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arm64: backtrace: Don't bother trying to unwind the userspace stack

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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>
This commit is contained in:
Will Deacon 2019-04-08 17:56:34 +01:00
parent 5a3ae7b314
commit 1e6f5440a6
1 changed files with 9 additions and 6 deletions
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15
arch/arm64/kernel/traps.c
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@ -102,10 +102,16 @@ 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;
@ -126,7 +132,6 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
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 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;
}