current_stack_pointer() simply returns current value of %r15. If
current_stack_pointer() caller allocates stack (which is the case in
unwind code) %r15 points to a stack frame allocated for callees, meaning
current_stack_pointer() caller (e.g. stack_trace_save) will end up in
the stacktrace. This is not expected by stack_trace_save*() callers and
causes problems.
current_frame_address() on the other hand returns function stack frame
address, which matches %r15 upon function invocation. Using it in
get_stack_pointer() makes it more aligned with x86 implementation
(according to BACKTRACE_SELF_TEST output) and meets stack_trace_save*()
caller's expectations, notably KCSAN.
Also make sure unwind_start is always inlined.
Reported-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Suggested-by: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
---
arch/s390/include/asm/stacktrace.h | 20 ++++++++++----------
arch/s390/include/asm/unwind.h | 8 ++++----
2 files changed, 14 insertions(+), 14 deletions(-)
diff --git a/arch/s390/include/asm/stacktrace.h b/arch/s390/include/asm/stacktrace.h
index 3d8a4b94c620..22c41d7fd95c 100644
--- a/arch/s390/include/asm/stacktrace.h
+++ b/arch/s390/include/asm/stacktrace.h
@@ -34,16 +34,6 @@ static inline bool on_stack(struct stack_info *info,
return addr >= info->begin && addr + len <= info->end;
}
-static __always_inline unsigned long get_stack_pointer(struct task_struct *task,
- struct pt_regs *regs)
-{
- if (regs)
- return (unsigned long) kernel_stack_pointer(regs);
- if (task == current)
- return current_stack_pointer();
- return (unsigned long) task->thread.ksp;
-}
-
/*
* Stack layout of a C stack frame.
*/
@@ -74,6 +64,16 @@ struct stack_frame {
((unsigned long)__builtin_frame_address(0) - \
offsetof(struct stack_frame, back_chain))
+static __always_inline unsigned long get_stack_pointer(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ if (regs)
+ return (unsigned long) kernel_stack_pointer(regs);
+ if (task == current)
+ return current_frame_address();
+ return (unsigned long) task->thread.ksp;
+}
+
/*
* To keep this simple mark register 2-6 as being changed (volatile)
* by the called function, even though register 6 is saved/nonvolatile.
diff --git a/arch/s390/include/asm/unwind.h b/arch/s390/include/asm/unwind.h
index de9006b0cfeb..5ebf534ef753 100644
--- a/arch/s390/include/asm/unwind.h
+++ b/arch/s390/include/asm/unwind.h
@@ -55,10 +55,10 @@ static inline bool unwind_error(struct unwind_state *state)
return state->error;
}
-static inline void unwind_start(struct unwind_state *state,
- struct task_struct *task,
- struct pt_regs *regs,
- unsigned long first_frame)
+static __always_inline void unwind_start(struct unwind_state *state,
+ struct task_struct *task,
+ struct pt_regs *regs,
+ unsigned long first_frame)
{
task = task ?: current;
first_frame = first_frame ?: get_stack_pointer(task, regs);
--
2.25.4
