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[PATCH] x86_64: reliable stack trace support (x86-64)

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These are the x86_64-specific pieces to enable reliable stack traces. The
only restriction with this is that it currently cannot unwind across the
interrupt->normal stack boundary, as that transition is lacking proper
annotation.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Jan Beulich 2006-06-26 13:57:32 +02:00 committed by Linus Torvalds
parent 4552d5dc08
commit b538ed278b
7 changed files with 199 additions and 9 deletions
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33
arch/x86_64/kernel/entry.S
View file

@ -1089,3 +1089,36 @@ ENTRY(call_softirq)
ret
CFI_ENDPROC
ENDPROC(call_softirq)
#ifdef CONFIG_STACK_UNWIND
ENTRY(arch_unwind_init_running)
CFI_STARTPROC
movq %r15, R15(%rdi)
movq %r14, R14(%rdi)
xchgq %rsi, %rdx
movq %r13, R13(%rdi)
movq %r12, R12(%rdi)
xorl %eax, %eax
movq %rbp, RBP(%rdi)
movq %rbx, RBX(%rdi)
movq (%rsp), %rcx
movq %rax, R11(%rdi)
movq %rax, R10(%rdi)
movq %rax, R9(%rdi)
movq %rax, R8(%rdi)
movq %rax, RAX(%rdi)
movq %rax, RCX(%rdi)
movq %rax, RDX(%rdi)
movq %rax, RSI(%rdi)
movq %rax, RDI(%rdi)
movq %rax, ORIG_RAX(%rdi)
movq %rcx, RIP(%rdi)
leaq 8(%rsp), %rcx
movq $__KERNEL_CS, CS(%rdi)
movq %rax, EFLAGS(%rdi)
movq %rcx, RSP(%rdi)
movq $__KERNEL_DS, SS(%rdi)
jmpq *%rdx
CFI_ENDPROC
ENDPROC(arch_unwind_init_running)
#endif

2
arch/x86_64/kernel/process.c
View file

@ -334,7 +334,7 @@ void show_regs(struct pt_regs *regs)
{
printk("CPU %d:", smp_processor_id());
__show_regs(regs);
show_trace(&regs->rsp);
show_trace(NULL, regs, (void *)(regs + 1));
}
/*

54
arch/x86_64/kernel/traps.c
View file

@ -29,6 +29,7 @@
#include <linux/nmi.h>
#include <linux/kprobes.h>
#include <linux/kexec.h>
#include <linux/unwind.h>
#include <asm/system.h>
#include <asm/uaccess.h>
@ -39,7 +40,7 @@
#include <asm/i387.h>
#include <asm/kdebug.h>
#include <asm/processor.h>
#include <asm/unwind.h>
#include <asm/smp.h>
#include <asm/pgalloc.h>
#include <asm/pda.h>
@ -189,6 +190,23 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
return NULL;
}
static void show_trace_unwind(struct unwind_frame_info *info, void *context)
{
int i = 11;
while (unwind(info) == 0 && UNW_PC(info)) {
if (i > 50) {
printk("\n ");
i = 7;
} else
i += printk(" ");
i += printk_address(UNW_PC(info));
if (arch_unw_user_mode(info))
break;
}
printk("\n");
}
/*
* x86-64 can have upto three kernel stacks:
* process stack
@ -196,15 +214,34 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
* severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
*/
void show_trace(unsigned long *stack)
void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * stack)
{
const unsigned cpu = safe_smp_processor_id();
unsigned long *irqstack_end = (unsigned long *)cpu_pda(cpu)->irqstackptr;
int i;
unsigned used = 0;
struct unwind_frame_info info;
printk("\nCall Trace:");
if (!tsk)
tsk = current;
if (regs) {
if (unwind_init_frame_info(&info, tsk, regs) == 0) {
show_trace_unwind(&info, NULL);
return;
}
} else if (tsk == current) {
if (unwind_init_running(&info, show_trace_unwind, NULL) == 0)
return;
} else {
if (unwind_init_blocked(&info, tsk) == 0) {
show_trace_unwind(&info, NULL);
return;
}
}
#define HANDLE_STACK(cond) \
do while (cond) { \
unsigned long addr = *stack++; \
@ -262,7 +299,7 @@ void show_trace(unsigned long *stack)
printk("\n");
}
void show_stack(struct task_struct *tsk, unsigned long * rsp)
static void _show_stack(struct task_struct *tsk, struct pt_regs *regs, unsigned long * rsp)
{
unsigned long *stack;
int i;
@ -296,7 +333,12 @@ void show_stack(struct task_struct *tsk, unsigned long * rsp)
printk("%016lx ", *stack++);
touch_nmi_watchdog();
}
show_trace((unsigned long *)rsp);
show_trace(tsk, regs, rsp);
}
void show_stack(struct task_struct *tsk, unsigned long * rsp)
{
_show_stack(tsk, NULL, rsp);
}
/*
@ -305,7 +347,7 @@ void show_stack(struct task_struct *tsk, unsigned long * rsp)
void dump_stack(void)
{
unsigned long dummy;
show_trace(&dummy);
show_trace(NULL, NULL, &dummy);
}
EXPORT_SYMBOL(dump_stack);
@ -332,7 +374,7 @@ void show_registers(struct pt_regs *regs)
if (in_kernel) {
printk("Stack: ");
show_stack(NULL, (unsigned long*)rsp);
_show_stack(NULL, regs, (unsigned long*)rsp);
printk("\nCode: ");
if (regs->rip < PAGE_OFFSET)

9
arch/x86_64/kernel/vmlinux.lds.S
View file

@ -45,6 +45,15 @@ SECTIONS
RODATA
#ifdef CONFIG_STACK_UNWIND
. = ALIGN(8);
.eh_frame : AT(ADDR(.eh_frame) - LOAD_OFFSET) {
__start_unwind = .;
*(.eh_frame)
__end_unwind = .;
}
#endif
/* Data */
.data : AT(ADDR(.data) - LOAD_OFFSET) {
*(.data)

2
include/asm-x86_64/proto.h
View file

@ -75,7 +75,7 @@ extern void main_timer_handler(struct pt_regs *regs);
extern unsigned long end_pfn_map;
extern void show_trace(unsigned long * rsp);
extern void show_trace(struct task_struct *, struct pt_regs *, unsigned long * rsp);
extern void show_registers(struct pt_regs *regs);
extern void exception_table_check(void);

106
include/asm-x86_64/unwind.h Normal file
View file

@ -0,0 +1,106 @@
#ifndef _ASM_X86_64_UNWIND_H
#define _ASM_X86_64_UNWIND_H
/*
* Copyright (C) 2002-2006 Novell, Inc.
* Jan Beulich <jbeulich@novell.com>
* This code is released under version 2 of the GNU GPL.
*/
#ifdef CONFIG_STACK_UNWIND
#include <linux/sched.h>
#include <asm/ptrace.h>
#include <asm/uaccess.h>
#include <asm/vsyscall.h>
struct unwind_frame_info
{
struct pt_regs regs;
struct task_struct *task;
};
#define UNW_PC(frame) (frame)->regs.rip
#define UNW_SP(frame) (frame)->regs.rsp
#ifdef CONFIG_FRAME_POINTER
#define UNW_FP(frame) (frame)->regs.rbp
#define FRAME_RETADDR_OFFSET 8
#define FRAME_LINK_OFFSET 0
#define STACK_BOTTOM(tsk) (((tsk)->thread.rsp0 - 1) & ~(THREAD_SIZE - 1))
#define STACK_TOP(tsk) ((tsk)->thread.rsp0)
#endif
/* Might need to account for the special exception and interrupt handling
stacks here, since normally
EXCEPTION_STACK_ORDER < THREAD_ORDER < IRQSTACK_ORDER,
but the construct is needed only for getting across the stack switch to
the interrupt stack - thus considering the IRQ stack itself is unnecessary,
and the overhead of comparing against all exception handling stacks seems
not desirable. */
#define STACK_LIMIT(ptr) (((ptr) - 1) & ~(THREAD_SIZE - 1))
#define UNW_REGISTER_INFO \
PTREGS_INFO(rax), \
PTREGS_INFO(rdx), \
PTREGS_INFO(rcx), \
PTREGS_INFO(rbx), \
PTREGS_INFO(rsi), \
PTREGS_INFO(rdi), \
PTREGS_INFO(rbp), \
PTREGS_INFO(rsp), \
PTREGS_INFO(r8), \
PTREGS_INFO(r9), \
PTREGS_INFO(r10), \
PTREGS_INFO(r11), \
PTREGS_INFO(r12), \
PTREGS_INFO(r13), \
PTREGS_INFO(r14), \
PTREGS_INFO(r15), \
PTREGS_INFO(rip)
static inline void arch_unw_init_frame_info(struct unwind_frame_info *info,
/*const*/ struct pt_regs *regs)
{
info->regs = *regs;
}
static inline void arch_unw_init_blocked(struct unwind_frame_info *info)
{
extern const char thread_return[];
memset(&info->regs, 0, sizeof(info->regs));
info->regs.rip = (unsigned long)thread_return;
info->regs.cs = __KERNEL_CS;
__get_user(info->regs.rbp, (unsigned long *)info->task->thread.rsp);
info->regs.rsp = info->task->thread.rsp;
info->regs.ss = __KERNEL_DS;
}
extern void arch_unwind_init_running(struct unwind_frame_info *,
void (*callback)(struct unwind_frame_info *,
void *arg),
void *arg);
static inline int arch_unw_user_mode(const struct unwind_frame_info *info)
{
#if 0 /* This can only work when selector register saves/restores
are properly annotated (and tracked in UNW_REGISTER_INFO). */
return user_mode(&info->regs);
#else
return (long)info->regs.rip >= 0
|| (info->regs.rip >= VSYSCALL_START && info->regs.rip < VSYSCALL_END)
|| (long)info->regs.rsp >= 0;
#endif
}
#else
#define UNW_PC(frame) ((void)(frame), 0)
static inline int arch_unw_user_mode(const void *info)
{
return 0;
}
#endif
#endif /* _ASM_X86_64_UNWIND_H */

2
lib/Kconfig.debug
View file

@ -199,7 +199,7 @@ config UNWIND_INFO
config STACK_UNWIND
bool "Stack unwind support"
depends on UNWIND_INFO
depends on n
depends on X86_64
help
This enables more precise stack traces, omitting all unrelated
occurrences of pointers into kernel code from the dump.