Messages in this thread Patch in this message | | | Date | Tue, 19 Jul 2022 10:46:48 +0200 | From | Peter Zijlstra <> | Subject | Re: [patch 36/38] x86/ftrace: Make it call depth tracking aware |
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On Mon, Jul 18, 2022 at 05:01:23PM -0400, Steven Rostedt wrote:
> From 533f10bd48ffbc4ee5d2a07f0a7fe99aeb1c823a 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
Only the RET should do I think; you definitely don't need an ENDBR here nor do you need to override the unwind hint. Lemme try..
Yeah, the below is sufficient:
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S index dfeb227de561..d6679b65b6f2 100644 --- a/arch/x86/kernel/ftrace_64.S +++ b/arch/x86/kernel/ftrace_64.S @@ -172,8 +172,7 @@ SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL) */ SYM_INNER_LABEL(ftrace_caller_end, SYM_L_GLOBAL) ANNOTATE_NOENDBR - - jmp ftrace_epilogue + RET SYM_FUNC_END(ftrace_caller); STACK_FRAME_NON_STANDARD_FP(ftrace_caller) @@ -269,7 +268,7 @@ SYM_INNER_LABEL(ftrace_regs_caller_jmp, SYM_L_GLOBAL) */ SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL) ANNOTATE_NOENDBR - jmp ftrace_epilogue + RET /* Swap the flags with orig_rax */ 1: movq MCOUNT_REG_SIZE(%rsp), %rdi @@ -280,7 +279,7 @@ SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL) /* Restore flags */ popfq UNWIND_HINT_FUNC - jmp ftrace_epilogue + RET SYM_FUNC_END(ftrace_regs_caller) STACK_FRAME_NON_STANDARD_FP(ftrace_regs_caller)
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