| From 1e6f5440a6814d28c32d347f338bfef68bc3e69d Mon Sep 17 00:00:00 2001 |
| From: Will Deacon <will.deacon@arm.com> |
| Date: Mon, 8 Apr 2019 17:56:34 +0100 |
| Subject: arm64: backtrace: Don't bother trying to unwind the userspace stack |
| |
| From: Will Deacon <will.deacon@arm.com> |
| |
| 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: <stable@vger.kernel.org> |
| Fixes: 1149aad10b1e ("arm64: Add dump_backtrace() in show_regs") |
| Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com> |
| Signed-off-by: Will Deacon <will.deacon@arm.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/arm64/kernel/traps.c | 15 +++++++++------ |
| 1 file changed, 9 insertions(+), 6 deletions(-) |
| |
| --- a/arch/arm64/kernel/traps.c |
| +++ b/arch/arm64/kernel/traps.c |
| @@ -102,10 +102,16 @@ static void dump_instr(const char *lvl, |
| 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; |
| |
| @@ -126,7 +132,6 @@ void dump_backtrace(struct pt_regs *regs |
| frame.graph = 0; |
| #endif |
| |
| - skip = !!regs; |
| printk("Call trace:\n"); |
| do { |
| /* skip until specified stack frame */ |
| @@ -176,15 +181,13 @@ static int __die(const char *str, int er |
| 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; |
| } |