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proc: add /proc/*/stack

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/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
	[<c010a271>] save_stack_trace_tsk+0x17/0x35
	[<c01827b4>] proc_pid_stack+0x4a/0x76
	[<c018312d>] proc_single_show+0x4a/0x5e
	[<c016bdec>] seq_read+0xf3/0x29f
	[<c015a004>] vfs_read+0x6d/0x91
	[<c015a0c1>] sys_read+0x3b/0x60
	[<c0102eda>] syscall_call+0x7/0xb
	[<ffffffff>] 0xffffffff

[add save_stack_trace_tsk() on mips, ACK Ralf --adobriyan]
Signed-off-by: Ken Chen <kenchen@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
This commit is contained in:
Ken Chen 2008-11-10 11:26:08 +03:00 committed by Alexey Dobriyan
parent 631f9c1868
commit 2ec220e27f
3 changed files with 57 additions and 6 deletions
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1
Documentation/filesystems/proc.txt
View File

@ -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
..............................................................................

24
arch/mips/kernel/stacktrace.c
View File

@ -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);

38
fs/proc/base.c
View File

@ -65,6 +65,7 @@
#include <linux/mm.h>
#include <linux/rcupdate.h>
#include <linux/kallsyms.h>
#include <linux/stacktrace.h>
#include <linux/resource.h>
#include <linux/module.h>
#include <linux/mount.h>
@ -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