This is a note to let you know that I've just added the patch titled
arm64: backtrace: Don't bother trying to unwind the userspace stack
to the 5.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-backtrace-don-t-bother-trying-to-unwind-the-userspace-stack.patch
and it can be found in the queue-5.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1e6f5440a6814d28c32d347f338bfef68bc3e69d Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@xxxxxxx>
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@xxxxxxx>
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@xxxxxxxxxxxxxxx>
Fixes: 1149aad10b1e ("arm64: Add dump_backtrace() in show_regs")
Reported-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
}
Patches currently in stable-queue which might be from will.deacon@xxxxxxx are
queue-5.0/arm64-futex-fix-futex_wake_op-atomic-ops-with-non-zero-result-value.patch
queue-5.0/arm64-ftrace-fix-inadvertent-bug-in-trampoline-check.patch
queue-5.0/arm64-backtrace-don-t-bother-trying-to-unwind-the-userspace-stack.patch
