syscalls/core, syscalls/x86: Rename struct pt_regs-based sys_*() to __x64_sys_*()

This rename allows us to have a coherent syscall stub naming convention on
64-bit x86 (0xffffffff prefix removed):

 810f0af0 t            kernel_waitid	# common (32/64) kernel helper

 <inline>            __do_sys_waitid	# inlined helper doing actual work
 810f0be0 t          __se_sys_waitid	# C func calling inlined helper

 <inline>     __do_compat_sys_waitid	# inlined helper doing actual work
 810f0d80 t   __se_compat_sys_waitid	# compat C func calling inlined helper

 810f2080 T         __x64_sys_waitid	# x64 64-bit-ptregs -> C stub
 810f20b0 T        __ia32_sys_waitid	# ia32 32-bit-ptregs -> C stub[*]
 810f2470 T __ia32_compat_sys_waitid	# ia32 32-bit-ptregs -> compat C stub
 810f2490 T  __x32_compat_sys_waitid	# x32 64-bit-ptregs -> compat C stub

    [*] This stub is unused, as the syscall table links
	__ia32_compat_sys_waitid instead of __ia32_sys_waitid as we need
	a compat variant here.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180409105145.5364-4-linux@dominikbrodowski.netSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/entry/syscalls/syscall_32.tbl

@@ -11,9 +11,9 @@
 #
 # The abi is always "i386" for this file.
 #
-0	i386	restart_syscall		sys_restart_syscall
+0	i386	restart_syscall		sys_restart_syscall		__ia32_sys_restart_syscall
 1	i386	exit			sys_exit			__ia32_sys_exit
-2	i386	fork			sys_fork
+2	i386	fork			sys_fork			__ia32_sys_fork
 3	i386	read			sys_read			__ia32_sys_read
 4	i386	write			sys_write			__ia32_sys_write
 5	i386	open			sys_open			__ia32_compat_sys_open
@@ -31,23 +31,23 @@
 17	i386	break
 18	i386	oldstat			sys_stat			__ia32_sys_stat
 19	i386	lseek			sys_lseek			__ia32_compat_sys_lseek
-20	i386	getpid			sys_getpid
+20	i386	getpid			sys_getpid			__ia32_sys_getpid
 21	i386	mount			sys_mount			__ia32_compat_sys_mount
 22	i386	umount			sys_oldumount			__ia32_sys_oldumount
 23	i386	setuid			sys_setuid16			__ia32_sys_setuid16
-24	i386	getuid			sys_getuid16
+24	i386	getuid			sys_getuid16			__ia32_sys_getuid16
 25	i386	stime			sys_stime			__ia32_compat_sys_stime
 26	i386	ptrace			sys_ptrace			__ia32_compat_sys_ptrace
 27	i386	alarm			sys_alarm			__ia32_sys_alarm
 28	i386	oldfstat		sys_fstat			__ia32_sys_fstat
-29	i386	pause			sys_pause
+29	i386	pause			sys_pause			__ia32_sys_pause
 30	i386	utime			sys_utime			__ia32_compat_sys_utime
 31	i386	stty
 32	i386	gtty
 33	i386	access			sys_access			__ia32_sys_access
 34	i386	nice			sys_nice			__ia32_sys_nice
 35	i386	ftime
-36	i386	sync			sys_sync
+36	i386	sync			sys_sync			__ia32_sys_sync
 37	i386	kill			sys_kill			__ia32_sys_kill
 38	i386	rename			sys_rename			__ia32_sys_rename
 39	i386	mkdir			sys_mkdir			__ia32_sys_mkdir
@@ -58,10 +58,10 @@
 44	i386	prof
 45	i386	brk			sys_brk				__ia32_sys_brk
 46	i386	setgid			sys_setgid16			__ia32_sys_setgid16
-47	i386	getgid			sys_getgid16
+47	i386	getgid			sys_getgid16			__ia32_sys_getgid16
 48	i386	signal			sys_signal			__ia32_sys_signal
-49	i386	geteuid			sys_geteuid16
-50	i386	getegid			sys_getegid16
+49	i386	geteuid			sys_geteuid16			__ia32_sys_geteuid16
+50	i386	getegid			sys_getegid16			__ia32_sys_getegid16
 51	i386	acct			sys_acct			__ia32_sys_acct
 52	i386	umount2			sys_umount			__ia32_sys_umount
 53	i386	lock
@@ -75,11 +75,11 @@
 61	i386	chroot			sys_chroot			__ia32_sys_chroot
 62	i386	ustat			sys_ustat			__ia32_compat_sys_ustat
 63	i386	dup2			sys_dup2			__ia32_sys_dup2
-64	i386	getppid			sys_getppid
-65	i386	getpgrp			sys_getpgrp
-66	i386	setsid			sys_setsid
+64	i386	getppid			sys_getppid			__ia32_sys_getppid
+65	i386	getpgrp			sys_getpgrp			__ia32_sys_getpgrp
+66	i386	setsid			sys_setsid			__ia32_sys_setsid
 67	i386	sigaction		sys_sigaction			__ia32_compat_sys_sigaction
-68	i386	sgetmask		sys_sgetmask
+68	i386	sgetmask		sys_sgetmask			__ia32_sys_sgetmask
 69	i386	ssetmask		sys_ssetmask			__ia32_sys_ssetmask
 70	i386	setreuid		sys_setreuid16			__ia32_sys_setreuid16
 71	i386	setregid		sys_setregid16			__ia32_sys_setregid16
@@ -122,7 +122,7 @@
 108	i386	fstat			sys_newfstat			__ia32_compat_sys_newfstat
 109	i386	olduname		sys_uname			__ia32_sys_uname
 110	i386	iopl			sys_iopl			__ia32_sys_iopl
-111	i386	vhangup			sys_vhangup
+111	i386	vhangup			sys_vhangup			__ia32_sys_vhangup
 112	i386	idle
 113	i386	vm86old			sys_vm86old			sys_ni_syscall
 114	i386	wait4			sys_wait4			__ia32_compat_sys_wait4
@@ -164,12 +164,12 @@
 150	i386	mlock			sys_mlock			__ia32_sys_mlock
 151	i386	munlock			sys_munlock			__ia32_sys_munlock
 152	i386	mlockall		sys_mlockall			__ia32_sys_mlockall
-153	i386	munlockall		sys_munlockall
+153	i386	munlockall		sys_munlockall			__ia32_sys_munlockall
 154	i386	sched_setparam		sys_sched_setparam		__ia32_sys_sched_setparam
 155	i386	sched_getparam		sys_sched_getparam		__ia32_sys_sched_getparam
 156	i386	sched_setscheduler	sys_sched_setscheduler		__ia32_sys_sched_setscheduler
 157	i386	sched_getscheduler	sys_sched_getscheduler		__ia32_sys_sched_getscheduler
-158	i386	sched_yield		sys_sched_yield
+158	i386	sched_yield		sys_sched_yield			__ia32_sys_sched_yield
 159	i386	sched_get_priority_max	sys_sched_get_priority_max	__ia32_sys_sched_get_priority_max
 160	i386	sched_get_priority_min	sys_sched_get_priority_min	__ia32_sys_sched_get_priority_min
 161	i386	sched_rr_get_interval	sys_sched_rr_get_interval	__ia32_compat_sys_sched_rr_get_interval
@@ -201,7 +201,7 @@
 187	i386	sendfile		sys_sendfile			__ia32_compat_sys_sendfile
 188	i386	getpmsg
 189	i386	putpmsg
-190	i386	vfork			sys_vfork
+190	i386	vfork			sys_vfork			__ia32_sys_vfork
 191	i386	ugetrlimit		sys_getrlimit			__ia32_compat_sys_getrlimit
 192	i386	mmap2			sys_mmap_pgoff			__ia32_sys_mmap_pgoff
 193	i386	truncate64		sys_truncate64			__ia32_compat_sys_x86_truncate64
@@ -210,10 +210,10 @@
 196	i386	lstat64			sys_lstat64			__ia32_compat_sys_x86_lstat64
 197	i386	fstat64			sys_fstat64			__ia32_compat_sys_x86_fstat64
 198	i386	lchown32		sys_lchown			__ia32_sys_lchown
-199	i386	getuid32		sys_getuid
-200	i386	getgid32		sys_getgid
-201	i386	geteuid32		sys_geteuid
-202	i386	getegid32		sys_getegid
+199	i386	getuid32		sys_getuid			__ia32_sys_getuid
+200	i386	getgid32		sys_getgid			__ia32_sys_getgid
+201	i386	geteuid32		sys_geteuid			__ia32_sys_geteuid
+202	i386	getegid32		sys_getegid			__ia32_sys_getegid
 203	i386	setreuid32		sys_setreuid			__ia32_sys_setreuid
 204	i386	setregid32		sys_setregid			__ia32_sys_setregid
 205	i386	getgroups32		sys_getgroups			__ia32_sys_getgroups
@@ -235,7 +235,7 @@
 221	i386	fcntl64			sys_fcntl64			__ia32_compat_sys_fcntl64
 # 222 is unused
 # 223 is unused
-224	i386	gettid			sys_gettid
+224	i386	gettid			sys_gettid			__ia32_sys_gettid
 225	i386	readahead		sys_readahead			__ia32_compat_sys_x86_readahead
 226	i386	setxattr		sys_setxattr			__ia32_sys_setxattr
 227	i386	lsetxattr		sys_lsetxattr			__ia32_sys_lsetxattr
@@ -302,7 +302,7 @@
 288	i386	keyctl			sys_keyctl			__ia32_compat_sys_keyctl
 289	i386	ioprio_set		sys_ioprio_set			__ia32_sys_ioprio_set
 290	i386	ioprio_get		sys_ioprio_get			__ia32_sys_ioprio_get
-291	i386	inotify_init		sys_inotify_init
+291	i386	inotify_init		sys_inotify_init		__ia32_sys_inotify_init
 292	i386	inotify_add_watch	sys_inotify_add_watch		__ia32_sys_inotify_add_watch
 293	i386	inotify_rm_watch	sys_inotify_rm_watch		__ia32_sys_inotify_rm_watch
 294	i386	migrate_pages		sys_migrate_pages		__ia32_sys_migrate_pages

arch/x86/entry/syscalls/syscalltbl.sh

@@ -25,15 +25,27 @@ emit() {
     nr="$2"
     entry="$3"
     compat="$4"
+    umlentry=""
 
     if [ "$abi" = "64" -a -n "$compat" ]; then
 	echo "a compat entry for a 64-bit syscall makes no sense" >&2
 	exit 1
     fi
 
+    # For CONFIG_UML, we need to strip the __x64_sys prefix
+    if [ "$abi" = "64" -a "${entry}" != "${entry#__x64_sys}" ]; then
+	    umlentry="sys${entry#__x64_sys}"
+    fi
+
     if [ -z "$compat" ]; then
-	if [ -n "$entry" ]; then
+	if [ -n "$entry" -a -z "$umlentry" ]; then
 	    syscall_macro "$abi" "$nr" "$entry"
+	elif [ -n "$umlentry" ]; then # implies -n "$entry"
+	    echo "#ifdef CONFIG_X86"
+	    syscall_macro "$abi" "$nr" "$entry"
+	    echo "#else /* CONFIG_UML */"
+	    syscall_macro "$abi" "$nr" "$umlentry"
+	    echo "#endif"
 	fi
     else
 	echo "#ifdef CONFIG_X86_32"

arch/x86/entry/vsyscall/vsyscall_64.c

@@ -229,12 +229,12 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
 	switch (vsyscall_nr) {
 	case 0:
 		/* this decodes regs->di and regs->si on its own */
-		ret = sys_gettimeofday(regs);
+		ret = __x64_sys_gettimeofday(regs);
 		break;
 
 	case 1:
 		/* this decodes regs->di on its own */
-		ret = sys_time(regs);
+		ret = __x64_sys_time(regs);
 		break;
 
 	case 2:
@@ -242,7 +242,7 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
 		orig_dx = regs->dx;
 		regs->dx = 0;
 		/* this decodes regs->di, regs->si and regs->dx on its own */
-		ret = sys_getcpu(regs);
+		ret = __x64_sys_getcpu(regs);
 		regs->dx = orig_dx;
 		break;
 	}

arch/x86/include/asm/syscall_wrapper.h

@@ -44,12 +44,23 @@
 		return __se_sys##name(SC_IA32_REGS_TO_ARGS(x,__VA_ARGS__));\
 	}
 
+/*
+ * To keep the naming coherent, re-define SYSCALL_DEFINE0 to create an alias
+ * named __ia32_sys_*()
+ */
+#define SYSCALL_DEFINE0(sname)					\
+	SYSCALL_METADATA(_##sname, 0);				\
+	asmlinkage long __x64_sys_##sname(void);		\
+	ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO);	\
+	SYSCALL_ALIAS(__ia32_sys_##sname, __x64_sys_##sname);	\
+	asmlinkage long __x64_sys_##sname(void)
+
 #define COND_SYSCALL(name)						\
-	cond_syscall(sys_##name);					\
+	cond_syscall(__x64_sys_##name);					\
 	cond_syscall(__ia32_sys_##name)
 
 #define SYS_NI(name)							\
-	SYSCALL_ALIAS(sys_##name, sys_ni_posix_timers);			\
+	SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers);		\
 	SYSCALL_ALIAS(__ia32_sys_##name, sys_ni_posix_timers)
 
 #else /* CONFIG_IA32_EMULATION */
@@ -81,8 +92,7 @@
 /*
  * Compat means IA32_EMULATION and/or X86_X32. As they use a different
  * mapping of registers to parameters, we need to generate stubs for each
- * of them. There is no need to implement COMPAT_SYSCALL_DEFINE0, as it is
- * unused on x86.
+ * of them.
  */
 #define COMPAT_SYSCALL_DEFINEx(x, name, ...)					\
 	static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));	\
@@ -114,13 +124,13 @@
 /*
  * Instead of the generic __SYSCALL_DEFINEx() definition, this macro takes
  * struct pt_regs *regs as the only argument of the syscall stub named
- * sys_*(). It decodes just the registers it needs and passes them on to
+ * __x64_sys_*(). It decodes just the registers it needs and passes them on to
  * the __se_sys_*() wrapper performing sign extension and then to the
  * __do_sys_*() function doing the actual job. These wrappers and functions
  * are inlined (at least in very most cases), meaning that the assembly looks
  * as follows (slightly re-ordered for better readability):
  *
- * <sys_recv>:			<-- syscall with 4 parameters
+ * <__x64_sys_recv>:		<-- syscall with 4 parameters
  *	callq	<__fentry__>
  *
  *	mov	0x70(%rdi),%rdi	<-- decode regs->di
@@ -143,18 +153,13 @@
  * If IA32_EMULATION is enabled, this macro generates an additional wrapper
  * named __ia32_sys_*() which decodes the struct pt_regs *regs according
  * to the i386 calling convention (bx, cx, dx, si, di, bp).
- *
- * As the generic SYSCALL_DEFINE0() macro does not decode any parameters for
- * obvious reasons, and passing struct pt_regs *regs to it in %rdi does not
- * hurt, there is no need to override it, or to define it differently for
- * IA32_EMULATION.
  */
 #define __SYSCALL_DEFINEx(x, name, ...)					\
-	asmlinkage long sys##name(const struct pt_regs *regs);		\
-	ALLOW_ERROR_INJECTION(sys##name, ERRNO);			\
+	asmlinkage long __x64_sys##name(const struct pt_regs *regs);	\
+	ALLOW_ERROR_INJECTION(__x64_sys##name, ERRNO);			\
 	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));	\
 	static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
-	asmlinkage long sys##name(const struct pt_regs *regs)		\
+	asmlinkage long __x64_sys##name(const struct pt_regs *regs)	\
 	{								\
 		return __se_sys##name(SC_X86_64_REGS_TO_ARGS(x,__VA_ARGS__));\
 	}								\
@@ -168,13 +173,37 @@
 	}								\
 	static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
 
+/*
+ * As the generic SYSCALL_DEFINE0() macro does not decode any parameters for
+ * obvious reasons, and passing struct pt_regs *regs to it in %rdi does not
+ * hurt, we only need to re-define it here to keep the naming congruent to
+ * SYSCALL_DEFINEx() -- which is essential for the COND_SYSCALL() and SYS_NI()
+ * macros to work correctly.
+ */
+#ifndef SYSCALL_DEFINE0
+#define SYSCALL_DEFINE0(sname)					\
+	SYSCALL_METADATA(_##sname, 0);				\
+	asmlinkage long __x64_sys_##sname(void);		\
+	ALLOW_ERROR_INJECTION(__x64_sys_##sname, ERRNO);	\
+	asmlinkage long __x64_sys_##sname(void)
+#endif
+
+#ifndef COND_SYSCALL
+#define COND_SYSCALL(name) cond_syscall(__x64_sys_##name)
+#endif
+
+#ifndef SYS_NI
+#define SYS_NI(name) SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers);
+#endif
+
+
 /*
  * For VSYSCALLS, we need to declare these three syscalls with the new
  * pt_regs-based calling convention for in-kernel use.
  */
 struct pt_regs;
-asmlinkage long sys_getcpu(const struct pt_regs *regs);		/* di,si,dx */
-asmlinkage long sys_gettimeofday(const struct pt_regs *regs);	/* di,si */
-asmlinkage long sys_time(const struct pt_regs *regs);		/* di */
+asmlinkage long __x64_sys_getcpu(const struct pt_regs *regs);
+asmlinkage long __x64_sys_gettimeofday(const struct pt_regs *regs);
+asmlinkage long __x64_sys_time(const struct pt_regs *regs);
 
 #endif /* _ASM_X86_SYSCALL_WRAPPER_H */