[PATCH v6 37/39] s390/unwind: Disable KMSAN checks

[Ilya Leoshkevich <iii@linux.ibm.com>]

The unwind code can read uninitialized frames. Furthermore, even in
the good case, KMSAN does not emit shadow for backchains. Therefore
disable it for the unwinding functions.

Reviewed-by: Alexander Potapenko <glider@google.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 arch/s390/kernel/unwind_bc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c
index 0ece156fdd7c..cd44be2b6ce8 100644
--- a/arch/s390/kernel/unwind_bc.c
+++ b/arch/s390/kernel/unwind_bc.c
@@ -49,6 +49,8 @@ static inline bool is_final_pt_regs(struct unwind_state *state,
 	       READ_ONCE_NOCHECK(regs->psw.mask) & PSW_MASK_PSTATE;
 }
 
+/* Avoid KMSAN false positives from touching uninitialized frames. */
+__no_kmsan_checks
 bool unwind_next_frame(struct unwind_state *state)
 {
 	struct stack_info *info = &state->stack_info;
@@ -118,6 +120,8 @@ bool unwind_next_frame(struct unwind_state *state)
 }
 EXPORT_SYMBOL_GPL(unwind_next_frame);
 
+/* Avoid KMSAN false positives from touching uninitialized frames. */
+__no_kmsan_checks
 void __unwind_start(struct unwind_state *state, struct task_struct *task,
 		    struct pt_regs *regs, unsigned long first_frame)
 {
-- 
2.45.1