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authorTong Li <tong.n.li@intel.com>2006-02-03 06:04:09 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-03 11:32:04 -0500
commit23332c2e9da16b717f18fd95bc90211a663aa6ee (patch)
tree873e445688472fd1726c0e48113f63a585d03b39
parent8145916996b91d42b8bb4b0fcd508af295222c7c (diff)
[PATCH] OProfile: fixed x86_64 incorrect kernel call graphs
Fix the problem in kernel 2.6.15.1 (and early versions) that OProfile on x86_64 does not correctly collect the stack traces for kernel functions. The original code in valid_kernel_stack() in arch/i386/oprofile/backtrace.c assumes that the frame pointer (headaddr) should be greater than stack (i.e., regs). This assumption is wrong for x86_64 because NMIs in x86_64 use a seperate stack different from the kernel stack. Therefore, the variable stack now points to some location on the NMI stack, which turns out to be at a higher address than the frame pointer (headaddr) on the kernel stack. The correct comparison here should be between headaddr and regs->rsp for x86_64. Signed-off-by: Tong Li <tong.n.li@intel.com> Cc: John Levon <levon@movementarian.org> Cc: Philippe Elie <phil.el@wanadoo.fr> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--arch/i386/oprofile/backtrace.c19
1 files changed, 17 insertions, 2 deletions
diff --git a/arch/i386/oprofile/backtrace.c b/arch/i386/oprofile/backtrace.c
index 21654be3f73f..acc18138fb22 100644
--- a/arch/i386/oprofile/backtrace.c
+++ b/arch/i386/oprofile/backtrace.c
@@ -49,7 +49,9 @@ dump_backtrace(struct frame_head * head)
49 * | stack | 49 * | stack |
50 * --------------- saved regs->ebp value if valid (frame_head address) 50 * --------------- saved regs->ebp value if valid (frame_head address)
51 * . . 51 * . .
52 * --------------- struct pt_regs stored on stack (struct pt_regs *) 52 * --------------- saved regs->rsp value if x86_64
53 * | |
54 * --------------- struct pt_regs * stored on stack if 32-bit
53 * | | 55 * | |
54 * . . 56 * . .
55 * | | 57 * | |
@@ -57,13 +59,26 @@ dump_backtrace(struct frame_head * head)
57 * | | 59 * | |
58 * | | \/ Lower addresses 60 * | | \/ Lower addresses
59 * 61 *
60 * Thus, &pt_regs <-> stack base restricts the valid(ish) ebp values 62 * Thus, regs (or regs->rsp for x86_64) <-> stack base restricts the
63 * valid(ish) ebp values. Note: (1) for x86_64, NMI and several other
64 * exceptions use special stacks, maintained by the interrupt stack table
65 * (IST). These stacks are set up in trap_init() in
66 * arch/x86_64/kernel/traps.c. Thus, for x86_64, regs now does not point
67 * to the kernel stack; instead, it points to some location on the NMI
68 * stack. On the other hand, regs->rsp is the stack pointer saved when the
69 * NMI occurred. (2) For 32-bit, regs->esp is not valid because the
70 * processor does not save %esp on the kernel stack when interrupts occur
71 * in the kernel mode.
61 */ 72 */
62#ifdef CONFIG_FRAME_POINTER 73#ifdef CONFIG_FRAME_POINTER
63static int valid_kernel_stack(struct frame_head * head, struct pt_regs * regs) 74static int valid_kernel_stack(struct frame_head * head, struct pt_regs * regs)
64{ 75{
65 unsigned long headaddr = (unsigned long)head; 76 unsigned long headaddr = (unsigned long)head;
77#ifdef CONFIG_X86_64
78 unsigned long stack = (unsigned long)regs->rsp;
79#else
66 unsigned long stack = (unsigned long)regs; 80 unsigned long stack = (unsigned long)regs;
81#endif
67 unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE; 82 unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE;
68 83
69 return headaddr > stack && headaddr < stack_base; 84 return headaddr > stack && headaddr < stack_base;