Merge tag 'xtensa-20220523' of https://github.com/jcmvbkbc/linux-xtensa

Pull xtensa architecture updates from Max Filippov:

 - support coprocessors on SMP

 - support KCSAN

 - support handling protection faults in noMMU configurations

 - support using coprocessors in the kernel mode

 - support hibernation

 - enable context tracking

 - enable HAVE_VIRT_CPU_ACCOUNTING_GEN

 - support division by 0 exception on cores without HW division option

 - clean up locking in the ISS network driver

 - clean up kernel entry assemly code

 - various minor fixes

* tag 'xtensa-20220523' of https://github.com/jcmvbkbc/linux-xtensa: (36 commits)
  xtensa: Return true/false (not 1/0) from bool function
  xtensa: improve call0 ABI probing
  xtensa: support artificial division by 0 exception
  xtensa: add trap handler for division by zero
  xtensa/simdisk: fix proc_read_simdisk()
  xtensa: no need to initialise statics to 0
  xtensa: clean up labels in the kernel entry assembly
  xtensa: don't leave invalid TLB entry in fast_store_prohibited
  xtensa: fix declaration of _SecondaryResetVector_text_*
  irqchip: irq-xtensa-mx: fix initial IRQ affinity
  xtensa: enable ARCH_HAS_DEBUG_VM_PGTABLE
  xtensa: add hibernation support
  xtensa: support coprocessors on SMP
  xtensa: get rid of stack frame in coprocessor_flush
  xtensa: merge SAVE_CP_REGS_TAB and LOAD_CP_REGS_TAB
  xtensa: add xtensa_xsr macro
  xtensa: handle coprocessor exceptions in kernel mode
  xtensa: use callx0 opcode in fast_coprocessor
  xtensa: clean up excsave1 initialization
  xtensa: clean up declarations in coprocessor.h
  ...

Documentation/features/debug/debug-vm-pgtable/arch-support.txt

@@ -27,5 +27,5 @@
     |       sparc: | TODO |
     |          um: | TODO |
     |         x86: |  ok  |
-    |      xtensa: | TODO |
+    |      xtensa: |  ok  |
     -----------------------

Documentation/features/time/context-tracking/arch-support.txt

@@ -27,5 +27,5 @@
     |       sparc: |  ok  |
     |          um: | TODO |
     |         x86: |  ok  |
-    |      xtensa: | TODO |
+    |      xtensa: |  ok  |
     -----------------------

Documentation/features/time/virt-cpuacct/arch-support.txt

@@ -27,5 +27,5 @@
     |       sparc: |  ok  |
     |          um: | TODO |
     |         x86: |  ok  |
-    |      xtensa: | TODO |
+    |      xtensa: |  ok  |
     -----------------------

arch/xtensa/Kconfig

@@ -4,6 +4,7 @@ config XTENSA
 	select ARCH_32BIT_OFF_T
 	select ARCH_HAS_BINFMT_FLAT if !MMU
 	select ARCH_HAS_CURRENT_STACK_POINTER
+	select ARCH_HAS_DEBUG_VM_PGTABLE
 	select ARCH_HAS_DMA_PREP_COHERENT if MMU
 	select ARCH_HAS_SYNC_DMA_FOR_CPU if MMU
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE if MMU
@@ -29,8 +30,10 @@ config XTENSA
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
 	select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
+	select HAVE_ARCH_KCSAN
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_TRACEHOOK
+	select HAVE_CONTEXT_TRACKING
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_EXIT_THREAD
@@ -42,6 +45,7 @@ config XTENSA
 	select HAVE_PERF_EVENTS
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
+	select HAVE_VIRT_CPU_ACCOUNTING_GEN
 	select IRQ_DOMAIN
 	select MODULES_USE_ELF_RELA
 	select PERF_USE_VMALLOC
@@ -79,6 +83,7 @@ config STACKTRACE_SUPPORT
 
 config MMU
 	def_bool n
+	select PFAULT
 
 config HAVE_XTENSA_GPIO32
 	def_bool n
@@ -178,6 +183,16 @@ config XTENSA_FAKE_NMI
 
 	  If unsure, say N.
 
+config PFAULT
+	bool "Handle protection faults" if EXPERT && !MMU
+	default y
+	help
+	  Handle protection faults. MMU configurations must enable it.
+	  noMMU configurations may disable it if used memory map never
+	  generates protection faults or faults are always fatal.
+
+	  If unsure, say Y.
+
 config XTENSA_UNALIGNED_USER
 	bool "Unaligned memory access in user space"
 	help
@@ -773,6 +788,9 @@ endmenu
 
 menu "Power management options"
 
+config ARCH_HIBERNATION_POSSIBLE
+	def_bool y
+
 source "kernel/power/Kconfig"
 
 endmenu

arch/xtensa/boot/lib/Makefile

@@ -16,6 +16,7 @@ CFLAGS_REMOVE_inffast.o = -pg
 endif
 
 KASAN_SANITIZE := n
+KCSAN_SANITIZE := n
 
 CFLAGS_REMOVE_inflate.o += -fstack-protector -fstack-protector-strong
 CFLAGS_REMOVE_zmem.o += -fstack-protector -fstack-protector-strong

arch/xtensa/include/asm/barrier.h

@@ -11,9 +11,15 @@
 
 #include <asm/core.h>
 
-#define mb()  ({ __asm__ __volatile__("memw" : : : "memory"); })
-#define rmb() barrier()
-#define wmb() mb()
+#define __mb()  ({ __asm__ __volatile__("memw" : : : "memory"); })
+#define __rmb() barrier()
+#define __wmb() __mb()
+
+#ifdef CONFIG_SMP
+#define __smp_mb() __mb()
+#define __smp_rmb() __rmb()
+#define __smp_wmb() __wmb()
+#endif
 
 #if XCHAL_HAVE_S32C1I
 #define __smp_mb__before_atomic()		barrier()

arch/xtensa/include/asm/bitops.h

@@ -99,7 +99,7 @@ static inline unsigned long __fls(unsigned long word)
 #if XCHAL_HAVE_EXCLUSIVE
 
 #define BIT_OP(op, insn, inv)						\
-static inline void op##_bit(unsigned int bit, volatile unsigned long *p)\
+static inline void arch_##op##_bit(unsigned int bit, volatile unsigned long *p)\
 {									\
 	unsigned long tmp;						\
 	unsigned long mask = 1UL << (bit & 31);				\
@@ -119,7 +119,7 @@ static inline void op##_bit(unsigned int bit, volatile unsigned long *p)\
 
 #define TEST_AND_BIT_OP(op, insn, inv)					\
 static inline int							\
-test_and_##op##_bit(unsigned int bit, volatile unsigned long *p)	\
+arch_test_and_##op##_bit(unsigned int bit, volatile unsigned long *p)	\
 {									\
 	unsigned long tmp, value;					\
 	unsigned long mask = 1UL << (bit & 31);				\
@@ -142,7 +142,7 @@ test_and_##op##_bit(unsigned int bit, volatile unsigned long *p)	\
 #elif XCHAL_HAVE_S32C1I
 
 #define BIT_OP(op, insn, inv)						\
-static inline void op##_bit(unsigned int bit, volatile unsigned long *p)\
+static inline void arch_##op##_bit(unsigned int bit, volatile unsigned long *p)\
 {									\
 	unsigned long tmp, value;					\
 	unsigned long mask = 1UL << (bit & 31);				\
@@ -163,7 +163,7 @@ static inline void op##_bit(unsigned int bit, volatile unsigned long *p)\
 
 #define TEST_AND_BIT_OP(op, insn, inv)					\
 static inline int							\
-test_and_##op##_bit(unsigned int bit, volatile unsigned long *p)	\
+arch_test_and_##op##_bit(unsigned int bit, volatile unsigned long *p)	\
 {									\
 	unsigned long tmp, value;					\
 	unsigned long mask = 1UL << (bit & 31);				\
@@ -205,6 +205,8 @@ BIT_OPS(change, "xor", )
 #undef BIT_OP
 #undef TEST_AND_BIT_OP
 
+#include <asm-generic/bitops/instrumented-atomic.h>
+
 #include <asm-generic/bitops/le.h>
 
 #include <asm-generic/bitops/ext2-atomic-setbit.h>

arch/xtensa/include/asm/coprocessor.h

@@ -142,11 +142,12 @@ typedef struct { XCHAL_CP6_SA_LIST(2) } xtregs_cp6_t
 typedef struct { XCHAL_CP7_SA_LIST(2) } xtregs_cp7_t
 	__attribute__ ((aligned (XCHAL_CP7_SA_ALIGN)));
 
-extern struct thread_info* coprocessor_owner[XCHAL_CP_MAX];
-extern void coprocessor_flush(struct thread_info*, int);
-
-extern void coprocessor_release_all(struct thread_info*);
-extern void coprocessor_flush_all(struct thread_info*);
+struct thread_info;
+void coprocessor_flush(struct thread_info *ti, int cp_index);
+void coprocessor_release_all(struct thread_info *ti);
+void coprocessor_flush_all(struct thread_info *ti);
+void coprocessor_flush_release_all(struct thread_info *ti);
+void local_coprocessors_flush_release_all(void);
 
 #endif	/* XTENSA_HAVE_COPROCESSORS */
 

arch/xtensa/include/asm/processor.h

@@ -246,6 +246,13 @@ extern unsigned long __get_wchan(struct task_struct *p);
 	 v; \
 	 })
 
+#define xtensa_xsr(x, sr) \
+	({ \
+	 unsigned int __v__ = (unsigned int)(x); \
+	 __asm__ __volatile__ ("xsr %0, " __stringify(sr) : "+a"(__v__)); \
+	 __v__; \
+	 })
+
 #if XCHAL_HAVE_EXTERN_REGS
 
 static inline void set_er(unsigned long value, unsigned long addr)

arch/xtensa/include/asm/sections.h

@@ -29,7 +29,7 @@ extern char _Level5InterruptVector_text_end[];
 extern char _Level6InterruptVector_text_start[];
 extern char _Level6InterruptVector_text_end[];
 #endif
-#ifdef CONFIG_SMP
+#ifdef CONFIG_SECONDARY_RESET_VECTOR
 extern char _SecondaryResetVector_text_start[];
 extern char _SecondaryResetVector_text_end[];
 #endif

arch/xtensa/include/asm/thread_info.h

@@ -52,12 +52,21 @@ struct thread_info {
 	__u32			cpu;		/* current CPU */
 	__s32			preempt_count;	/* 0 => preemptable,< 0 => BUG*/
 
-	unsigned long		cpenable;
 #if XCHAL_HAVE_EXCLUSIVE
 	/* result of the most recent exclusive store */
 	unsigned long		atomctl8;
 #endif
+#ifdef CONFIG_USER_ABI_CALL0_PROBE
+	/* Address where PS.WOE was enabled by the ABI probing code */
+	unsigned long		ps_woe_fix_addr;
+#endif
 
+	/*
+	 * If i-th bit is set then coprocessor state is loaded into the
+	 * coprocessor i on CPU cp_owner_cpu.
+	 */
+	unsigned long		cpenable;
+	u32			cp_owner_cpu;
 	/* Allocate storage for extra user states and coprocessor states. */
 #if XTENSA_HAVE_COPROCESSORS
 	xtregs_coprocessor_t	xtregs_cp;

arch/xtensa/include/asm/traps.h

@@ -12,6 +12,8 @@
 
 #include <asm/ptrace.h>
 
+typedef void xtensa_exception_handler(struct pt_regs *regs);
+
 /*
  * Per-CPU exception handling data structure.
  * EXCSAVE1 points to it.
@@ -25,31 +27,47 @@ struct exc_table {
 	void *fixup;
 	/* For passing a parameter to fixup */
 	void *fixup_param;
+#if XTENSA_HAVE_COPROCESSORS
+	/* Pointers to owner struct thread_info */
+	struct thread_info *coprocessor_owner[XCHAL_CP_MAX];
+#endif
 	/* Fast user exception handlers */
 	void *fast_user_handler[EXCCAUSE_N];
 	/* Fast kernel exception handlers */
 	void *fast_kernel_handler[EXCCAUSE_N];
 	/* Default C-Handlers */
-	void *default_handler[EXCCAUSE_N];
+	xtensa_exception_handler *default_handler[EXCCAUSE_N];
 };
 
-/*
- * handler must be either of the following:
- *  void (*)(struct pt_regs *regs);
- *  void (*)(struct pt_regs *regs, unsigned long exccause);
- */
-extern void * __init trap_set_handler(int cause, void *handler);
-extern void do_unhandled(struct pt_regs *regs, unsigned long exccause);
-void fast_second_level_miss(void);
+DECLARE_PER_CPU(struct exc_table, exc_table);
+
+xtensa_exception_handler *
+__init trap_set_handler(int cause, xtensa_exception_handler *handler);
+
+asmlinkage void fast_illegal_instruction_user(void);
+asmlinkage void fast_syscall_user(void);
+asmlinkage void fast_alloca(void);
+asmlinkage void fast_unaligned(void);
+asmlinkage void fast_second_level_miss(void);
+asmlinkage void fast_store_prohibited(void);
+asmlinkage void fast_coprocessor(void);
+
+asmlinkage void kernel_exception(void);
+asmlinkage void user_exception(void);
+asmlinkage void system_call(struct pt_regs *regs);
+
+void do_IRQ(int hwirq, struct pt_regs *regs);
+void do_page_fault(struct pt_regs *regs);
+void do_unhandled(struct pt_regs *regs);
 
 /* Initialize minimal exc_table structure sufficient for basic paging */
 static inline void __init early_trap_init(void)
 {
-	static struct exc_table exc_table __initdata = {
+	static struct exc_table init_exc_table __initdata = {
 		.fast_kernel_handler[EXCCAUSE_DTLB_MISS] =
 			fast_second_level_miss,
 	};
-	__asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (&exc_table));
+	xtensa_set_sr(&init_exc_table, excsave1);
 }
 
 void secondary_trap_init(void);

arch/xtensa/kernel/Makefile

@@ -19,6 +19,7 @@ obj-$(CONFIG_XTENSA_VARIANT_HAVE_PERF_EVENTS) += perf_event.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
 obj-$(CONFIG_S32C1I_SELFTEST) += s32c1i_selftest.o
 obj-$(CONFIG_JUMP_LABEL) += jump_label.o
+obj-$(CONFIG_HIBERNATION) += hibernate.o
 
 # In the Xtensa architecture, assembly generates literals which must always
 # precede the L32R instruction with a relative offset less than 256 kB.

arch/xtensa/kernel/asm-offsets.c

@@ -21,6 +21,7 @@
 #include <linux/ptrace.h>
 #include <linux/mm.h>
 #include <linux/kbuild.h>
+#include <linux/suspend.h>
 
 #include <asm/ptrace.h>
 #include <asm/traps.h>
@@ -87,14 +88,19 @@ int main(void)
 	OFFSET(TI_STSTUS, thread_info, status);
 	OFFSET(TI_CPU, thread_info, cpu);
 	OFFSET(TI_PRE_COUNT, thread_info, preempt_count);
+#ifdef CONFIG_USER_ABI_CALL0_PROBE
+	OFFSET(TI_PS_WOE_FIX_ADDR, thread_info, ps_woe_fix_addr);
+#endif
 
 	/* struct thread_info (offset from start_struct) */
 	DEFINE(THREAD_RA, offsetof (struct task_struct, thread.ra));
 	DEFINE(THREAD_SP, offsetof (struct task_struct, thread.sp));
-	DEFINE(THREAD_CPENABLE, offsetof (struct thread_info, cpenable));
 #if XCHAL_HAVE_EXCLUSIVE
 	DEFINE(THREAD_ATOMCTL8, offsetof (struct thread_info, atomctl8));
 #endif
+	DEFINE(THREAD_CPENABLE, offsetof(struct thread_info, cpenable));
+	DEFINE(THREAD_CPU, offsetof(struct thread_info, cpu));
+	DEFINE(THREAD_CP_OWNER_CPU, offsetof(struct thread_info, cp_owner_cpu));
 #if XTENSA_HAVE_COPROCESSORS
 	DEFINE(THREAD_XTREGS_CP0, offsetof(struct thread_info, xtregs_cp.cp0));
 	DEFINE(THREAD_XTREGS_CP1, offsetof(struct thread_info, xtregs_cp.cp1));
@@ -137,11 +143,22 @@ int main(void)
 	DEFINE(EXC_TABLE_DOUBLE_SAVE, offsetof(struct exc_table, double_save));
 	DEFINE(EXC_TABLE_FIXUP, offsetof(struct exc_table, fixup));
 	DEFINE(EXC_TABLE_PARAM, offsetof(struct exc_table, fixup_param));
+#if XTENSA_HAVE_COPROCESSORS
+	DEFINE(EXC_TABLE_COPROCESSOR_OWNER,
+	       offsetof(struct exc_table, coprocessor_owner));
+#endif
 	DEFINE(EXC_TABLE_FAST_USER,
 	       offsetof(struct exc_table, fast_user_handler));
 	DEFINE(EXC_TABLE_FAST_KERNEL,
 	       offsetof(struct exc_table, fast_kernel_handler));
 	DEFINE(EXC_TABLE_DEFAULT, offsetof(struct exc_table, default_handler));
 
+#ifdef CONFIG_HIBERNATION
+	DEFINE(PBE_ADDRESS, offsetof(struct pbe, address));
+	DEFINE(PBE_ORIG_ADDRESS, offsetof(struct pbe, orig_address));
+	DEFINE(PBE_NEXT, offsetof(struct pbe, next));
+	DEFINE(PBE_SIZE, sizeof(struct pbe));
+#endif
+
 	return 0;
 }

arch/xtensa/kernel/coprocessor.S

@@ -19,6 +19,26 @@
 #include <asm/current.h>
 #include <asm/regs.h>
 
+/*
+ * Rules for coprocessor state manipulation on SMP:
+ *
+ * - a task may have live coprocessors only on one CPU.
+ *
+ * - whether coprocessor context of task T is live on some CPU is
+ *   denoted by T's thread_info->cpenable.
+ *
+ * - non-zero thread_info->cpenable means that thread_info->cp_owner_cpu
+ *   is valid in the T's thread_info. Zero thread_info->cpenable means that
+ *   coprocessor context is valid in the T's thread_info.
+ *
+ * - if a coprocessor context of task T is live on CPU X, only CPU X changes
+ *   T's thread_info->cpenable, cp_owner_cpu and coprocessor save area.
+ *   This is done by making sure that for the task T with live coprocessor
+ *   on CPU X cpenable SR is 0 when T runs on any other CPU Y.
+ *   When fast_coprocessor exception is taken on CPU Y it goes to the
+ *   C-level do_coprocessor that uses IPI to make CPU X flush T's coprocessors.
+ */
+
 #if XTENSA_HAVE_COPROCESSORS
 
 /*
@@ -30,34 +50,30 @@
 		.align 4;						\
 	.Lsave_cp_regs_cp##x:						\
 		xchal_cp##x##_store a2 a3 a4 a5 a6;			\
-		jx	a0;						\
+		ret;							\
 	.endif
 
-#define SAVE_CP_REGS_TAB(x)						\
-	.if XTENSA_HAVE_COPROCESSOR(x);					\
-		.long .Lsave_cp_regs_cp##x;				\
-	.else;								\
-		.long 0;						\
-	.endif;								\
-	.long THREAD_XTREGS_CP##x
-
-
 #define LOAD_CP_REGS(x)							\
 	.if XTENSA_HAVE_COPROCESSOR(x);					\
 		.align 4;						\
 	.Lload_cp_regs_cp##x:						\
 		xchal_cp##x##_load a2 a3 a4 a5 a6;			\
-		jx	a0;						\
+		ret;							\
 	.endif
 
-#define LOAD_CP_REGS_TAB(x)						\
+#define CP_REGS_TAB(x)							\
 	.if XTENSA_HAVE_COPROCESSOR(x);					\
+		.long .Lsave_cp_regs_cp##x;				\
 		.long .Lload_cp_regs_cp##x;				\
 	.else;								\
-		.long 0;						\
+		.long 0, 0;						\
 	.endif;								\
 	.long THREAD_XTREGS_CP##x
 
+#define CP_REGS_TAB_SAVE 0
+#define CP_REGS_TAB_LOAD 4
+#define CP_REGS_TAB_OFFSET 8
+
 	__XTENSA_HANDLER
 
 	SAVE_CP_REGS(0)
@@ -79,25 +95,15 @@
 	LOAD_CP_REGS(7)
 
 	.align 4
-.Lsave_cp_regs_jump_table:
-	SAVE_CP_REGS_TAB(0)
-	SAVE_CP_REGS_TAB(1)
-	SAVE_CP_REGS_TAB(2)
-	SAVE_CP_REGS_TAB(3)
-	SAVE_CP_REGS_TAB(4)
-	SAVE_CP_REGS_TAB(5)
-	SAVE_CP_REGS_TAB(6)
-	SAVE_CP_REGS_TAB(7)
-
-.Lload_cp_regs_jump_table:
-	LOAD_CP_REGS_TAB(0)
-	LOAD_CP_REGS_TAB(1)
-	LOAD_CP_REGS_TAB(2)
-	LOAD_CP_REGS_TAB(3)
-	LOAD_CP_REGS_TAB(4)
-	LOAD_CP_REGS_TAB(5)
-	LOAD_CP_REGS_TAB(6)
-	LOAD_CP_REGS_TAB(7)
+.Lcp_regs_jump_table:
+	CP_REGS_TAB(0)
+	CP_REGS_TAB(1)
+	CP_REGS_TAB(2)
+	CP_REGS_TAB(3)
+	CP_REGS_TAB(4)
+	CP_REGS_TAB(5)
+	CP_REGS_TAB(6)
+	CP_REGS_TAB(7)
 
 /*
  * Entry condition:
@@ -115,9 +121,37 @@
 
 ENTRY(fast_coprocessor)
 
+	s32i	a3, a2, PT_AREG3
+
+#ifdef CONFIG_SMP
+	/*
+	 * Check if any coprocessor context is live on another CPU
+	 * and if so go through the C-level coprocessor exception handler
+	 * to flush it to memory.
+	 */
+	GET_THREAD_INFO (a0, a2)
+	l32i	a3, a0, THREAD_CPENABLE
+	beqz	a3, .Lload_local
+
+	/*
+	 * Pairs with smp_wmb in local_coprocessor_release_all
+	 * and with both memws below.
+	 */
+	memw
+	l32i	a3, a0, THREAD_CPU
+	l32i	a0, a0, THREAD_CP_OWNER_CPU
+	beq	a0, a3, .Lload_local
+
+	rsr	a0, ps
+	l32i	a3, a2, PT_AREG3
+	bbci.l	a0, PS_UM_BIT, 1f
+	call0	user_exception
+1:	call0	kernel_exception
+#endif
+
 	/* Save remaining registers a1-a3 and SAR */
 
-	s32i	a3, a2, PT_AREG3
+.Lload_local:
 	rsr	a3, sar
 	s32i	a1, a2, PT_AREG1
 	s32i	a3, a2, PT_SAR
@@ -125,13 +159,15 @@ ENTRY(fast_coprocessor)
 	rsr	a2, depc
 	s32i	a2, a1, PT_AREG2
 
-	/*
-	 * The hal macros require up to 4 temporary registers. We use a3..a6.
-	 */
+	/* The hal macros require up to 4 temporary registers. We use a3..a6. */
 
 	s32i	a4, a1, PT_AREG4
 	s32i	a5, a1, PT_AREG5
 	s32i	a6, a1, PT_AREG6
+	s32i	a7, a1, PT_AREG7
+	s32i	a8, a1, PT_AREG8
+	s32i	a9, a1, PT_AREG9
+	s32i	a10, a1, PT_AREG10
 
 	/* Find coprocessor number. Subtract first CP EXCCAUSE from EXCCAUSE */
 
@@ -148,58 +184,74 @@ ENTRY(fast_coprocessor)
 	wsr	a0, cpenable
 	rsync
 
-	/* Retrieve previous owner. (a3 still holds CP number) */
+	/* Get coprocessor save/load table entry (a7). */
 
-	movi	a0, coprocessor_owner	# list of owners
-	addx4	a0, a3, a0		# entry for CP
-	l32i	a4, a0, 0
+	movi	a7, .Lcp_regs_jump_table
+	addx8	a7, a3, a7
+	addx4	a7, a3, a7
 
-	beqz	a4, 1f			# skip 'save' if no previous owner
+	/* Retrieve previous owner (a8). */
 
-	/* Disable coprocessor for previous owner. (a2 = 1 << CP number) */
+	rsr	a0, excsave1		# exc_table
+	addx4	a0, a3, a0		# entry for CP
+	l32i	a8, a0, EXC_TABLE_COPROCESSOR_OWNER
+
+	/* Set new owner (a9). */
 
-	l32i	a5, a4, THREAD_CPENABLE
-	xor	a5, a5, a2		# (1 << cp-id) still in a2
-	s32i	a5, a4, THREAD_CPENABLE
+	GET_THREAD_INFO (a9, a1)
+	l32i	a4, a9, THREAD_CPU
+	s32i	a9, a0, EXC_TABLE_COPROCESSOR_OWNER
+	s32i	a4, a9, THREAD_CP_OWNER_CPU
 
 	/*
-	 * Get context save area and 'call' save routine. 
-	 * (a4 still holds previous owner (thread_info), a3 CP number)
+	 * Enable coprocessor for the new owner. (a2 = 1 << CP number)
+	 * This can be done before loading context into the coprocessor.
 	 */
+	l32i	a4, a9, THREAD_CPENABLE
+	or	a4, a4, a2
 
-	movi	a5, .Lsave_cp_regs_jump_table
-	movi	a0, 2f			# a0: 'return' address
-	addx8	a3, a3, a5		# a3: coprocessor number
-	l32i	a2, a3, 4		# a2: xtregs offset
-	l32i	a3, a3, 0		# a3: jump address
-	add	a2, a2, a4
-	jx	a3
+	/*
+	 * Make sure THREAD_CP_OWNER_CPU is in memory before updating
+	 * THREAD_CPENABLE
+	 */
+	memw				# (2)
+	s32i	a4, a9, THREAD_CPENABLE
 
-	/* Note that only a0 and a1 were preserved. */
+	beqz	a8, 1f			# skip 'save' if no previous owner
 
-2:	rsr	a3, exccause
-	addi	a3, a3, -EXCCAUSE_COPROCESSOR0_DISABLED
-	movi	a0, coprocessor_owner
-	addx4	a0, a3, a0
+	/* Disable coprocessor for previous owner. (a2 = 1 << CP number) */
 
-	/* Set new 'owner' (a0 points to the CP owner, a3 contains the CP nr) */
+	l32i	a10, a8, THREAD_CPENABLE
+	xor	a10, a10, a2
 
-1:	GET_THREAD_INFO (a4, a1)
-	s32i	a4, a0, 0
+	/* Get context save area and call save routine. */
 
-	/* Get context save area and 'call' load routine. */
+	l32i	a2, a7, CP_REGS_TAB_OFFSET
+	l32i	a3, a7, CP_REGS_TAB_SAVE
+	add	a2, a2, a8
+	callx0	a3
 
-	movi	a5, .Lload_cp_regs_jump_table
-	movi	a0, 1f
-	addx8	a3, a3, a5
-	l32i	a2, a3, 4		# a2: xtregs offset
-	l32i	a3, a3, 0		# a3: jump address
-	add	a2, a2, a4
-	jx	a3
+	/*
+	 * Make sure coprocessor context and THREAD_CP_OWNER_CPU are in memory
+	 * before updating THREAD_CPENABLE
+	 */
+	memw				# (3)
+	s32i	a10, a8, THREAD_CPENABLE
+1:
+	/* Get context save area and call load routine. */
+
+	l32i	a2, a7, CP_REGS_TAB_OFFSET
+	l32i	a3, a7, CP_REGS_TAB_LOAD
+	add	a2, a2, a9
+	callx0	a3
 
 	/* Restore all registers and return from exception handler. */
 
-1:	l32i	a6, a1, PT_AREG6
+	l32i	a10, a1, PT_AREG10
+	l32i	a9, a1, PT_AREG9
+	l32i	a8, a1, PT_AREG8
+	l32i	a7, a1, PT_AREG7
+	l32i	a6, a1, PT_AREG6
 	l32i	a5, a1, PT_AREG5
 	l32i	a4, a1, PT_AREG4
 
@@ -230,29 +282,21 @@ ENDPROC(fast_coprocessor)
 
 ENTRY(coprocessor_flush)
 
-	/* reserve 4 bytes on stack to save a0 */
-	abi_entry(4)
-
-	s32i	a0, a1, 0
-	movi	a0, .Lsave_cp_regs_jump_table
-	addx8	a3, a3, a0
-	l32i	a4, a3, 4
-	l32i	a3, a3, 0
-	add	a2, a2, a4
-	beqz	a3, 1f
-	callx0	a3
-1:	l32i	a0, a1, 0
-
-	abi_ret(4)
+	abi_entry_default
+
+	movi	a4, .Lcp_regs_jump_table
+	addx8	a4, a3, a4
+	addx4	a3, a3, a4
+	l32i	a4, a3, CP_REGS_TAB_SAVE
+	beqz	a4, 1f
+	l32i	a3, a3, CP_REGS_TAB_OFFSET
+	add	a2, a2, a3
+	mov	a7, a0
+	callx0	a4
+	mov	a0, a7
+1:
+	abi_ret_default
 
 ENDPROC(coprocessor_flush)
 
-	.data
-
-ENTRY(coprocessor_owner)
-
-	.fill XCHAL_CP_MAX, 4, 0
-
-END(coprocessor_owner)
-
 #endif /* XTENSA_HAVE_COPROCESSORS */

arch/xtensa/kernel/hibernate.c

+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/mm.h>
+#include <linux/suspend.h>
+#include <asm/coprocessor.h>
+
+int pfn_is_nosave(unsigned long pfn)
+{
+	unsigned long nosave_begin_pfn = PFN_DOWN(__pa(&__nosave_begin));
+	unsigned long nosave_end_pfn = PFN_UP(__pa(&__nosave_end));
+
+	return	(pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
+}
+
+void notrace save_processor_state(void)
+{
+	WARN_ON(num_online_cpus() != 1);
+#if XTENSA_HAVE_COPROCESSORS
+	local_coprocessors_flush_release_all();
+#endif
+}
+
+void notrace restore_processor_state(void)
+{
+}

arch/xtensa/kernel/process.c

@@ -47,6 +47,7 @@
 #include <asm/asm-offsets.h>
 #include <asm/regs.h>
 #include <asm/hw_breakpoint.h>
+#include <asm/traps.h>
 
 extern void ret_from_fork(void);
 extern void ret_from_kernel_thread(void);
@@ -63,52 +64,114 @@ EXPORT_SYMBOL(__stack_chk_guard);
 
 #if XTENSA_HAVE_COPROCESSORS
 
-void coprocessor_release_all(struct thread_info *ti)
+void local_coprocessors_flush_release_all(void)
 {
-	unsigned long cpenable;
-	int i;
+	struct thread_info **coprocessor_owner;
+	struct thread_info *unique_owner[XCHAL_CP_MAX];
+	int n = 0;
+	int i, j;
 
-	/* Make sure we don't switch tasks during this operation. */
+	coprocessor_owner = this_cpu_ptr(&exc_table)->coprocessor_owner;
+	xtensa_set_sr(XCHAL_CP_MASK, cpenable);
 
-	preempt_disable();
+	for (i = 0; i < XCHAL_CP_MAX; i++) {
+		struct thread_info *ti = coprocessor_owner[i];
 
-	/* Walk through all cp owners and release it for the requested one. */
+		if (ti) {
+			coprocessor_flush(ti, i);
 
-	cpenable = ti->cpenable;
+			for (j = 0; j < n; j++)
+				if (unique_owner[j] == ti)
+					break;
+			if (j == n)
+				unique_owner[n++] = ti;
 
-	for (i = 0; i < XCHAL_CP_MAX; i++) {
-		if (coprocessor_owner[i] == ti) {
-			coprocessor_owner[i] = 0;
-			cpenable &= ~(1 << i);
+			coprocessor_owner[i] = NULL;
 		}
 	}
+	for (i = 0; i < n; i++) {
+		/* pairs with memw (1) in fast_coprocessor and memw in switch_to */
+		smp_wmb();
+		unique_owner[i]->cpenable = 0;
+	}
+	xtensa_set_sr(0, cpenable);
+}
 
-	ti->cpenable = cpenable;
+static void local_coprocessor_release_all(void *info)
+{
+	struct thread_info *ti = info;
+	struct thread_info **coprocessor_owner;
+	int i;
+
+	coprocessor_owner = this_cpu_ptr(&exc_table)->coprocessor_owner;
+
+	/* Walk through all cp owners and release it for the requested one. */
+
+	for (i = 0; i < XCHAL_CP_MAX; i++) {
+		if (coprocessor_owner[i] == ti)
+			coprocessor_owner[i] = NULL;
+	}
+	/* pairs with memw (1) in fast_coprocessor and memw in switch_to */
+	smp_wmb();
+	ti->cpenable = 0;
 	if (ti == current_thread_info())
 		xtensa_set_sr(0, cpenable);
+}
 
-	preempt_enable();
+void coprocessor_release_all(struct thread_info *ti)
+{
+	if (ti->cpenable) {
+		/* pairs with memw (2) in fast_coprocessor */
+		smp_rmb();
+		smp_call_function_single(ti->cp_owner_cpu,
+					 local_coprocessor_release_all,
+					 ti, true);
+	}
 }
 
-void coprocessor_flush_all(struct thread_info *ti)
+static void local_coprocessor_flush_all(void *info)
 {
-	unsigned long cpenable, old_cpenable;
+	struct thread_info *ti = info;
+	struct thread_info **coprocessor_owner;
+	unsigned long old_cpenable;
 	int i;
 
-	preempt_disable();
-
-	old_cpenable = xtensa_get_sr(cpenable);
-	cpenable = ti->cpenable;
-	xtensa_set_sr(cpenable, cpenable);
+	coprocessor_owner = this_cpu_ptr(&exc_table)->coprocessor_owner;
+	old_cpenable = xtensa_xsr(ti->cpenable, cpenable);
 
 	for (i = 0; i < XCHAL_CP_MAX; i++) {
-		if ((cpenable & 1) != 0 && coprocessor_owner[i] == ti)
+		if (coprocessor_owner[i] == ti)
 			coprocessor_flush(ti, i);
-		cpenable >>= 1;
 	}
 	xtensa_set_sr(old_cpenable, cpenable);
+}
 
-	preempt_enable();
+void coprocessor_flush_all(struct thread_info *ti)
+{
+	if (ti->cpenable) {
+		/* pairs with memw (2) in fast_coprocessor */
+		smp_rmb();
+		smp_call_function_single(ti->cp_owner_cpu,
+					 local_coprocessor_flush_all,
+					 ti, true);
+	}
+}
+
+static void local_coprocessor_flush_release_all(void *info)
+{
+	local_coprocessor_flush_all(info);
+	local_coprocessor_release_all(info);
+}
+
+void coprocessor_flush_release_all(struct thread_info *ti)
+{
+	if (ti->cpenable) {
+		/* pairs with memw (2) in fast_coprocessor */
+		smp_rmb();
+		smp_call_function_single(ti->cp_owner_cpu,
+					 local_coprocessor_flush_release_all,
+					 ti, true);
+	}
 }
 
 #endif
@@ -140,8 +203,7 @@ void flush_thread(void)
 {
 #if XTENSA_HAVE_COPROCESSORS
 	struct thread_info *ti = current_thread_info();
-	coprocessor_flush_all(ti);
-	coprocessor_release_all(ti);
+	coprocessor_flush_release_all(ti);
 #endif
 	flush_ptrace_hw_breakpoint(current);
 }

arch/xtensa/kernel/ptrace.c

@@ -171,8 +171,7 @@ static int tie_set(struct task_struct *target,
 
 #if XTENSA_HAVE_COPROCESSORS
 	/* Flush all coprocessors before we overwrite them. */
-	coprocessor_flush_all(ti);
-	coprocessor_release_all(ti);
+	coprocessor_flush_release_all(ti);
 	ti->xtregs_cp.cp0 = newregs->cp0;
 	ti->xtregs_cp.cp1 = newregs->cp1;
 	ti->xtregs_cp.cp2 = newregs->cp2;

arch/xtensa/kernel/s32c1i_selftest.c

@@ -40,14 +40,13 @@ static inline int probed_compare_swap(int *v, int cmp, int set)
 
 /* Handle probed exception */
 
-static void __init do_probed_exception(struct pt_regs *regs,
-				       unsigned long exccause)
+static void __init do_probed_exception(struct pt_regs *regs)
 {
 	if (regs->pc == rcw_probe_pc) {	/* exception on s32c1i ? */
 		regs->pc += 3;		/* skip the s32c1i instruction */
-		rcw_exc = exccause;
+		rcw_exc = regs->exccause;
 	} else {
-		do_unhandled(regs, exccause);
+		do_unhandled(regs);
 	}
 }
 

arch/xtensa/kernel/signal.c

@@ -162,8 +162,7 @@ setup_sigcontext(struct rt_sigframe __user *frame, struct pt_regs *regs)
 		return err;
 
 #if XTENSA_HAVE_COPROCESSORS
-	coprocessor_flush_all(ti);
-	coprocessor_release_all(ti);
+	coprocessor_flush_release_all(ti);
 	err |= __copy_to_user(&frame->xtregs.cp, &ti->xtregs_cp,
 			      sizeof (frame->xtregs.cp));
 #endif

arch/xtensa/kernel/smp.c

@@ -30,6 +30,7 @@
 #include <linux/thread_info.h>
 
 #include <asm/cacheflush.h>
+#include <asm/coprocessor.h>
 #include <asm/kdebug.h>
 #include <asm/mmu_context.h>
 #include <asm/mxregs.h>
@@ -272,6 +273,12 @@ int __cpu_disable(void)
 	 */
 	set_cpu_online(cpu, false);
 
+#if XTENSA_HAVE_COPROCESSORS
+	/*
+	 * Flush coprocessor contexts that are active on the current CPU.
+	 */
+	local_coprocessors_flush_release_all();
+#endif
 	/*
 	 * OK - migrate IRQs away from this CPU
 	 */

arch/xtensa/kernel/traps.c

@@ -48,25 +48,20 @@
  * Machine specific interrupt handlers
  */
 
-extern void kernel_exception(void);
-extern void user_exception(void);
-
-extern void fast_illegal_instruction_user(void);
-extern void fast_syscall_user(void);
-extern void fast_alloca(void);
-extern void fast_unaligned(void);
-extern void fast_second_level_miss(void);
-extern void fast_store_prohibited(void);
-extern void fast_coprocessor(void);
-
-extern void do_illegal_instruction (struct pt_regs*);
-extern void do_interrupt (struct pt_regs*);
-extern void do_nmi(struct pt_regs *);
-extern void do_unaligned_user (struct pt_regs*);
-extern void do_multihit (struct pt_regs*, unsigned long);
-extern void do_page_fault (struct pt_regs*, unsigned long);
-extern void do_debug (struct pt_regs*);
-extern void system_call (struct pt_regs*);
+static void do_illegal_instruction(struct pt_regs *regs);
+static void do_div0(struct pt_regs *regs);
+static void do_interrupt(struct pt_regs *regs);
+#if XTENSA_FAKE_NMI
+static void do_nmi(struct pt_regs *regs);
+#endif
+#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
+static void do_unaligned_user(struct pt_regs *regs);
+#endif
+static void do_multihit(struct pt_regs *regs);
+#if XTENSA_HAVE_COPROCESSORS
+static void do_coprocessor(struct pt_regs *regs);
+#endif
+static void do_debug(struct pt_regs *regs);
 
 /*
  * The vector table must be preceded by a save area (which
@@ -78,7 +73,8 @@ extern void system_call (struct pt_regs*);
 #define USER		0x02
 
 #define COPROCESSOR(x)							\
-{ EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor }
+{ EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER|KRNL, fast_coprocessor },\
+{ EXCCAUSE_COPROCESSOR ## x ## _DISABLED, 0, do_coprocessor }
 
 typedef struct {
 	int cause;
@@ -100,7 +96,7 @@ static dispatch_init_table_t __initdata dispatch_init_table[] = {
 #ifdef SUPPORT_WINDOWED
 { EXCCAUSE_ALLOCA,		USER|KRNL, fast_alloca },
 #endif
-/* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
+{ EXCCAUSE_INTEGER_DIVIDE_BY_ZERO, 0,	   do_div0 },
 /* EXCCAUSE_PRIVILEGED unhandled */
 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 #ifdef CONFIG_XTENSA_UNALIGNED_USER
@@ -110,21 +106,21 @@ static dispatch_init_table_t __initdata dispatch_init_table[] = {
 { EXCCAUSE_UNALIGNED,		KRNL,	   fast_unaligned },
 #endif
 #ifdef CONFIG_MMU
-{ EXCCAUSE_ITLB_MISS,		0,	   do_page_fault },
-{ EXCCAUSE_ITLB_MISS,		USER|KRNL, fast_second_level_miss},
+{ EXCCAUSE_ITLB_MISS,			0,	   do_page_fault },
+{ EXCCAUSE_ITLB_MISS,			USER|KRNL, fast_second_level_miss},
+{ EXCCAUSE_DTLB_MISS,			USER|KRNL, fast_second_level_miss},
+{ EXCCAUSE_DTLB_MISS,			0,	   do_page_fault },
+{ EXCCAUSE_STORE_CACHE_ATTRIBUTE,	USER|KRNL, fast_store_prohibited },
+#endif /* CONFIG_MMU */
+#ifdef CONFIG_PFAULT
 { EXCCAUSE_ITLB_MULTIHIT,		0,	   do_multihit },
-{ EXCCAUSE_ITLB_PRIVILEGE,	0,	   do_page_fault },
-/* EXCCAUSE_SIZE_RESTRICTION unhandled */
+{ EXCCAUSE_ITLB_PRIVILEGE,		0,	   do_page_fault },
 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE,	0,	   do_page_fault },
-{ EXCCAUSE_DTLB_MISS,		USER|KRNL, fast_second_level_miss},
-{ EXCCAUSE_DTLB_MISS,		0,	   do_page_fault },
 { EXCCAUSE_DTLB_MULTIHIT,		0,	   do_multihit },
-{ EXCCAUSE_DTLB_PRIVILEGE,	0,	   do_page_fault },
-/* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
-{ EXCCAUSE_STORE_CACHE_ATTRIBUTE,	USER|KRNL, fast_store_prohibited },
+{ EXCCAUSE_DTLB_PRIVILEGE,		0,	   do_page_fault },
 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,	0,	   do_page_fault },
 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE,	0,	   do_page_fault },
-#endif /* CONFIG_MMU */
+#endif
 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
 #if XTENSA_HAVE_COPROCESSOR(0)
 COPROCESSOR(0),
@@ -179,7 +175,7 @@ __die_if_kernel(const char *str, struct pt_regs *regs, long err)
  * Unhandled Exceptions. Kill user task or panic if in kernel space.
  */
 
-void do_unhandled(struct pt_regs *regs, unsigned long exccause)
+void do_unhandled(struct pt_regs *regs)
 {
 	__die_if_kernel("Caught unhandled exception - should not happen",
 			regs, SIGKILL);
@@ -189,7 +185,7 @@ void do_unhandled(struct pt_regs *regs, unsigned long exccause)
 			    "(pid = %d, pc = %#010lx) - should not happen\n"
 			    "\tEXCCAUSE is %ld\n",
 			    current->comm, task_pid_nr(current), regs->pc,
-			    exccause);
+			    regs->exccause);
 	force_sig(SIGILL);
 }
 
@@ -197,7 +193,7 @@ void do_unhandled(struct pt_regs *regs, unsigned long exccause)
  * Multi-hit exception. This if fatal!
  */
 
-void do_multihit(struct pt_regs *regs, unsigned long exccause)
+static void do_multihit(struct pt_regs *regs)
 {
 	die("Caught multihit exception", regs, SIGKILL);
 }
@@ -206,8 +202,6 @@ void do_multihit(struct pt_regs *regs, unsigned long exccause)
  * IRQ handler.
  */
 
-extern void do_IRQ(int, struct pt_regs *);
-
 #if XTENSA_FAKE_NMI
 
 #define IS_POW2(v) (((v) & ((v) - 1)) == 0)
@@ -240,14 +234,10 @@ irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
 
 DEFINE_PER_CPU(unsigned long, nmi_count);
 
-void do_nmi(struct pt_regs *regs)
+static void do_nmi(struct pt_regs *regs)
 {
-	struct pt_regs *old_regs;
-
-	if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL)
-		trace_hardirqs_off();
+	struct pt_regs *old_regs = set_irq_regs(regs);
 
-	old_regs = set_irq_regs(regs);
 	nmi_enter();
 	++*this_cpu_ptr(&nmi_count);
 	check_valid_nmi();
@@ -257,7 +247,7 @@ void do_nmi(struct pt_regs *regs)
 }
 #endif
 
-void do_interrupt(struct pt_regs *regs)
+static void do_interrupt(struct pt_regs *regs)
 {
 	static const unsigned int_level_mask[] = {
 		0,
@@ -269,12 +259,9 @@ void do_interrupt(struct pt_regs *regs)
 		XCHAL_INTLEVEL6_MASK,
 		XCHAL_INTLEVEL7_MASK,
 	};
-	struct pt_regs *old_regs;
+	struct pt_regs *old_regs = set_irq_regs(regs);
 	unsigned unhandled = ~0u;
 
-	trace_hardirqs_off();
-
-	old_regs = set_irq_regs(regs);
 	irq_enter();
 
 	for (;;) {
@@ -306,13 +293,47 @@ void do_interrupt(struct pt_regs *regs)
 	set_irq_regs(old_regs);
 }
 
+static bool check_div0(struct pt_regs *regs)
+{
+	static const u8 pattern[] = {'D', 'I', 'V', '0'};
+	const u8 *p;
+	u8 buf[5];
+
+	if (user_mode(regs)) {
+		if (copy_from_user(buf, (void __user *)regs->pc + 2, 5))
+			return false;
+		p = buf;
+	} else {
+		p = (const u8 *)regs->pc + 2;
+	}
+
+	return memcmp(p, pattern, sizeof(pattern)) == 0 ||
+		memcmp(p + 1, pattern, sizeof(pattern)) == 0;
+}
+
 /*
  * Illegal instruction. Fatal if in kernel space.
  */
 
-void
-do_illegal_instruction(struct pt_regs *regs)
+static void do_illegal_instruction(struct pt_regs *regs)
 {
+#ifdef CONFIG_USER_ABI_CALL0_PROBE
+	/*
+	 * When call0 application encounters an illegal instruction fast
+	 * exception handler will attempt to set PS.WOE and retry failing
+	 * instruction.
+	 * If we get here we know that that instruction is also illegal
+	 * with PS.WOE set, so it's not related to the windowed option
+	 * hence PS.WOE may be cleared.
+	 */
+	if (regs->pc == current_thread_info()->ps_woe_fix_addr)
+		regs->ps &= ~PS_WOE_MASK;
+#endif
+	if (check_div0(regs)) {
+		do_div0(regs);
+		return;
+	}
+
 	__die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
 
 	/* If in user mode, send SIGILL signal to current process. */
@@ -322,6 +343,11 @@ do_illegal_instruction(struct pt_regs *regs)
 	force_sig(SIGILL);
 }
 
+static void do_div0(struct pt_regs *regs)
+{
+	__die_if_kernel("Unhandled division by 0 in kernel", regs, SIGKILL);
+	force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->pc);
+}
 
 /*
  * Handle unaligned memory accesses from user space. Kill task.
@@ -331,8 +357,7 @@ do_illegal_instruction(struct pt_regs *regs)
  */
 
 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
-void
-do_unaligned_user (struct pt_regs *regs)
+static void do_unaligned_user(struct pt_regs *regs)
 {
 	__die_if_kernel("Unhandled unaligned exception in kernel",
 			regs, SIGKILL);
@@ -347,14 +372,20 @@ do_unaligned_user (struct pt_regs *regs)
 }
 #endif
 
+#if XTENSA_HAVE_COPROCESSORS
+static void do_coprocessor(struct pt_regs *regs)
+{
+	coprocessor_flush_release_all(current_thread_info());
+}
+#endif
+
 /* Handle debug events.
  * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with
  * preemption disabled to avoid rescheduling and keep mapping of hardware
  * breakpoint structures to debug registers intact, so that
  * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit.
  */
-void
-do_debug(struct pt_regs *regs)
+static void do_debug(struct pt_regs *regs)
 {
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 	int ret = check_hw_breakpoint(regs);
@@ -381,7 +412,8 @@ do_debug(struct pt_regs *regs)
 
 /* Set exception C handler - for temporary use when probing exceptions */
 
-void * __init trap_set_handler(int cause, void *handler)
+xtensa_exception_handler *
+__init trap_set_handler(int cause, xtensa_exception_handler *handler)
 {
 	void *previous = per_cpu(exc_table, 0).default_handler[cause];
 
@@ -392,8 +424,7 @@ void * __init trap_set_handler(int cause, void *handler)
 
 static void trap_init_excsave(void)
 {
-	unsigned long excsave1 = (unsigned long)this_cpu_ptr(&exc_table);
-	__asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
+	xtensa_set_sr(this_cpu_ptr(&exc_table), excsave1);
 }
 
 static void trap_init_debug(void)

arch/xtensa/lib/Makefile

@@ -8,3 +8,5 @@ lib-y	+= memcopy.o memset.o checksum.o \
 	   divsi3.o udivsi3.o modsi3.o umodsi3.o mulsi3.o \
 	   usercopy.o strncpy_user.o strnlen_user.o
 lib-$(CONFIG_PCI) += pci-auto.o
+lib-$(CONFIG_KCSAN) += kcsan-stubs.o
+KCSAN_SANITIZE_kcsan-stubs.o := n

arch/xtensa/lib/kcsan-stubs.c

+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bug.h>
+#include <linux/types.h>
+
+void __atomic_store_8(volatile void *p, u64 v, int i)
+{
+	BUG();
+}
+
+u64 __atomic_load_8(const volatile void *p, int i)
+{
+	BUG();
+}
+
+u64 __atomic_exchange_8(volatile void *p, u64 v, int i)
+{
+	BUG();
+}
+
+bool __atomic_compare_exchange_8(volatile void *p1, void *p2, u64 v, bool b, int i1, int i2)
+{
+	BUG();
+}
+
+u64 __atomic_fetch_add_8(volatile void *p, u64 v, int i)
+{
+	BUG();
+}
+
+u64 __atomic_fetch_sub_8(volatile void *p, u64 v, int i)
+{
+	BUG();
+}
+
+u64 __atomic_fetch_and_8(volatile void *p, u64 v, int i)
+{
+	BUG();
+}
+
+u64 __atomic_fetch_or_8(volatile void *p, u64 v, int i)
+{
+	BUG();
+}
+
+u64 __atomic_fetch_xor_8(volatile void *p, u64 v, int i)
+{
+	BUG();
+}
+
+u64 __atomic_fetch_nand_8(volatile void *p, u64 v, int i)
+{
+	BUG();
+}

arch/xtensa/lib/memcopy.S

@@ -402,13 +402,13 @@ WEAK(memmove)
 	 */
 	# copy 16 bytes per iteration for word-aligned dst and word-aligned src
 #if XCHAL_HAVE_LOOPS
-	loopnez	a7, .backLoop1done
+	loopnez	a7, .LbackLoop1done
 #else /* !XCHAL_HAVE_LOOPS */
-	beqz	a7, .backLoop1done
+	beqz	a7, .LbackLoop1done
 	slli	a8, a7, 4
 	sub	a8, a3, a8	# a8 = start of first 16B source chunk
 #endif /* !XCHAL_HAVE_LOOPS */
-.backLoop1:
+.LbackLoop1:
 	addi	a3, a3, -16
 	l32i	a7, a3, 12
 	l32i	a6, a3,  8
@@ -420,9 +420,9 @@ WEAK(memmove)
 	s32i	a7, a5,  4
 	s32i	a6, a5,  0
 #if !XCHAL_HAVE_LOOPS
-	bne	a3, a8, .backLoop1  # continue loop if a3:src != a8:src_start
+	bne	a3, a8, .LbackLoop1  # continue loop if a3:src != a8:src_start
 #endif /* !XCHAL_HAVE_LOOPS */
-.backLoop1done:
+.LbackLoop1done:
 	bbci.l	a4, 3, .Lback2
 	# copy 8 bytes
 	addi	a3, a3, -8
@@ -479,13 +479,13 @@ WEAK(memmove)
 #endif
 	l32i	a6, a3, 0	# load first word
 #if XCHAL_HAVE_LOOPS
-	loopnez	a7, .backLoop2done
+	loopnez	a7, .LbackLoop2done
 #else /* !XCHAL_HAVE_LOOPS */
-	beqz	a7, .backLoop2done
+	beqz	a7, .LbackLoop2done
 	slli	a10, a7, 4
 	sub	a10, a3, a10	# a10 = start of first 16B source chunk
 #endif /* !XCHAL_HAVE_LOOPS */
-.backLoop2:
+.LbackLoop2:
 	addi	a3, a3, -16
 	l32i	a7, a3, 12
 	l32i	a8, a3,  8
@@ -501,9 +501,9 @@ WEAK(memmove)
 	__src_b	a9, a6, a9
 	s32i	a9, a5,  0
 #if !XCHAL_HAVE_LOOPS
-	bne	a3, a10, .backLoop2 # continue loop if a3:src != a10:src_start
+	bne	a3, a10, .LbackLoop2 # continue loop if a3:src != a10:src_start
 #endif /* !XCHAL_HAVE_LOOPS */
-.backLoop2done:
+.LbackLoop2done:
 	bbci.l	a4, 3, .Lback12
 	# copy 8 bytes
 	addi	a3, a3, -8

arch/xtensa/mm/Makefile

@@ -4,7 +4,8 @@
 #
 
 obj-y			:= init.o misc.o
-obj-$(CONFIG_MMU)	+= cache.o fault.o ioremap.o mmu.o tlb.o
+obj-$(CONFIG_PFAULT)	+= fault.o
+obj-$(CONFIG_MMU)	+= cache.o ioremap.o mmu.o tlb.o
 obj-$(CONFIG_HIGHMEM)	+= highmem.o
 obj-$(CONFIG_KASAN)	+= kasan_init.o
 

arch/xtensa/mm/fault.c

@@ -21,9 +21,61 @@
 #include <asm/cacheflush.h>
 #include <asm/hardirq.h>
 
-DEFINE_PER_CPU(unsigned long, asid_cache) = ASID_USER_FIRST;
 void bad_page_fault(struct pt_regs*, unsigned long, int);
 
+static void vmalloc_fault(struct pt_regs *regs, unsigned int address)
+{
+#ifdef CONFIG_MMU
+	/* Synchronize this task's top level page-table
+	 * with the 'reference' page table.
+	 */
+	struct mm_struct *act_mm = current->active_mm;
+	int index = pgd_index(address);
+	pgd_t *pgd, *pgd_k;
+	p4d_t *p4d, *p4d_k;
+	pud_t *pud, *pud_k;
+	pmd_t *pmd, *pmd_k;
+	pte_t *pte_k;
+
+	if (act_mm == NULL)
+		goto bad_page_fault;
+
+	pgd = act_mm->pgd + index;
+	pgd_k = init_mm.pgd + index;
+
+	if (!pgd_present(*pgd_k))
+		goto bad_page_fault;
+
+	pgd_val(*pgd) = pgd_val(*pgd_k);
+
+	p4d = p4d_offset(pgd, address);
+	p4d_k = p4d_offset(pgd_k, address);
+	if (!p4d_present(*p4d) || !p4d_present(*p4d_k))
+		goto bad_page_fault;
+
+	pud = pud_offset(p4d, address);
+	pud_k = pud_offset(p4d_k, address);
+	if (!pud_present(*pud) || !pud_present(*pud_k))
+		goto bad_page_fault;
+
+	pmd = pmd_offset(pud, address);
+	pmd_k = pmd_offset(pud_k, address);
+	if (!pmd_present(*pmd) || !pmd_present(*pmd_k))
+		goto bad_page_fault;
+
+	pmd_val(*pmd) = pmd_val(*pmd_k);
+	pte_k = pte_offset_kernel(pmd_k, address);
+
+	if (!pte_present(*pte_k))
+		goto bad_page_fault;
+	return;
+
+bad_page_fault:
+	bad_page_fault(regs, address, SIGKILL);
+#else
+	WARN_ONCE(1, "%s in noMMU configuration\n", __func__);
+#endif
+}
 /*
  * This routine handles page faults.  It determines the address,
  * and the problem, and then passes it off to one of the appropriate
@@ -49,8 +101,10 @@ void do_page_fault(struct pt_regs *regs)
 	/* We fault-in kernel-space virtual memory on-demand. The
 	 * 'reference' page table is init_mm.pgd.
 	 */
-	if (address >= TASK_SIZE && !user_mode(regs))
-		goto vmalloc_fault;
+	if (address >= TASK_SIZE && !user_mode(regs)) {
+		vmalloc_fault(regs, address);
+		return;
+	}
 
 	/* If we're in an interrupt or have no user
 	 * context, we must not take the fault..
@@ -114,7 +168,7 @@ void do_page_fault(struct pt_regs *regs)
 
 	if (fault_signal_pending(fault, regs)) {
 		if (!user_mode(regs))
-			goto bad_page_fault;
+			bad_page_fault(regs, address, SIGKILL);
 		return;
 	}
 
@@ -181,56 +235,6 @@ void do_page_fault(struct pt_regs *regs)
 	if (!user_mode(regs))
 		bad_page_fault(regs, address, SIGBUS);
 	return;
-
-vmalloc_fault:
-	{
-		/* Synchronize this task's top level page-table
-		 * with the 'reference' page table.
-		 */
-		struct mm_struct *act_mm = current->active_mm;
-		int index = pgd_index(address);
-		pgd_t *pgd, *pgd_k;
-		p4d_t *p4d, *p4d_k;
-		pud_t *pud, *pud_k;
-		pmd_t *pmd, *pmd_k;
-		pte_t *pte_k;
-
-		if (act_mm == NULL)
-			goto bad_page_fault;
-
-		pgd = act_mm->pgd + index;
-		pgd_k = init_mm.pgd + index;
-
-		if (!pgd_present(*pgd_k))
-			goto bad_page_fault;
-
-		pgd_val(*pgd) = pgd_val(*pgd_k);
-
-		p4d = p4d_offset(pgd, address);
-		p4d_k = p4d_offset(pgd_k, address);
-		if (!p4d_present(*p4d) || !p4d_present(*p4d_k))
-			goto bad_page_fault;
-
-		pud = pud_offset(p4d, address);
-		pud_k = pud_offset(p4d_k, address);
-		if (!pud_present(*pud) || !pud_present(*pud_k))
-			goto bad_page_fault;
-
-		pmd = pmd_offset(pud, address);
-		pmd_k = pmd_offset(pud_k, address);
-		if (!pmd_present(*pmd) || !pmd_present(*pmd_k))
-			goto bad_page_fault;
-
-		pmd_val(*pmd) = pmd_val(*pmd_k);
-		pte_k = pte_offset_kernel(pmd_k, address);
-
-		if (!pte_present(*pte_k))
-			goto bad_page_fault;
-		return;
-	}
-bad_page_fault:
-	bad_page_fault(regs, address, SIGKILL);
-	return;
 }
 
 

arch/xtensa/mm/mmu.c

@@ -18,6 +18,8 @@
 #include <asm/initialize_mmu.h>
 #include <asm/io.h>
 
+DEFINE_PER_CPU(unsigned long, asid_cache) = ASID_USER_FIRST;
+
 #if defined(CONFIG_HIGHMEM)
 static void * __init init_pmd(unsigned long vaddr, unsigned long n_pages)
 {

arch/xtensa/platforms/iss/network.c

@@ -38,9 +38,6 @@
 #define ISS_NET_TIMER_VALUE (HZ / 10)
 
 
-static DEFINE_SPINLOCK(opened_lock);
-static LIST_HEAD(opened);
-
 static DEFINE_SPINLOCK(devices_lock);
 static LIST_HEAD(devices);
 
@@ -59,17 +56,27 @@ struct tuntap_info {
 /* ------------------------------------------------------------------------- */
 
 
+struct iss_net_private;
+
+struct iss_net_ops {
+	int (*open)(struct iss_net_private *lp);
+	void (*close)(struct iss_net_private *lp);
+	int (*read)(struct iss_net_private *lp, struct sk_buff **skb);
+	int (*write)(struct iss_net_private *lp, struct sk_buff **skb);
+	unsigned short (*protocol)(struct sk_buff *skb);
+	int (*poll)(struct iss_net_private *lp);
+};
+
 /* This structure contains out private information for the driver. */
 
 struct iss_net_private {
 	struct list_head device_list;
-	struct list_head opened_list;
 
 	spinlock_t lock;
 	struct net_device *dev;
 	struct platform_device pdev;
 	struct timer_list tl;
-	struct net_device_stats stats;
+	struct rtnl_link_stats64 stats;
 
 	struct timer_list timer;
 	unsigned int timer_val;
@@ -82,12 +89,7 @@ struct iss_net_private {
 			struct tuntap_info tuntap;
 		} info;
 
-		int (*open)(struct iss_net_private *lp);
-		void (*close)(struct iss_net_private *lp);
-		int (*read)(struct iss_net_private *lp, struct sk_buff **skb);
-		int (*write)(struct iss_net_private *lp, struct sk_buff **skb);
-		unsigned short (*protocol)(struct sk_buff *skb);
-		int (*poll)(struct iss_net_private *lp);
+		const struct iss_net_ops *net_ops;
 	} tp;
 
 };
@@ -215,6 +217,15 @@ static int tuntap_poll(struct iss_net_private *lp)
 	return simc_poll(lp->tp.info.tuntap.fd);
 }
 
+static const struct iss_net_ops tuntap_ops = {
+	.open		= tuntap_open,
+	.close		= tuntap_close,
+	.read		= tuntap_read,
+	.write		= tuntap_write,
+	.protocol	= tuntap_protocol,
+	.poll		= tuntap_poll,
+};
+
 /*
  * ethX=tuntap,[mac address],device name
  */
@@ -257,13 +268,7 @@ static int tuntap_probe(struct iss_net_private *lp, int index, char *init)
 	lp->mtu = TRANSPORT_TUNTAP_MTU;
 
 	lp->tp.info.tuntap.fd = -1;
-
-	lp->tp.open = tuntap_open;
-	lp->tp.close = tuntap_close;
-	lp->tp.read = tuntap_read;
-	lp->tp.write = tuntap_write;
-	lp->tp.protocol = tuntap_protocol;
-	lp->tp.poll = tuntap_poll;
+	lp->tp.net_ops = &tuntap_ops;
 
 	return 1;
 }
@@ -278,14 +283,16 @@ static int iss_net_rx(struct net_device *dev)
 
 	/* Check if there is any new data. */
 
-	if (lp->tp.poll(lp) == 0)
+	if (lp->tp.net_ops->poll(lp) == 0)
 		return 0;
 
 	/* Try to allocate memory, if it fails, try again next round. */
 
 	skb = dev_alloc_skb(dev->mtu + 2 + ETH_HEADER_OTHER);
 	if (skb == NULL) {
+		spin_lock_bh(&lp->lock);
 		lp->stats.rx_dropped++;
+		spin_unlock_bh(&lp->lock);
 		return 0;
 	}
 
@@ -295,15 +302,17 @@ static int iss_net_rx(struct net_device *dev)
 
 	skb->dev = dev;
 	skb_reset_mac_header(skb);
-	pkt_len = lp->tp.read(lp, &skb);
+	pkt_len = lp->tp.net_ops->read(lp, &skb);
 	skb_put(skb, pkt_len);
 
 	if (pkt_len > 0) {
 		skb_trim(skb, pkt_len);
-		skb->protocol = lp->tp.protocol(skb);
+		skb->protocol = lp->tp.net_ops->protocol(skb);
 
+		spin_lock_bh(&lp->lock);
 		lp->stats.rx_bytes += skb->len;
 		lp->stats.rx_packets++;
+		spin_unlock_bh(&lp->lock);
 		netif_rx(skb);
 		return pkt_len;
 	}
@@ -311,38 +320,24 @@ static int iss_net_rx(struct net_device *dev)
 	return pkt_len;
 }
 
-static int iss_net_poll(void)
+static int iss_net_poll(struct iss_net_private *lp)
 {
-	struct list_head *ele;
 	int err, ret = 0;
 
-	spin_lock(&opened_lock);
-
-	list_for_each(ele, &opened) {
-		struct iss_net_private *lp;
-
-		lp = list_entry(ele, struct iss_net_private, opened_list);
-
-		if (!netif_running(lp->dev))
-			break;
-
-		spin_lock(&lp->lock);
-
-		while ((err = iss_net_rx(lp->dev)) > 0)
-			ret++;
+	if (!netif_running(lp->dev))
+		return 0;
 
-		spin_unlock(&lp->lock);
+	while ((err = iss_net_rx(lp->dev)) > 0)
+		ret++;
 
-		if (err < 0) {
-			pr_err("Device '%s' read returned %d, shutting it down\n",
-			       lp->dev->name, err);
-			dev_close(lp->dev);
-		} else {
-			/* FIXME reactivate_fd(lp->fd, ISS_ETH_IRQ); */
-		}
+	if (err < 0) {
+		pr_err("Device '%s' read returned %d, shutting it down\n",
+		       lp->dev->name, err);
+		dev_close(lp->dev);
+	} else {
+		/* FIXME reactivate_fd(lp->fd, ISS_ETH_IRQ); */
 	}
 
-	spin_unlock(&opened_lock);
 	return ret;
 }
 
@@ -351,10 +346,8 @@ static void iss_net_timer(struct timer_list *t)
 {
 	struct iss_net_private *lp = from_timer(lp, t, timer);
 
-	iss_net_poll();
-	spin_lock(&lp->lock);
+	iss_net_poll(lp);
 	mod_timer(&lp->timer, jiffies + lp->timer_val);
-	spin_unlock(&lp->lock);
 }
 
 
@@ -363,11 +356,9 @@ static int iss_net_open(struct net_device *dev)
 	struct iss_net_private *lp = netdev_priv(dev);
 	int err;
 
-	spin_lock_bh(&lp->lock);
-
-	err = lp->tp.open(lp);
+	err = lp->tp.net_ops->open(lp);
 	if (err < 0)
-		goto out;
+		return err;
 
 	netif_start_queue(dev);
 
@@ -378,36 +369,21 @@ static int iss_net_open(struct net_device *dev)
 	while ((err = iss_net_rx(dev)) > 0)
 		;
 
-	spin_unlock_bh(&lp->lock);
-	spin_lock_bh(&opened_lock);
-	list_add(&lp->opened_list, &opened);
-	spin_unlock_bh(&opened_lock);
-	spin_lock_bh(&lp->lock);
-
 	timer_setup(&lp->timer, iss_net_timer, 0);
 	lp->timer_val = ISS_NET_TIMER_VALUE;
 	mod_timer(&lp->timer, jiffies + lp->timer_val);
 
-out:
-	spin_unlock_bh(&lp->lock);
 	return err;
 }
 
 static int iss_net_close(struct net_device *dev)
 {
 	struct iss_net_private *lp = netdev_priv(dev);
-	netif_stop_queue(dev);
-	spin_lock_bh(&lp->lock);
-
-	spin_lock(&opened_lock);
-	list_del(&opened);
-	spin_unlock(&opened_lock);
 
+	netif_stop_queue(dev);
 	del_timer_sync(&lp->timer);
+	lp->tp.net_ops->close(lp);
 
-	lp->tp.close(lp);
-
-	spin_unlock_bh(&lp->lock);
 	return 0;
 }
 
@@ -417,13 +393,14 @@ static int iss_net_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	int len;
 
 	netif_stop_queue(dev);
-	spin_lock_bh(&lp->lock);
 
-	len = lp->tp.write(lp, &skb);
+	len = lp->tp.net_ops->write(lp, &skb);
 
 	if (len == skb->len) {
+		spin_lock_bh(&lp->lock);
 		lp->stats.tx_packets++;
 		lp->stats.tx_bytes += skb->len;
+		spin_unlock_bh(&lp->lock);
 		netif_trans_update(dev);
 		netif_start_queue(dev);
 
@@ -432,24 +409,29 @@ static int iss_net_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	} else if (len == 0) {
 		netif_start_queue(dev);
+		spin_lock_bh(&lp->lock);
 		lp->stats.tx_dropped++;
+		spin_unlock_bh(&lp->lock);
 
 	} else {
 		netif_start_queue(dev);
 		pr_err("%s: %s failed(%d)\n", dev->name, __func__, len);
 	}
 
-	spin_unlock_bh(&lp->lock);
 
 	dev_kfree_skb(skb);
 	return NETDEV_TX_OK;
 }
 
 
-static struct net_device_stats *iss_net_get_stats(struct net_device *dev)
+static void iss_net_get_stats64(struct net_device *dev,
+				struct rtnl_link_stats64 *stats)
 {
 	struct iss_net_private *lp = netdev_priv(dev);
-	return &lp->stats;
+
+	spin_lock_bh(&lp->lock);
+	*stats = lp->stats;
+	spin_unlock_bh(&lp->lock);
 }
 
 static void iss_net_set_multicast_list(struct net_device *dev)
@@ -460,19 +442,6 @@ static void iss_net_tx_timeout(struct net_device *dev, unsigned int txqueue)
 {
 }
 
-static int iss_net_set_mac(struct net_device *dev, void *addr)
-{
-	struct iss_net_private *lp = netdev_priv(dev);
-	struct sockaddr *hwaddr = addr;
-
-	if (!is_valid_ether_addr(hwaddr->sa_data))
-		return -EADDRNOTAVAIL;
-	spin_lock_bh(&lp->lock);
-	eth_hw_addr_set(dev, hwaddr->sa_data);
-	spin_unlock_bh(&lp->lock);
-	return 0;
-}
-
 static int iss_net_change_mtu(struct net_device *dev, int new_mtu)
 {
 	return -EINVAL;
@@ -494,11 +463,11 @@ static int driver_registered;
 static const struct net_device_ops iss_netdev_ops = {
 	.ndo_open		= iss_net_open,
 	.ndo_stop		= iss_net_close,
-	.ndo_get_stats		= iss_net_get_stats,
+	.ndo_get_stats64	= iss_net_get_stats64,
 	.ndo_start_xmit		= iss_net_start_xmit,
 	.ndo_validate_addr	= eth_validate_addr,
 	.ndo_change_mtu		= iss_net_change_mtu,
-	.ndo_set_mac_address	= iss_net_set_mac,
+	.ndo_set_mac_address	= eth_mac_addr,
 	.ndo_tx_timeout		= iss_net_tx_timeout,
 	.ndo_set_rx_mode	= iss_net_set_multicast_list,
 };
@@ -520,7 +489,6 @@ static int iss_net_configure(int index, char *init)
 	lp = netdev_priv(dev);
 	*lp = (struct iss_net_private) {
 		.device_list		= LIST_HEAD_INIT(lp->device_list),
-		.opened_list		= LIST_HEAD_INIT(lp->opened_list),
 		.dev			= dev,
 		.index			= index,
 	};

arch/xtensa/platforms/iss/simdisk.c

@@ -211,12 +211,18 @@ static ssize_t proc_read_simdisk(struct file *file, char __user *buf,
 	struct simdisk *dev = pde_data(file_inode(file));
 	const char *s = dev->filename;
 	if (s) {
-		ssize_t n = simple_read_from_buffer(buf, size, ppos,
-							s, strlen(s));
-		if (n < 0)
-			return n;
-		buf += n;
-		size -= n;
+		ssize_t len = strlen(s);
+		char *temp = kmalloc(len + 2, GFP_KERNEL);
+
+		if (!temp)
+			return -ENOMEM;
+
+		len = scnprintf(temp, len + 2, "%s\n", s);
+		len = simple_read_from_buffer(buf, size, ppos,
+					      temp, len);
+
+		kfree(temp);
+		return len;
 	}
 	return simple_read_from_buffer(buf, size, ppos, "\n", 1);
 }

arch/xtensa/platforms/xt2000/setup.c

@@ -78,7 +78,7 @@ void __init platform_init(bp_tag_t *first)
 
 void platform_heartbeat(void)
 {
-	static int i=0, t = 0;
+	static int i, t;
 
 	if (--t < 0)
 	{