path: root/arch/s390/include
diff options
authorVasily Gorbik <gor@linux.ibm.com>2019-11-27 17:37:51 +0100
committerVasily Gorbik <gor@linux.ibm.com>2019-11-30 10:52:48 +0100
commit222ee9087a730b1df08d09baed0d03626e67600f (patch)
treed54f365c33449a1697ab1d0b4b07a7921ce6a837 /arch/s390/include
parentde6921ccbd0fb2882a1f615a6d3cdfbdcd64532c (diff)
s390/unwind: start unwinding from reliable state
A comment in arch/s390/include/asm/unwind.h says: > If 'first_frame' is not zero unwind_start skips unwind frames until it > reaches the specified stack pointer. > The end of the unwinding is indicated with unwind_done, this can be true > right after unwind_start, e.g. with first_frame!=0 that can not be found. > unwind_next_frame skips to the next frame. > Once the unwind is completed unwind_error() can be used to check if there > has been a situation where the unwinder could not correctly understand > the tasks call chain. With this change backchain unwinder now comply with behaviour described. As well as matches orc unwinder implementation. Now unwinder starts from reliable state, i.e. __unwind_start own stack frame is taken or stack frame generated by __switch_to (ksp) - both known to be valid. In case of pt_regs %r15 is better match for pt_regs psw, than sometimes random "sp" caller passed. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/include')
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/s390/include/asm/unwind.h b/arch/s390/include/asm/unwind.h
index 5d6c8fe7a271..de9006b0cfeb 100644
--- a/arch/s390/include/asm/unwind.h
+++ b/arch/s390/include/asm/unwind.h
@@ -58,11 +58,11 @@ static inline bool unwind_error(struct unwind_state *state)
static inline void unwind_start(struct unwind_state *state,
struct task_struct *task,
struct pt_regs *regs,
- unsigned long sp)
+ unsigned long first_frame)
task = task ?: current;
- sp = sp ?: get_stack_pointer(task, regs);
- __unwind_start(state, task, regs, sp);
+ first_frame = first_frame ?: get_stack_pointer(task, regs);
+ __unwind_start(state, task, regs, first_frame);
static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)

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