linux/arch/x86/kernel/dumpstack_64.c

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/*
* 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>
#define N_EXCEPTION_STACKS_END \
(N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)
static char x86_stack_ids[][8] = {
[ DEBUG_STACK-1 ] = "#DB",
[ NMI_STACK-1 ] = "NMI",
[ DOUBLEFAULT_STACK-1 ] = "#DF",
[ STACKFAULT_STACK-1 ] = "#SS",
[ MCE_STACK-1 ] = "#MC",
#if DEBUG_STKSZ > EXCEPTION_STKSZ
[ N_EXCEPTION_STACKS ...
N_EXCEPTION_STACKS_END ] = "#DB[?]"
#endif
};
static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
unsigned *usedp, char **idp)
{
unsigned k;
/*
* Iterate over all exception stacks, and figure out whether
* 'stack' is in one of them:
*/
for (k = 0; k < N_EXCEPTION_STACKS; k++) {
unsigned long end = per_cpu(orig_ist, cpu).ist[k];
/*
* Is 'stack' above this exception frame's end?
* If yes then skip to the next frame.
*/
if (stack >= end)
continue;
/*
* Is 'stack' above this exception frame's start address?
* If yes then we found the right frame.
*/
if (stack >= end - EXCEPTION_STKSZ) {
/*
* Make sure we only iterate through an exception
* stack once. If it comes up for the second time
* then there's something wrong going on - just
* break out and return NULL:
*/
if (*usedp & (1U << k))
break;
*usedp |= 1U << k;
*idp = x86_stack_ids[k];
return (unsigned long *)end;
}
/*
* If this is a debug stack, and if it has a larger size than
* the usual exception stacks, then 'stack' might still
* be within the lower portion of the debug stack:
*/
#if DEBUG_STKSZ > EXCEPTION_STKSZ
if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
unsigned j = N_EXCEPTION_STACKS - 1;
/*
* Black magic. A large debug stack is composed of
* multiple exception stack entries, which we
* iterate through now. Dont look:
*/
do {
++j;
end -= EXCEPTION_STKSZ;
x86_stack_ids[j][4] = '1' +
(j - N_EXCEPTION_STACKS);
} while (stack < end - EXCEPTION_STKSZ);
if (*usedp & (1U << j))
break;
*usedp |= 1U << j;
*idp = x86_stack_ids[j];
return (unsigned long *)end;
}
#endif
}
return NULL;
}
x86: Fixup wrong irq frame link in stacktraces When we enter in irq, two things can happen to preserve the link to the previous frame pointer: - If we were in an irq already, we don't switch to the irq stack as we are inside. We just need to save the previous frame pointer and to link the new one to the previous. - Otherwise we need another level of indirection. We enter the irq with the previous stack. We save the previous bp inside and make bp pointing to its saved address. Then we switch to the irq stack and push bp another time but to the new stack. This makes two levels to dereference instead of one. In the second case, the current stacktrace code omits the second level and loses the frame pointer accuracy. The stack that follows will then be considered as unreliable. Handling that makes the perf callchain happier. Before: 43.94% [k] _raw_read_lock | --- _read_lock | |--60.53%-- send_sigio | __kill_fasync | kill_fasync | evdev_pass_event | evdev_event | input_pass_event | input_handle_event | input_event | synaptics_process_byte | psmouse_handle_byte | psmouse_interrupt | serio_interrupt | i8042_interrupt | handle_IRQ_event | handle_edge_irq | handle_irq | __irqentry_text_start | ret_from_intr | | | |--30.43%-- __select | | | |--17.39%-- 0x454f15 | | | |--13.04%-- __read | | | |--13.04%-- vread_hpet | | | |--13.04%-- _xcb_lock_io | | | --13.04%-- 0x7f630878ce8 After: 50.00% [k] _raw_read_lock | --- _read_lock | |--98.97%-- send_sigio | __kill_fasync | kill_fasync | evdev_pass_event | evdev_event | input_pass_event | input_handle_event | input_event | | | |--96.88%-- synaptics_process_byte | | psmouse_handle_byte | | psmouse_interrupt | | serio_interrupt | | i8042_interrupt | | handle_IRQ_event | | handle_edge_irq | | handle_irq | | __irqentry_text_start | | ret_from_intr | | | | | |--39.78%-- __const_udelay | | | | | | | |--91.89%-- ath5k_hw_register_timeout | | | | ath5k_hw_noise_floor_calibration | | | | ath5k_hw_reset | | | | ath5k_reset | | | | ath5k_config | | | | ieee80211_hw_config | | | | | | | | | |--88.24%-- ieee80211_scan_work | | | | | worker_thread | | | | | kthread | | | | | child_rip | | | | | | | | | --11.76%-- ieee80211_scan_completed | | | | ieee80211_scan_work | | | | worker_thread | | | | kthread | | | | child_rip | | | | | | | --8.11%-- ath5k_hw_noise_floor_calibration | | | ath5k_hw_reset | | | ath5k_reset | | | ath5k_config Note: This does not only affect perf events but also x86-64 stacktraces. They were considered as unreliable once we quit the irq stack frame. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: "K. Prasad" <prasad@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com>
2009-12-06 04:34:27 +00:00
static inline int
in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
unsigned long *irq_stack_end)
{
return (stack >= irq_stack && stack < irq_stack_end);
}
/*
* x86-64 can have up to three kernel stacks:
* process stack
* interrupt stack
* severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
*/
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 9c0729dc8062 ("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 02:40:06 +00:00
void dump_trace(struct task_struct *task, struct pt_regs *regs,
unsigned long *stack, unsigned long bp,
const struct stacktrace_ops *ops, void *data)
{
const unsigned cpu = get_cpu();
unsigned long *irq_stack_end =
(unsigned long *)per_cpu(irq_stack_ptr, cpu);
unsigned used = 0;
struct thread_info *tinfo;
int graph = 0;
unsigned long dummy;
if (!task)
task = current;
if (!stack) {
x86: Fetch stack from regs when possible in dump_trace() When regs are passed to dump_stack(), we fetch the frame pointer from the regs but the stack pointer is taken from the current frame. Thus the frame and stack pointers may not come from the same context. For example this can result in the unwinder to think the context is in irq, due to the current value of the stack, but the frame pointer coming from the regs points to a frame from another place. It then tries to fix up the irq link but ends up dereferencing a random frame pointer that doesn't belong to the irq stack: [ 9131.706906] ------------[ cut here ]------------ [ 9131.707003] WARNING: at arch/x86/kernel/dumpstack_64.c:129 dump_trace+0x2aa/0x330() [ 9131.707003] Hardware name: AMD690VM-FMH [ 9131.707003] Perf: bad frame pointer = 0000000000000005 in callchain [ 9131.707003] Modules linked in: [ 9131.707003] Pid: 1050, comm: perf Not tainted 3.0.0-rc3+ #181 [ 9131.707003] Call Trace: [ 9131.707003] <IRQ> [<ffffffff8104bd4a>] warn_slowpath_common+0x7a/0xb0 [ 9131.707003] [<ffffffff8104be21>] warn_slowpath_fmt+0x41/0x50 [ 9131.707003] [<ffffffff8178b873>] ? bad_to_user+0x6d/0x10be [ 9131.707003] [<ffffffff8100c2da>] dump_trace+0x2aa/0x330 [ 9131.707003] [<ffffffff810107d3>] ? native_sched_clock+0x13/0x50 [ 9131.707003] [<ffffffff8101b164>] perf_callchain_kernel+0x54/0x70 [ 9131.707003] [<ffffffff810d391f>] perf_prepare_sample+0x19f/0x2a0 [ 9131.707003] [<ffffffff810d546c>] __perf_event_overflow+0x16c/0x290 [ 9131.707003] [<ffffffff810d5430>] ? __perf_event_overflow+0x130/0x290 [ 9131.707003] [<ffffffff810107d3>] ? native_sched_clock+0x13/0x50 [ 9131.707003] [<ffffffff8100fbb9>] ? sched_clock+0x9/0x10 [ 9131.707003] [<ffffffff810752e5>] ? T.375+0x15/0x90 [ 9131.707003] [<ffffffff81084da4>] ? trace_hardirqs_on_caller+0x64/0x180 [ 9131.707003] [<ffffffff810817bd>] ? trace_hardirqs_off+0xd/0x10 [ 9131.707003] [<ffffffff810d5764>] perf_event_overflow+0x14/0x20 [ 9131.707003] [<ffffffff810d588c>] perf_swevent_hrtimer+0x11c/0x130 [ 9131.707003] [<ffffffff817821a1>] ? error_exit+0x51/0xb0 [ 9131.707003] [<ffffffff81072e93>] __run_hrtimer+0x83/0x1e0 [ 9131.707003] [<ffffffff810d5770>] ? perf_event_overflow+0x20/0x20 [ 9131.707003] [<ffffffff81073256>] hrtimer_interrupt+0x106/0x250 [ 9131.707003] [<ffffffff812a3bfd>] ? trace_hardirqs_off_thunk+0x3a/0x3c [ 9131.707003] [<ffffffff81024833>] smp_apic_timer_interrupt+0x53/0x90 [ 9131.707003] [<ffffffff81789053>] apic_timer_interrupt+0x13/0x20 [ 9131.707003] <EOI> [<ffffffff817821a1>] ? error_exit+0x51/0xb0 [ 9131.707003] [<ffffffff8178219c>] ? error_exit+0x4c/0xb0 [ 9131.707003] ---[ end trace b2560d4876709347 ]--- Fix this by simply taking the stack pointer from regs->sp when regs are provided. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
2011-06-30 17:04:56 +00:00
if (regs)
stack = (unsigned long *)regs->sp;
else if (task != current)
stack = (unsigned long *)task->thread.sp;
x86: Fetch stack from regs when possible in dump_trace() When regs are passed to dump_stack(), we fetch the frame pointer from the regs but the stack pointer is taken from the current frame. Thus the frame and stack pointers may not come from the same context. For example this can result in the unwinder to think the context is in irq, due to the current value of the stack, but the frame pointer coming from the regs points to a frame from another place. It then tries to fix up the irq link but ends up dereferencing a random frame pointer that doesn't belong to the irq stack: [ 9131.706906] ------------[ cut here ]------------ [ 9131.707003] WARNING: at arch/x86/kernel/dumpstack_64.c:129 dump_trace+0x2aa/0x330() [ 9131.707003] Hardware name: AMD690VM-FMH [ 9131.707003] Perf: bad frame pointer = 0000000000000005 in callchain [ 9131.707003] Modules linked in: [ 9131.707003] Pid: 1050, comm: perf Not tainted 3.0.0-rc3+ #181 [ 9131.707003] Call Trace: [ 9131.707003] <IRQ> [<ffffffff8104bd4a>] warn_slowpath_common+0x7a/0xb0 [ 9131.707003] [<ffffffff8104be21>] warn_slowpath_fmt+0x41/0x50 [ 9131.707003] [<ffffffff8178b873>] ? bad_to_user+0x6d/0x10be [ 9131.707003] [<ffffffff8100c2da>] dump_trace+0x2aa/0x330 [ 9131.707003] [<ffffffff810107d3>] ? native_sched_clock+0x13/0x50 [ 9131.707003] [<ffffffff8101b164>] perf_callchain_kernel+0x54/0x70 [ 9131.707003] [<ffffffff810d391f>] perf_prepare_sample+0x19f/0x2a0 [ 9131.707003] [<ffffffff810d546c>] __perf_event_overflow+0x16c/0x290 [ 9131.707003] [<ffffffff810d5430>] ? __perf_event_overflow+0x130/0x290 [ 9131.707003] [<ffffffff810107d3>] ? native_sched_clock+0x13/0x50 [ 9131.707003] [<ffffffff8100fbb9>] ? sched_clock+0x9/0x10 [ 9131.707003] [<ffffffff810752e5>] ? T.375+0x15/0x90 [ 9131.707003] [<ffffffff81084da4>] ? trace_hardirqs_on_caller+0x64/0x180 [ 9131.707003] [<ffffffff810817bd>] ? trace_hardirqs_off+0xd/0x10 [ 9131.707003] [<ffffffff810d5764>] perf_event_overflow+0x14/0x20 [ 9131.707003] [<ffffffff810d588c>] perf_swevent_hrtimer+0x11c/0x130 [ 9131.707003] [<ffffffff817821a1>] ? error_exit+0x51/0xb0 [ 9131.707003] [<ffffffff81072e93>] __run_hrtimer+0x83/0x1e0 [ 9131.707003] [<ffffffff810d5770>] ? perf_event_overflow+0x20/0x20 [ 9131.707003] [<ffffffff81073256>] hrtimer_interrupt+0x106/0x250 [ 9131.707003] [<ffffffff812a3bfd>] ? trace_hardirqs_off_thunk+0x3a/0x3c [ 9131.707003] [<ffffffff81024833>] smp_apic_timer_interrupt+0x53/0x90 [ 9131.707003] [<ffffffff81789053>] apic_timer_interrupt+0x13/0x20 [ 9131.707003] <EOI> [<ffffffff817821a1>] ? error_exit+0x51/0xb0 [ 9131.707003] [<ffffffff8178219c>] ? error_exit+0x4c/0xb0 [ 9131.707003] ---[ end trace b2560d4876709347 ]--- Fix this by simply taking the stack pointer from regs->sp when regs are provided. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
2011-06-30 17:04:56 +00:00
else
stack = &dummy;
}
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 9c0729dc8062 ("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 02:40:06 +00:00
if (!bp)
bp = stack_frame(task, regs);
/*
* Print function call entries in all stacks, starting at the
* current stack address. If the stacks consist of nested
* exceptions
*/
tinfo = task_thread_info(task);
for (;;) {
char *id;
unsigned long *estack_end;
estack_end = in_exception_stack(cpu, (unsigned long)stack,
&used, &id);
if (estack_end) {
if (ops->stack(data, id) < 0)
break;
bp = ops->walk_stack(tinfo, stack, bp, ops,
data, estack_end, &graph);
ops->stack(data, "<EOE>");
/*
* We link to the next stack via the
* second-to-last pointer (index -2 to end) in the
* exception stack:
*/
stack = (unsigned long *) estack_end[-2];
continue;
}
if (irq_stack_end) {
unsigned long *irq_stack;
irq_stack = irq_stack_end -
(IRQ_STACK_SIZE - 64) / sizeof(*irq_stack);
x86: Fixup wrong irq frame link in stacktraces When we enter in irq, two things can happen to preserve the link to the previous frame pointer: - If we were in an irq already, we don't switch to the irq stack as we are inside. We just need to save the previous frame pointer and to link the new one to the previous. - Otherwise we need another level of indirection. We enter the irq with the previous stack. We save the previous bp inside and make bp pointing to its saved address. Then we switch to the irq stack and push bp another time but to the new stack. This makes two levels to dereference instead of one. In the second case, the current stacktrace code omits the second level and loses the frame pointer accuracy. The stack that follows will then be considered as unreliable. Handling that makes the perf callchain happier. Before: 43.94% [k] _raw_read_lock | --- _read_lock | |--60.53%-- send_sigio | __kill_fasync | kill_fasync | evdev_pass_event | evdev_event | input_pass_event | input_handle_event | input_event | synaptics_process_byte | psmouse_handle_byte | psmouse_interrupt | serio_interrupt | i8042_interrupt | handle_IRQ_event | handle_edge_irq | handle_irq | __irqentry_text_start | ret_from_intr | | | |--30.43%-- __select | | | |--17.39%-- 0x454f15 | | | |--13.04%-- __read | | | |--13.04%-- vread_hpet | | | |--13.04%-- _xcb_lock_io | | | --13.04%-- 0x7f630878ce8 After: 50.00% [k] _raw_read_lock | --- _read_lock | |--98.97%-- send_sigio | __kill_fasync | kill_fasync | evdev_pass_event | evdev_event | input_pass_event | input_handle_event | input_event | | | |--96.88%-- synaptics_process_byte | | psmouse_handle_byte | | psmouse_interrupt | | serio_interrupt | | i8042_interrupt | | handle_IRQ_event | | handle_edge_irq | | handle_irq | | __irqentry_text_start | | ret_from_intr | | | | | |--39.78%-- __const_udelay | | | | | | | |--91.89%-- ath5k_hw_register_timeout | | | | ath5k_hw_noise_floor_calibration | | | | ath5k_hw_reset | | | | ath5k_reset | | | | ath5k_config | | | | ieee80211_hw_config | | | | | | | | | |--88.24%-- ieee80211_scan_work | | | | | worker_thread | | | | | kthread | | | | | child_rip | | | | | | | | | --11.76%-- ieee80211_scan_completed | | | | ieee80211_scan_work | | | | worker_thread | | | | kthread | | | | child_rip | | | | | | | --8.11%-- ath5k_hw_noise_floor_calibration | | | ath5k_hw_reset | | | ath5k_reset | | | ath5k_config Note: This does not only affect perf events but also x86-64 stacktraces. They were considered as unreliable once we quit the irq stack frame. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: "K. Prasad" <prasad@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com>
2009-12-06 04:34:27 +00:00
if (in_irq_stack(stack, irq_stack, irq_stack_end)) {
if (ops->stack(data, "IRQ") < 0)
break;
bp = ops->walk_stack(tinfo, stack, bp,
ops, data, irq_stack_end, &graph);
/*
* We link to the next stack (which would be
* the process stack normally) the last
* pointer (index -1 to end) in the IRQ stack:
*/
stack = (unsigned long *) (irq_stack_end[-1]);
irq_stack_end = NULL;
ops->stack(data, "EOI");
continue;
}
}
break;
}
/*
* This handles the process stack:
*/
bp = ops->walk_stack(tinfo, stack, bp, ops, data, NULL, &graph);
put_cpu();
}
EXPORT_SYMBOL(dump_trace);
void
show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
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 9c0729dc8062 ("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 02:40:06 +00:00
unsigned long *sp, unsigned long bp, char *log_lvl)
{
x86: dumpstack, 64-bit: Disable preemption when walking the IRQ/exception stacks This warning: [ 847.140022] rb_producer D 0000000000000000 5928 519 2 0x00000000 [ 847.203627] BUG: using smp_processor_id() in preemptible [00000000] code: khungtaskd/517 [ 847.207360] caller is show_stack_log_lvl+0x2e/0x241 [ 847.210364] Pid: 517, comm: khungtaskd Not tainted 2.6.32-rc8-tip+ #13761 [ 847.213395] Call Trace: [ 847.215847] [<ffffffff81413bde>] debug_smp_processor_id+0x1f0/0x20a [ 847.216809] [<ffffffff81015eae>] show_stack_log_lvl+0x2e/0x241 [ 847.220027] [<ffffffff81018512>] show_stack+0x1c/0x1e [ 847.223365] [<ffffffff8107b7db>] sched_show_task+0xe4/0xe9 [ 847.226694] [<ffffffff8112f21f>] check_hung_task+0x140/0x199 [ 847.230261] [<ffffffff8112f4a8>] check_hung_uninterruptible_tasks+0x1b7/0x20f [ 847.233371] [<ffffffff8112f500>] ? watchdog+0x0/0x50 [ 847.236683] [<ffffffff8112f54e>] watchdog+0x4e/0x50 [ 847.240034] [<ffffffff810cee56>] kthread+0x97/0x9f [ 847.243372] [<ffffffff81012aea>] child_rip+0xa/0x20 [ 847.246690] [<ffffffff81e43494>] ? restore_args+0x0/0x30 [ 847.250019] [<ffffffff81e43083>] ? _spin_lock+0xe/0x10 [ 847.253351] [<ffffffff810cedbf>] ? kthread+0x0/0x9f [ 847.256833] [<ffffffff81012ae0>] ? child_rip+0x0/0x20 Happens because on preempt-RCU, khungd calls show_stack() with preemption enabled. Make sure we are not preemptible while walking the IRQ and exception stacks on 64-bit. (32-bit stack dumping is preemption safe.) Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-26 07:29:10 +00:00
unsigned long *irq_stack_end;
unsigned long *irq_stack;
unsigned long *stack;
x86: dumpstack, 64-bit: Disable preemption when walking the IRQ/exception stacks This warning: [ 847.140022] rb_producer D 0000000000000000 5928 519 2 0x00000000 [ 847.203627] BUG: using smp_processor_id() in preemptible [00000000] code: khungtaskd/517 [ 847.207360] caller is show_stack_log_lvl+0x2e/0x241 [ 847.210364] Pid: 517, comm: khungtaskd Not tainted 2.6.32-rc8-tip+ #13761 [ 847.213395] Call Trace: [ 847.215847] [<ffffffff81413bde>] debug_smp_processor_id+0x1f0/0x20a [ 847.216809] [<ffffffff81015eae>] show_stack_log_lvl+0x2e/0x241 [ 847.220027] [<ffffffff81018512>] show_stack+0x1c/0x1e [ 847.223365] [<ffffffff8107b7db>] sched_show_task+0xe4/0xe9 [ 847.226694] [<ffffffff8112f21f>] check_hung_task+0x140/0x199 [ 847.230261] [<ffffffff8112f4a8>] check_hung_uninterruptible_tasks+0x1b7/0x20f [ 847.233371] [<ffffffff8112f500>] ? watchdog+0x0/0x50 [ 847.236683] [<ffffffff8112f54e>] watchdog+0x4e/0x50 [ 847.240034] [<ffffffff810cee56>] kthread+0x97/0x9f [ 847.243372] [<ffffffff81012aea>] child_rip+0xa/0x20 [ 847.246690] [<ffffffff81e43494>] ? restore_args+0x0/0x30 [ 847.250019] [<ffffffff81e43083>] ? _spin_lock+0xe/0x10 [ 847.253351] [<ffffffff810cedbf>] ? kthread+0x0/0x9f [ 847.256833] [<ffffffff81012ae0>] ? child_rip+0x0/0x20 Happens because on preempt-RCU, khungd calls show_stack() with preemption enabled. Make sure we are not preemptible while walking the IRQ and exception stacks on 64-bit. (32-bit stack dumping is preemption safe.) Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-26 07:29:10 +00:00
int cpu;
int i;
x86: dumpstack, 64-bit: Disable preemption when walking the IRQ/exception stacks This warning: [ 847.140022] rb_producer D 0000000000000000 5928 519 2 0x00000000 [ 847.203627] BUG: using smp_processor_id() in preemptible [00000000] code: khungtaskd/517 [ 847.207360] caller is show_stack_log_lvl+0x2e/0x241 [ 847.210364] Pid: 517, comm: khungtaskd Not tainted 2.6.32-rc8-tip+ #13761 [ 847.213395] Call Trace: [ 847.215847] [<ffffffff81413bde>] debug_smp_processor_id+0x1f0/0x20a [ 847.216809] [<ffffffff81015eae>] show_stack_log_lvl+0x2e/0x241 [ 847.220027] [<ffffffff81018512>] show_stack+0x1c/0x1e [ 847.223365] [<ffffffff8107b7db>] sched_show_task+0xe4/0xe9 [ 847.226694] [<ffffffff8112f21f>] check_hung_task+0x140/0x199 [ 847.230261] [<ffffffff8112f4a8>] check_hung_uninterruptible_tasks+0x1b7/0x20f [ 847.233371] [<ffffffff8112f500>] ? watchdog+0x0/0x50 [ 847.236683] [<ffffffff8112f54e>] watchdog+0x4e/0x50 [ 847.240034] [<ffffffff810cee56>] kthread+0x97/0x9f [ 847.243372] [<ffffffff81012aea>] child_rip+0xa/0x20 [ 847.246690] [<ffffffff81e43494>] ? restore_args+0x0/0x30 [ 847.250019] [<ffffffff81e43083>] ? _spin_lock+0xe/0x10 [ 847.253351] [<ffffffff810cedbf>] ? kthread+0x0/0x9f [ 847.256833] [<ffffffff81012ae0>] ? child_rip+0x0/0x20 Happens because on preempt-RCU, khungd calls show_stack() with preemption enabled. Make sure we are not preemptible while walking the IRQ and exception stacks on 64-bit. (32-bit stack dumping is preemption safe.) Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-26 07:29:10 +00:00
preempt_disable();
cpu = smp_processor_id();
irq_stack_end = (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
irq_stack = (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
/*
x86: dumpstack, 64-bit: Disable preemption when walking the IRQ/exception stacks This warning: [ 847.140022] rb_producer D 0000000000000000 5928 519 2 0x00000000 [ 847.203627] BUG: using smp_processor_id() in preemptible [00000000] code: khungtaskd/517 [ 847.207360] caller is show_stack_log_lvl+0x2e/0x241 [ 847.210364] Pid: 517, comm: khungtaskd Not tainted 2.6.32-rc8-tip+ #13761 [ 847.213395] Call Trace: [ 847.215847] [<ffffffff81413bde>] debug_smp_processor_id+0x1f0/0x20a [ 847.216809] [<ffffffff81015eae>] show_stack_log_lvl+0x2e/0x241 [ 847.220027] [<ffffffff81018512>] show_stack+0x1c/0x1e [ 847.223365] [<ffffffff8107b7db>] sched_show_task+0xe4/0xe9 [ 847.226694] [<ffffffff8112f21f>] check_hung_task+0x140/0x199 [ 847.230261] [<ffffffff8112f4a8>] check_hung_uninterruptible_tasks+0x1b7/0x20f [ 847.233371] [<ffffffff8112f500>] ? watchdog+0x0/0x50 [ 847.236683] [<ffffffff8112f54e>] watchdog+0x4e/0x50 [ 847.240034] [<ffffffff810cee56>] kthread+0x97/0x9f [ 847.243372] [<ffffffff81012aea>] child_rip+0xa/0x20 [ 847.246690] [<ffffffff81e43494>] ? restore_args+0x0/0x30 [ 847.250019] [<ffffffff81e43083>] ? _spin_lock+0xe/0x10 [ 847.253351] [<ffffffff810cedbf>] ? kthread+0x0/0x9f [ 847.256833] [<ffffffff81012ae0>] ? child_rip+0x0/0x20 Happens because on preempt-RCU, khungd calls show_stack() with preemption enabled. Make sure we are not preemptible while walking the IRQ and exception stacks on 64-bit. (32-bit stack dumping is preemption safe.) Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-26 07:29:10 +00:00
* Debugging aid: "show_stack(NULL, NULL);" prints the
* back trace for this cpu:
*/
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 (stack >= irq_stack && stack <= irq_stack_end) {
if (stack == irq_stack_end) {
stack = (unsigned long *) (irq_stack_end[-1]);
pr_cont(" <EOI> ");
}
} else {
if (((long) stack & (THREAD_SIZE-1)) == 0)
break;
}
if (i && ((i % STACKSLOTS_PER_LINE) == 0))
pr_cont("\n");
pr_cont(" %016lx", *stack++);
touch_nmi_watchdog();
}
x86: dumpstack, 64-bit: Disable preemption when walking the IRQ/exception stacks This warning: [ 847.140022] rb_producer D 0000000000000000 5928 519 2 0x00000000 [ 847.203627] BUG: using smp_processor_id() in preemptible [00000000] code: khungtaskd/517 [ 847.207360] caller is show_stack_log_lvl+0x2e/0x241 [ 847.210364] Pid: 517, comm: khungtaskd Not tainted 2.6.32-rc8-tip+ #13761 [ 847.213395] Call Trace: [ 847.215847] [<ffffffff81413bde>] debug_smp_processor_id+0x1f0/0x20a [ 847.216809] [<ffffffff81015eae>] show_stack_log_lvl+0x2e/0x241 [ 847.220027] [<ffffffff81018512>] show_stack+0x1c/0x1e [ 847.223365] [<ffffffff8107b7db>] sched_show_task+0xe4/0xe9 [ 847.226694] [<ffffffff8112f21f>] check_hung_task+0x140/0x199 [ 847.230261] [<ffffffff8112f4a8>] check_hung_uninterruptible_tasks+0x1b7/0x20f [ 847.233371] [<ffffffff8112f500>] ? watchdog+0x0/0x50 [ 847.236683] [<ffffffff8112f54e>] watchdog+0x4e/0x50 [ 847.240034] [<ffffffff810cee56>] kthread+0x97/0x9f [ 847.243372] [<ffffffff81012aea>] child_rip+0xa/0x20 [ 847.246690] [<ffffffff81e43494>] ? restore_args+0x0/0x30 [ 847.250019] [<ffffffff81e43083>] ? _spin_lock+0xe/0x10 [ 847.253351] [<ffffffff810cedbf>] ? kthread+0x0/0x9f [ 847.256833] [<ffffffff81012ae0>] ? child_rip+0x0/0x20 Happens because on preempt-RCU, khungd calls show_stack() with preemption enabled. Make sure we are not preemptible while walking the IRQ and exception stacks on 64-bit. (32-bit stack dumping is preemption safe.) Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-26 07:29:10 +00:00
preempt_enable();
pr_cont("\n");
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 9c0729dc8062 ("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 02:40:06 +00:00
show_trace_log_lvl(task, regs, sp, bp, log_lvl);
}
void show_regs(struct pt_regs *regs)
{
int i;
unsigned long sp;
const int cpu = smp_processor_id();
struct task_struct *cur = current;
sp = regs->sp;
printk("CPU %d ", cpu);
__show_regs(regs, 1);
printk(KERN_DEFAULT "Process %s (pid: %d, threadinfo %p, task %p)\n",
cur->comm, cur->pid, task_thread_info(cur), cur);
/*
* When in-kernel, we also print out the stack and code at the
* time of the fault..
*/
if (!user_mode(regs)) {
unsigned int code_prologue = code_bytes * 43 / 64;
unsigned int code_len = code_bytes;
unsigned char c;
u8 *ip;
bugs, x86: Fix printk levels for panic, softlockups and stack dumps rsyslog will display KERN_EMERG messages on a connected terminal. However, these messages are useless/undecipherable for a general user. For example, after a softlockup we get: Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ... kernel:Stack: Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ... kernel:Call Trace: Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ... kernel:Code: ff ff a8 08 75 25 31 d2 48 8d 86 38 e0 ff ff 48 89 d1 0f 01 c8 0f ae f0 48 8b 86 38 e0 ff ff a8 08 75 08 b1 01 4c 89 e0 0f 01 c9 <e8> ea 69 dd ff 4c 29 e8 48 89 c7 e8 0f bc da ff 49 89 c4 49 89 This happens because the printk levels for these messages are incorrect. Only an informational message should be displayed on a terminal. I modified the printk levels for various messages in the kernel and tested the output by using the drivers/misc/lkdtm.c kernel modules (ie, softlockups, panics, hard lockups, etc.) and confirmed that the console output was still the same and that the output to the terminals was correct. For example, in the case of a softlockup we now see the much more informative: Message from syslogd@intel-s3e37-04 at Jan 25 10:18:06 ... BUG: soft lockup - CPU4 stuck for 60s! instead of the above confusing messages. AFAICT, the messages no longer have to be KERN_EMERG. In the most important case of a panic we set console_verbose(). As for the other less severe cases the correct data is output to the console and /var/log/messages. Successfully tested by me using the drivers/misc/lkdtm.c module. Signed-off-by: Prarit Bhargava <prarit@redhat.com> Cc: dzickus@redhat.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/1327586134-11926-1-git-send-email-prarit@redhat.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-01-26 13:55:34 +00:00
printk(KERN_DEFAULT "Stack:\n");
show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
bugs, x86: Fix printk levels for panic, softlockups and stack dumps rsyslog will display KERN_EMERG messages on a connected terminal. However, these messages are useless/undecipherable for a general user. For example, after a softlockup we get: Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ... kernel:Stack: Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ... kernel:Call Trace: Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ... kernel:Code: ff ff a8 08 75 25 31 d2 48 8d 86 38 e0 ff ff 48 89 d1 0f 01 c8 0f ae f0 48 8b 86 38 e0 ff ff a8 08 75 08 b1 01 4c 89 e0 0f 01 c9 <e8> ea 69 dd ff 4c 29 e8 48 89 c7 e8 0f bc da ff 49 89 c4 49 89 This happens because the printk levels for these messages are incorrect. Only an informational message should be displayed on a terminal. I modified the printk levels for various messages in the kernel and tested the output by using the drivers/misc/lkdtm.c kernel modules (ie, softlockups, panics, hard lockups, etc.) and confirmed that the console output was still the same and that the output to the terminals was correct. For example, in the case of a softlockup we now see the much more informative: Message from syslogd@intel-s3e37-04 at Jan 25 10:18:06 ... BUG: soft lockup - CPU4 stuck for 60s! instead of the above confusing messages. AFAICT, the messages no longer have to be KERN_EMERG. In the most important case of a panic we set console_verbose(). As for the other less severe cases the correct data is output to the console and /var/log/messages. Successfully tested by me using the drivers/misc/lkdtm.c module. Signed-off-by: Prarit Bhargava <prarit@redhat.com> Cc: dzickus@redhat.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/1327586134-11926-1-git-send-email-prarit@redhat.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-01-26 13:55:34 +00:00
0, KERN_DEFAULT);
bugs, x86: Fix printk levels for panic, softlockups and stack dumps rsyslog will display KERN_EMERG messages on a connected terminal. However, these messages are useless/undecipherable for a general user. For example, after a softlockup we get: Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ... kernel:Stack: Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ... kernel:Call Trace: Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ... kernel:Code: ff ff a8 08 75 25 31 d2 48 8d 86 38 e0 ff ff 48 89 d1 0f 01 c8 0f ae f0 48 8b 86 38 e0 ff ff a8 08 75 08 b1 01 4c 89 e0 0f 01 c9 <e8> ea 69 dd ff 4c 29 e8 48 89 c7 e8 0f bc da ff 49 89 c4 49 89 This happens because the printk levels for these messages are incorrect. Only an informational message should be displayed on a terminal. I modified the printk levels for various messages in the kernel and tested the output by using the drivers/misc/lkdtm.c kernel modules (ie, softlockups, panics, hard lockups, etc.) and confirmed that the console output was still the same and that the output to the terminals was correct. For example, in the case of a softlockup we now see the much more informative: Message from syslogd@intel-s3e37-04 at Jan 25 10:18:06 ... BUG: soft lockup - CPU4 stuck for 60s! instead of the above confusing messages. AFAICT, the messages no longer have to be KERN_EMERG. In the most important case of a panic we set console_verbose(). As for the other less severe cases the correct data is output to the console and /var/log/messages. Successfully tested by me using the drivers/misc/lkdtm.c module. Signed-off-by: Prarit Bhargava <prarit@redhat.com> Cc: dzickus@redhat.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/1327586134-11926-1-git-send-email-prarit@redhat.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-01-26 13:55:34 +00:00
printk(KERN_DEFAULT "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 RIP 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 (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
return 0;
return ud2 == 0x0b0f;
}