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Subject[PATCH] arm: add save_stack_trace_regs() support
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From: ivan lam <ivan.lam2014@gmail.com>
Date: Mon, 4 Nov 2013 23:35:55 +0800
Subject: [PATCH] arm: add save_stack_trace_regs() support

When configure kprobe events of ftrace with stacktrace option enabled
in arm, not stacktrace was recorded after the kprobe was triggered.

Implement the save_stack_trace_regs() function in arm.

After this fix, stacktrace can be recorded, for example:

# mount -t debugfs nodev /sys/kernel/debug
# echo "p:netrx net_rx_action" >> /sys/kernel/debug/tracing/kprobe_events
# echo 1 > /sys/kernel/debug/tracing/events/kprobes/netrx/enable
# echo 1 > /sys/kernel/debug/tracing/options/stacktrace
# echo 1 > /sys/kernel/debug/tracing/tracing_on
# ping 127.0.0.1 -c 1
# echo 0 > /sys/kernel/debug/tracing/tracing_on

# cat /sys/kernel/debug/tracing/trace
# tracer: nop
#
# entries-in-buffer/entries-written: 12/12 #P:1
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
ping-1200 [000] dNs1 667.603250: netrx: (net_rx_action+0x0/0x1f8)
ping-1200 [000] dNs1 667.604738: <stack trace>
=> net_rx_action
=> do_softirq
=> local_bh_enable
=> ip_finish_output
=> ip_output
=> ip_local_out
=> ip_send_skb
=> ip_push_pending_frames
=> raw_sendmsg
=> inet_sendmsg
=> sock_sendmsg
=> SyS_sendto
=> ret_fast_syscall

Signed-off-by: ivan lam <ivan.lam2014@gmail.com>
---
arch/arm/kernel/stacktrace.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index 00f79e5..2b52fac0 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -123,6 +123,25 @@ void save_stack_trace_tsk(struct task_struct
*tsk, struct stack_trace *trace)
trace->entries[trace->nr_entries++] = ULONG_MAX;
}

+void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
+{
+ struct stack_trace_data data;
+ struct stackframe frame;
+
+ data.trace = trace;
+ data.skip = trace->skip;
+ data.no_sched_functions = 1;
+
+ frame.fp = regs->ARM_fp;
+ frame.sp = regs->ARM_sp;
+ frame.lr = regs->ARM_lr;
+ frame.pc = regs->ARM_pc;
+
+ walk_stackframe(&frame, save_trace, &data);
+ if (trace->nr_entries < trace->max_entries)
+ trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+
void save_stack_trace(struct stack_trace *trace)
{
save_stack_trace_tsk(current, trace);
--
1.7.9.5

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