1 files changed, 53 insertions, 0 deletions

diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c
index d640a86198b1..2d49d4e19a36 100644
--- a/arch/x86/oprofile/backtrace.c
+++ b/arch/x86/oprofile/backtrace.c
@@ -14,6 +14,7 @@
 #include <asm/ptrace.h>
 #include <asm/uaccess.h>
 #include <asm/stacktrace.h>
+#include <linux/compat.h>
 
 static void backtrace_warning_symbol(void *data, char *msg,
                                      unsigned long symbol)
@@ -48,6 +49,55 @@ static struct stacktrace_ops backtrace_ops = {
         .walk_stack     = print_context_stack,
 };
 
+#ifdef CONFIG_COMPAT
+static struct stack_frame_ia32 *
+dump_user_backtrace_32(struct stack_frame_ia32 *head)
+{
+        struct stack_frame_ia32 bufhead[2];
+        struct stack_frame_ia32 *fp;
+
+        /* Also check accessibility of one struct frame_head beyond */
+        if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
+                return NULL;
+        if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
+                return NULL;
+
+        fp = (struct stack_frame_ia32 *) compat_ptr(bufhead[0].next_frame);
+
+        oprofile_add_trace(bufhead[0].return_address);
+
+        /* frame pointers should strictly progress back up the stack
+        * (towards higher addresses) */
+        if (head >= fp)
+                return NULL;
+
+        return fp;
+}
+
+static inline int
+x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
+{
+        struct stack_frame_ia32 *head;
+
+        /* User process is 32-bit */
+        if (!current || !test_thread_flag(TIF_IA32))
+                return 0;
+
+        head = (struct stack_frame_ia32 *) regs->bp;
+        while (depth-- && head)
+                head = dump_user_backtrace_32(head);
+
+        return 1;
+}
+
+#else
+static inline int
+x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
+{
+        return 0;
+}
+#endif /* CONFIG_COMPAT */
+
 static struct stack_frame *dump_user_backtrace(struct stack_frame *head)
 {
         struct stack_frame bufhead[2];
@@ -81,6 +131,9 @@ x86_backtrace(struct pt_regs * const regs, unsigned int depth)
                 return;
         }
 
+        if (x86_backtrace_32(regs, depth))
+                return;
+
         while (depth-- && head)
                 head = dump_user_backtrace(head);
 }