commit 2ec220e27f5040aec1e88901c1b6ea3d135787ad
author Ken Chen <kenchen@google.com> Mon Nov 10 11:26:08 2008 +0300
committer Alexey Dobriyan <adobriyan@gmail.com> Mon Jan 05 12:27:44 2009 +0300
tree 06ed111c8e331d47927d9b46386f4063b74ec419
parent 631f9c1868b970197747c80fc5168ad7d9fd5d53

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>

arch/mips/kernel/stacktrace.c

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);