[PATCH 4.2.y-ckt 260/273] s390/stacktrace: fix address ranges for asynchronous and panic stack

[Kamal Mostafa]

4.2.8-ckt5 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>

commit 9900c48c46d8bcf497972024c5fe366e6d9771f3 upstream.

git commit dc7ee00d4771 ("s390: lowcore stack pointer offsets")
introduced a regression in regard to save_stack_trace(). The stack
pointer for the asynchronous and the panic stack in the lowcore now
have an additional offset applied to them. This offset needs to be
taken into account in the calculation for the low and high address for
the stacks.

This bug was already partially fixed with 9cc5c206d9b4
("s390/dumpstack: fix address ranges for asynchronous and panic
stack"). This patch fixes it also for the stacktrace code.

Fixes: dc7ee00d4771 ("s390: lowcore stack pointer offsets")
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Tested-by: Peter Oberparleiter <oberpar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
 arch/s390/kernel/stacktrace.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c
index 1785cd8..8be2c35 100644
--- a/arch/s390/kernel/stacktrace.c
+++ b/arch/s390/kernel/stacktrace.c
@@ -63,17 +63,18 @@ static unsigned long save_context_stack(struct stack_trace *trace,
 void save_stack_trace(struct stack_trace *trace)
 {
 	register unsigned long sp asm ("15");
-	unsigned long orig_sp, new_sp;
+	unsigned long orig_sp, new_sp, frame_size;
 
+	frame_size = STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
 	orig_sp = sp & PSW_ADDR_INSN;
 	new_sp = save_context_stack(trace, orig_sp,
-				    S390_lowcore.panic_stack - PAGE_SIZE,
-				    S390_lowcore.panic_stack, 1);
+			S390_lowcore.panic_stack + frame_size - PAGE_SIZE,
+			S390_lowcore.panic_stack + frame_size, 1);
 	if (new_sp != orig_sp)
 		return;
 	new_sp = save_context_stack(trace, new_sp,
-				    S390_lowcore.async_stack - ASYNC_SIZE,
-				    S390_lowcore.async_stack, 1);
+			S390_lowcore.async_stack + frame_size - ASYNC_SIZE,
+			S390_lowcore.async_stack + frame_size, 1);
 	if (new_sp != orig_sp)
 		return;
 	save_context_stack(trace, new_sp,
-- 
2.7.0