| Date | Fri, 9 Dec 2022 10:41:17 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH v3 56/59] x86/ftrace: Remove ftrace_epilogue() |
| |
On Thu, 15 Sep 2022 13:11:35 +0200 Peter Zijlstra <peterz@infradead.org> wrote:
> From: Peter Zijlstra <peterz@infradead.org> > > Remove the weird jumps to RET and simply use RET. > > This then promotes ftrace_stub() to a real function; which becomes > important for kcfi. > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> >
Moving my setup to a new machine, I found I had this patch queued and never pushed out :-p
-- Steve
From e55c8c52510be3ac996f3567e1d2dbdf76ed23de Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" <rostedt@goodmis.org> Date: Mon, 18 Jul 2022 16:01:07 -0400 Subject: [PATCH] ftrace/x86: Remove jumps to ftrace_epilogue
The jumps to ftrace_epilogue were done as a way to make sure all the function tracing trampolines ended at the function graph trampoline, as the ftrace_epilogue was the location that it would handle that.
With the advent of function graph tracer now being just one of the callbacks of the function tracer there is no more requirement that all trampolines go to a single location.
Remove the jumps to the ftrace_epilogue and replace them with return statements.
Note, the ftrace_epilogue can probably be renamed to ftrace_stub and the weak logic for that could probably be removed. But lets leave that as a separate change.
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> --- arch/x86/kernel/ftrace_64.S | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S index dfeb227de561..8f225fafa5fb 100644 --- a/arch/x86/kernel/ftrace_64.S +++ b/arch/x86/kernel/ftrace_64.S @@ -173,7 +173,9 @@ SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL) SYM_INNER_LABEL(ftrace_caller_end, SYM_L_GLOBAL) ANNOTATE_NOENDBR - jmp ftrace_epilogue + UNWIND_HINT_FUNC + ENDBR + RET SYM_FUNC_END(ftrace_caller); STACK_FRAME_NON_STANDARD_FP(ftrace_caller) @@ -261,15 +263,9 @@ SYM_INNER_LABEL(ftrace_regs_caller_jmp, SYM_L_GLOBAL) /* Restore flags */ popfq - /* - * As this jmp to ftrace_epilogue can be a short jump - * it must not be copied into the trampoline. - * The trampoline will add the code to jump - * to the return. - */ SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL) ANNOTATE_NOENDBR - jmp ftrace_epilogue + jmp 2f /* Swap the flags with orig_rax */ 1: movq MCOUNT_REG_SIZE(%rsp), %rdi @@ -279,8 +275,10 @@ SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL) restore_mcount_regs 8 /* Restore flags */ popfq +2: UNWIND_HINT_FUNC - jmp ftrace_epilogue + ENDBR + RET SYM_FUNC_END(ftrace_regs_caller) STACK_FRAME_NON_STANDARD_FP(ftrace_regs_caller) -- 2.35.1
|