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[PATCH] x86: Make backtracer fallback logic more bullet-proof 

The unwinder fallback logic still had potential for falling through to
the legacy stack trace code without printing an indication (at once
serving as a separator) of this.

Further, the stack pointer retrieval for the fallback should be as
restrictive as possible (in order to avoid having the legacy stack
tracer try to access invalid memory). The patch tightens that, but
this could certainly be further improved.

Also making the call_trace command line option now conditional upon
CONFIG_STACK_UNWIND (as it's meaningless otherwise).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
wifi-calibration
Jan Beulich 2006-08-30 19:37:11 +02:00 committed by Linus Torvalds
parent 61171b8dbd
commit ea424055b7
4 changed files with 35 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
arch/i386/kernel/traps.c
View File

@ -92,7 +92,11 @@ asmlinkage void spurious_interrupt_bug(void);
asmlinkage void machine_check(void);
static int kstack_depth_to_print = 24;
#ifdef CONFIG_STACK_UNWIND
static int call_trace = 1;
#else
#define call_trace (-1)
#endif
ATOMIC_NOTIFIER_HEAD(i386die_chain);
int register_die_notifier(struct notifier_block *nb)
@ -187,22 +191,21 @@ static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
if (unwind_init_blocked(&info, task) == 0)
unw_ret = show_trace_unwind(&info, log_lvl);
}
if (unw_ret > 0 && !arch_unw_user_mode(&info)) {
#ifdef CONFIG_STACK_UNWIND
print_symbol("DWARF2 unwinder stuck at %s\n",
UNW_PC(&info));
if (call_trace == 1) {
printk("Leftover inexact backtrace:\n");
if (UNW_SP(&info))
if (unw_ret > 0) {
if (call_trace == 1 && !arch_unw_user_mode(&info)) {
print_symbol("DWARF2 unwinder stuck at %s\n",
UNW_PC(&info));
if (UNW_SP(&info) >= PAGE_OFFSET) {
printk("Leftover inexact backtrace:\n");
stack = (void *)UNW_SP(&info);
} else if (call_trace > 1)
} else
printk("Full inexact backtrace again:\n");
} else if (call_trace >= 1)
return;
else
printk("Full inexact backtrace again:\n");
#else
} else
printk("Inexact backtrace:\n");
#endif
}
}
if (task == current) {
@ -1241,6 +1244,7 @@ static int __init kstack_setup(char *s)
}
__setup("kstack=", kstack_setup);
#ifdef CONFIG_STACK_UNWIND
static int __init call_trace_setup(char *s)
{
if (strcmp(s, "old") == 0)
@ -1254,3 +1258,4 @@ static int __init call_trace_setup(char *s)
return 1;
}
__setup("call_trace=", call_trace_setup);
#endif

28
arch/x86_64/kernel/traps.c
View File

@ -107,7 +107,11 @@ static inline void preempt_conditional_cli(struct pt_regs *regs)
}
static int kstack_depth_to_print = 12;
#ifdef CONFIG_STACK_UNWIND
static int call_trace = 1;
#else
#define call_trace (-1)
#endif
#ifdef CONFIG_KALLSYMS
# include <linux/kallsyms.h>
@ -274,21 +278,21 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
if (unwind_init_blocked(&info, tsk) == 0)
unw_ret = show_trace_unwind(&info, NULL);
}
if (unw_ret > 0 && !arch_unw_user_mode(&info)) {
#ifdef CONFIG_STACK_UNWIND
unsigned long rip = info.regs.rip;
print_symbol("DWARF2 unwinder stuck at %s\n", rip);
if (call_trace == 1) {
printk("Leftover inexact backtrace:\n");
stack = (unsigned long *)info.regs.rsp;
} else if (call_trace > 1)
if (unw_ret > 0) {
if (call_trace == 1 && !arch_unw_user_mode(&info)) {
print_symbol("DWARF2 unwinder stuck at %s\n",
UNW_PC(&info));
if ((long)UNW_SP(&info) < 0) {
printk("Leftover inexact backtrace:\n");
stack = (unsigned long *)UNW_SP(&info);
} else
printk("Full inexact backtrace again:\n");
} else if (call_trace >= 1)
return;
else
printk("Full inexact backtrace again:\n");
#else
} else
printk("Inexact backtrace:\n");
#endif
}
}
/*
@ -1120,6 +1124,7 @@ static int __init kstack_setup(char *s)
}
__setup("kstack=", kstack_setup);
#ifdef CONFIG_STACK_UNWIND
static int __init call_trace_setup(char *s)
{
if (strcmp(s, "old") == 0)
@ -1133,3 +1138,4 @@ static int __init call_trace_setup(char *s)
return 1;
}
__setup("call_trace=", call_trace_setup);
#endif

1
include/asm-i386/unwind.h
View File

@ -87,6 +87,7 @@ static inline int arch_unw_user_mode(const struct unwind_frame_info *info)
#else
#define UNW_PC(frame) ((void)(frame), 0)
#define UNW_SP(frame) ((void)(frame), 0)
static inline int arch_unw_user_mode(const void *info)
{

1
include/asm-x86_64/unwind.h
View File

@ -95,6 +95,7 @@ static inline int arch_unw_user_mode(const struct unwind_frame_info *info)
#else
#define UNW_PC(frame) ((void)(frame), 0)
#define UNW_SP(frame) ((void)(frame), 0)
static inline int arch_unw_user_mode(const void *info)
{