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linux-next/arch/x86/kernel/dumpstack_32.c
Steven Rostedt 7743a536be i386: Remove unneeded test of 'task' in dump_trace() (again)
Commit 028a690a1e "i386: Remove unneeded test of 'task' in
dump_trace()" correctly removed the unneeded 'task != NULL'
check because it would be set to current if it was NULL.

Commit 2bc5f927d4 "i386: split out dumpstack code from
traps_32.c" moved the code from traps_32.c to its own file
dump_stack.c for preparation of the i386 / x86_64 merge.

Commit 8a541665b9 "dumpstack: x86: various small unification
steps" worked to make i386 and x86_64 dump_stack logic similar.
But this actually reverted the correct change from
028a690a1e.

Commit d0caf29250 "x86/dumpstack: Remove unneeded check in
dump_trace()" removed the unneeded "task != NULL" check for
x86_64 but left that same unneeded check for i386, that was
added because x86_64 had it!

This chain of events ironically had i386 add back the unneeded
task != NULL check because x86_64 did it, and then the fix for
x86_64 was fixed by Dan. And even more ironically, it was Dan's
smatch bot that told me that a change to dump_stack_32 I made
may be wrong if current can be NULL (it can't), as there was a
check for it by assigning task to current, and then checking if
task is NULL.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Alexander van Heukelum <heukelum@fastmail.fm>
Cc: Jesper Juhl <jesper.juhl@gmail.com>
Link: http://lkml.kernel.org/r/20140307105242.79a0befd@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-03-11 12:02:31 +01:00

139 lines
2.8 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 != 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))
pr_cont("\n");
pr_cont(" %08lx", *stack++);
touch_nmi_watchdog();
}
pr_cont("\n");
show_trace_log_lvl(task, regs, sp, bp, log_lvl);
}
void show_regs(struct pt_regs *regs)
{
int i;
show_regs_print_info(KERN_EMERG);
__show_regs(regs, !user_mode_vm(regs));
/*
* 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;
pr_emerg("Stack:\n");
show_stack_log_lvl(NULL, regs, &regs->sp, 0, KERN_EMERG);
pr_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)) {
pr_cont(" Bad EIP value.");
break;
}
if (ip == (u8 *)regs->ip)
pr_cont(" <%02x>", c);
else
pr_cont(" %02x", c);
}
}
pr_cont("\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;
}