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i386: make callgraph use dump_trace() on i386/x86_64

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This patch improves oprofile callgraphs for i386/x86_64. The old
backtracing code was unable to produce kernel backtraces if the
kernel wasn't compiled with framepointers. The code now uses
dump_trace().

[ tglx: arch/x86 adaptation ]

Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Jan Blunck 2007-10-19 20:35:03 +02:00 committed by Thomas Gleixner
parent 9480626830
commit 574a60421c
1 changed files with 40 additions and 68 deletions
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108
arch/x86/oprofile/backtrace.c
View file

@ -13,25 +13,45 @@
#include <linux/mm.h>
#include <asm/ptrace.h>
#include <asm/uaccess.h>
#include <asm/stacktrace.h>
static void backtrace_warning_symbol(void *data, char *msg,
unsigned long symbol)
{
/* Ignore warnings */
}
static void backtrace_warning(void *data, char *msg)
{
/* Ignore warnings */
}
static int backtrace_stack(void *data, char *name)
{
/* Yes, we want all stacks */
return 0;
}
static void backtrace_address(void *data, unsigned long addr)
{
unsigned int *depth = data;
if ((*depth)--)
oprofile_add_trace(addr);
}
static struct stacktrace_ops backtrace_ops = {
.warning = backtrace_warning,
.warning_symbol = backtrace_warning_symbol,
.stack = backtrace_stack,
.address = backtrace_address,
};
struct frame_head {
struct frame_head * ebp;
struct frame_head *ebp;
unsigned long ret;
} __attribute__((packed));
static struct frame_head *
dump_kernel_backtrace(struct frame_head * head)
{
oprofile_add_trace(head->ret);
/* frame pointers should strictly progress back up the stack
* (towards higher addresses) */
if (head >= head->ebp)
return NULL;
return head->ebp;
}
static struct frame_head *
dump_user_backtrace(struct frame_head * head)
{
@ -53,72 +73,24 @@ dump_user_backtrace(struct frame_head * head)
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;
unsigned long stack;
#ifdef CONFIG_X86_64
head = (struct frame_head *)regs->rbp;
stack = regs->rsp;
#else
head = (struct frame_head *)regs->ebp;
stack = regs->esp;
#endif
if (!user_mode_vm(regs)) {
while (depth-- && valid_kernel_stack(head, regs))
head = dump_kernel_backtrace(head);
if (depth)
dump_trace(NULL, regs, (unsigned long *)stack,
&backtrace_ops, &depth);
return;
}