Commit e76e6961 authored by Vasily Gorbik's avatar Vasily Gorbik
Browse files

s390/unwind: stop gracefully at task pt_regs 



Consider reaching task pt_regs graceful unwinder termination. Task
pt_regs itself never contains a valid state to which a task might return
within the kernel context (user task pt_regs is a special case). Since
we already avoid printing user task pt_regs and in most cases we don't
even bother filling task pt_regs psw and r15 with something reasonable
simply skip task pt_regs altogether. With this change unwind_error() now
accurately represent whether unwinder reached task pt_regs successfully
or failed along the way.

Reviewed-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent cb7948e8

arch/s390/kernel/unwind_bc.c

+7 −1
Original line number Diff line number Diff line
@@ -36,6 +36,12 @@ static bool update_stack_info(struct unwind_state *state, unsigned long sp) 
	return true;

}



static inline bool is_task_pt_regs(struct unwind_state *state,

				   struct pt_regs *regs)

{

	return task_pt_regs(state->task) == regs;

}



bool unwind_next_frame(struct unwind_state *state)

{

	struct stack_info *info = &state->stack_info;
@@ -69,7 +75,7 @@ bool unwind_next_frame(struct unwind_state *state) 
			if (!on_stack(info, sp, sizeof(struct pt_regs)))

				goto out_err;

			regs = (struct pt_regs *) sp;

			if (READ_ONCE_NOCHECK(regs->psw.mask) & PSW_MASK_PSTATE)

			if (is_task_pt_regs(state, regs))

				goto out_stop;

			ip = READ_ONCE_NOCHECK(regs->psw.addr);

			sp = READ_ONCE_NOCHECK(regs->gprs[15]);