Jan Kiszka wrote: > This is not a must-have, and it is not for all archs so far anyway: > > Dump an I-pipe panic trace on ordinary kernel oopses. For me this turned > out to be useful already, but not everyone may love to see his/her > console flooded with call-history traces on oops, though this only > happens if the tracer is enabled. > > Comments welcome. >
Following your suggestion, this version makes the panic freezing a
configurable option. Also, it adds support for x86_64 (note that all
arch bits are in the same patch here!) and should now cover any arch
I-pipe runs on.
I would say: No longer an RFC, now a request to apply.
Jan
---
arch/i386/mm/fault.c | 5 +++
arch/x86_64/mm/fault.c | 3 ++
include/linux/ipipe_trace.h | 10 +++----
kernel/ipipe/Kconfig.debug | 18 +++++++++---
kernel/ipipe/tracer.c | 62 ++++++++++++++++++++++++--------------------
lib/bust_spinlocks.c | 5 +++
6 files changed, 65 insertions(+), 38 deletions(-)
Index: linux-2.6.20/arch/i386/mm/fault.c
===================================================================
--- linux-2.6.20.orig/arch/i386/mm/fault.c
+++ linux-2.6.20/arch/i386/mm/fault.c
@@ -23,6 +23,7 @@
#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
+#include <linux/ipipe_trace.h>
#include <asm/system.h>
#include <asm/desc.h>
@@ -68,9 +69,13 @@ void bust_spinlocks(int yes)
int loglevel_save = console_loglevel;
if (yes) {
+ ipipe_trace_panic_freeze();
oops_in_progress = 1;
return;
}
+
+ ipipe_trace_panic_dump();
+
#ifdef CONFIG_VT
unblank_screen();
#endif
Index: linux-2.6.20/lib/bust_spinlocks.c
===================================================================
--- linux-2.6.20.orig/lib/bust_spinlocks.c
+++ linux-2.6.20/lib/bust_spinlocks.c
@@ -12,14 +12,19 @@
#include <linux/tty.h>
#include <linux/wait.h>
#include <linux/vt_kern.h>
+#include <linux/ipipe_trace.h>
void bust_spinlocks(int yes)
{
if (yes) {
+ ipipe_trace_panic_freeze();
oops_in_progress = 1;
} else {
int loglevel_save = console_loglevel;
+
+ ipipe_trace_panic_dump();
+
#ifdef CONFIG_VT
unblank_screen();
#endif
Index: linux-2.6.20/include/linux/ipipe_trace.h
===================================================================
--- linux-2.6.20.orig/include/linux/ipipe_trace.h
+++ linux-2.6.20/include/linux/ipipe_trace.h
@@ -2,7 +2,7 @@
* include/linux/ipipe_trace.h
*
* Copyright (C) 2005 Luotao Fu.
- * 2005, 2006 Jan Kiszka.
+ * 2005-2007 Jan Kiszka.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@@ -23,8 +23,6 @@
#ifndef _LINUX_IPIPE_TRACE_H
#define _LINUX_IPIPE_TRACE_H
-#ifdef CONFIG_IPIPE_TRACE
-
#include <linux/types.h>
void ipipe_trace_begin(unsigned long v);
@@ -36,14 +34,16 @@ void ipipe_trace_pid(pid_t pid, short pr
int ipipe_trace_max_reset(void);
int ipipe_trace_frozen_reset(void);
+#ifdef CONFIG_IPIPE_TRACE_PANIC
+
void ipipe_trace_panic_freeze(void);
void ipipe_trace_panic_dump(void);
-#else /* !CONFIG_IPIPE_TRACE */
+#else /* !CONFIG_IPIPE_TRACE_PANIC */
static inline void ipipe_trace_panic_freeze(void) { }
static inline void ipipe_trace_panic_dump(void) { }
-#endif /* !CONFIG_IPIPE_TRACE */
+#endif /* !CONFIG_IPIPE_TRACE_PANIC */
#endif /* !__LINUX_IPIPE_H */
Index: linux-2.6.20/kernel/ipipe/Kconfig.debug
===================================================================
--- linux-2.6.20.orig/kernel/ipipe/Kconfig.debug
+++ linux-2.6.20/kernel/ipipe/Kconfig.debug
@@ -31,9 +31,10 @@ config IPIPE_TRACE
in-kernel tracing API. The collected data and runtime control
is available via /proc/ipipe/trace/*.
+if IPIPE_TRACE
+
config IPIPE_TRACE_ENABLE
bool "Enable tracing on boot"
- depends on IPIPE_TRACE
default y
---help---
Disable this option if you want to arm the tracer after booting
@@ -42,7 +43,6 @@ config IPIPE_TRACE_ENABLE
config IPIPE_TRACE_MCOUNT
bool "Instrument function entries"
- depends on IPIPE_TRACE
default y
---help---
When enabled, records every kernel function entry in the tracer
@@ -53,7 +53,6 @@ config IPIPE_TRACE_MCOUNT
config IPIPE_TRACE_IRQSOFF
bool "Trace IRQs-off times"
- depends on IPIPE_TRACE
default y
---help---
Activate this option if I-pipe shall trace the longest path
@@ -63,14 +62,12 @@ config IPIPE_TRACE_SHIFT
int "Depth of trace log (14 => 16Kpoints, 15 => 32Kpoints)"
range 10 18
default 14
- depends on IPIPE_TRACE
---help---
The number of trace points to hold tracing data for each
trace path, as a power of 2.
config IPIPE_TRACE_VMALLOC
bool "Use vmalloc'ed trace buffer"
- depends on IPIPE_TRACE
default y if EMBEDDED
---help---
Instead of reserving static kernel data, the required buffer
@@ -79,9 +76,20 @@ config IPIPE_TRACE_VMALLOC
but it slightly degrades overall performance. Try this option
when a traced kernel hangs unexpectedly at boot time.
+config IPIPE_TRACE_PANIC
+ bool "Enable panic back traces"
+ default y
+ ---help---
+ Provides services to freeze and dump a back trace on panic
+ situations. This is used on IPIPE_DEBUG_CONTEXT exceptions
+ as well as ordinary kernel oopses. You can control the number
+ of printed back trace points via /proc/ipipe/trace.
+
config IPIPE_TRACE_ENABLE_VALUE
int
default 0 if !IPIPE_TRACE_ENABLE
default 1 if IPIPE_TRACE_ENABLE
endif
+
+endif
Index: linux-2.6.20/kernel/ipipe/tracer.c
===================================================================
--- linux-2.6.20.orig/kernel/ipipe/tracer.c
+++ linux-2.6.20/kernel/ipipe/tracer.c
@@ -132,7 +132,9 @@ static unsigned long trace_overhead;
static DEFINE_MUTEX(out_mutex);
static struct ipipe_trace_path *print_path;
+#ifdef CONFIG_IPIPE_TRACE_PANIC
static struct ipipe_trace_path *panic_path;
+#endif /* CONFIG_IPIPE_TRACE_PANIC */
static int print_pre_trace;
static int print_post_trace;
@@ -564,25 +566,6 @@ int ipipe_trace_frozen_reset(void)
}
EXPORT_SYMBOL(ipipe_trace_frozen_reset);
-void ipipe_trace_panic_freeze(void)
-{
- unsigned long flags;
- int cpuid;
-
- if (!ipipe_trace_enable)
- return;
-
- ipipe_trace_enable = 0;
- local_irq_save_hw_notrace(flags);
-
- cpuid = raw_smp_processor_id();
-
- panic_path = &trace_paths[cpuid][active_path[cpuid]];
-
- local_irq_restore_hw(flags);
-}
-EXPORT_SYMBOL(ipipe_trace_panic_freeze);
-
static void
__ipipe_get_task_info(char *task_info, struct ipipe_trace_point *point,
int trylock)
@@ -615,6 +598,26 @@ __ipipe_get_task_info(char *task_info, s
strcpy(task_info + (11 - strlen(buf)), buf);
}
+#ifdef CONFIG_IPIPE_TRACE_PANIC
+void ipipe_trace_panic_freeze(void)
+{
+ unsigned long flags;
+ int cpuid;
+
+ if (!ipipe_trace_enable)
+ return;
+
+ ipipe_trace_enable = 0;
+ local_irq_save_hw_notrace(flags);
+
+ cpuid = raw_smp_processor_id();
+
+ panic_path = &trace_paths[cpuid][active_path[cpuid]];
+
+ local_irq_restore_hw(flags);
+}
+EXPORT_SYMBOL(ipipe_trace_panic_freeze);
+
void ipipe_trace_panic_dump(void)
{
int cnt = back_trace;
@@ -681,6 +684,7 @@ void ipipe_trace_panic_dump(void)
panic_path = NULL;
}
EXPORT_SYMBOL(ipipe_trace_panic_dump);
+#endif /* CONFIG_IPIPE_TRACE_PANIC */
/* --- /proc output --- */
@@ -803,8 +807,17 @@ static void __ipipe_print_symname(struct
sym_name = kallsyms_lookup(eip, &size, &offset, &modname, namebuf);
- /* printing to /proc? */
- if (m) {
+#ifdef CONFIG_IPIPE_TRACE_PANIC
+ if (!m) {
+ /* panic dump */
+ if (sym_name) {
+ printk("%s+0x%lx", sym_name, offset);
+ if (modname)
+ printk(" [%s]", modname);
+ }
+ } else
+#endif /* CONFIG_IPIPE_TRACE_PANIC */
+ {
if (sym_name) {
if (verbose_trace) {
seq_printf(m, "%s+0x%lx", sym_name, offset);
@@ -814,13 +827,6 @@ static void __ipipe_print_symname(struct
seq_puts(m, sym_name);
} else
seq_printf(m, "<%08lx>", eip);
- } else {
- /* panic dump */
- if (sym_name) {
- printk("%s+0x%lx", sym_name, offset);
- if (modname)
- printk(" [%s]", modname);
- }
}
}
Index: linux-2.6.20/arch/x86_64/mm/fault.c
===================================================================
--- linux-2.6.20.orig/arch/x86_64/mm/fault.c
+++ linux-2.6.20/arch/x86_64/mm/fault.c
@@ -24,6 +24,7 @@
#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
+#include <linux/ipipe_trace.h>
#include <asm/system.h>
#include <asm/pgalloc.h>
@@ -73,8 +74,10 @@ void bust_spinlocks(int yes)
{
int loglevel_save = console_loglevel;
if (yes) {
+ ipipe_trace_panic_freeze();
oops_in_progress = 1;
} else {
+ ipipe_trace_panic_dump();
#ifdef CONFIG_VT
unblank_screen();
#endif
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