1 /**
2 * @file backtrace.c
3 *
4 * @remark Copyright 2002 OProfile authors
5 * @remark Read the file COPYING
6 *
7 * @author John Levon
8 * @author David Smith
9 */
10
11 #include <linux/oprofile.h>
12 #include <linux/sched.h>
13 #include <linux/mm.h>
14 #include <asm/ptrace.h>
15 #include <asm/uaccess.h>
16 #include <asm/stacktrace.h>
17
backtrace_warning_symbol(void * data,char * msg,unsigned long symbol)18 static void backtrace_warning_symbol(void *data, char *msg,
19 unsigned long symbol)
20 {
21 /* Ignore warnings */
22 }
23
backtrace_warning(void * data,char * msg)24 static void backtrace_warning(void *data, char *msg)
25 {
26 /* Ignore warnings */
27 }
28
backtrace_stack(void * data,char * name)29 static int backtrace_stack(void *data, char *name)
30 {
31 /* Yes, we want all stacks */
32 return 0;
33 }
34
backtrace_address(void * data,unsigned long addr,int reliable)35 static void backtrace_address(void *data, unsigned long addr, int reliable)
36 {
37 unsigned int *depth = data;
38
39 if ((*depth)--)
40 oprofile_add_trace(addr);
41 }
42
43 static struct stacktrace_ops backtrace_ops = {
44 .warning = backtrace_warning,
45 .warning_symbol = backtrace_warning_symbol,
46 .stack = backtrace_stack,
47 .address = backtrace_address,
48 };
49
50 struct frame_head {
51 struct frame_head *bp;
52 unsigned long ret;
53 } __attribute__((packed));
54
dump_user_backtrace(struct frame_head * head)55 static struct frame_head *dump_user_backtrace(struct frame_head *head)
56 {
57 struct frame_head bufhead[2];
58
59 /* Also check accessibility of one struct frame_head beyond */
60 if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
61 return NULL;
62 if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
63 return NULL;
64
65 oprofile_add_trace(bufhead[0].ret);
66
67 /* frame pointers should strictly progress back up the stack
68 * (towards higher addresses) */
69 if (head >= bufhead[0].bp)
70 return NULL;
71
72 return bufhead[0].bp;
73 }
74
75 void
x86_backtrace(struct pt_regs * const regs,unsigned int depth)76 x86_backtrace(struct pt_regs * const regs, unsigned int depth)
77 {
78 struct frame_head *head = (struct frame_head *)frame_pointer(regs);
79 unsigned long stack = kernel_trap_sp(regs);
80
81 if (!user_mode_vm(regs)) {
82 if (depth)
83 dump_trace(NULL, regs, (unsigned long *)stack, 0,
84 &backtrace_ops, &depth);
85 return;
86 }
87
88 while (depth-- && head)
89 head = dump_user_backtrace(head);
90 }
91