From 84c6c2af4c532dc3ce26d5c3f5e8b0824ac6b441 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Mon, 8 Apr 2019 17:56:34 +0100 Subject: [PATCH] arm64: backtrace: Don't bother trying to unwind the userspace stack commit 1e6f5440a6814d28c32d347f338bfef68bc3e69d upstream. Calling dump_backtrace() with a pt_regs argument corresponding to userspace doesn't make any sense and our unwinder will simply print "Call trace:" before unwinding the stack looking for user frames. Rather than go through this song and dance, just return early if we're passed a user register state. Cc: Fixes: 1149aad10b1e ("arm64: Add dump_backtrace() in show_regs") Reported-by: Kefeng Wang Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/traps.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index b9da093..a0099be 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -101,10 +101,16 @@ static void dump_instr(const char *lvl, struct pt_regs *regs) void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) { struct stackframe frame; - int skip; + int skip = 0; pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk); + if (regs) { + if (user_mode(regs)) + return; + skip = 1; + } + if (!tsk) tsk = current; @@ -125,7 +131,6 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) frame.graph = tsk->curr_ret_stack; #endif - skip = !!regs; printk("Call trace:\n"); do { /* skip until specified stack frame */ @@ -175,15 +180,13 @@ static int __die(const char *str, int err, struct pt_regs *regs) return ret; print_modules(); - __show_regs(regs); pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n", TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk)); + show_regs(regs); - if (!user_mode(regs)) { - dump_backtrace(regs, tsk); + if (!user_mode(regs)) dump_instr(KERN_EMERG, regs); - } return ret; } -- 2.7.4