Thread (11 messages) 11 messages, 2 authors, 2020-06-30

Re: Question: livepatch failed for new fork() task stack unreliable

From: Josh Poimboeuf <hidden>
Date: 2020-06-05 01:51:56
Also in: lkml

Possibly related (same subject, not in this thread)

On Fri, Jun 05, 2020 at 09:26:42AM +0800, Wangshaobo (bobo) wrote:
quoted
quoted
So, I want to ask is there any side effects if i modify like this ? this
modification is based on

your fix. It looks like ok with proper test.
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index e9cc182aa97e..ecce5051e8fd 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -620,6 +620,7 @@ void __unwind_start(struct unwind_state *state, struct
task_struct *task,
                 state->sp = task->thread.sp;
                 state->bp = READ_ONCE_NOCHECK(frame->bp);
                 state->ip = READ_ONCE_NOCHECK(frame->ret_addr);
+              state->signal = ((void *)state->ip == ret_from_fork);
         }
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 7f969b2d240f..d7396431261a 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -540,7 +540,7 @@ bool unwind_next_frame(struct unwind_state *state)
          state->sp = sp;
          state->regs = NULL;
          state->prev_regs = NULL;
-        state->signal = ((void *)state->ip == ret_from_fork);
+        state->signal = false;
          break;
Yes that's correct.
Hi, josh

Could i ask when are you free to send the patch, all the tests are passed
by.
I want to run some regression tests, so it will probably be next week.

-- 
Josh
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