From: Mark Rutland <mark.rutland@arm.com>
To: "GONG, Ruiqi" <gongruiqi@huaweicloud.com>,
Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
Florent Revest <revest@chromium.org>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
gongruiqi1@huawei.com
Subject: Re: [PATCH] samples: ftrace: replace bti assembly with hint for older compiler
Date: Mon, 21 Aug 2023 17:12:51 +0100 [thread overview]
Message-ID: <ZOONA8yHeszPwdEz@FVFF77S0Q05N> (raw)
In-Reply-To: <20230820111509.1470826-1-gongruiqi@huaweicloud.com>
On Sun, Aug 20, 2023 at 07:15:09PM +0800, GONG, Ruiqi wrote:
> From: "GONG, Ruiqi" <gongruiqi1@huawei.com>
>
> When cross-building the arm64 kernel with allmodconfig using GCC 9.4,
> the following error occurs on multiple files under samples/ftrace/:
>
> /tmp/ccPC1ODs.s: Assembler messages:
> /tmp/ccPC1ODs.s:8: Error: selected processor does not support `bti c'
>
> Fix this issue by replacing `bti c` with `hint 34`, which is compatible
> for the older compiler.
>
> Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
Sorry about this; I'd forgotten about earlier compilers when reviewing the
original patch. It's a bit unfortunate to have to hand-code this each time, but
I'm not sure that it'd actually be cleaner to have a macro.
For the moment, I reckon this is worth taking as-is.
Steve, are you happy to add:
Fixes: 8c3526fb86060cb5 ("arm64: ftrace: Add direct call trampoline samples support")
Acked-by: Mark Rutland <mark.rutland@arm.com>
... ?
Thanks,
Mark.
> ---
> samples/ftrace/ftrace-direct-modify.c | 4 ++--
> samples/ftrace/ftrace-direct-multi-modify.c | 4 ++--
> samples/ftrace/ftrace-direct-multi.c | 2 +-
> samples/ftrace/ftrace-direct-too.c | 2 +-
> samples/ftrace/ftrace-direct.c | 2 +-
> 5 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c
> index e5ed08098ff3..e2a6a69352df 100644
> --- a/samples/ftrace/ftrace-direct-modify.c
> +++ b/samples/ftrace/ftrace-direct-modify.c
> @@ -105,7 +105,7 @@ asm (
> " .type my_tramp1, @function\n"
> " .globl my_tramp1\n"
> " my_tramp1:"
> -" bti c\n"
> +" hint 34\n" // bti c
> " sub sp, sp, #16\n"
> " stp x9, x30, [sp]\n"
> " bl my_direct_func1\n"
> @@ -117,7 +117,7 @@ asm (
> " .type my_tramp2, @function\n"
> " .globl my_tramp2\n"
> " my_tramp2:"
> -" bti c\n"
> +" hint 34\n" // bti c
> " sub sp, sp, #16\n"
> " stp x9, x30, [sp]\n"
> " bl my_direct_func2\n"
> diff --git a/samples/ftrace/ftrace-direct-multi-modify.c b/samples/ftrace/ftrace-direct-multi-modify.c
> index 292cff2b3f5d..2e349834d63c 100644
> --- a/samples/ftrace/ftrace-direct-multi-modify.c
> +++ b/samples/ftrace/ftrace-direct-multi-modify.c
> @@ -112,7 +112,7 @@ asm (
> " .type my_tramp1, @function\n"
> " .globl my_tramp1\n"
> " my_tramp1:"
> -" bti c\n"
> +" hint 34\n" // bti c
> " sub sp, sp, #32\n"
> " stp x9, x30, [sp]\n"
> " str x0, [sp, #16]\n"
> @@ -127,7 +127,7 @@ asm (
> " .type my_tramp2, @function\n"
> " .globl my_tramp2\n"
> " my_tramp2:"
> -" bti c\n"
> +" hint 34\n" // bti c
> " sub sp, sp, #32\n"
> " stp x9, x30, [sp]\n"
> " str x0, [sp, #16]\n"
> diff --git a/samples/ftrace/ftrace-direct-multi.c b/samples/ftrace/ftrace-direct-multi.c
> index b4391e08c913..9243dbfe4d0c 100644
> --- a/samples/ftrace/ftrace-direct-multi.c
> +++ b/samples/ftrace/ftrace-direct-multi.c
> @@ -75,7 +75,7 @@ asm (
> " .type my_tramp, @function\n"
> " .globl my_tramp\n"
> " my_tramp:"
> -" bti c\n"
> +" hint 34\n" // bti c
> " sub sp, sp, #32\n"
> " stp x9, x30, [sp]\n"
> " str x0, [sp, #16]\n"
> diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c
> index e9804c5307c0..e39c3563ae4e 100644
> --- a/samples/ftrace/ftrace-direct-too.c
> +++ b/samples/ftrace/ftrace-direct-too.c
> @@ -81,7 +81,7 @@ asm (
> " .type my_tramp, @function\n"
> " .globl my_tramp\n"
> " my_tramp:"
> -" bti c\n"
> +" hint 34\n" // bti c
> " sub sp, sp, #48\n"
> " stp x9, x30, [sp]\n"
> " stp x0, x1, [sp, #16]\n"
> diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c
> index 20f4a7caa810..32c477da1e9a 100644
> --- a/samples/ftrace/ftrace-direct.c
> +++ b/samples/ftrace/ftrace-direct.c
> @@ -72,7 +72,7 @@ asm (
> " .type my_tramp, @function\n"
> " .globl my_tramp\n"
> " my_tramp:"
> -" bti c\n"
> +" hint 34\n" // bti c
> " sub sp, sp, #32\n"
> " stp x9, x30, [sp]\n"
> " str x0, [sp, #16]\n"
> --
> 2.25.1
>
prev parent reply other threads:[~2023-08-21 16:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-20 11:15 [PATCH] samples: ftrace: replace bti assembly with hint for older compiler GONG, Ruiqi
2023-08-21 15:34 ` Steven Rostedt
2023-08-21 15:41 ` Florent Revest
2023-08-21 16:04 ` Mark Rutland
2023-08-21 16:12 ` Mark Rutland [this message]
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