From 98ab10e9770e3ce9fbd263689644be9d81a06885 Mon Sep 17 00:00:00 2001 From: Pratyush Anand Date: Mon, 5 Sep 2016 08:03:16 +0530 Subject: [PATCH] arm64: ftrace: add save_stack_trace_regs() Currently, enabling stacktrace of a kprobe events generates warning: echo stacktrace > /sys/kernel/debug/tracing/trace_options echo "p xhci_irq" > /sys/kernel/debug/tracing/kprobe_events echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable save_stack_trace_regs() not implemented yet. ------------[ cut here ]------------ WARNING: CPU: 1 PID: 0 at ../kernel/stacktrace.c:74 save_stack_trace_regs+0x3c/0x48 Modules linked in: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.8.0-rc4-dirty #5128 Hardware name: ARM Juno development board (r1) (DT) task: ffff800975dd1900 task.stack: ffff800975ddc000 PC is at save_stack_trace_regs+0x3c/0x48 LR is at save_stack_trace_regs+0x3c/0x48 pc : [] lr : [] pstate: 600003c5 sp : ffff80097ef52c00 Call trace: save_stack_trace_regs+0x3c/0x48 __ftrace_trace_stack+0x168/0x208 trace_buffer_unlock_commit_regs+0x5c/0x7c kprobe_trace_func+0x308/0x3d8 kprobe_dispatcher+0x58/0x60 kprobe_breakpoint_handler+0xbc/0x18c brk_handler+0x50/0x90 do_debug_exception+0x50/0xbc This patch implements save_stack_trace_regs(), so that stacktrace of a kprobe events can be obtained. After this patch, there is no warning and we can see the stacktrace for kprobe events in trace buffer. more /sys/kernel/debug/tracing/trace -0 [004] d.h. 1356.000496: p_xhci_irq_0:(xhci_irq+0x0/0x9ac) -0 [004] d.h. 1356.000497: => xhci_irq => __handle_irq_event_percpu => handle_irq_event_percpu => handle_irq_event => handle_fasteoi_irq => generic_handle_irq => __handle_domain_irq => gic_handle_irq => el1_irq => arch_cpu_idle => default_idle_call => cpu_startup_entry => secondary_start_kernel => Tested-by: David A. Long Reviewed-by: James Morse Signed-off-by: Pratyush Anand Signed-off-by: Will Deacon --- arch/arm64/kernel/stacktrace.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index d9751a4769e7..ca01addf8c4c 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -152,6 +152,27 @@ static int save_trace(struct stackframe *frame, void *d) return trace->nr_entries >= trace->max_entries; } +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 = 0; + + frame.fp = regs->regs[29]; + frame.sp = regs->sp; + frame.pc = regs->pc; +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + frame.graph = current->curr_ret_stack; +#endif + + walk_stackframe(current, &frame, save_trace, &data); + if (trace->nr_entries < trace->max_entries) + trace->entries[trace->nr_entries++] = ULONG_MAX; +} + void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) { struct stack_trace_data data; -- 2.30.2