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[PATCH] i386: reliable stack trace support (i386)

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These are the i386-specific pieces to enable reliable stack traces. This is
going to be even more useful once CFI annotations get added to he assembly
code, namely to entry.S.

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 13:57:41 +02:00 committed by Linus Torvalds
parent dffead4e42
commit 176a2718f4
7 changed files with 179 additions and 13 deletions
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29
arch/i386/kernel/entry.S
View File

@ -663,6 +663,35 @@ ENTRY(spurious_interrupt_bug)
pushl $do_spurious_interrupt_bug
jmp error_code
#ifdef CONFIG_STACK_UNWIND
ENTRY(arch_unwind_init_running)
movl 4(%esp), %edx
movl (%esp), %ecx
leal 4(%esp), %eax
movl %ebx, EBX(%edx)
xorl %ebx, %ebx
movl %ebx, ECX(%edx)
movl %ebx, EDX(%edx)
movl %esi, ESI(%edx)
movl %edi, EDI(%edx)
movl %ebp, EBP(%edx)
movl %ebx, EAX(%edx)
movl $__USER_DS, DS(%edx)
movl $__USER_DS, ES(%edx)
movl %ebx, ORIG_EAX(%edx)
movl %ecx, EIP(%edx)
movl 12(%esp), %ecx
movl $__KERNEL_CS, CS(%edx)
movl %ebx, EFLAGS(%edx)
movl %eax, OLDESP(%edx)
movl 8(%esp), %eax
movl %ecx, 8(%esp)
movl EBX(%edx), %ebx
movl $__KERNEL_DS, OLDSS(%edx)
jmpl *%eax
ENDPROC(arch_unwind_init_running)
#endif
.section .rodata,"a"
#include "syscall_table.S"

2
arch/i386/kernel/process.c
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@ -312,7 +312,7 @@ void show_regs(struct pt_regs * regs)
cr3 = read_cr3();
cr4 = read_cr4_safe();
printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0, cr2, cr3, cr4);
show_trace(NULL, &regs->esp);
show_trace(NULL, regs, &regs->esp);
}
/*

50
arch/i386/kernel/traps.c
View File

@ -28,6 +28,7 @@
#include <linux/utsname.h>
#include <linux/kprobes.h>
#include <linux/kexec.h>
#include <linux/unwind.h>
#ifdef CONFIG_EISA
#include <linux/ioport.h>
@ -47,7 +48,7 @@
#include <asm/desc.h>
#include <asm/i387.h>
#include <asm/nmi.h>
#include <asm/unwind.h>
#include <asm/smp.h>
#include <asm/arch_hooks.h>
#include <asm/kdebug.h>
@ -170,14 +171,43 @@ static inline unsigned long print_context_stack(struct thread_info *tinfo,
return ebp;
}
static void show_trace_log_lvl(struct task_struct *task,
static asmlinkage void show_trace_unwind(struct unwind_frame_info *info, void *log_lvl)
{
int printed = 0; /* nr of entries already printed on current line */
while (unwind(info) == 0 && UNW_PC(info)) {
printed = print_addr_and_symbol(UNW_PC(info), log_lvl, printed);
if (arch_unw_user_mode(info))
break;
}
if (printed)
printk("\n");
}
static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
unsigned long *stack, char *log_lvl)
{
unsigned long ebp;
struct unwind_frame_info info;
if (!task)
task = current;
if (regs) {
if (unwind_init_frame_info(&info, task, regs) == 0) {
show_trace_unwind(&info, log_lvl);
return;
}
} else if (task == current) {
if (unwind_init_running(&info, show_trace_unwind, log_lvl) == 0)
return;
} else {
if (unwind_init_blocked(&info, task) == 0) {
show_trace_unwind(&info, log_lvl);
return;
}
}
if (task == current) {
/* Grab ebp right from our regs */
asm ("movl %%ebp, %0" : "=r" (ebp) : );
@ -198,13 +228,13 @@ static void show_trace_log_lvl(struct task_struct *task,
}
}
void show_trace(struct task_struct *task, unsigned long * stack)
void show_trace(struct task_struct *task, struct pt_regs *regs, unsigned long * stack)
{
show_trace_log_lvl(task, stack, "");
show_trace_log_lvl(task, regs, stack, "");
}
static void show_stack_log_lvl(struct task_struct *task, unsigned long *esp,
char *log_lvl)
static void show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
unsigned long *esp, char *log_lvl)
{
unsigned long *stack;
int i;
@ -225,13 +255,13 @@ static void show_stack_log_lvl(struct task_struct *task, unsigned long *esp,
printk("%08lx ", *stack++);
}
printk("\n%sCall Trace:\n", log_lvl);
show_trace_log_lvl(task, esp, log_lvl);
show_trace_log_lvl(task, regs, esp, log_lvl);
}
void show_stack(struct task_struct *task, unsigned long *esp)
{
printk(" ");
show_stack_log_lvl(task, esp, "");
show_stack_log_lvl(task, NULL, esp, "");
}
/*
@ -241,7 +271,7 @@ void dump_stack(void)
{
unsigned long stack;
show_trace(current, &stack);
show_trace(current, NULL, &stack);
}
EXPORT_SYMBOL(dump_stack);
@ -285,7 +315,7 @@ void show_registers(struct pt_regs *regs)
u8 __user *eip;
printk("\n" KERN_EMERG "Stack: ");
show_stack_log_lvl(NULL, (unsigned long *)esp, KERN_EMERG);
show_stack_log_lvl(NULL, regs, (unsigned long *)esp, KERN_EMERG);
printk(KERN_EMERG "Code: ");

9
arch/i386/kernel/vmlinux.lds.S
View File

@ -71,6 +71,15 @@ SECTIONS
.data.read_mostly : AT(ADDR(.data.read_mostly) - LOAD_OFFSET) { *(.data.read_mostly) }
_edata = .; /* End of data section */
#ifdef CONFIG_STACK_UNWIND
. = ALIGN(4);
.eh_frame : AT(ADDR(.eh_frame) - LOAD_OFFSET) {
__start_unwind = .;
*(.eh_frame)
__end_unwind = .;
}
#endif
. = ALIGN(THREAD_SIZE); /* init_task */
.data.init_task : AT(ADDR(.data.init_task) - LOAD_OFFSET) {
*(.data.init_task)

2
include/asm-i386/processor.h
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@ -555,7 +555,7 @@ extern void prepare_to_copy(struct task_struct *tsk);
extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
extern unsigned long thread_saved_pc(struct task_struct *tsk);
void show_trace(struct task_struct *task, unsigned long *stack);
void show_trace(struct task_struct *task, struct pt_regs *regs, unsigned long *stack);
unsigned long get_wchan(struct task_struct *p);

98
include/asm-i386/unwind.h Normal file
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@ -0,0 +1,98 @@
#ifndef _ASM_I386_UNWIND_H
#define _ASM_I386_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/fixmap.h>
#include <asm/ptrace.h>
#include <asm/uaccess.h>
struct unwind_frame_info
{
struct pt_regs regs;
struct task_struct *task;
};
#define UNW_PC(frame) (frame)->regs.eip
#define UNW_SP(frame) (frame)->regs.esp
#ifdef CONFIG_FRAME_POINTER
#define UNW_FP(frame) (frame)->regs.ebp
#define FRAME_RETADDR_OFFSET 4
#define FRAME_LINK_OFFSET 0
#define STACK_BOTTOM(tsk) STACK_LIMIT((tsk)->thread.esp0)
#define STACK_TOP(tsk) ((tsk)->thread.esp0)
#endif
#define STACK_LIMIT(ptr) (((ptr) - 1) & ~(THREAD_SIZE - 1))
#define UNW_REGISTER_INFO \
PTREGS_INFO(eax), \
PTREGS_INFO(ecx), \
PTREGS_INFO(edx), \
PTREGS_INFO(ebx), \
PTREGS_INFO(esp), \
PTREGS_INFO(ebp), \
PTREGS_INFO(esi), \
PTREGS_INFO(edi), \
PTREGS_INFO(eip)
static inline void arch_unw_init_frame_info(struct unwind_frame_info *info,
/*const*/ struct pt_regs *regs)
{
if (user_mode_vm(regs))
info->regs = *regs;
else {
memcpy(&info->regs, regs, offsetof(struct pt_regs, esp));
info->regs.esp = (unsigned long)&regs->esp;
info->regs.xss = __KERNEL_DS;
}
}
static inline void arch_unw_init_blocked(struct unwind_frame_info *info)
{
memset(&info->regs, 0, sizeof(info->regs));
info->regs.eip = info->task->thread.eip;
info->regs.xcs = __KERNEL_CS;
__get_user(info->regs.ebp, (long *)info->task->thread.esp);
info->regs.esp = info->task->thread.esp;
info->regs.xss = __KERNEL_DS;
info->regs.xds = __USER_DS;
info->regs.xes = __USER_DS;
}
extern asmlinkage void arch_unwind_init_running(struct unwind_frame_info *,
asmlinkage 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 and EFLAGS saves/restores
are properly annotated (and tracked in UNW_REGISTER_INFO). */
return user_mode_vm(&info->regs);
#else
return info->regs.eip < PAGE_OFFSET
|| (info->regs.eip >= __fix_to_virt(FIX_VSYSCALL)
&& info->regs.eip < __fix_to_virt(FIX_VSYSCALL) + PAGE_SIZE)
|| info->regs.esp < PAGE_OFFSET;
#endif
}
#else
#define UNW_PC(frame) ((void)(frame), 0)
static inline int arch_unw_user_mode(const void *info)
{
return 0;
}
#endif
#endif /* _ASM_I386_UNWIND_H */

2
lib/Kconfig.debug
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@ -199,7 +199,7 @@ config UNWIND_INFO
config STACK_UNWIND
bool "Stack unwind support"
depends on UNWIND_INFO
depends on X86_64
depends on X86
help
This enables more precise stack traces, omitting all unrelated
occurrences of pointers into kernel code from the dump.