When using function graph tracer, the printed call trace will be as following that has many ftrace_graph_caller (return_to_handler - 4), which is been placed in the stack by ftrace_graph tracer to replace the real return address.
[ 198.582568] Call trace: [ 198.583313] [<ffffffc0002a1070>] next_tgid+0x30/0x100 [ 198.584359] [<ffffffc0000907bc>] ftrace_graph_caller+0x6c/0x70 [ 198.585503] [<ffffffc0000907bc>] ftrace_graph_caller+0x6c/0x70 [ 198.586574] [<ffffffc0000907bc>] ftrace_graph_caller+0x6c/0x70 [ 198.587660] [<ffffffc0000907bc>] ftrace_graph_caller+0x6c/0x70 [ 198.588896] Code: aa0003f5 2a0103f4 b4000102 91004043 (885f7c60) [ 198.591092] ---[ end trace 6a346f8f20949ac8 ]--- This patch fix it, and dump the real return address in the call trace. Signed-off-by: Li Bin <huawei.li...@huawei.com> --- arch/arm64/kernel/traps.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index f93aae5..4a4e679 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -143,9 +143,38 @@ static void dump_instr(const char *lvl, struct pt_regs *regs) set_fs(fs); } +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +static void print_ftrace_graph_addr(unsigned long addr, + struct task_struct *tsk, + unsigned long sp, int *graph) +{ + unsigned long ret_addr; + int index = tsk->curr_ret_stack; + + if (addr != ((unsigned long)return_to_handler - 4)) + return; + + if (!tsk->ret_stack || index < *graph) + return; + + index -= *graph; + ret_addr = tsk->ret_stack[index].ret; + + dump_backtrace_entry(ret_addr - 4, sp); + + (*graph)++; +} +#else +static inline void print_ftrace_graph_addr(unsigned long addr, + struct task_struct *tsk, + unsigned long sp, int *graph) +{} +#endif + static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) { struct stackframe frame; + int graph = 0; pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk); @@ -177,7 +206,9 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) ret = unwind_frame(&frame); if (ret < 0) break; + dump_backtrace_entry(where, frame.sp); + print_ftrace_graph_addr(where, tsk, frame.sp, &graph); } } -- 1.7.12.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/