From 2ec220e27f5040aec1e88901c1b6ea3d135787ad Mon Sep 17 00:00:00 2001 From: Ken Chen Date: Mon, 10 Nov 2008 11:26:08 +0300 Subject: proc: add /proc/*/stack /proc/*/stack adds the ability to query a task's stack trace. It is more useful than /proc/*/wchan as it provides full stack trace instead of single depth. Example output: $ cat /proc/self/stack [] save_stack_trace_tsk+0x17/0x35 [] proc_pid_stack+0x4a/0x76 [] proc_single_show+0x4a/0x5e [] seq_read+0xf3/0x29f [] vfs_read+0x6d/0x91 [] sys_read+0x3b/0x60 [] syscall_call+0x7/0xb [] 0xffffffff [add save_stack_trace_tsk() on mips, ACK Ralf --adobriyan] Signed-off-by: Ken Chen Signed-off-by: Ingo Molnar Signed-off-by: Alexey Dobriyan --- Documentation/filesystems/proc.txt | 1 + arch/mips/kernel/stacktrace.c | 24 ++++++++++++++++++------ fs/proc/base.c | 38 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 57 insertions(+), 6 deletions(-) diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 71df353e367c..334ef2f983fa 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -140,6 +140,7 @@ Table 1-1: Process specific entries in /proc statm Process memory status information status Process status in human readable form wchan If CONFIG_KALLSYMS is set, a pre-decoded wchan + stack Report full stack trace, enable via CONFIG_STACKTRACE smaps Extension based on maps, the rss size for each mapped file .............................................................................. diff --git a/arch/mips/kernel/stacktrace.c b/arch/mips/kernel/stacktrace.c index 0632e2a849c0..58f5cd76c8c3 100644 --- a/arch/mips/kernel/stacktrace.c +++ b/arch/mips/kernel/stacktrace.c @@ -32,7 +32,8 @@ static void save_raw_context_stack(struct stack_trace *trace, } } -static void save_context_stack(struct stack_trace *trace, struct pt_regs *regs) +static void save_context_stack(struct stack_trace *trace, + struct task_struct *tsk, struct pt_regs *regs) { unsigned long sp = regs->regs[29]; #ifdef CONFIG_KALLSYMS @@ -41,7 +42,7 @@ static void save_context_stack(struct stack_trace *trace, struct pt_regs *regs) if (raw_show_trace || !__kernel_text_address(pc)) { unsigned long stack_page = - (unsigned long)task_stack_page(current); + (unsigned long)task_stack_page(tsk); if (stack_page && sp >= stack_page && sp <= stack_page + THREAD_SIZE - 32) save_raw_context_stack(trace, sp); @@ -54,7 +55,7 @@ static void save_context_stack(struct stack_trace *trace, struct pt_regs *regs) trace->entries[trace->nr_entries++] = pc; if (trace->nr_entries >= trace->max_entries) break; - pc = unwind_stack(current, &sp, pc, &ra); + pc = unwind_stack(tsk, &sp, pc, &ra); } while (pc); #else save_raw_context_stack(trace, sp); @@ -65,13 +66,24 @@ static void save_context_stack(struct stack_trace *trace, struct pt_regs *regs) * Save stack-backtrace addresses into a stack_trace buffer. */ void save_stack_trace(struct stack_trace *trace) +{ + save_stack_trace_tsk(current, trace); +} +EXPORT_SYMBOL_GPL(save_stack_trace); + +void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) { struct pt_regs dummyregs; struct pt_regs *regs = &dummyregs; WARN_ON(trace->nr_entries || !trace->max_entries); - prepare_frametrace(regs); - save_context_stack(trace, regs); + if (tsk != current) { + regs->regs[29] = tsk->thread.reg29; + regs->regs[31] = 0; + regs->cp0_epc = tsk->thread.reg31; + } else + prepare_frametrace(regs); + save_context_stack(trace, tsk, regs); } -EXPORT_SYMBOL_GPL(save_stack_trace); +EXPORT_SYMBOL_GPL(save_stack_trace_tsk); diff --git a/fs/proc/base.c b/fs/proc/base.c index ce7a6da1b6a0..eb7b4654d6aa 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -65,6 +65,7 @@ #include #include #include +#include #include #include #include @@ -337,6 +338,37 @@ static int proc_pid_wchan(struct task_struct *task, char *buffer) } #endif /* CONFIG_KALLSYMS */ +#ifdef CONFIG_STACKTRACE + +#define MAX_STACK_TRACE_DEPTH 64 + +static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns, + struct pid *pid, struct task_struct *task) +{ + struct stack_trace trace; + unsigned long *entries; + int i; + + entries = kmalloc(MAX_STACK_TRACE_DEPTH * sizeof(*entries), GFP_KERNEL); + if (!entries) + return -ENOMEM; + + trace.nr_entries = 0; + trace.max_entries = MAX_STACK_TRACE_DEPTH; + trace.entries = entries; + trace.skip = 0; + save_stack_trace_tsk(task, &trace); + + for (i = 0; i < trace.nr_entries; i++) { + seq_printf(m, "[<%p>] %pS\n", + (void *)entries[i], (void *)entries[i]); + } + kfree(entries); + + return 0; +} +#endif + #ifdef CONFIG_SCHEDSTATS /* * Provides /proc/PID/schedstat @@ -2500,6 +2532,9 @@ static const struct pid_entry tgid_base_stuff[] = { #ifdef CONFIG_KALLSYMS INF("wchan", S_IRUGO, proc_pid_wchan), #endif +#ifdef CONFIG_STACKTRACE + ONE("stack", S_IRUSR, proc_pid_stack), +#endif #ifdef CONFIG_SCHEDSTATS INF("schedstat", S_IRUGO, proc_pid_schedstat), #endif @@ -2835,6 +2870,9 @@ static const struct pid_entry tid_base_stuff[] = { #ifdef CONFIG_KALLSYMS INF("wchan", S_IRUGO, proc_pid_wchan), #endif +#ifdef CONFIG_STACKTRACE + ONE("stack", S_IRUSR, proc_pid_stack), +#endif #ifdef CONFIG_SCHEDSTATS INF("schedstat", S_IRUGO, proc_pid_schedstat), #endif -- cgit v1.2.1