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Commit 1e6f5440 authored by Will Deacon's avatar Will Deacon
Browse files

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



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: 1149aad1 ("arm64: Add dump_backtrace() in show_regs")
Reported-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 5a3ae7b3

arch/arm64/kernel/traps.c

+9 −6
Original line number Diff line number Diff line
@@ -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;

}