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s390/unwind: stop gracefully at user mode pt_regs in irq stack

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Consider reaching user mode pt_regs at the bottom of irq stack graceful
unwinder termination. This is the case when irq/mcck/ext interrupt arrives
while in user mode.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2019-12-11 17:27:31 +01:00
parent c23587c92f
commit eef06cbf67
1 changed files with 11 additions and 4 deletions
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15
arch/s390/kernel/unwind_bc.c
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@ -36,10 +36,17 @@ 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)
static inline bool is_final_pt_regs(struct unwind_state *state,
struct pt_regs *regs)
{
return task_pt_regs(state->task) == regs;
/* user mode or kernel thread pt_regs at the bottom of task stack */
if (task_pt_regs(state->task) == regs)
return true;
/* user mode pt_regs at the bottom of irq stack */
return state->stack_info.type == STACK_TYPE_IRQ &&
state->stack_info.end - sizeof(struct pt_regs) == (unsigned long)regs &&
READ_ONCE_NOCHECK(regs->psw.mask) & PSW_MASK_PSTATE;
}
bool unwind_next_frame(struct unwind_state *state)
@ -80,7 +87,7 @@ 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 (is_task_pt_regs(state, regs))
if (is_final_pt_regs(state, regs))
goto out_stop;
ip = READ_ONCE_NOCHECK(regs->psw.addr);
sp = READ_ONCE_NOCHECK(regs->gprs[15]);