x86 user stack frame reads: switch to explicit __get_user()

rather than relying upon the magic in raw_copy_from_user()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 7 insertions, 20 deletions

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 3bb738f5a472..a619763e96e1 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2490,7 +2490,7 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent
 	/* 32-bit process in 64-bit kernel. */
 	unsigned long ss_base, cs_base;
 	struct stack_frame_ia32 frame;
-	const void __user *fp;
+	const struct stack_frame_ia32 __user *fp;
 
 	if (!test_thread_flag(TIF_IA32))
 		return 0;
@@ -2501,18 +2501,12 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent
 	fp = compat_ptr(ss_base + regs->bp);
 	pagefault_disable();
 	while (entry->nr < entry->max_stack) {
-		unsigned long bytes;
-		frame.next_frame     = 0;
-		frame.return_address = 0;
-
 		if (!valid_user_frame(fp, sizeof(frame)))
 			break;
 
-		bytes = __copy_from_user_nmi(&frame.next_frame, fp, 4);
-		if (bytes != 0)
+		if (__get_user(frame.next_frame, &fp->next_frame))
 			break;
-		bytes = __copy_from_user_nmi(&frame.return_address, fp+4, 4);
-		if (bytes != 0)
+		if (__get_user(frame.return_address, &fp->return_address))
 			break;
 
 		perf_callchain_store(entry, cs_base + frame.return_address);
@@ -2533,7 +2527,7 @@ void
 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
 	struct stack_frame frame;
-	const unsigned long __user *fp;
+	const struct stack_frame __user *fp;
 
 	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
 		/* TODO: We don't support guest os callchain now */
@@ -2546,7 +2540,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
 	if (regs->flags & (X86_VM_MASK | PERF_EFLAGS_VM))
 		return;
 
-	fp = (unsigned long __user *)regs->bp;
+	fp = (void __user *)regs->bp;
 
 	perf_callchain_store(entry, regs->ip);
 
@@ -2558,19 +2552,12 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
 
 	pagefault_disable();
 	while (entry->nr < entry->max_stack) {
-		unsigned long bytes;
-
-		frame.next_frame	     = NULL;
-		frame.return_address = 0;
-
 		if (!valid_user_frame(fp, sizeof(frame)))
 			break;
 
-		bytes = __copy_from_user_nmi(&frame.next_frame, fp, sizeof(*fp));
-		if (bytes != 0)
+		if (__get_user(frame.next_frame, &fp->next_frame))
 			break;
-		bytes = __copy_from_user_nmi(&frame.return_address, fp + 1, sizeof(*fp));
-		if (bytes != 0)
+		if (__get_user(frame.return_address, &fp->return_address))
 			break;
 
 		perf_callchain_store(entry, frame.return_address);