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
[<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>
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 71df353..334ef2f 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -140,6 +140,7 @@
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 0632e2a..58f5cd7 100644
--- a/arch/mips/kernel/stacktrace.c
+++ b/arch/mips/kernel/stacktrace.c
@@ -32,7 +32,8 @@
}
}
-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 @@
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 @@
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);
@@ -66,12 +67,23 @@
*/
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 ce7a6da..eb7b465 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -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 @@
}
#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 @@
#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 @@
#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