linux-kernel-test/arch/x86/kernel/dumpstack_32.c
Namhyung Kim e8e999cf3c x86, dumpstack: Correct stack dump info when frame pointer is available
Current stack dump code scans entire stack and check each entry
contains a pointer to kernel code. If CONFIG_FRAME_POINTER=y it
could mark whether the pointer is valid or not based on value of
the frame pointer. Invalid entries could be preceded by '?' sign.

However this was not going to happen because scan start point
was always higher than the frame pointer so that they could not
meet.

Commit 9c0729dc80 ("x86: Eliminate bp argument from the stack
tracing routines") delayed bp acquisition point, so the bp was
read in lower frame, thus all of the entries were marked
invalid.

This patch fixes this by reverting above commit while retaining
stack_frame() helper as suggested by Frederic Weisbecker.

End result looks like below:

before:

 [    3.508329] Call Trace:
 [    3.508551]  [<ffffffff814f35c9>] ? panic+0x91/0x199
 [    3.508662]  [<ffffffff814f3739>] ? printk+0x68/0x6a
 [    3.508770]  [<ffffffff81a981b2>] ? mount_block_root+0x257/0x26e
 [    3.508876]  [<ffffffff81a9821f>] ? mount_root+0x56/0x5a
 [    3.508975]  [<ffffffff81a98393>] ? prepare_namespace+0x170/0x1a9
 [    3.509216]  [<ffffffff81a9772b>] ? kernel_init+0x1d2/0x1e2
 [    3.509335]  [<ffffffff81003894>] ? kernel_thread_helper+0x4/0x10
 [    3.509442]  [<ffffffff814f6880>] ? restore_args+0x0/0x30
 [    3.509542]  [<ffffffff81a97559>] ? kernel_init+0x0/0x1e2
 [    3.509641]  [<ffffffff81003890>] ? kernel_thread_helper+0x0/0x10

after:

 [    3.522991] Call Trace:
 [    3.523351]  [<ffffffff814f35b9>] panic+0x91/0x199
 [    3.523468]  [<ffffffff814f3729>] ? printk+0x68/0x6a
 [    3.523576]  [<ffffffff81a981b2>] mount_block_root+0x257/0x26e
 [    3.523681]  [<ffffffff81a9821f>] mount_root+0x56/0x5a
 [    3.523780]  [<ffffffff81a98393>] prepare_namespace+0x170/0x1a9
 [    3.523885]  [<ffffffff81a9772b>] kernel_init+0x1d2/0x1e2
 [    3.523987]  [<ffffffff81003894>] kernel_thread_helper+0x4/0x10
 [    3.524228]  [<ffffffff814f6880>] ? restore_args+0x0/0x30
 [    3.524345]  [<ffffffff81a97559>] ? kernel_init+0x0/0x1e2
 [    3.524445]  [<ffffffff81003890>] ? kernel_thread_helper+0x0/0x10

 -v5:
   * fix build breakage with oprofile

 -v4:
   * use 0 instead of regs->bp
   * separate out printk changes

 -v3:
   * apply comment from Frederic
   * add a couple of printk fixes

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Soren Sandmann <ssp@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Robert Richter <robert.richter@amd.com>
LKML-Reference: <1300416006-3163-1-git-send-email-namhyung@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-03-18 10:51:42 +01:00

142 lines
3.0 KiB
C

/*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
*/
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/kexec.h>
#include <linux/sysfs.h>
#include <linux/bug.h>
#include <linux/nmi.h>
#include <asm/stacktrace.h>
void dump_trace(struct task_struct *task, struct pt_regs *regs,
unsigned long *stack, unsigned long bp,
const struct stacktrace_ops *ops, void *data)
{
int graph = 0;
if (!task)
task = current;
if (!stack) {
unsigned long dummy;
stack = &dummy;
if (task && task != current)
stack = (unsigned long *)task->thread.sp;
}
if (!bp)
bp = stack_frame(task, regs);
for (;;) {
struct thread_info *context;
context = (struct thread_info *)
((unsigned long)stack & (~(THREAD_SIZE - 1)));
bp = ops->walk_stack(context, stack, bp, ops, data, NULL, &graph);
stack = (unsigned long *)context->previous_esp;
if (!stack)
break;
if (ops->stack(data, "IRQ") < 0)
break;
touch_nmi_watchdog();
}
}
EXPORT_SYMBOL(dump_trace);
void
show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
unsigned long *sp, unsigned long bp, char *log_lvl)
{
unsigned long *stack;
int i;
if (sp == NULL) {
if (task)
sp = (unsigned long *)task->thread.sp;
else
sp = (unsigned long *)&sp;
}
stack = sp;
for (i = 0; i < kstack_depth_to_print; i++) {
if (kstack_end(stack))
break;
if (i && ((i % STACKSLOTS_PER_LINE) == 0))
printk(KERN_CONT "\n");
printk(KERN_CONT " %08lx", *stack++);
touch_nmi_watchdog();
}
printk(KERN_CONT "\n");
show_trace_log_lvl(task, regs, sp, bp, log_lvl);
}
void show_registers(struct pt_regs *regs)
{
int i;
print_modules();
__show_regs(regs, 0);
printk(KERN_EMERG "Process %.*s (pid: %d, ti=%p task=%p task.ti=%p)\n",
TASK_COMM_LEN, current->comm, task_pid_nr(current),
current_thread_info(), current, task_thread_info(current));
/*
* When in-kernel, we also print out the stack and code at the
* time of the fault..
*/
if (!user_mode_vm(regs)) {
unsigned int code_prologue = code_bytes * 43 / 64;
unsigned int code_len = code_bytes;
unsigned char c;
u8 *ip;
printk(KERN_EMERG "Stack:\n");
show_stack_log_lvl(NULL, regs, &regs->sp, 0, KERN_EMERG);
printk(KERN_EMERG "Code: ");
ip = (u8 *)regs->ip - code_prologue;
if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
/* try starting at IP */
ip = (u8 *)regs->ip;
code_len = code_len - code_prologue + 1;
}
for (i = 0; i < code_len; i++, ip++) {
if (ip < (u8 *)PAGE_OFFSET ||
probe_kernel_address(ip, c)) {
printk(" Bad EIP value.");
break;
}
if (ip == (u8 *)regs->ip)
printk("<%02x> ", c);
else
printk("%02x ", c);
}
}
printk("\n");
}
int is_valid_bugaddr(unsigned long ip)
{
unsigned short ud2;
if (ip < PAGE_OFFSET)
return 0;
if (probe_kernel_address((unsigned short *)ip, ud2))
return 0;
return ud2 == 0x0b0f;
}