[PATCH 6.9 134/374] s390/vdso: Introduce and use struct stack_frame_vdso_wrapper

Greg Kroah-Hartman
2024-06-06T14:09:26Z

From: Heiko Carstens <hca@linux.ibm.com>

[ Upstream commit be72ea09c1a5273abf8c6c52ef53e36c701cbf6a ]

Introduce and use struct stack_frame_vdso_wrapper within vdso user wrapper
code. With this structure it is possible to automatically generate an
asm-offset define which can be used to save and restore the return address
of the calling function.

Also use STACK_FRAME_USER_OVERHEAD instead of STACK_FRAME_OVERHEAD to
document that the code works with user space stack frames with the standard
stack frame layout.

Fixes: aa44433ac4ee ("s390: add USER_STACKTRACE support")
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/include/asm/stacktrace.h | 5 +++++
arch/s390/kernel/asm-offsets.c | 4 ++++
arch/s390/kernel/vdso64/vdso_user_wrapper.S | 18 ++++++++----------
3 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/arch/s390/include/asm/stacktrace.h b/arch/s390/include/asm/stacktrace.h
index 4aefbe32265d8..85b6738b826af 100644
--- a/arch/s390/include/asm/stacktrace.h
+++ b/arch/s390/include/asm/stacktrace.h
@@ -13,6 +13,11 @@ struct stack_frame_user {
unsigned long empty2[4];
};

+struct stack_frame_vdso_wrapper {
+ struct stack_frame_user sf;
+ unsigned long return_address;
+};
+
struct perf_callchain_entry_ctx;

void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *cookie,
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index fa5f6885c74aa..28017c418442b 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -66,6 +66,10 @@ int main(void)
OFFSET(__SF_SIE_CONTROL_PHYS, stack_frame, sie_control_block_phys);
DEFINE(STACK_FRAME_OVERHEAD, sizeof(struct stack_frame));
BLANK();
+ DEFINE(STACK_FRAME_USER_OVERHEAD, sizeof(struct stack_frame_user));
+ OFFSET(__SFVDSO_RETURN_ADDRESS, stack_frame_vdso_wrapper, return_address);
+ DEFINE(STACK_FRAME_VDSO_OVERHEAD, sizeof(struct stack_frame_vdso_wrapper));
+ BLANK();
/* idle data offsets */
OFFSET(__CLOCK_IDLE_ENTER, s390_idle_data, clock_idle_enter);
OFFSET(__TIMER_IDLE_ENTER, s390_idle_data, timer_idle_enter);
diff --git a/arch/s390/kernel/vdso64/vdso_user_wrapper.S b/arch/s390/kernel/vdso64/vdso_user_wrapper.S
index 85247ef5a41b8..deee8ca9cdbf0 100644
--- a/arch/s390/kernel/vdso64/vdso_user_wrapper.S
+++ b/arch/s390/kernel/vdso64/vdso_user_wrapper.S
@@ -6,8 +6,6 @@
#include <asm/dwarf.h>
#include <asm/ptrace.h>

-#define WRAPPER_FRAME_SIZE (STACK_FRAME_OVERHEAD+8)
-
/*
* Older glibc version called vdso without allocating a stackframe. This wrapper
* is just used to allocate a stackframe. See
@@ -20,16 +18,16 @@
__ALIGN
__kernel_\func:
CFI_STARTPROC
- aghi %r15,-WRAPPER_FRAME_SIZE
- CFI_DEF_CFA_OFFSET (STACK_FRAME_OVERHEAD + WRAPPER_FRAME_SIZE)
- CFI_VAL_OFFSET 15, -STACK_FRAME_OVERHEAD
- stg %r14,STACK_FRAME_OVERHEAD(%r15)
- CFI_REL_OFFSET 14, STACK_FRAME_OVERHEAD
+ aghi %r15,-STACK_FRAME_VDSO_OVERHEAD
+ CFI_DEF_CFA_OFFSET (STACK_FRAME_USER_OVERHEAD + STACK_FRAME_VDSO_OVERHEAD)
+ CFI_VAL_OFFSET 15,-STACK_FRAME_USER_OVERHEAD
+ stg %r14,__SFVDSO_RETURN_ADDRESS(%r15)
+ CFI_REL_OFFSET 14,__SFVDSO_RETURN_ADDRESS
brasl %r14,__s390_vdso_\func
- lg %r14,STACK_FRAME_OVERHEAD(%r15)
+ lg %r14,__SFVDSO_RETURN_ADDRESS(%r15)
CFI_RESTORE 14
- aghi %r15,WRAPPER_FRAME_SIZE
- CFI_DEF_CFA_OFFSET STACK_FRAME_OVERHEAD
+ aghi %r15,STACK_FRAME_VDSO_OVERHEAD
+ CFI_DEF_CFA_OFFSET STACK_FRAME_USER_OVERHEAD
CFI_RESTORE 15
br %r14
CFI_ENDPROC
--
2.43.0