23332c2e9d
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>
115 lines
3.0 KiB
C
115 lines
3.0 KiB
C
/**
|
|
* @file backtrace.c
|
|
*
|
|
* @remark Copyright 2002 OProfile authors
|
|
* @remark Read the file COPYING
|
|
*
|
|
* @author John Levon
|
|
* @author David Smith
|
|
*/
|
|
|
|
#include <linux/oprofile.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/mm.h>
|
|
#include <asm/ptrace.h>
|
|
#include <asm/uaccess.h>
|
|
|
|
struct frame_head {
|
|
struct frame_head * ebp;
|
|
unsigned long ret;
|
|
} __attribute__((packed));
|
|
|
|
static struct frame_head *
|
|
dump_backtrace(struct frame_head * head)
|
|
{
|
|
struct frame_head bufhead[2];
|
|
|
|
/* 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;
|
|
|
|
oprofile_add_trace(bufhead[0].ret);
|
|
|
|
/* frame pointers should strictly progress back up the stack
|
|
* (towards higher addresses) */
|
|
if (head >= bufhead[0].ebp)
|
|
return NULL;
|
|
|
|
return bufhead[0].ebp;
|
|
}
|
|
|
|
/*
|
|
* | | /\ Higher addresses
|
|
* | |
|
|
* --------------- stack base (address of current_thread_info)
|
|
* | thread info |
|
|
* . .
|
|
* | stack |
|
|
* --------------- saved regs->ebp value if valid (frame_head address)
|
|
* . .
|
|
* --------------- saved regs->rsp value if x86_64
|
|
* | |
|
|
* --------------- struct pt_regs * stored on stack if 32-bit
|
|
* | |
|
|
* . .
|
|
* | |
|
|
* --------------- %esp
|
|
* | |
|
|
* | | \/ Lower addresses
|
|
*
|
|
* Thus, regs (or regs->rsp for x86_64) <-> stack base restricts the
|
|
* valid(ish) ebp values. Note: (1) for x86_64, NMI and several other
|
|
* exceptions use special stacks, maintained by the interrupt stack table
|
|
* (IST). These stacks are set up in trap_init() in
|
|
* arch/x86_64/kernel/traps.c. Thus, for x86_64, regs now does not point
|
|
* to the kernel stack; instead, it points to some location on the NMI
|
|
* stack. On the other hand, regs->rsp is the stack pointer saved when the
|
|
* NMI occurred. (2) For 32-bit, regs->esp is not valid because the
|
|
* processor does not save %esp on the kernel stack when interrupts occur
|
|
* in the kernel mode.
|
|
*/
|
|
#ifdef CONFIG_FRAME_POINTER
|
|
static int valid_kernel_stack(struct frame_head * head, struct pt_regs * regs)
|
|
{
|
|
unsigned long headaddr = (unsigned long)head;
|
|
#ifdef CONFIG_X86_64
|
|
unsigned long stack = (unsigned long)regs->rsp;
|
|
#else
|
|
unsigned long stack = (unsigned long)regs;
|
|
#endif
|
|
unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE;
|
|
|
|
return headaddr > stack && headaddr < stack_base;
|
|
}
|
|
#else
|
|
/* without fp, it's just junk */
|
|
static int valid_kernel_stack(struct frame_head * head, struct pt_regs * regs)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
|
|
void
|
|
x86_backtrace(struct pt_regs * const regs, unsigned int depth)
|
|
{
|
|
struct frame_head *head;
|
|
|
|
#ifdef CONFIG_X86_64
|
|
head = (struct frame_head *)regs->rbp;
|
|
#else
|
|
head = (struct frame_head *)regs->ebp;
|
|
#endif
|
|
|
|
if (!user_mode_vm(regs)) {
|
|
while (depth-- && valid_kernel_stack(head, regs))
|
|
head = dump_backtrace(head);
|
|
return;
|
|
}
|
|
|
|
while (depth-- && head)
|
|
head = dump_backtrace(head);
|
|
}
|