From bfeeeeb991cf75081e6c2f74d44ae5da05b50a94 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Mon, 12 May 2008 21:21:14 +0200 Subject: [PATCH 1/9] stacktrace: don't crash on invalid stack trace structs This patch makes the stacktrace printout code \warn when the entries pointer is unset rather than crashing when trying to access it in an attempt to make it a bit more robust. I was saving a stacktrace into an skb and forgot to copy it across skb copies... I have since fixed the code, but it would have been easier had the kernel not crashed in an interrupt. Signed-off-by: Johannes Berg Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- kernel/stacktrace.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c index b71816e47a30..0914d0cbc83c 100644 --- a/kernel/stacktrace.c +++ b/kernel/stacktrace.c @@ -13,6 +13,9 @@ void print_stack_trace(struct stack_trace *trace, int spaces) { int i, j; + if (WARN_ON(!trace->entries)) + return; + for (i = 0; i < trace->nr_entries; i++) { unsigned long ip = trace->entries[i]; From 886dd58258e6ddebe20e7aebef7b167a24bad7ee Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Mon, 12 May 2008 15:44:38 +0200 Subject: [PATCH 2/9] debugging: make stacktrace independent from DEBUG_KERNEL Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- lib/Kconfig.debug | 1 - 1 file changed, 1 deletion(-) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index d2099f41aa1e..9c17fb9d1d5e 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -419,7 +419,6 @@ config DEBUG_LOCKING_API_SELFTESTS config STACKTRACE bool - depends on DEBUG_KERNEL depends on STACKTRACE_SUPPORT config DEBUG_KOBJECT From a5a242dceed5d1c74fe46088762a9e4312c2d000 Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Fri, 13 Jun 2008 11:00:14 +0200 Subject: [PATCH 3/9] stacktrace: print_stack_trace() cleanup - shorter code and better atomicity with regards to printk(). (It's been tested with the backtrace self-test code on i386 and x86_64.) Cc: Arjan van de Ven Signed-off-by: Vegard Nossum Signed-off-by: Ingo Molnar --- kernel/stacktrace.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c index 0914d0cbc83c..7eaea9d02a52 100644 --- a/kernel/stacktrace.c +++ b/kernel/stacktrace.c @@ -11,17 +11,14 @@ void print_stack_trace(struct stack_trace *trace, int spaces) { - int i, j; + int i; if (WARN_ON(!trace->entries)) return; for (i = 0; i < trace->nr_entries; i++) { - unsigned long ip = trace->entries[i]; - - for (j = 0; j < spaces + 1; j++) - printk(" "); - print_ip_sym(ip); + printk("%*c", 1 + spaces, ' '); + print_ip_sym(trace->entries[i]); } } From ad118c54a3587b2c69a769d0ba37d4d8dce4559d Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Fri, 27 Jun 2008 18:04:48 +0200 Subject: [PATCH 4/9] stacktrace: add saved stack traces to backtrace self-test This patch adds saved stack-traces to the backtrace suite of self-tests. Note that we don't depend on or unconditionally enable CONFIG_STACKTRACE because not all architectures may have it (and we still want to enable the other tests for those architectures). Cc: Arjan van de Ven Signed-off-by: Vegard Nossum Cc: Arjan van de Ven Cc: Andrew Morton Signed-off-by: Ingo Molnar --- kernel/backtracetest.c | 30 +++++++++++++++++++++++++++++- lib/Kconfig.debug | 3 +++ 2 files changed, 32 insertions(+), 1 deletion(-) diff --git a/kernel/backtracetest.c b/kernel/backtracetest.c index d1a7605c5b8f..50f7abd0813d 100644 --- a/kernel/backtracetest.c +++ b/kernel/backtracetest.c @@ -10,9 +10,10 @@ * of the License. */ +#include #include #include -#include +#include static struct timer_list backtrace_timer; @@ -22,6 +23,31 @@ static void backtrace_test_timer(unsigned long data) printk("The following trace is a kernel self test and not a bug!\n"); dump_stack(); } + +#ifdef CONFIG_STACKTRACE +static void backtrace_test_saved(void) +{ + struct stack_trace trace; + unsigned long entries[8]; + + printk("Testing a saved backtrace.\n"); + printk("The following trace is a kernel self test and not a bug!\n"); + + trace.nr_entries = 0; + trace.max_entries = ARRAY_SIZE(entries); + trace.entries = entries; + trace.skip = 0; + + save_stack_trace(&trace); + print_stack_trace(&trace, 0); +} +#else +static void backtrace_test_saved(void) +{ + printk("Saved backtrace test skipped.\n"); +} +#endif + static int backtrace_regression_test(void) { printk("====[ backtrace testing ]===========\n"); @@ -29,6 +55,8 @@ static int backtrace_regression_test(void) printk("The following trace is a kernel self test and not a bug!\n"); dump_stack(); + backtrace_test_saved(); + init_timer(&backtrace_timer); backtrace_timer.function = backtrace_test_timer; mod_timer(&backtrace_timer, jiffies + 10); diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 9c17fb9d1d5e..6263e2d851f1 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -562,6 +562,9 @@ config BACKTRACE_SELF_TEST for distributions or general kernels, but only for kernel developers working on architecture code. + Note that if you want to also test saved backtraces, you will + have to enable STACKTRACE as well. + Say N if you are unsure. config LKDTM From 4e6a0535dd036377961027262aecb138099f925d Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Fri, 27 Jun 2008 18:06:54 +0200 Subject: [PATCH 5/9] backtrace: replace timer with tasklet + completions On qemu, the backtrace would show up _after_ the "end of backtrace testing" message. This patch changes it to use completions instead, which will guarantee that no such race exists. Cc: Arjan van de Ven Signed-off-by: Vegard Nossum Cc: Arjan van de Ven Cc: Andrew Morton Signed-off-by: Ingo Molnar --- kernel/backtracetest.c | 37 ++++++++++++++++++++++++++----------- 1 file changed, 26 insertions(+), 11 deletions(-) diff --git a/kernel/backtracetest.c b/kernel/backtracetest.c index 50f7abd0813d..a5e026bc45c4 100644 --- a/kernel/backtracetest.c +++ b/kernel/backtracetest.c @@ -10,18 +10,39 @@ * of the License. */ +#include #include +#include #include #include #include -static struct timer_list backtrace_timer; +static void backtrace_test_normal(void) +{ + printk("Testing a backtrace from process context.\n"); + printk("The following trace is a kernel self test and not a bug!\n"); -static void backtrace_test_timer(unsigned long data) + dump_stack(); +} + +static DECLARE_COMPLETION(backtrace_work); + +static void backtrace_test_irq_callback(unsigned long data) +{ + dump_stack(); + complete(&backtrace_work); +} + +static DECLARE_TASKLET(backtrace_tasklet, &backtrace_test_irq_callback, 0); + +static void backtrace_test_irq(void) { printk("Testing a backtrace from irq context.\n"); printk("The following trace is a kernel self test and not a bug!\n"); - dump_stack(); + + init_completion(&backtrace_work); + tasklet_schedule(&backtrace_tasklet); + wait_for_completion(&backtrace_work); } #ifdef CONFIG_STACKTRACE @@ -51,17 +72,11 @@ static void backtrace_test_saved(void) static int backtrace_regression_test(void) { printk("====[ backtrace testing ]===========\n"); - printk("Testing a backtrace from process context.\n"); - printk("The following trace is a kernel self test and not a bug!\n"); - dump_stack(); + backtrace_test_normal(); + backtrace_test_irq(); backtrace_test_saved(); - init_timer(&backtrace_timer); - backtrace_timer.function = backtrace_test_timer; - mod_timer(&backtrace_timer, jiffies + 10); - - msleep(10); printk("====[ end of backtrace testing ]====\n"); return 0; } From 8594698ebddeef5443b7da8258ae33b3eaca61d5 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Fri, 27 Jun 2008 21:20:17 +0200 Subject: [PATCH 6/9] stacktrace: fix modular build, export print_stack_trace and save_stack_trace fix: ERROR: "print_stack_trace" [kernel/backtracetest.ko] undefined! ERROR: "save_stack_trace" [kernel/backtracetest.ko] undefined! Signed-off-by: Ingo Molnar and fix: Building modules, stage 2. MODPOST 376 modules ERROR: "print_stack_trace" [kernel/backtracetest.ko] undefined! make[1]: *** [__modpost] Error 1 Signed-off-by: Ingo Molnar --- arch/x86/kernel/stacktrace.c | 2 ++ kernel/stacktrace.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c index c28c342c162f..a03e7f6d90c3 100644 --- a/arch/x86/kernel/stacktrace.c +++ b/arch/x86/kernel/stacktrace.c @@ -74,6 +74,7 @@ void save_stack_trace(struct stack_trace *trace) if (trace->nr_entries < trace->max_entries) trace->entries[trace->nr_entries++] = ULONG_MAX; } +EXPORT_SYMBOL_GPL(save_stack_trace); void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) { @@ -81,3 +82,4 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) if (trace->nr_entries < trace->max_entries) trace->entries[trace->nr_entries++] = ULONG_MAX; } +EXPORT_SYMBOL_GPL(save_stack_trace_tsk); diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c index 7eaea9d02a52..94b527ef1d1e 100644 --- a/kernel/stacktrace.c +++ b/kernel/stacktrace.c @@ -6,6 +6,7 @@ * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar */ #include +#include #include #include @@ -21,4 +22,5 @@ void print_stack_trace(struct stack_trace *trace, int spaces) print_ip_sym(trace->entries[i]); } } +EXPORT_SYMBOL_GPL(print_stack_trace); From 7b4c9505f2fd82b117dd015b561f723b9a5dab79 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 3 Jul 2008 09:17:55 +0200 Subject: [PATCH 7/9] stacktrace: export save_stack_trace[_tsk] Andrew Morton reported this against linux-next: ERROR: ".save_stack_trace" [tests/backtracetest.ko] undefined! Reported-by: Andrew Morton Signed-off-by: Ingo Molnar --- arch/arm/kernel/stacktrace.c | 1 + arch/avr32/kernel/stacktrace.c | 1 + arch/mips/kernel/stacktrace.c | 1 + arch/powerpc/kernel/stacktrace.c | 1 + arch/s390/kernel/stacktrace.c | 2 ++ arch/sh/kernel/stacktrace.c | 1 + arch/sparc64/kernel/stacktrace.c | 1 + 7 files changed, 8 insertions(+) diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c index ae31deb2d065..6b3ffde5deaa 100644 --- a/arch/arm/kernel/stacktrace.c +++ b/arch/arm/kernel/stacktrace.c @@ -66,4 +66,5 @@ void save_stack_trace(struct stack_trace *trace) walk_stackframe(fp, base, base + THREAD_SIZE, save_trace, &data); } +EXPORT_SYMBOL_GPL(save_stack_trace); #endif diff --git a/arch/avr32/kernel/stacktrace.c b/arch/avr32/kernel/stacktrace.c index 9a68190bbffd..f4bdb448049c 100644 --- a/arch/avr32/kernel/stacktrace.c +++ b/arch/avr32/kernel/stacktrace.c @@ -51,3 +51,4 @@ void save_stack_trace(struct stack_trace *trace) fp = frame->fp; } } +EXPORT_SYMBOL_GPL(save_stack_trace); diff --git a/arch/mips/kernel/stacktrace.c b/arch/mips/kernel/stacktrace.c index ebd9db8d1ece..5eb4681a73d2 100644 --- a/arch/mips/kernel/stacktrace.c +++ b/arch/mips/kernel/stacktrace.c @@ -73,3 +73,4 @@ void save_stack_trace(struct stack_trace *trace) prepare_frametrace(regs); save_context_stack(trace, regs); } +EXPORT_SYMBOL_GPL(save_stack_trace); diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c index 962944038430..9861f17258da 100644 --- a/arch/powerpc/kernel/stacktrace.c +++ b/arch/powerpc/kernel/stacktrace.c @@ -44,3 +44,4 @@ void save_stack_trace(struct stack_trace *trace) sp = newsp; } } +EXPORT_SYMBOL_GPL(save_stack_trace); diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c index 85e46a5d0e08..57571f10270c 100644 --- a/arch/s390/kernel/stacktrace.c +++ b/arch/s390/kernel/stacktrace.c @@ -81,6 +81,7 @@ void save_stack_trace(struct stack_trace *trace) S390_lowcore.thread_info, S390_lowcore.thread_info + THREAD_SIZE, 1); } +EXPORT_SYMBOL_GPL(save_stack_trace); void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) { @@ -93,3 +94,4 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) if (trace->nr_entries < trace->max_entries) trace->entries[trace->nr_entries++] = ULONG_MAX; } +EXPORT_SYMBOL_GPL(save_stack_trace_tsk); diff --git a/arch/sh/kernel/stacktrace.c b/arch/sh/kernel/stacktrace.c index d41e561be20e..1b2ae35c4a76 100644 --- a/arch/sh/kernel/stacktrace.c +++ b/arch/sh/kernel/stacktrace.c @@ -34,3 +34,4 @@ void save_stack_trace(struct stack_trace *trace) } } } +EXPORT_SYMBOL_GPL(save_stack_trace); diff --git a/arch/sparc64/kernel/stacktrace.c b/arch/sparc64/kernel/stacktrace.c index c73ce3f4197e..49656ed6ab18 100644 --- a/arch/sparc64/kernel/stacktrace.c +++ b/arch/sparc64/kernel/stacktrace.c @@ -47,3 +47,4 @@ void save_stack_trace(struct stack_trace *trace) trace->entries[trace->nr_entries++] = pc; } while (trace->nr_entries < trace->max_entries); } +EXPORT_SYMBOL_GPL(save_stack_trace); From a05fe0389b72f43b9e29d6fbfc5885084be2f96f Mon Sep 17 00:00:00 2001 From: Stephen Rothwell Date: Tue, 8 Jul 2008 22:15:40 +1000 Subject: [PATCH 8/9] stacktrace: fix build failure on sparc64 Today's linux-next build (spac64 allmodconfig) failed like this: arch/sparc64/kernel/stacktrace.c:50: warning: type defaults to `int' in declaration of `EXPORT_SYMBOL_GPL' arch/sparc64/kernel/stacktrace.c:50: warning: parameter names (without types) in function declaration arch/sparc64/kernel/stacktrace.c:50: warning: data definition has no type or storage class Signed-off-by: Stephen Rothwell Cc: "David S. Miller" Signed-off-by: Ingo Molnar --- arch/sparc64/kernel/stacktrace.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/sparc64/kernel/stacktrace.c b/arch/sparc64/kernel/stacktrace.c index 49656ed6ab18..b3e3737750d8 100644 --- a/arch/sparc64/kernel/stacktrace.c +++ b/arch/sparc64/kernel/stacktrace.c @@ -1,6 +1,7 @@ #include #include #include +#include #include #include From 7798ed0f57b4d137e660fbf5be1e1528e40f89ac Mon Sep 17 00:00:00 2001 From: Stephen Rothwell Date: Mon, 14 Jul 2008 19:55:03 +1000 Subject: [PATCH 9/9] generic-ipi: powerpc/generic-ipi tree build failure Today's linux-next build (powerpc allmodconfig) failed like this: ERROR: ".save_stack_trace" [tests/backtracetest.ko] undefined! But save_stack_trace is exported in arch/powerpc/kernel/stacktrace.c I couldn't figure it out until I noticed these earlier warnings: arch/powerpc/kernel/stacktrace.c:47: warning: data definition has no type or storage class arch/powerpc/kernel/stacktrace.c:47: warning: type defaults to 'int' in declaration of 'EXPORT_SYMBOL_GPL' arch/powerpc/kernel/stacktrace.c:47: warning: parameter names (without types) in function declaration I applied the patch below. Signed-off-by: Stephen Rothwell Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Signed-off-by: Ingo Molnar --- arch/powerpc/kernel/stacktrace.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c index 9861f17258da..3cf0d94ba340 100644 --- a/arch/powerpc/kernel/stacktrace.c +++ b/arch/powerpc/kernel/stacktrace.c @@ -12,6 +12,7 @@ #include #include +#include #include /*