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s390/unwind: use current_frame_address() to unwind current task 

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@kernel.org>
Suggested-by: Marco Elver <elver@google.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Tested-by: Marco Elver <elver@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/patch.git-04dd26be3043.your-ad-here.call-01630504868-ext-6188@work.hours
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2021-09-01 16:05:59 +02:00 committed by Heiko Carstens
parent 81912856e0
commit 88b604263f
2 changed files with 14 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
arch/s390/include/asm/stacktrace.h
View File

@ -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.

8
arch/s390/include/asm/unwind.h
View File

@ -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);