From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Donglin Peng <pengdonglin@sangfor.com.cn>,
mhiramat@kernel.org, linux@armlinux.org.uk, mark.rutland@arm.com,
will@kernel.org, catalin.marinas@arm.com, palmer@dabbelt.com,
paul.walmsley@sifive.com, tglx@linutronix.de,
dave.hansen@linux.intel.com, x86@kernel.org, mingo@redhat.com,
xiehuan09@gmail.com, dinghui@sangfor.com.cn,
huangcun@sangfor.com.cn, dolinux.peng@gmail.com,
linux-trace-kernel@vger.kernel.org,
linux-riscv@lists.infradead.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/2] function_graph: Support recording and printing the return value of function
Date: Wed, 15 Mar 2023 15:57:57 +0100 [thread overview]
Message-ID: <20230315145757.GE2006103@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20230315101348.1234c7f5@gandalf.local.home>
On Wed, Mar 15, 2023 at 10:13:48AM -0400, Steven Rostedt wrote:
> On Wed, 15 Mar 2023 14:49:11 +0100
> Peter Zijlstra <peterz@infradead.org> wrote:
>
> > > diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
> > > index 1265ad519249..35ac9c58dc77 100644
> > > --- a/arch/x86/kernel/ftrace_64.S
> > > +++ b/arch/x86/kernel/ftrace_64.S
> > > @@ -348,6 +348,10 @@ SYM_CODE_START(return_to_handler)
> > > movq %rax, (%rsp)
> > > movq %rdx, 8(%rsp)
> > > movq %rbp, %rdi
> > > +#ifdef CONFIG_FUNCTION_GRAPH_RETVAL
> > > + /* Pass the function return value to ftrace_return_to_handler */
> > > + movq %rax, %rsi
> > > +#endif
> > >
> > > call ftrace_return_to_handler
> >
> > What about the case of double register return values (when the value
> > is returned in the A,D pair) ?
>
> Is there anything that does that in 64 bit kernels?
Note sure; but I have a patch series that introduces cmpxchg128 and
friends. Most of the actual functions are __always_inline, but still,
the moment a compiler decides to break out a subfunction on a u128
boundary we're in luck.
next prev parent reply other threads:[~2023-03-15 15:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-15 13:39 [PATCH v4 0/2] function_graph: Support recording and printing the return value of function Donglin Peng
2023-03-15 13:39 ` [PATCH v4 1/2] " Donglin Peng
2023-03-15 13:49 ` Peter Zijlstra
2023-03-15 14:13 ` Steven Rostedt
2023-03-15 14:57 ` Peter Zijlstra [this message]
2023-03-16 3:18 ` Donglin Peng
2023-03-16 12:39 ` Masami Hiramatsu
2023-03-16 13:13 ` Donglin Peng
2023-03-16 23:21 ` Russell King (Oracle)
2023-03-17 2:49 ` Donglin Peng
2023-03-18 16:40 ` Steven Rostedt
2023-03-19 4:14 ` Donglin Peng
2023-03-15 13:39 ` [PATCH v4 2/2] tracing: Add documentation for funcgraph-retval and graph_retval_hex Donglin Peng
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