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From: Sudeep Holla <sudeep.holla@arm.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: linux@armlinux.org.uk, linux-arm-kernel@lists.infradead.org,
	Steven Rostedt <rostedt@goodmis.org>,
	Cristian Marussi <cristian.marussi@arm.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Linus Walleij <linus.walleij@linaro.org>,
	Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [PATCH v2 10/12] drivers/firmware/scmi: disable ftrace for Clang Thumb2 builds
Date: Mon, 31 Jan 2022 22:04:22 +0000	[thread overview]
Message-ID: <20220131220422.7u4i2knzaq4qt4zp@bogus> (raw)
In-Reply-To: <20220131170347.381551-11-ardb@kernel.org>

On Mon, Jan 31, 2022 at 06:03:45PM +0100, Ard Biesheuvel wrote:
> The SMC calling convention designates R0-R7 as input registers in
> AArch32 mode, and this conflicts with the compiler's use of R7 as a
> frame pointer when building in Thumb2 mode. Generally, we don't enable
> the frame pointer, and GCC happily enables the -pg profiling hooks
> without them. However, Clang refuses, and errors out with the message
> below:
>
> drivers/firmware/arm_scmi/smc.c:152:2: error: write to reserved register 'R7'
>         arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
>         ^
> include/linux/arm-smccc.h:550:4: note: expanded from macro 'arm_smccc_1_1_invoke'
>                         arm_smccc_1_1_smc(__VA_ARGS__);                 \
>                         ^
> Let's just disable ftrace for the compilation unit when building this
> configuration.
>

Acked-by: Sudeep Holla <sudeep.holla@arm.com>

--
Regards,
Sudeep

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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2022-01-31 22:06 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-31 17:03 [PATCH v2 00/12] ARM: ftrace fixes and cleanups Ard Biesheuvel
2022-01-31 17:03 ` [PATCH v2 01/12] ARM: ftrace: ensure that ADR take Thumb bit into account Ard Biesheuvel
2022-01-31 17:03 ` [PATCH v2 02/12] ARM: ftrace: use ADD not POP to counter PUSH at entry Ard Biesheuvel
2022-01-31 17:03 ` [PATCH v2 03/12] ARM: ftrace: use trampolines to keep .init.text in branching range Ard Biesheuvel
2022-01-31 17:03 ` [PATCH v2 04/12] ARM: ftrace: avoid redundant loads or clobbering IP Ard Biesheuvel
2022-01-31 17:03 ` [PATCH v2 05/12] ARM: ftrace: avoid unnecessary literal loads Ard Biesheuvel
2022-01-31 17:03 ` [PATCH v2 06/12] ARM: ftrace: enable HAVE_FUNCTION_GRAPH_FP_TEST Ard Biesheuvel
2022-01-31 17:03 ` [PATCH v2 07/12] ARM: unwind: track location of LR value in stack frame Ard Biesheuvel
2022-01-31 17:03 ` [PATCH v2 08/12] ARM: ftrace: enable the graph tracer with the EABI unwinder Ard Biesheuvel
2022-01-31 17:03 ` [PATCH v2 09/12] ARM: kprobes: treat R7 as the frame pointer register in Thumb2 builds Ard Biesheuvel
2022-01-31 18:31   ` Nick Desaulniers
2022-02-01  7:42     ` Ard Biesheuvel
2022-02-01 13:18   ` Masami Hiramatsu
2022-02-01 14:05     ` Ard Biesheuvel
2022-02-02  6:10       ` Masami Hiramatsu
2022-02-02  8:00         ` Ard Biesheuvel
2022-01-31 17:03 ` [PATCH v2 10/12] drivers/firmware/scmi: disable ftrace for Clang " Ard Biesheuvel
2022-01-31 18:37   ` Nick Desaulniers
2022-02-01  8:12     ` Ard Biesheuvel
2022-01-31 22:04   ` Sudeep Holla [this message]
2022-01-31 17:03 ` [PATCH v2 11/12] ARM: cacheflush: avoid clobbering the frame pointer in Thumb2 mode Ard Biesheuvel
2022-01-31 18:40   ` Nick Desaulniers
2022-01-31 17:03 ` [PATCH v2 12/12] Revert "ARM: 9144/1: forbid ftrace with clang and thumb2_kernel" Ard Biesheuvel
2022-01-31 18:42   ` Nick Desaulniers
2022-01-31 17:21 ` [PATCH v2 00/12] ARM: ftrace fixes and cleanups Steven Rostedt

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