SV39 based
 	default 17
 
+config ARCH_MMAP_RND_COMPAT_BITS_MAX
+	default 17
+
 # set if we run in machine mode, cleared if we run in supervisor mode
 config RISCV_M_MODE
 	bool
@@ -422,6 +429,18 @@ config CRASH_DUMP
 
 	  For more details see Documentation/admin-guide/kdump/kdump.rst
 
+config COMPAT
+	bool "Kernel support for 32-bit U-mode"
+	default 64BIT
+	depends on 64BIT && MMU
+	help
+	  This option enables support for a 32-bit U-mode running under a 64-bit
+	  kernel at S-mode. riscv32-specific components such as system calls,
+	  the user helper functions (vdso), signal rt_frame functions and the
+	  ptrace interface are handled appropriately by the kernel.
+
+	  If you want to execute 32-bit userspace applications, say Y.
+
 endmenu
 
 menu "Boot options"

arch/riscv/Makefile

@@ -112,12 +112,17 @@ libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
 PHONY += vdso_install
 vdso_install:
 	$(Q)$(MAKE) $(build)=arch/riscv/kernel/vdso $@
+	$(if $(CONFIG_COMPAT),$(Q)$(MAKE) \
+		$(build)=arch/riscv/kernel/compat_vdso $@)
 
 ifeq ($(KBUILD_EXTMOD),)
 ifeq ($(CONFIG_MMU),y)
 prepare: vdso_prepare
 vdso_prepare: prepare0
 	$(Q)$(MAKE) $(build)=arch/riscv/kernel/vdso include/generated/vdso-offsets.h
+	$(if $(CONFIG_COMPAT),$(Q)$(MAKE) \
+		$(build)=arch/riscv/kernel/compat_vdso include/generated/compat_vdso-offsets.h)
+
 endif
 endif
 
@@ -154,3 +159,7 @@ PHONY += rv64_randconfig
 rv64_randconfig:
 	$(Q)$(MAKE) KCONFIG_ALLCONFIG=$(srctree)/arch/riscv/configs/64-bit.config \
 		-f $(srctree)/Makefile randconfig
+
+PHONY += rv32_defconfig
+rv32_defconfig:
+	$(Q)$(MAKE) -f $(srctree)/Makefile defconfig 32-bit.config

arch/riscv/include/asm/compat.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __ASM_COMPAT_H
+#define __ASM_COMPAT_H
+
+#define COMPAT_UTS_MACHINE	"riscv\0\0"
+
+/*
+ * Architecture specific compatibility types
+ */
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+#include <asm-generic/compat.h>
+
+static inline int is_compat_task(void)
+{
+	return test_thread_flag(TIF_32BIT);
+}
+
+struct compat_user_regs_struct {
+	compat_ulong_t pc;
+	compat_ulong_t ra;
+	compat_ulong_t sp;
+	compat_ulong_t gp;
+	compat_ulong_t tp;
+	compat_ulong_t t0;
+	compat_ulong_t t1;
+	compat_ulong_t t2;
+	compat_ulong_t s0;
+	compat_ulong_t s1;
+	compat_ulong_t a0;
+	compat_ulong_t a1;
+	compat_ulong_t a2;
+	compat_ulong_t a3;
+	compat_ulong_t a4;
+	compat_ulong_t a5;
+	compat_ulong_t a6;
+	compat_ulong_t a7;
+	compat_ulong_t s2;
+	compat_ulong_t s3;
+	compat_ulong_t s4;
+	compat_ulong_t s5;
+	compat_ulong_t s6;
+	compat_ulong_t s7;
+	compat_ulong_t s8;
+	compat_ulong_t s9;
+	compat_ulong_t s10;
+	compat_ulong_t s11;
+	compat_ulong_t t3;
+	compat_ulong_t t4;
+	compat_ulong_t t5;
+	compat_ulong_t t6;
+};
+
+static inline void regs_to_cregs(struct compat_user_regs_struct *cregs,
+				 struct pt_regs *regs)
+{
+	cregs->pc	= (compat_ulong_t) regs->epc;
+	cregs->ra	= (compat_ulong_t) regs->ra;
+	cregs->sp	= (compat_ulong_t) regs->sp;
+	cregs->gp	= (compat_ulong_t) regs->gp;
+	cregs->tp	= (compat_ulong_t) regs->tp;
+	cregs->t0	= (compat_ulong_t) regs->t0;
+	cregs->t1	= (compat_ulong_t) regs->t1;
+	cregs->t2	= (compat_ulong_t) regs->t2;
+	cregs->s0	= (compat_ulong_t) regs->s0;
+	cregs->s1	= (compat_ulong_t) regs->s1;
+	cregs->a0	= (compat_ulong_t) regs->a0;
+	cregs->a1	= (compat_ulong_t) regs->a1;
+	cregs->a2	= (compat_ulong_t) regs->a2;
+	cregs->a3	= (compat_ulong_t) regs->a3;
+	cregs->a4	= (compat_ulong_t) regs->a4;
+	cregs->a5	= (compat_ulong_t) regs->a5;
+	cregs->a6	= (compat_ulong_t) regs->a6;
+	cregs->a7	= (compat_ulong_t) regs->a7;
+	cregs->s2	= (compat_ulong_t) regs->s2;
+	cregs->s3	= (compat_ulong_t) regs->s3;
+	cregs->s4	= (compat_ulong_t) regs->s4;
+	cregs->s5	= (compat_ulong_t) regs->s5;
+	cregs->s6	= (compat_ulong_t) regs->s6;
+	cregs->s7	= (compat_ulong_t) regs->s7;
+	cregs->s8	= (compat_ulong_t) regs->s8;
+	cregs->s9	= (compat_ulong_t) regs->s9;
+	cregs->s10	= (compat_ulong_t) regs->s10;
+	cregs->s11	= (compat_ulong_t) regs->s11;
+	cregs->t3	= (compat_ulong_t) regs->t3;
+	cregs->t4	= (compat_ulong_t) regs->t4;
+	cregs->t5	= (compat_ulong_t) regs->t5;
+	cregs->t6	= (compat_ulong_t) regs->t6;
+};
+
+static inline void cregs_to_regs(struct compat_user_regs_struct *cregs,
+				 struct pt_regs *regs)
+{
+	regs->epc	= (unsigned long) cregs->pc;
+	regs->ra	= (unsigned long) cregs->ra;
+	regs->sp	= (unsigned long) cregs->sp;
+	regs->gp	= (unsigned long) cregs->gp;
+	regs->tp	= (unsigned long) cregs->tp;
+	regs->t0	= (unsigned long) cregs->t0;
+	regs->t1	= (unsigned long) cregs->t1;
+	regs->t2	= (unsigned long) cregs->t2;
+	regs->s0	= (unsigned long) cregs->s0;
+	regs->s1	= (unsigned long) cregs->s1;
+	regs->a0	= (unsigned long) cregs->a0;
+	regs->a1	= (unsigned long) cregs->a1;
+	regs->a2	= (unsigned long) cregs->a2;
+	regs->a3	= (unsigned long) cregs->a3;
+	regs->a4	= (unsigned long) cregs->a4;
+	regs->a5	= (unsigned long) cregs->a5;
+	regs->a6	= (unsigned long) cregs->a6;
+	regs->a7	= (unsigned long) cregs->a7;
+	regs->s2	= (unsigned long) cregs->s2;
+	regs->s3	= (unsigned long) cregs->s3;
+	regs->s4	= (unsigned long) cregs->s4;
+	regs->s5	= (unsigned long) cregs->s5;
+	regs->s6	= (unsigned long) cregs->s6;
+	regs->s7	= (unsigned long) cregs->s7;
+	regs->s8	= (unsigned long) cregs->s8;
+	regs->s9	= (unsigned long) cregs->s9;
+	regs->s10	= (unsigned long) cregs->s10;
+	regs->s11	= (unsigned long) cregs->s11;
+	regs->t3	= (unsigned long) cregs->t3;
+	regs->t4	= (unsigned long) cregs->t4;
+	regs->t5	= (unsigned long) cregs->t5;
+	regs->t6	= (unsigned long) cregs->t6;
+};
+
+#endif /* __ASM_COMPAT_H */

arch/riscv/include/asm/csr.h

@@ -36,6 +36,13 @@
 #define SR_SD		_AC(0x8000000000000000, UL) /* FS/XS dirty */
 #endif
 
+#ifdef CONFIG_64BIT
+#define SR_UXL		_AC(0x300000000, UL) /* XLEN mask for U-mode */
+#define SR_UXL_32	_AC(0x100000000, UL) /* XLEN = 32 for U-mode */
+#define SR_UXL_64	_AC(0x200000000, UL) /* XLEN = 64 for U-mode */
+#define SR_UXL_SHIFT	32
+#endif
+
 /* SATP flags */
 #ifndef CONFIG_64BIT
 #define SATP_PPN	_AC(0x003FFFFF, UL)

arch/riscv/include/asm/elf.h

@@ -8,6 +8,8 @@
 #ifndef _ASM_RISCV_ELF_H
 #define _ASM_RISCV_ELF_H
 
+#include <uapi/linux/elf.h>
+#include <linux/compat.h>
 #include <uapi/asm/elf.h>
 #include <asm/auxvec.h>
 #include <asm/byteorder.h>
@@ -18,18 +20,24 @@
  */
 #define ELF_ARCH	EM_RISCV
 
+#ifndef ELF_CLASS
 #ifdef CONFIG_64BIT
 #define ELF_CLASS	ELFCLASS64
 #else
 #define ELF_CLASS	ELFCLASS32
 #endif
+#endif
 
 #define ELF_DATA	ELFDATA2LSB
 
 /*
  * This is used to ensure we don't load something for the wrong architecture.
  */
-#define elf_check_arch(x) ((x)->e_machine == EM_RISCV)
+#define elf_check_arch(x) (((x)->e_machine == EM_RISCV) && \
+			   ((x)->e_ident[EI_CLASS] == ELF_CLASS))
+
+extern bool compat_elf_check_arch(Elf32_Ehdr *hdr);
+#define compat_elf_check_arch	compat_elf_check_arch
 
 #define CORE_DUMP_USE_REGSET
 #define ELF_EXEC_PAGESIZE	(PAGE_SIZE)
@@ -43,8 +51,14 @@
 #define ELF_ET_DYN_BASE		((TASK_SIZE / 3) * 2)
 
 #ifdef CONFIG_64BIT
+#ifdef CONFIG_COMPAT
+#define STACK_RND_MASK		(test_thread_flag(TIF_32BIT) ? \
+				 0x7ff >> (PAGE_SHIFT - 12) : \
+				 0x3ffff >> (PAGE_SHIFT - 12))
+#else
 #define STACK_RND_MASK		(0x3ffff >> (PAGE_SHIFT - 12))
 #endif
+#endif
 /*
  * This yields a mask that user programs can use to figure out what
  * instruction set this CPU supports.  This could be done in user space,
@@ -60,11 +74,19 @@ extern unsigned long elf_hwcap;
  */
 #define ELF_PLATFORM	(NULL)
 
+#define COMPAT_ELF_PLATFORM	(NULL)
+
 #ifdef CONFIG_MMU
 #define ARCH_DLINFO						\
 do {								\
+	/*							\
+	 * Note that we add ulong after elf_addr_t because	\
+	 * casting current->mm->context.vdso triggers a cast	\
+	 * warning of cast from pointer to integer for		\
+	 * COMPAT ELFCLASS32.					\
+	 */							\
 	NEW_AUX_ENT(AT_SYSINFO_EHDR,				\
-		(elf_addr_t)current->mm->context.vdso);		\
+		(elf_addr_t)(ulong)current->mm->context.vdso);	\
 	NEW_AUX_ENT(AT_L1I_CACHESIZE,				\
 		get_cache_size(1, CACHE_TYPE_INST));		\
 	NEW_AUX_ENT(AT_L1I_CACHEGEOMETRY,			\
@@ -90,4 +112,28 @@ do {							\
 		*(struct user_regs_struct *)regs;	\
 } while (0);
 
+#ifdef CONFIG_COMPAT
+
+#define SET_PERSONALITY(ex)					\
+do {    if ((ex).e_ident[EI_CLASS] == ELFCLASS32)		\
+		set_thread_flag(TIF_32BIT);			\
+	else							\
+		clear_thread_flag(TIF_32BIT);			\
+	if (personality(current->personality) != PER_LINUX32)	\
+		set_personality(PER_LINUX |			\
+			(current->personality & (~PER_MASK)));	\
+} while (0)
+
+#define COMPAT_ELF_ET_DYN_BASE		((TASK_SIZE_32 / 3) * 2)
+
+/* rv32 registers */
+typedef compat_ulong_t			compat_elf_greg_t;
+typedef compat_elf_greg_t		compat_elf_gregset_t[ELF_NGREG];
+
+extern int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
+					      int uses_interp);
+#define compat_arch_setup_additional_pages \
+				compat_arch_setup_additional_pages
+
+#endif /* CONFIG_COMPAT */
 #endif /* _ASM_RISCV_ELF_H */

arch/riscv/include/asm/mmu.h

@@ -16,6 +16,7 @@ typedef struct {
 	atomic_long_t id;
 #endif
 	void *vdso;
+	void *vdso_info;
 #ifdef CONFIG_SMP
 	/* A local icache flush is needed before user execution can resume. */
 	cpumask_t icache_stale_mask;

arch/riscv/include/asm/pgtable.h

@@ -740,8 +740,17 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
  * 63–48 all equal to bit 47, or else a page-fault exception will occur."
  */
 #ifdef CONFIG_64BIT
-#define TASK_SIZE      (PGDIR_SIZE * PTRS_PER_PGD / 2)
-#define TASK_SIZE_MIN  (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)
+#define TASK_SIZE_64	(PGDIR_SIZE * PTRS_PER_PGD / 2)
+#define TASK_SIZE_MIN	(PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)
+
+#ifdef CONFIG_COMPAT
+#define TASK_SIZE_32	(_AC(0x80000000, UL) - PAGE_SIZE)
+#define TASK_SIZE	(test_thread_flag(TIF_32BIT) ? \
+			 TASK_SIZE_32 : TASK_SIZE_64)
+#else
+#define TASK_SIZE	TASK_SIZE_64
+#endif
+
 #else
 #define TASK_SIZE	FIXADDR_START
 #define TASK_SIZE_MIN	TASK_SIZE

arch/riscv/include/asm/processor.h

@@ -19,7 +19,11 @@
 #define TASK_UNMAPPED_BASE	PAGE_ALIGN(TASK_SIZE / 3)
 
 #define STACK_TOP		TASK_SIZE
-#define STACK_TOP_MAX		STACK_TOP
+#ifdef CONFIG_64BIT
+#define STACK_TOP_MAX		TASK_SIZE_64
+#else
+#define STACK_TOP_MAX		TASK_SIZE
+#endif
 #define STACK_ALIGN		16
 
 #ifndef __ASSEMBLY__

arch/riscv/include/asm/signal32.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __ASM_SIGNAL32_H
+#define __ASM_SIGNAL32_H
+
+#if IS_ENABLED(CONFIG_COMPAT)
+int compat_setup_rt_frame(struct ksignal *ksig, sigset_t *set,
+			  struct pt_regs *regs);
+#else
+static inline
+int compat_setup_rt_frame(struct ksignal *ksig, sigset_t *set,
+			  struct pt_regs *regs)
+{
+	return -1;
+}
+#endif
+
+#endif

arch/riscv/include/asm/syscall.h

@@ -16,6 +16,7 @@
 
 /* The array of function pointers for syscalls. */
 extern void * const sys_call_table[];
+extern void * const compat_sys_call_table[];
 
 /*
  * Only the low 32 bits of orig_r0 are meaningful, so we return int.

arch/riscv/include/asm/thread_info.h

@@ -97,6 +97,7 @@ struct thread_info {
 #define TIF_SECCOMP		8	/* syscall secure computing */
 #define TIF_NOTIFY_SIGNAL	9	/* signal notifications exist */
 #define TIF_UPROBE		10	/* uprobe breakpoint or singlestep */
+#define TIF_32BIT		11	/* compat-mode 32bit process */
 
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)

arch/riscv/include/asm/unistd.h

@@ -11,6 +11,17 @@
 #define __ARCH_WANT_SYS_CLONE
 #define __ARCH_WANT_MEMFD_SECRET
 
+#ifdef CONFIG_COMPAT
+#define __ARCH_WANT_COMPAT_TRUNCATE64
+#define __ARCH_WANT_COMPAT_FTRUNCATE64
+#define __ARCH_WANT_COMPAT_FALLOCATE
+#define __ARCH_WANT_COMPAT_PREAD64
+#define __ARCH_WANT_COMPAT_PWRITE64
+#define __ARCH_WANT_COMPAT_SYNC_FILE_RANGE
+#define __ARCH_WANT_COMPAT_READAHEAD
+#define __ARCH_WANT_COMPAT_FADVISE64_64
+#endif
+
 #include <uapi/asm/unistd.h>
 
 #define NR_syscalls (__NR_syscalls)

arch/riscv/include/asm/vdso.h

@@ -21,6 +21,15 @@
 
 #define VDSO_SYMBOL(base, name)							\
 	(void __user *)((unsigned long)(base) + __vdso_##name##_offset)
+
+#ifdef CONFIG_COMPAT
+#include <generated/compat_vdso-offsets.h>
+
+#define COMPAT_VDSO_SYMBOL(base, name)						\
+	(void __user *)((unsigned long)(base) + compat__vdso_##name##_offset)
+
+#endif /* CONFIG_COMPAT */
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* CONFIG_MMU */

arch/riscv/include/uapi/asm/unistd.h

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-#ifdef __LP64__
+#if defined(__LP64__) && !defined(__SYSCALL_COMPAT)
 #define __ARCH_WANT_NEW_STAT
 #define __ARCH_WANT_SET_GET_RLIMIT
 #endif /* __LP64__ */

arch/riscv/kernel/Makefile

@@ -84,3 +84,6 @@ obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
 obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o
 
 obj-$(CONFIG_EFI)		+= efi.o
+obj-$(CONFIG_COMPAT)		+= compat_syscall_table.o
+obj-$(CONFIG_COMPAT)		+= compat_signal.o
+obj-$(CONFIG_COMPAT)		+= compat_vdso/

arch/riscv/kernel/compat_signal.c

+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/compat.h>
+#include <linux/signal.h>
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+#include <linux/linkage.h>
+
+#include <asm/csr.h>
+#include <asm/signal32.h>
+#include <asm/switch_to.h>
+#include <asm/ucontext.h>
+#include <asm/vdso.h>
+
+#define COMPAT_DEBUG_SIG 0
+
+struct compat_sigcontext {
+	struct compat_user_regs_struct sc_regs;
+	union __riscv_fp_state sc_fpregs;
+};
+
+struct compat_ucontext {
+	compat_ulong_t		uc_flags;
+	struct compat_ucontext	*uc_link;
+	compat_stack_t		uc_stack;
+	sigset_t		uc_sigmask;
+	/* There's some padding here to allow sigset_t to be expanded in the
+	 * future.  Though this is unlikely, other architectures put uc_sigmask
+	 * at the end of this structure and explicitly state it can be
+	 * expanded, so we didn't want to box ourselves in here. */
+	__u8		  __unused[1024 / 8 - sizeof(sigset_t)];
+	/* We can't put uc_sigmask at the end of this structure because we need
+	 * to be able to expand sigcontext in the future.  For example, the
+	 * vector ISA extension will almost certainly add ISA state.  We want
+	 * to ensure all user-visible ISA state can be saved and restored via a
+	 * ucontext, so we're putting this at the end in order to allow for
+	 * infinite extensibility.  Since we know this will be extended and we
+	 * assume sigset_t won't be extended an extreme amount, we're
+	 * prioritizing this. */
+	struct compat_sigcontext uc_mcontext;
+};
+
+struct compat_rt_sigframe {
+	struct compat_siginfo info;
+	struct compat_ucontext uc;
+};
+
+#ifdef CONFIG_FPU
+static long compat_restore_fp_state(struct pt_regs *regs,
+	union __riscv_fp_state __user *sc_fpregs)
+{
+	long err;
+	struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
+	size_t i;
+
+	err = __copy_from_user(&current->thread.fstate, state, sizeof(*state));
+	if (unlikely(err))
+		return err;
+
+	fstate_restore(current, regs);
+
+	/* We support no other extension state at this time. */
+	for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
+		u32 value;
+
+		err = __get_user(value, &sc_fpregs->q.reserved[i]);
+		if (unlikely(err))
+			break;
+		if (value != 0)
+			return -EINVAL;
+	}
+
+	return err;
+}
+
+static long compat_save_fp_state(struct pt_regs *regs,
+			  union __riscv_fp_state __user *sc_fpregs)
+{
+	long err;
+	struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
+	size_t i;
+
+	fstate_save(current, regs);
+	err = __copy_to_user(state, &current->thread.fstate, sizeof(*state));
+	if (unlikely(err))
+		return err;
+
+	/* We support no other extension state at this time. */
+	for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
+		err = __put_user(0, &sc_fpregs->q.reserved[i]);
+		if (unlikely(err))
+			break;
+	}
+
+	return err;
+}
+#else
+#define compat_save_fp_state(task, regs) (0)
+#define compat_restore_fp_state(task, regs) (0)
+#endif
+
+static long compat_restore_sigcontext(struct pt_regs *regs,
+	struct compat_sigcontext __user *sc)
+{
+	long err;
+	struct compat_user_regs_struct cregs;
+
+	/* sc_regs is structured the same as the start of pt_regs */
+	err = __copy_from_user(&cregs, &sc->sc_regs, sizeof(sc->sc_regs));
+
+	cregs_to_regs(&cregs, regs);
+
+	/* Restore the floating-point state. */
+	if (has_fpu())
+		err |= compat_restore_fp_state(regs, &sc->sc_fpregs);
+	return err;
+}
+
+COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
+{
+	struct pt_regs *regs = current_pt_regs();
+	struct compat_rt_sigframe __user *frame;
+	struct task_struct *task;
+	sigset_t set;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current->restart_block.fn = do_no_restart_syscall;
+
+	frame = (struct compat_rt_sigframe __user *)regs->sp;
+
+	if (!access_ok(frame, sizeof(*frame)))
+		goto badframe;
+
+	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
+		goto badframe;
+
+	set_current_blocked(&set);
+
+	if (compat_restore_sigcontext(regs, &frame->uc.uc_mcontext))
+		goto badframe;
+
+	if (compat_restore_altstack(&frame->uc.uc_stack))
+		goto badframe;
+
+	return regs->a0;
+
+badframe:
+	task = current;
+	if (show_unhandled_signals) {
+		pr_info_ratelimited(
+			"%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n",
+			task->comm, task_pid_nr(task), __func__,
+			frame, (void *)regs->epc, (void *)regs->sp);
+	}
+	force_sig(SIGSEGV);
+	return 0;
+}
+
+static long compat_setup_sigcontext(struct compat_rt_sigframe __user *frame,
+	struct pt_regs *regs)
+{
+	struct compat_sigcontext __user *sc = &frame->uc.uc_mcontext;
+	struct compat_user_regs_struct cregs;
+	long err;
+
+	regs_to_cregs(&cregs, regs);
+
+	/* sc_regs is structured the same as the start of pt_regs */
+	err = __copy_to_user(&sc->sc_regs, &cregs, sizeof(sc->sc_regs));
+	/* Save the floating-point state. */
+	if (has_fpu())
+		err |= compat_save_fp_state(regs, &sc->sc_fpregs);
+	return err;
+}
+
+static inline void __user *compat_get_sigframe(struct ksignal *ksig,
+	struct pt_regs *regs, size_t framesize)
+{
+	unsigned long sp;
+	/* Default to using normal stack */
+	sp = regs->sp;
+
+	/*
+	 * If we are on the alternate signal stack and would overflow it, don't.
+	 * Return an always-bogus address instead so we will die with SIGSEGV.
+	 */
+	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
+		return (void __user __force *)(-1UL);
+
+	/* This is the X/Open sanctioned signal stack switching. */
+	sp = sigsp(sp, ksig) - framesize;
+
+	/* Align the stack frame. */
+	sp &= ~0xfUL;
+
+	return (void __user *)sp;
+}
+
+int compat_setup_rt_frame(struct ksignal *ksig, sigset_t *set,
+	struct pt_regs *regs)
+{
+	struct compat_rt_sigframe __user *frame;
+	long err = 0;
+
+	frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
+	if (!access_ok(frame, sizeof(*frame)))
+		return -EFAULT;
+
+	err |= copy_siginfo_to_user32(&frame->info, &ksig->info);
+
+	/* Create the ucontext. */
+	err |= __put_user(0, &frame->uc.uc_flags);
+	err |= __put_user(NULL, &frame->uc.uc_link);
+	err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp);
+	err |= compat_setup_sigcontext(frame, regs);
+	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
+	if (err)
+		return -EFAULT;
+
+	regs->ra = (unsigned long)COMPAT_VDSO_SYMBOL(
+			current->mm->context.vdso, rt_sigreturn);
+
+	/*
+	 * Set up registers for signal handler.
+	 * Registers that we don't modify keep the value they had from
+	 * user-space at the time we took the signal.
+	 * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
+	 * since some things rely on this (e.g. glibc's debug/segfault.c).
+	 */
+	regs->epc = (unsigned long)ksig->ka.sa.sa_handler;
+	regs->sp = (unsigned long)frame;
+	regs->a0 = ksig->sig;                     /* a0: signal number */
+	regs->a1 = (unsigned long)(&frame->info); /* a1: siginfo pointer */
+	regs->a2 = (unsigned long)(&frame->uc);   /* a2: ucontext pointer */
+
+#if COMPAT_DEBUG_SIG
+	pr_info("SIG deliver (%s:%d): sig=%d pc=%p ra=%p sp=%p\n",
+		current->comm, task_pid_nr(current), ksig->sig,
+		(void *)regs->epc, (void *)regs->ra, frame);
+#endif
+
+	return 0;
+}

arch/riscv/kernel/compat_syscall_table.c

+// SPDX-License-Identifier: GPL-2.0-only
+
+#define __SYSCALL_COMPAT
+
+#include <linux/compat.h>
+#include <linux/syscalls.h>
+#include <asm-generic/mman-common.h>
+#include <asm-generic/syscalls.h>
+#include <asm/syscall.h>
+
+#undef __SYSCALL
+#define __SYSCALL(nr, call)      [nr] = (call),
+
+asmlinkage long compat_sys_rt_sigreturn(void);
+
+void * const compat_sys_call_table[__NR_syscalls] = {
+	[0 ... __NR_syscalls - 1] = sys_ni_syscall,
+#include <asm/unistd.h>
+};

arch/riscv/kernel/compat_vdso/.gitignore

+# SPDX-License-Identifier: GPL-2.0-only
+compat_vdso.lds

arch/riscv/kernel/compat_vdso/Makefile

+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for compat_vdso
+#
+
+# Symbols present in the compat_vdso
+compat_vdso-syms  = rt_sigreturn
+compat_vdso-syms += getcpu
+compat_vdso-syms += flush_icache
+
+COMPAT_CC := $(CC)
+COMPAT_LD := $(LD)
+
+COMPAT_CC_FLAGS := -march=rv32g -mabi=ilp32
+COMPAT_LD_FLAGS := -melf32lriscv
+
+# Files to link into the compat_vdso
+obj-compat_vdso = $(patsubst %, %.o, $(compat_vdso-syms)) note.o
+
+# Build rules
+targets := $(obj-compat_vdso) compat_vdso.so compat_vdso.so.dbg compat_vdso.lds
+obj-compat_vdso := $(addprefix $(obj)/, $(obj-compat_vdso))
+
+obj-y += compat_vdso.o
+CPPFLAGS_compat_vdso.lds += -P -C -U$(ARCH)
+
+# Disable profiling and instrumentation for VDSO code
+GCOV_PROFILE := n
+KCOV_INSTRUMENT := n
+KASAN_SANITIZE := n
+UBSAN_SANITIZE := n
+
+# Force dependency
+$(obj)/compat_vdso.o: $(obj)/compat_vdso.so
+
+# link rule for the .so file, .lds has to be first
+$(obj)/compat_vdso.so.dbg: $(obj)/compat_vdso.lds $(obj-compat_vdso) FORCE
+	$(call if_changed,compat_vdsold)
+LDFLAGS_compat_vdso.so.dbg = -shared -S -soname=linux-compat_vdso.so.1 \
+	--build-id=sha1 --hash-style=both --eh-frame-hdr
+
+$(obj-compat_vdso): %.o: %.S FORCE
+	$(call if_changed_dep,compat_vdsoas)
+
+# strip rule for the .so file
+$(obj)/%.so: OBJCOPYFLAGS := -S
+$(obj)/%.so: $(obj)/%.so.dbg FORCE
+	$(call if_changed,objcopy)
+
+# Generate VDSO offsets using helper script
+gen-compat_vdsosym := $(srctree)/$(src)/gen_compat_vdso_offsets.sh
+quiet_cmd_compat_vdsosym = VDSOSYM $@
+	cmd_compat_vdsosym = $(NM) $< | $(gen-compat_vdsosym) | LC_ALL=C sort > $@
+
+include/generated/compat_vdso-offsets.h: $(obj)/compat_vdso.so.dbg FORCE
+	$(call if_changed,compat_vdsosym)
+
+# actual build commands
+# The DSO images are built using a special linker script
+# Make sure only to export the intended __compat_vdso_xxx symbol offsets.
+quiet_cmd_compat_vdsold = VDSOLD  $@
+      cmd_compat_vdsold = $(COMPAT_LD) $(ld_flags) $(COMPAT_LD_FLAGS) -T $(filter-out FORCE,$^) -o $@.tmp && \
+                   $(OBJCOPY) $(patsubst %, -G __compat_vdso_%, $(compat_vdso-syms)) $@.tmp $@ && \
+                   rm $@.tmp
+
+# actual build commands
+quiet_cmd_compat_vdsoas = VDSOAS $@
+      cmd_compat_vdsoas = $(COMPAT_CC) $(a_flags) $(COMPAT_CC_FLAGS) -c -o $@ $<
+
+# install commands for the unstripped file
+quiet_cmd_compat_vdso_install = INSTALL $@
+      cmd_compat_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/compat_vdso/$@
+
+compat_vdso.so: $(obj)/compat_vdso.so.dbg
+	@mkdir -p $(MODLIB)/compat_vdso
+	$(call cmd,compat_vdso_install)
+
+compat_vdso_install: compat_vdso.so

arch/riscv/kernel/compat_vdso/compat_vdso.S

+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#define	vdso_start	compat_vdso_start
+#define	vdso_end	compat_vdso_end
+
+#define	__VDSO_PATH	"arch/riscv/kernel/compat_vdso/compat_vdso.so"
+
+#include "../vdso/vdso.S"

arch/riscv/kernel/compat_vdso/compat_vdso.lds.S

+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include "../vdso/vdso.lds.S"

arch/riscv/kernel/compat_vdso/flush_icache.S

+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include "../vdso/flush_icache.S"

arch/riscv/kernel/compat_vdso/gen_compat_vdso_offsets.sh

+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+LC_ALL=C
+sed -n -e 's/^[0]\+\(0[0-9a-fA-F]*\) . \(__vdso_[a-zA-Z0-9_]*\)$/\#define compat\2_offset\t0x\1/p'

arch/riscv/kernel/compat_vdso/getcpu.S

+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include "../vdso/getcpu.S"

arch/riscv/kernel/compat_vdso/note.S

+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include "../vdso/note.S"

arch/riscv/kernel/compat_vdso/rt_sigreturn.S

+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include "../vdso/rt_sigreturn.S"

arch/riscv/kernel/entry.S

@@ -207,13 +207,27 @@ check_syscall_nr:
 	 * Syscall number held in a7.
 	 * If syscall number is above allowed value, redirect to ni_syscall.
 	 */
-	bgeu a7, t0, 1f
+	bgeu a7, t0, 3f
+#ifdef CONFIG_COMPAT
+	REG_L s0, PT_STATUS(sp)
+	srli s0, s0, SR_UXL_SHIFT
+	andi s0, s0, (SR_UXL >> SR_UXL_SHIFT)
+	li t0, (SR_UXL_32 >> SR_UXL_SHIFT)
+	sub t0, s0, t0
+	bnez t0, 1f
+
+	/* Call compat_syscall */
+	la s0, compat_sys_call_table
+	j 2f
+1:
+#endif
 	/* Call syscall */
 	la s0, sys_call_table
+2:
 	slli t0, a7, RISCV_LGPTR
 	add s0, s0, t0
 	REG_L s0, 0(s0)
-1:
+3:
 	jalr s0
 
 ret_from_syscall:

arch/riscv/kernel/process.c

@@ -84,6 +84,34 @@ void show_regs(struct pt_regs *regs)
 		dump_backtrace(regs, NULL, KERN_DEFAULT);
 }
 
+#ifdef CONFIG_COMPAT
+static bool compat_mode_supported __read_mostly;
+
+bool compat_elf_check_arch(Elf32_Ehdr *hdr)
+{
+	return compat_mode_supported &&
+	       hdr->e_machine == EM_RISCV &&
+	       hdr->e_ident[EI_CLASS] == ELFCLASS32;
+}
+
+static int __init compat_mode_detect(void)
+{
+	unsigned long tmp = csr_read(CSR_STATUS);
+
+	csr_write(CSR_STATUS, (tmp & ~SR_UXL) | SR_UXL_32);
+	compat_mode_supported =
+			(csr_read(CSR_STATUS) & SR_UXL) == SR_UXL_32;
+
+	csr_write(CSR_STATUS, tmp);
+
+	pr_info("riscv: ELF compat mode %s",
+			compat_mode_supported ? "supported" : "failed");
+
+	return 0;
+}
+early_initcall(compat_mode_detect);
+#endif
+
 void start_thread(struct pt_regs *regs, unsigned long pc,
 	unsigned long sp)
 {
@@ -98,6 +126,15 @@ void start_thread(struct pt_regs *regs, unsigned long pc,
 	}
 	regs->epc = pc;
 	regs->sp = sp;
+
+#ifdef CONFIG_64BIT
+	regs->status &= ~SR_UXL;
+
+	if (is_compat_task())
+		regs->status |= SR_UXL_32;
+	else
+		regs->status |= SR_UXL_64;
+#endif
 }
 
 void flush_thread(void)

arch/riscv/kernel/ptrace.c

@@ -12,6 +12,7 @@
 #include <asm/thread_info.h>
 #include <asm/switch_to.h>
 #include <linux/audit.h>
+#include <linux/compat.h>
 #include <linux/ptrace.h>
 #include <linux/elf.h>
 #include <linux/regset.h>
@@ -110,11 +111,6 @@ static const struct user_regset_view riscv_user_native_view = {
 	.n = ARRAY_SIZE(riscv_user_regset),
 };
 
-const struct user_regset_view *task_user_regset_view(struct task_struct *task)
-{
-	return &riscv_user_native_view;
-}
-
 struct pt_regs_offset {
 	const char *name;
 	int offset;
@@ -272,3 +268,84 @@ __visible void do_syscall_trace_exit(struct pt_regs *regs)
 		trace_sys_exit(regs, regs_return_value(regs));
 #endif
 }
+
+#ifdef CONFIG_COMPAT
+static int compat_riscv_gpr_get(struct task_struct *target,
+				const struct user_regset *regset,
+				struct membuf to)
+{
+	struct compat_user_regs_struct cregs;
+
+	regs_to_cregs(&cregs, task_pt_regs(target));
+
+	return membuf_write(&to, &cregs,
+			    sizeof(struct compat_user_regs_struct));
+}
+
+static int compat_riscv_gpr_set(struct task_struct *target,
+				const struct user_regset *regset,
+				unsigned int pos, unsigned int count,
+				const void *kbuf, const void __user *ubuf)
+{
+	int ret;
+	struct compat_user_regs_struct cregs;
+
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &cregs, 0, -1);
+
+	cregs_to_regs(&cregs, task_pt_regs(target));
+
+	return ret;
+}
+
+static const struct user_regset compat_riscv_user_regset[] = {
+	[REGSET_X] = {
+		.core_note_type = NT_PRSTATUS,
+		.n = ELF_NGREG,
+		.size = sizeof(compat_elf_greg_t),
+		.align = sizeof(compat_elf_greg_t),
+		.regset_get = compat_riscv_gpr_get,
+		.set = compat_riscv_gpr_set,
+	},
+#ifdef CONFIG_FPU
+	[REGSET_F] = {
+		.core_note_type = NT_PRFPREG,
+		.n = ELF_NFPREG,
+		.size = sizeof(elf_fpreg_t),
+		.align = sizeof(elf_fpreg_t),
+		.regset_get = riscv_fpr_get,
+		.set = riscv_fpr_set,
+	},
+#endif
+};
+
+static const struct user_regset_view compat_riscv_user_native_view = {
+	.name = "riscv",
+	.e_machine = EM_RISCV,
+	.regsets = compat_riscv_user_regset,
+	.n = ARRAY_SIZE(compat_riscv_user_regset),
+};
+
+long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
+			compat_ulong_t caddr, compat_ulong_t cdata)
+{
+	long ret = -EIO;
+
+	switch (request) {
+	default:
+		ret = compat_ptrace_request(child, request, caddr, cdata);
+		break;
+	}
+
+	return ret;
+}
+#endif /* CONFIG_COMPAT */
+
+const struct user_regset_view *task_user_regset_view(struct task_struct *task)
+{
+#ifdef CONFIG_COMPAT
+	if (test_tsk_thread_flag(task, TIF_32BIT))
+		return &compat_riscv_user_native_view;
+	else
+#endif
+		return &riscv_user_native_view;
+}

arch/riscv/kernel/signal.c

@@ -6,6 +6,7 @@
  * Copyright (C) 2012 Regents of the University of California
  */
 
+#include <linux/compat.h>
 #include <linux/signal.h>
 #include <linux/uaccess.h>
 #include <linux/syscalls.h>
@@ -14,6 +15,7 @@
 
 #include <asm/ucontext.h>
 #include <asm/vdso.h>
+#include <asm/signal32.h>
 #include <asm/switch_to.h>
 #include <asm/csr.h>
 
@@ -261,7 +263,10 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 	rseq_signal_deliver(ksig, regs);
 
 	/* Set up the stack frame */
-	ret = setup_rt_frame(ksig, oldset, regs);
+	if (is_compat_task())
+		ret = compat_setup_rt_frame(ksig, oldset, regs);
+	else
+		ret = setup_rt_frame(ksig, oldset, regs);
 
 	signal_setup_done(ret, ksig, 0);
 }

arch/riscv/kernel/sys_riscv.c

@@ -33,7 +33,9 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
 {
 	return riscv_sys_mmap(addr, len, prot, flags, fd, offset, 0);
 }
-#else
+#endif
+
+#if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT)
 SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
 	unsigned long, prot, unsigned long, flags,
 	unsigned long, fd, off_t, offset)
@@ -44,7 +46,7 @@ SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
 	 */
 	return riscv_sys_mmap(addr, len, prot, flags, fd, offset, 12);
 }
-#endif /* !CONFIG_64BIT */
+#endif
 
 /*
  * Allows the instruction cache to be flushed from userspace.  Despite RISC-V

arch/riscv/kernel/vdso.c

@@ -23,6 +23,9 @@ struct vdso_data {
 #endif
 
 extern char vdso_start[], vdso_end[];
+#ifdef CONFIG_COMPAT
+extern char compat_vdso_start[], compat_vdso_end[];
+#endif
 
 enum vvar_pages {
 	VVAR_DATA_PAGE_OFFSET,
@@ -30,6 +33,11 @@ enum vvar_pages {
 	VVAR_NR_PAGES,
 };
 
+enum rv_vdso_map {
+	RV_VDSO_MAP_VVAR,
+	RV_VDSO_MAP_VDSO,
+};
+
 #define VVAR_SIZE  (VVAR_NR_PAGES << PAGE_SHIFT)
 
 /*
@@ -52,12 +60,6 @@ struct __vdso_info {
 	struct vm_special_mapping *cm;
 };
 
-static struct __vdso_info vdso_info __ro_after_init = {
-	.name = "vdso",
-	.vdso_code_start = vdso_start,
-	.vdso_code_end = vdso_end,
-};
-
 static int vdso_mremap(const struct vm_special_mapping *sm,
 		       struct vm_area_struct *new_vma)
 {
@@ -66,37 +68,33 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
 	return 0;
 }
 
-static int __init __vdso_init(void)
+static void __init __vdso_init(struct __vdso_info *vdso_info)
 {
 	unsigned int i;
 	struct page **vdso_pagelist;
 	unsigned long pfn;
 
-	if (memcmp(vdso_info.vdso_code_start, "\177ELF", 4)) {
-		pr_err("vDSO is not a valid ELF object!\n");
-		return -EINVAL;
-	}
+	if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4))
+		panic("vDSO is not a valid ELF object!\n");
 
-	vdso_info.vdso_pages = (
-		vdso_info.vdso_code_end -
-		vdso_info.vdso_code_start) >>
+	vdso_info->vdso_pages = (
+		vdso_info->vdso_code_end -
+		vdso_info->vdso_code_start) >>
 		PAGE_SHIFT;
 
-	vdso_pagelist = kcalloc(vdso_info.vdso_pages,
+	vdso_pagelist = kcalloc(vdso_info->vdso_pages,
 				sizeof(struct page *),
 				GFP_KERNEL);
 	if (vdso_pagelist == NULL)
-		return -ENOMEM;
+		panic("vDSO kcalloc failed!\n");
 
 	/* Grab the vDSO code pages. */
-	pfn = sym_to_pfn(vdso_info.vdso_code_start);
+	pfn = sym_to_pfn(vdso_info->vdso_code_start);
 
-	for (i = 0; i < vdso_info.vdso_pages; i++)
+	for (i = 0; i < vdso_info->vdso_pages; i++)
 		vdso_pagelist[i] = pfn_to_page(pfn + i);
 
-	vdso_info.cm->pages = vdso_pagelist;
-
-	return 0;
+	vdso_info->cm->pages = vdso_pagelist;
 }
 
 #ifdef CONFIG_TIME_NS
@@ -116,13 +114,14 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
 {
 	struct mm_struct *mm = task->mm;
 	struct vm_area_struct *vma;
+	struct __vdso_info *vdso_info = mm->context.vdso_info;
 
 	mmap_read_lock(mm);
 
 	for (vma = mm->mmap; vma; vma = vma->vm_next) {
 		unsigned long size = vma->vm_end - vma->vm_start;
 
-		if (vma_is_special_mapping(vma, vdso_info.dm))
+		if (vma_is_special_mapping(vma, vdso_info->dm))
 			zap_page_range(vma, vma->vm_start, size);
 	}
 
@@ -187,11 +186,6 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 	return vmf_insert_pfn(vma, vmf->address, pfn);
 }
 
-enum rv_vdso_map {
-	RV_VDSO_MAP_VVAR,
-	RV_VDSO_MAP_VDSO,
-};
-
 static struct vm_special_mapping rv_vdso_maps[] __ro_after_init = {
 	[RV_VDSO_MAP_VVAR] = {
 		.name   = "[vvar]",
@@ -203,25 +197,46 @@ static struct vm_special_mapping rv_vdso_maps[] __ro_after_init = {
 	},
 };
 
+static struct __vdso_info vdso_info __ro_after_init = {
+	.name = "vdso",
+	.vdso_code_start = vdso_start,
+	.vdso_code_end = vdso_end,
+	.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
+	.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
+};
+
+#ifdef CONFIG_COMPAT
+static struct __vdso_info compat_vdso_info __ro_after_init = {
+	.name = "compat_vdso",
+	.vdso_code_start = compat_vdso_start,
+	.vdso_code_end = compat_vdso_end,
+	.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
+	.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
+};
+#endif
+
 static int __init vdso_init(void)
 {
-	vdso_info.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR];
-	vdso_info.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO];
+	__vdso_init(&vdso_info);
+#ifdef CONFIG_COMPAT
+	__vdso_init(&compat_vdso_info);
+#endif
 
-	return __vdso_init();
+	return 0;
 }
 arch_initcall(vdso_init);
 
 static int __setup_additional_pages(struct mm_struct *mm,
 				    struct linux_binprm *bprm,
-				    int uses_interp)
+				    int uses_interp,
+				    struct __vdso_info *vdso_info)
 {
 	unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
 	void *ret;
 
 	BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
 
-	vdso_text_len = vdso_info.vdso_pages << PAGE_SHIFT;
+	vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT;
 	/* Be sure to map the data page */
 	vdso_mapping_len = vdso_text_len + VVAR_SIZE;
 
@@ -232,16 +247,18 @@ static int __setup_additional_pages(struct mm_struct *mm,
 	}
 
 	ret = _install_special_mapping(mm, vdso_base, VVAR_SIZE,
-		(VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info.dm);
+		(VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info->dm);
 	if (IS_ERR(ret))
 		goto up_fail;
 
 	vdso_base += VVAR_SIZE;
 	mm->context.vdso = (void *)vdso_base;
+	mm->context.vdso_info = (void *)vdso_info;
+
 	ret =
 	   _install_special_mapping(mm, vdso_base, vdso_text_len,
 		(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
-		vdso_info.cm);
+		vdso_info->cm);
 
 	if (IS_ERR(ret))
 		goto up_fail;
@@ -253,6 +270,24 @@ static int __setup_additional_pages(struct mm_struct *mm,
 	return PTR_ERR(ret);
 }
 
+#ifdef CONFIG_COMPAT
+int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
+				       int uses_interp)
+{
+	struct mm_struct *mm = current->mm;
+	int ret;
+
+	if (mmap_write_lock_killable(mm))
+		return -EINTR;
+
+	ret = __setup_additional_pages(mm, bprm, uses_interp,
+							&compat_vdso_info);
+	mmap_write_unlock(mm);
+
+	return ret;
+}
+#endif
+
 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 {
 	struct mm_struct *mm = current->mm;
@@ -261,7 +296,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 	if (mmap_write_lock_killable(mm))
 		return -EINTR;
 
-	ret = __setup_additional_pages(mm, bprm, uses_interp);
+	ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info);
 	mmap_write_unlock(mm);
 
 	return ret;

arch/riscv/kernel/vdso/vdso.S

@@ -7,12 +7,16 @@
 #include <linux/linkage.h>
 #include <asm/page.h>
 
+#ifndef __VDSO_PATH
+#define __VDSO_PATH "arch/riscv/kernel/vdso/vdso.so"
+#endif
+
 	__PAGE_ALIGNED_DATA
 
 	.globl vdso_start, vdso_end
 	.balign PAGE_SIZE
 vdso_start:
-	.incbin "arch/riscv/kernel/vdso/vdso.so"
+	.incbin __VDSO_PATH
 	.balign PAGE_SIZE
 vdso_end:
 

arch/s390/Kconfig

@@ -399,9 +399,6 @@ config COMPAT
 	  (and some other stuff like libraries and such) is needed for
 	  executing 31 bit applications.  It is safe to say "Y".
 
-config SYSVIPC_COMPAT
-	def_bool y if COMPAT && SYSVIPC
-
 config SMP
 	def_bool y
 

arch/s390/include/asm/compat.h

@@ -12,6 +12,18 @@
 #define compat_mode_t	compat_mode_t
 typedef u16		compat_mode_t;
 
+#define __compat_uid_t	__compat_uid_t
+typedef u16		__compat_uid_t;
+typedef u16		__compat_gid_t;
+
+#define compat_dev_t	compat_dev_t
+typedef u16		compat_dev_t;
+
+#define compat_ipc_pid_t compat_ipc_pid_t
+typedef u16		 compat_ipc_pid_t;
+
+#define compat_statfs	compat_statfs
+
 #include <asm-generic/compat.h>
 
 #define __TYPE_IS_PTR(t) (!__builtin_types_compatible_p( \
@@ -53,15 +65,9 @@ typedef u16		compat_mode_t;
 			 PSW32_MASK_MCHECK | PSW32_MASK_PSTATE | \
 			 PSW32_ASC_PRIMARY)
 
-#define COMPAT_USER_HZ		100
 #define COMPAT_UTS_MACHINE	"s390\0\0\0\0"
 
-typedef u16		__compat_uid_t;
-typedef u16		__compat_gid_t;
-typedef u16		compat_dev_t;
 typedef u16		compat_nlink_t;
-typedef u16		compat_ipc_pid_t;
-typedef __kernel_fsid_t	compat_fsid_t;
 
 typedef struct {
 	u32 mask;
@@ -102,26 +108,6 @@ struct compat_stat {
 	u32		__unused5;
 };
 
-struct compat_flock {
-	short		l_type;
-	short		l_whence;
-	compat_off_t	l_start;
-	compat_off_t	l_len;
-	compat_pid_t	l_pid;
-};
-
-#define F_GETLK64       12
-#define F_SETLK64       13
-#define F_SETLKW64      14    
-
-struct compat_flock64 {
-	short		l_type;
-	short		l_whence;
-	compat_loff_t	l_start;
-	compat_loff_t	l_len;
-	compat_pid_t	l_pid;
-};
-
 struct compat_statfs {
 	u32		f_type;
 	u32		f_bsize;
@@ -152,10 +138,6 @@ struct compat_statfs64 {
 	u32		f_spare[4];
 };
 
-#define COMPAT_RLIM_INFINITY		0xffffffff
-
-#define COMPAT_OFF_T_MAX	0x7fffffff
-
 /*
  * A pointer passed in from user mode. This should not
  * be used for syscall parameters, just declare them
@@ -178,61 +160,4 @@ static inline int is_compat_task(void)
 
 #endif
 
-struct compat_ipc64_perm {
-	compat_key_t key;
-	__compat_uid32_t uid;
-	__compat_gid32_t gid;
-	__compat_uid32_t cuid;
-	__compat_gid32_t cgid;
-	compat_mode_t mode;
-	unsigned short __pad1;
-	unsigned short seq;
-	unsigned short __pad2;
-	unsigned int __unused1;
-	unsigned int __unused2;
-};
-
-struct compat_semid64_ds {
-	struct compat_ipc64_perm sem_perm;
-	compat_ulong_t sem_otime;
-	compat_ulong_t sem_otime_high;
-	compat_ulong_t sem_ctime;
-	compat_ulong_t sem_ctime_high;
-	compat_ulong_t sem_nsems;
-	compat_ulong_t __unused1;
-	compat_ulong_t __unused2;
-};
-
-struct compat_msqid64_ds {
-	struct compat_ipc64_perm msg_perm;
-	compat_ulong_t msg_stime;
-	compat_ulong_t msg_stime_high;
-	compat_ulong_t msg_rtime;
-	compat_ulong_t msg_rtime_high;
-	compat_ulong_t msg_ctime;
-	compat_ulong_t msg_ctime_high;
-	compat_ulong_t msg_cbytes;
-	compat_ulong_t msg_qnum;
-	compat_ulong_t msg_qbytes;
-	compat_pid_t   msg_lspid;
-	compat_pid_t   msg_lrpid;
-	compat_ulong_t __unused1;
-	compat_ulong_t __unused2;
-};
-
-struct compat_shmid64_ds {
-	struct compat_ipc64_perm shm_perm;
-	compat_size_t  shm_segsz;
-	compat_ulong_t shm_atime;
-	compat_ulong_t shm_atime_high;
-	compat_ulong_t shm_dtime;
-	compat_ulong_t shm_dtime_high;
-	compat_ulong_t shm_ctime;
-	compat_ulong_t shm_ctime_high;
-	compat_pid_t   shm_cpid;
-	compat_pid_t   shm_lpid;
-	compat_ulong_t shm_nattch;
-	compat_ulong_t __unused1;
-	compat_ulong_t __unused2;
-};
 #endif /* _ASM_S390X_COMPAT_H */

arch/s390/include/asm/unistd.h

@@ -28,6 +28,7 @@
 #define __ARCH_WANT_SYS_SIGPENDING
 #define __ARCH_WANT_SYS_SIGPROCMASK
 # ifdef CONFIG_COMPAT
+#   define __ARCH_WANT_COMPAT_STAT
 #   define __ARCH_WANT_SYS_TIME32
 #   define __ARCH_WANT_SYS_UTIME32
 # endif

arch/sparc/Kconfig

@@ -488,9 +488,4 @@ config COMPAT
 	select ARCH_WANT_OLD_COMPAT_IPC
 	select COMPAT_OLD_SIGACTION
 
-config SYSVIPC_COMPAT
-	bool
-	depends on COMPAT && SYSVIPC
-	default y
-
 source "drivers/sbus/char/Kconfig"

arch/sparc/include/asm/compat.h

@@ -9,17 +9,25 @@
 #define compat_mode_t	compat_mode_t
 typedef u16		compat_mode_t;
 
+#define __compat_uid_t	__compat_uid_t
+typedef u16		__compat_uid_t;
+typedef u16		__compat_gid_t;
+
+#define compat_dev_t	compat_dev_t
+typedef u16		compat_dev_t;
+
+#define compat_ipc_pid_t compat_ipc_pid_t
+typedef u16		 compat_ipc_pid_t;
+
+#define compat_ipc64_perm compat_ipc64_perm
+
+#define COMPAT_RLIM_INFINITY 0x7fffffff
+
 #include <asm-generic/compat.h>
 
-#define COMPAT_USER_HZ		100
 #define COMPAT_UTS_MACHINE	"sparc\0\0"
 
-typedef u16		__compat_uid_t;
-typedef u16		__compat_gid_t;
-typedef u16		compat_dev_t;
 typedef s16		compat_nlink_t;
-typedef u16		compat_ipc_pid_t;
-typedef __kernel_fsid_t	compat_fsid_t;
 
 struct compat_stat {
 	compat_dev_t	st_dev;
@@ -75,46 +83,7 @@ struct compat_stat64 {
 	unsigned int	__unused5;
 };
 
-struct compat_flock {
-	short		l_type;
-	short		l_whence;
-	compat_off_t	l_start;
-	compat_off_t	l_len;
-	compat_pid_t	l_pid;
-	short		__unused;
-};
-
-#define F_GETLK64	12
-#define F_SETLK64	13
-#define F_SETLKW64	14
-
-struct compat_flock64 {
-	short		l_type;
-	short		l_whence;
-	compat_loff_t	l_start;
-	compat_loff_t	l_len;
-	compat_pid_t	l_pid;
-	short		__unused;
-};
-
-struct compat_statfs {
-	int		f_type;
-	int		f_bsize;
-	int		f_blocks;
-	int		f_bfree;
-	int		f_bavail;
-	int		f_files;
-	int		f_ffree;
-	compat_fsid_t	f_fsid;
-	int		f_namelen;	/* SunOS ignores this field. */
-	int		f_frsize;
-	int		f_flags;
-	int		f_spare[4];
-};
-
-#define COMPAT_RLIM_INFINITY 0x7fffffff
-
-#define COMPAT_OFF_T_MAX	0x7fffffff
+#define __ARCH_COMPAT_FLOCK_PAD		short __unused;
 
 struct compat_ipc64_perm {
 	compat_key_t key;

arch/sparc/include/asm/unistd.h

@@ -46,6 +46,7 @@
 #define __ARCH_WANT_SYS_TIME
 #define __ARCH_WANT_SYS_UTIME
 #define __ARCH_WANT_COMPAT_SYS_SENDFILE
+#define __ARCH_WANT_COMPAT_STAT
 #endif
 
 #ifdef __32bit_syscall_numbers__

arch/x86/Kconfig

@@ -2872,10 +2872,6 @@ config COMPAT
 if COMPAT
 config COMPAT_FOR_U64_ALIGNMENT
 	def_bool y
-
-config SYSVIPC_COMPAT
-	def_bool y
-	depends on SYSVIPC
 endif
 
 endmenu

arch/x86/include/asm/compat.h

@@ -15,17 +15,23 @@
 #define compat_mode_t	compat_mode_t
 typedef u16		compat_mode_t;
 
+#define __compat_uid_t	__compat_uid_t
+typedef u16		__compat_uid_t;
+typedef u16		__compat_gid_t;
+
+#define compat_dev_t	compat_dev_t
+typedef u16		compat_dev_t;
+
+#define compat_ipc_pid_t compat_ipc_pid_t
+typedef u16		 compat_ipc_pid_t;
+
+#define compat_statfs	compat_statfs
+
 #include <asm-generic/compat.h>
 
-#define COMPAT_USER_HZ		100
 #define COMPAT_UTS_MACHINE	"i686\0\0"
 
-typedef u16		__compat_uid_t;
-typedef u16		__compat_gid_t;
-typedef u16		compat_dev_t;
 typedef u16		compat_nlink_t;
-typedef u16		compat_ipc_pid_t;
-typedef __kernel_fsid_t	compat_fsid_t;
 
 struct compat_stat {
 	compat_dev_t	st_dev;
@@ -50,29 +56,11 @@ struct compat_stat {
 	u32		__unused5;
 };
 
-struct compat_flock {
-	short		l_type;
-	short		l_whence;
-	compat_off_t	l_start;
-	compat_off_t	l_len;
-	compat_pid_t	l_pid;
-};
-
-#define F_GETLK64	12	/*  using 'struct flock64' */
-#define F_SETLK64	13
-#define F_SETLKW64	14
-
 /*
- * IA32 uses 4 byte alignment for 64 bit quantities,
- * so we need to pack this structure.
+ * IA32 uses 4 byte alignment for 64 bit quantities, so we need to pack the
+ * compat flock64 structure.
  */
-struct compat_flock64 {
-	short		l_type;
-	short		l_whence;
-	compat_loff_t	l_start;
-	compat_loff_t	l_len;
-	compat_pid_t	l_pid;
-} __attribute__((packed));
+#define __ARCH_NEED_COMPAT_FLOCK64_PACKED
 
 struct compat_statfs {
 	int		f_type;
@@ -89,68 +77,6 @@ struct compat_statfs {
 	int		f_spare[4];
 };
 
-#define COMPAT_RLIM_INFINITY		0xffffffff
-
-#define COMPAT_OFF_T_MAX	0x7fffffff
-
-struct compat_ipc64_perm {
-	compat_key_t key;
-	__compat_uid32_t uid;
-	__compat_gid32_t gid;
-	__compat_uid32_t cuid;
-	__compat_gid32_t cgid;
-	unsigned short mode;
-	unsigned short __pad1;
-	unsigned short seq;
-	unsigned short __pad2;
-	compat_ulong_t unused1;
-	compat_ulong_t unused2;
-};
-
-struct compat_semid64_ds {
-	struct compat_ipc64_perm sem_perm;
-	compat_ulong_t sem_otime;
-	compat_ulong_t sem_otime_high;
-	compat_ulong_t sem_ctime;
-	compat_ulong_t sem_ctime_high;
-	compat_ulong_t sem_nsems;
-	compat_ulong_t __unused3;
-	compat_ulong_t __unused4;
-};
-
-struct compat_msqid64_ds {
-	struct compat_ipc64_perm msg_perm;
-	compat_ulong_t msg_stime;
-	compat_ulong_t msg_stime_high;
-	compat_ulong_t msg_rtime;
-	compat_ulong_t msg_rtime_high;
-	compat_ulong_t msg_ctime;
-	compat_ulong_t msg_ctime_high;
-	compat_ulong_t msg_cbytes;
-	compat_ulong_t msg_qnum;
-	compat_ulong_t msg_qbytes;
-	compat_pid_t   msg_lspid;
-	compat_pid_t   msg_lrpid;
-	compat_ulong_t __unused4;
-	compat_ulong_t __unused5;
-};
-
-struct compat_shmid64_ds {
-	struct compat_ipc64_perm shm_perm;
-	compat_size_t  shm_segsz;
-	compat_ulong_t shm_atime;
-	compat_ulong_t shm_atime_high;
-	compat_ulong_t shm_dtime;
-	compat_ulong_t shm_dtime_high;
-	compat_ulong_t shm_ctime;
-	compat_ulong_t shm_ctime_high;
-	compat_pid_t   shm_cpid;
-	compat_pid_t   shm_lpid;
-	compat_ulong_t shm_nattch;
-	compat_ulong_t __unused4;
-	compat_ulong_t __unused5;
-};
-
 #ifdef CONFIG_X86_X32_ABI
 #define COMPAT_USE_64BIT_TIME \
 	(!!(task_pt_regs(current)->orig_ax & __X32_SYSCALL_BIT))

arch/x86/include/asm/unistd.h

@@ -22,6 +22,7 @@
 #  include <asm/unistd_32_ia32.h>
 #  define __ARCH_WANT_SYS_TIME
 #  define __ARCH_WANT_SYS_UTIME
+#  define __ARCH_WANT_COMPAT_STAT
 #  define __ARCH_WANT_COMPAT_SYS_PREADV64
 #  define __ARCH_WANT_COMPAT_SYS_PWRITEV64
 #  define __ARCH_WANT_COMPAT_SYS_PREADV64V2

fs/open.c

@@ -224,6 +224,21 @@ SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
 }
 #endif /* BITS_PER_LONG == 32 */
 
+#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_TRUNCATE64)
+COMPAT_SYSCALL_DEFINE3(truncate64, const char __user *, pathname,
+		       compat_arg_u64_dual(length))
+{
+	return ksys_truncate(pathname, compat_arg_u64_glue(length));
+}
+#endif
+
+#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FTRUNCATE64)
+COMPAT_SYSCALL_DEFINE3(ftruncate64, unsigned int, fd,
+		       compat_arg_u64_dual(length))
+{
+	return ksys_ftruncate(fd, compat_arg_u64_glue(length));
+}
+#endif
 
 int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 {
@@ -339,6 +354,15 @@ SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
 	return ksys_fallocate(fd, mode, offset, len);
 }
 
+#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FALLOCATE)
+COMPAT_SYSCALL_DEFINE6(fallocate, int, fd, int, mode, compat_arg_u64_dual(offset),
+		       compat_arg_u64_dual(len))
+{
+	return ksys_fallocate(fd, mode, compat_arg_u64_glue(offset),
+			      compat_arg_u64_glue(len));
+}
+#endif
+
 /*
  * access() needs to use the real uid/gid, not the effective uid/gid.
  * We do this by temporarily clearing all FS-related capabilities and

fs/read_write.c

@@ -682,6 +682,14 @@ SYSCALL_DEFINE4(pread64, unsigned int, fd, char __user *, buf,
 	return ksys_pread64(fd, buf, count, pos);
 }
 
+#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_PREAD64)
+COMPAT_SYSCALL_DEFINE5(pread64, unsigned int, fd, char __user *, buf,
+		       size_t, count, compat_arg_u64_dual(pos))
+{
+	return ksys_pread64(fd, buf, count, compat_arg_u64_glue(pos));
+}
+#endif
+
 ssize_t ksys_pwrite64(unsigned int fd, const char __user *buf,
 		      size_t count, loff_t pos)
 {
@@ -708,6 +716,14 @@ SYSCALL_DEFINE4(pwrite64, unsigned int, fd, const char __user *, buf,
 	return ksys_pwrite64(fd, buf, count, pos);
 }
 
+#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_PWRITE64)
+COMPAT_SYSCALL_DEFINE5(pwrite64, unsigned int, fd, const char __user *, buf,
+		       size_t, count, compat_arg_u64_dual(pos))
+{
+	return ksys_pwrite64(fd, buf, count, compat_arg_u64_glue(pos));
+}
+#endif
+
 static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
 		loff_t *ppos, int type, rwf_t flags)
 {

fs/stat.c

@@ -660,7 +660,7 @@ SYSCALL_DEFINE5(statx,
 	return ret;
 }
 
-#ifdef CONFIG_COMPAT
+#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_STAT)
 static int cp_compat_stat(struct kstat *stat, struct compat_stat __user *ubuf)
 {
 	struct compat_stat tmp;

fs/sync.c

@@ -373,6 +373,15 @@ SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes,
 	return ksys_sync_file_range(fd, offset, nbytes, flags);
 }
 
+#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_SYNC_FILE_RANGE)
+COMPAT_SYSCALL_DEFINE6(sync_file_range, int, fd, compat_arg_u64_dual(offset),
+		       compat_arg_u64_dual(nbytes), unsigned int, flags)
+{
+	return ksys_sync_file_range(fd, compat_arg_u64_glue(offset),
+				    compat_arg_u64_glue(nbytes), flags);
+}
+#endif
+
 /* It would be nice if people remember that not all the world's an i386
    when they introduce new system calls */
 SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags,

include/asm-generic/compat.h

@@ -2,6 +2,25 @@
 #ifndef __ASM_GENERIC_COMPAT_H
 #define __ASM_GENERIC_COMPAT_H
 
+#ifndef COMPAT_USER_HZ
+#define COMPAT_USER_HZ		100
+#endif
+
+#ifndef COMPAT_RLIM_INFINITY
+#define COMPAT_RLIM_INFINITY	0xffffffff
+#endif
+
+#ifndef COMPAT_OFF_T_MAX
+#define COMPAT_OFF_T_MAX	0x7fffffff
+#endif
+
+#if !defined(compat_arg_u64) && !defined(CONFIG_CPU_BIG_ENDIAN)
+#define compat_arg_u64(name)		u32  name##_lo, u32  name##_hi
+#define compat_arg_u64_dual(name)	u32, name##_lo, u32, name##_hi
+#define compat_arg_u64_glue(name)	(((u64)name##_lo & 0xffffffffUL) | \
+					 ((u64)name##_hi << 32))
+#endif
+
 /* These types are common across all compat ABIs */
 typedef u32 compat_size_t;
 typedef s32 compat_ssize_t;
@@ -24,6 +43,11 @@ typedef u32 compat_caddr_t;
 typedef u32 compat_aio_context_t;
 typedef u32 compat_old_sigset_t;
 
+#ifndef __compat_uid_t
+typedef u32 __compat_uid_t;
+typedef u32 __compat_gid_t;
+#endif
+
 #ifndef __compat_uid32_t
 typedef u32 __compat_uid32_t;
 typedef u32 __compat_gid32_t;
@@ -47,4 +71,93 @@ typedef u32 compat_sigset_word;
 #define _COMPAT_NSIG_BPW 32
 #endif
 
+#ifndef compat_dev_t
+typedef u32 compat_dev_t;
+#endif
+
+#ifndef compat_ipc_pid_t
+typedef s32 compat_ipc_pid_t;
+#endif
+
+#ifndef compat_fsid_t
+typedef __kernel_fsid_t	compat_fsid_t;
+#endif
+
+#ifndef compat_statfs
+struct compat_statfs {
+	compat_int_t	f_type;
+	compat_int_t	f_bsize;
+	compat_int_t	f_blocks;
+	compat_int_t	f_bfree;
+	compat_int_t	f_bavail;
+	compat_int_t	f_files;
+	compat_int_t	f_ffree;
+	compat_fsid_t	f_fsid;
+	compat_int_t	f_namelen;
+	compat_int_t	f_frsize;
+	compat_int_t	f_flags;
+	compat_int_t	f_spare[4];
+};
+#endif
+
+#ifndef compat_ipc64_perm
+struct compat_ipc64_perm {
+	compat_key_t key;
+	__compat_uid32_t uid;
+	__compat_gid32_t gid;
+	__compat_uid32_t cuid;
+	__compat_gid32_t cgid;
+	compat_mode_t	mode;
+	unsigned char	__pad1[4 - sizeof(compat_mode_t)];
+	compat_ushort_t	seq;
+	compat_ushort_t	__pad2;
+	compat_ulong_t	unused1;
+	compat_ulong_t	unused2;
+};
+
+struct compat_semid64_ds {
+	struct compat_ipc64_perm sem_perm;
+	compat_ulong_t sem_otime;
+	compat_ulong_t sem_otime_high;
+	compat_ulong_t sem_ctime;
+	compat_ulong_t sem_ctime_high;
+	compat_ulong_t sem_nsems;
+	compat_ulong_t __unused3;
+	compat_ulong_t __unused4;
+};
+
+struct compat_msqid64_ds {
+	struct compat_ipc64_perm msg_perm;
+	compat_ulong_t msg_stime;
+	compat_ulong_t msg_stime_high;
+	compat_ulong_t msg_rtime;
+	compat_ulong_t msg_rtime_high;
+	compat_ulong_t msg_ctime;
+	compat_ulong_t msg_ctime_high;
+	compat_ulong_t msg_cbytes;
+	compat_ulong_t msg_qnum;
+	compat_ulong_t msg_qbytes;
+	compat_pid_t   msg_lspid;
+	compat_pid_t   msg_lrpid;
+	compat_ulong_t __unused4;
+	compat_ulong_t __unused5;
+};
+
+struct compat_shmid64_ds {
+	struct compat_ipc64_perm shm_perm;
+	compat_size_t  shm_segsz;
+	compat_ulong_t shm_atime;
+	compat_ulong_t shm_atime_high;
+	compat_ulong_t shm_dtime;
+	compat_ulong_t shm_dtime_high;
+	compat_ulong_t shm_ctime;
+	compat_ulong_t shm_ctime_high;
+	compat_pid_t   shm_cpid;
+	compat_pid_t   shm_lpid;
+	compat_ulong_t shm_nattch;
+	compat_ulong_t __unused4;
+	compat_ulong_t __unused5;
+};
+#endif
+
 #endif

include/linux/compat.h

@@ -258,6 +258,37 @@ struct compat_rlimit {
 	compat_ulong_t	rlim_max;
 };
 
+#ifdef __ARCH_NEED_COMPAT_FLOCK64_PACKED
+#define __ARCH_COMPAT_FLOCK64_PACK	__attribute__((packed))
+#else
+#define __ARCH_COMPAT_FLOCK64_PACK
+#endif
+
+struct compat_flock {
+	short			l_type;
+	short			l_whence;
+	compat_off_t		l_start;
+	compat_off_t		l_len;
+#ifdef __ARCH_COMPAT_FLOCK_EXTRA_SYSID
+	__ARCH_COMPAT_FLOCK_EXTRA_SYSID
+#endif
+	compat_pid_t		l_pid;
+#ifdef __ARCH_COMPAT_FLOCK_PAD
+	__ARCH_COMPAT_FLOCK_PAD
+#endif
+};
+
+struct compat_flock64 {
+	short		l_type;
+	short		l_whence;
+	compat_loff_t	l_start;
+	compat_loff_t	l_len;
+	compat_pid_t	l_pid;
+#ifdef __ARCH_COMPAT_FLOCK64_PAD
+	__ARCH_COMPAT_FLOCK64_PAD
+#endif
+} __ARCH_COMPAT_FLOCK64_PACK;
+
 struct compat_rusage {
 	struct old_timeval32 ru_utime;
 	struct old_timeval32 ru_stime;
@@ -895,6 +926,43 @@ asmlinkage long compat_sys_sigaction(int sig,
 /* obsolete: net/socket.c */
 asmlinkage long compat_sys_socketcall(int call, u32 __user *args);
 
+#ifdef __ARCH_WANT_COMPAT_TRUNCATE64
+asmlinkage long compat_sys_truncate64(const char __user *pathname, compat_arg_u64(len));
+#endif
+
+#ifdef __ARCH_WANT_COMPAT_FTRUNCATE64
+asmlinkage long compat_sys_ftruncate64(unsigned int fd, compat_arg_u64(len));
+#endif
+
+#ifdef __ARCH_WANT_COMPAT_FALLOCATE
+asmlinkage long compat_sys_fallocate(int fd, int mode, compat_arg_u64(offset),
+				     compat_arg_u64(len));
+#endif
+
+#ifdef __ARCH_WANT_COMPAT_PREAD64
+asmlinkage long compat_sys_pread64(unsigned int fd, char __user *buf, size_t count,
+				   compat_arg_u64(pos));
+#endif
+
+#ifdef __ARCH_WANT_COMPAT_PWRITE64
+asmlinkage long compat_sys_pwrite64(unsigned int fd, const char __user *buf, size_t count,
+				    compat_arg_u64(pos));
+#endif
+
+#ifdef __ARCH_WANT_COMPAT_SYNC_FILE_RANGE
+asmlinkage long compat_sys_sync_file_range(int fd, compat_arg_u64(pos),
+					   compat_arg_u64(nbytes), unsigned int flags);
+#endif
+
+#ifdef __ARCH_WANT_COMPAT_FADVISE64_64
+asmlinkage long compat_sys_fadvise64_64(int fd, compat_arg_u64(pos),
+					compat_arg_u64(len), int advice);
+#endif
+
+#ifdef __ARCH_WANT_COMPAT_READAHEAD
+asmlinkage long compat_sys_readahead(int fd, compat_arg_u64(offset), size_t count);
+#endif
+
 #endif /* CONFIG_ARCH_HAS_SYSCALL_WRAPPER */
 
 /**

include/uapi/asm-generic/fcntl.h

@@ -116,13 +116,13 @@
 #define F_GETSIG	11	/* for sockets. */
 #endif
 
-#ifndef CONFIG_64BIT
+#if __BITS_PER_LONG == 32 || defined(__KERNEL__)
 #ifndef F_GETLK64
 #define F_GETLK64	12	/*  using 'struct flock64' */
 #define F_SETLK64	13
 #define F_SETLKW64	14
 #endif
-#endif
+#endif /* __BITS_PER_LONG == 32 || defined(__KERNEL__) */
 
 #ifndef F_SETOWN_EX
 #define F_SETOWN_EX	15
@@ -192,25 +192,19 @@ struct f_owner_ex {
 
 #define F_LINUX_SPECIFIC_BASE	1024
 
-#ifndef HAVE_ARCH_STRUCT_FLOCK
-#ifndef __ARCH_FLOCK_PAD
-#define __ARCH_FLOCK_PAD
-#endif
-
 struct flock {
 	short	l_type;
 	short	l_whence;
 	__kernel_off_t	l_start;
 	__kernel_off_t	l_len;
 	__kernel_pid_t	l_pid;
-	__ARCH_FLOCK_PAD
-};
+#ifdef	__ARCH_FLOCK_EXTRA_SYSID
+	__ARCH_FLOCK_EXTRA_SYSID
 #endif
-
-#ifndef HAVE_ARCH_STRUCT_FLOCK64
-#ifndef __ARCH_FLOCK64_PAD
-#define __ARCH_FLOCK64_PAD
+#ifdef	__ARCH_FLOCK_PAD
+	__ARCH_FLOCK_PAD
 #endif
+};
 
 struct flock64 {
 	short  l_type;
@@ -218,8 +212,9 @@ struct flock64 {
 	__kernel_loff_t l_start;
 	__kernel_loff_t l_len;
 	__kernel_pid_t  l_pid;
+#ifdef	__ARCH_FLOCK64_PAD
 	__ARCH_FLOCK64_PAD
-};
 #endif
+};
 
 #endif /* _ASM_GENERIC_FCNTL_H */

include/uapi/asm-generic/unistd.h

@@ -383,7 +383,7 @@ __SYSCALL(__NR_syslog, sys_syslog)
 
 /* kernel/ptrace.c */
 #define __NR_ptrace 117
-__SYSCALL(__NR_ptrace, sys_ptrace)
+__SC_COMP(__NR_ptrace, sys_ptrace, compat_sys_ptrace)
 
 /* kernel/sched/core.c */
 #define __NR_sched_setparam 118
@@ -779,7 +779,7 @@ __SYSCALL(__NR_rseq, sys_rseq)
 #define __NR_kexec_file_load 294
 __SYSCALL(__NR_kexec_file_load,     sys_kexec_file_load)
 /* 295 through 402 are unassigned to sync up with generic numbers, don't use */
-#if __BITS_PER_LONG == 32
+#if defined(__SYSCALL_COMPAT) || __BITS_PER_LONG == 32
 #define __NR_clock_gettime64 403
 __SYSCALL(__NR_clock_gettime64, sys_clock_gettime)
 #define __NR_clock_settime64 404

init/Kconfig

@@ -390,6 +390,10 @@ config SYSVIPC_SYSCTL
 	depends on SYSCTL
 	default y
 
+config SYSVIPC_COMPAT
+	def_bool y
+	depends on COMPAT && SYSVIPC
+
 config POSIX_MQUEUE
 	bool "POSIX Message Queues"
 	depends on NET

mm/fadvise.c

@@ -214,5 +214,16 @@ SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
 	return ksys_fadvise64_64(fd, offset, len, advice);
 }
 
+#endif
+
+#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FADVISE64_64)
+
+COMPAT_SYSCALL_DEFINE6(fadvise64_64, int, fd, compat_arg_u64_dual(offset),
+		       compat_arg_u64_dual(len), int, advice)
+{
+	return ksys_fadvise64_64(fd, compat_arg_u64_glue(offset),
+				 compat_arg_u64_glue(len), advice);
+}
+
 #endif
 #endif

mm/readahead.c

@@ -746,6 +746,13 @@ SYSCALL_DEFINE3(readahead, int, fd, loff_t, offset, size_t, count)
 	return ksys_readahead(fd, offset, count);
 }
 
+#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_READAHEAD)
+COMPAT_SYSCALL_DEFINE4(readahead, int, fd, compat_arg_u64_dual(offset), size_t, count)
+{
+	return ksys_readahead(fd, compat_arg_u64_glue(offset), count);
+}
+#endif
+
 /**
  * readahead_expand - Expand a readahead request
  * @ractl: The request to be expanded

tools/include/uapi/asm-generic/fcntl.h

@@ -115,13 +115,11 @@
 #define F_GETSIG	11	/* for sockets. */
 #endif
 
-#ifndef CONFIG_64BIT
 #ifndef F_GETLK64
 #define F_GETLK64	12	/*  using 'struct flock64' */
 #define F_SETLK64	13
 #define F_SETLKW64	14
 #endif
-#endif
 
 #ifndef F_SETOWN_EX
 #define F_SETOWN_EX	15
@@ -187,25 +185,19 @@ struct f_owner_ex {
 
 #define F_LINUX_SPECIFIC_BASE	1024
 
-#ifndef HAVE_ARCH_STRUCT_FLOCK
-#ifndef __ARCH_FLOCK_PAD
-#define __ARCH_FLOCK_PAD
-#endif
-
 struct flock {
 	short	l_type;
 	short	l_whence;
 	__kernel_off_t	l_start;
 	__kernel_off_t	l_len;
 	__kernel_pid_t	l_pid;
-	__ARCH_FLOCK_PAD
-};
+#ifdef	__ARCH_FLOCK_EXTRA_SYSID
+	__ARCH_FLOCK_EXTRA_SYSID
 #endif
-
-#ifndef HAVE_ARCH_STRUCT_FLOCK64
-#ifndef __ARCH_FLOCK64_PAD
-#define __ARCH_FLOCK64_PAD
+#ifdef	__ARCH_FLOCK_PAD
+	__ARCH_FLOCK_PAD
 #endif
+};
 
 struct flock64 {
 	short  l_type;
@@ -213,8 +205,9 @@ struct flock64 {
 	__kernel_loff_t l_start;
 	__kernel_loff_t l_len;
 	__kernel_pid_t  l_pid;
+#ifdef	__ARCH_FLOCK64_PAD
 	__ARCH_FLOCK64_PAD
-};
 #endif
+};
 
 #endif /* _ASM_GENERIC_FCNTL_H */

tools/include/uapi/asm-generic/unistd.h

@@ -383,7 +383,7 @@ __SYSCALL(__NR_syslog, sys_syslog)
 
 /* kernel/ptrace.c */
 #define __NR_ptrace 117
-__SYSCALL(__NR_ptrace, sys_ptrace)
+__SC_COMP(__NR_ptrace, sys_ptrace, compat_sys_ptrace)
 
 /* kernel/sched/core.c */
 #define __NR_sched_setparam 118
@@ -779,7 +779,7 @@ __SYSCALL(__NR_rseq, sys_rseq)
 #define __NR_kexec_file_load 294
 __SYSCALL(__NR_kexec_file_load,     sys_kexec_file_load)
 /* 295 through 402 are unassigned to sync up with generic numbers, don't use */
-#if __BITS_PER_LONG == 32
+#if defined(__SYSCALL_COMPAT) || __BITS_PER_LONG == 32
 #define __NR_clock_gettime64 403
 __SYSCALL(__NR_clock_gettime64, sys_clock_gettime)
 #define __NR_clock_settime64 404