From: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
commit a1d863ac3e1085e1fea9caafd87252d08731de2e upstream.
unwind_for_each_frame stops after the first frame if regs->gprs[15] <=
sp.
The reason is that in case regs are specified, the first frame should be
regs->psw.addr and the second frame should be sp->gprs[8]. However,
currently the second frame is regs->gprs[15], which confuses
outside_of_stack().
Fix by introducing a flag to distinguish this special case from
unwinding the interrupt handler, for which the current behavior is
appropriate.
Fixes: 78c98f907413 ("s390/unwind: introduce stack unwind API")
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v5.2+
Reviewed-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/include/asm/unwind.h | 1 +
arch/s390/kernel/unwind_bc.c | 18 +++++++++++++-----
2 files changed, 14 insertions(+), 5 deletions(-)
--- a/arch/s390/include/asm/unwind.h
+++ b/arch/s390/include/asm/unwind.h
@@ -35,6 +35,7 @@ struct unwind_state {
struct task_struct *task;
struct pt_regs *regs;
unsigned long sp, ip;
+ bool reuse_sp;
int graph_idx;
bool reliable;
bool error;
--- a/arch/s390/kernel/unwind_bc.c
+++ b/arch/s390/kernel/unwind_bc.c
@@ -46,10 +46,15 @@ bool unwind_next_frame(struct unwind_sta
regs = state->regs;
if (unlikely(regs)) {
- sp = READ_ONCE_NOCHECK(regs->gprs[15]);
- if (unlikely(outside_of_stack(state, sp))) {
- if (!update_stack_info(state, sp))
- goto out_err;
+ if (state->reuse_sp) {
+ sp = state->sp;
+ state->reuse_sp = false;
+ } else {
+ sp = READ_ONCE_NOCHECK(regs->gprs[15]);
+ if (unlikely(outside_of_stack(state, sp))) {
+ if (!update_stack_info(state, sp))
+ goto out_err;
+ }
}
sf = (struct stack_frame *) sp;
ip = READ_ONCE_NOCHECK(sf->gprs[8]);
@@ -107,9 +112,9 @@ void __unwind_start(struct unwind_state
{
struct stack_info *info = &state->stack_info;
unsigned long *mask = &state->stack_mask;
+ bool reliable, reuse_sp;
struct stack_frame *sf;
unsigned long ip;
- bool reliable;
memset(state, 0, sizeof(*state));
state->task = task;
@@ -134,10 +139,12 @@ void __unwind_start(struct unwind_state
if (regs) {
ip = READ_ONCE_NOCHECK(regs->psw.addr);
reliable = true;
+ reuse_sp = true;
} else {
sf = (struct stack_frame *) sp;
ip = READ_ONCE_NOCHECK(sf->gprs[8]);
reliable = false;
+ reuse_sp = false;
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
@@ -151,5 +158,6 @@ void __unwind_start(struct unwind_state
state->sp = sp;
state->ip = ip;
state->reliable = reliable;
+ state->reuse_sp = reuse_sp;
}
EXPORT_SYMBOL_GPL(__unwind_start);
