* [RESEND PATCH v2] bus: arm-cci: use asm unreachable
@ 2018-05-08 11:32 ` Stefan Agner
0 siblings, 0 replies; 6+ messages in thread
From: Stefan Agner @ 2018-05-08 11:32 UTC (permalink / raw)
To: arm, arnd
Cc: linux, ard.biesheuvel, robin.murphy, nicolas.pitre, marc.zyngier,
behanw, keescook, Bernhard.Rosenkranzer, mka, linux-arm-kernel,
linux-kernel, Stefan Agner
Mixing asm and C code is not recommended in a naked function by
gcc and leads to an error when using clang:
drivers/bus/arm-cci.c:2107:2: error: non-ASM statement in naked
function is not supported
unreachable();
^
While the function is marked __naked it actually properly return
in asm. There is no need for the unreachable() call.
Suggested-by: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Nicolas Pitre <nico@linaro.org>
---
drivers/bus/arm-cci.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index 443e4c3fd357..b8184a903583 100644
--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -371,8 +371,6 @@ asmlinkage void __naked cci_enable_port_for_self(void)
[sizeof_struct_cpu_port] "i" (sizeof(struct cpu_port)),
[sizeof_struct_ace_port] "i" (sizeof(struct cci_ace_port)),
[offsetof_port_phys] "i" (offsetof(struct cci_ace_port, phys)) );
-
- unreachable();
}
/**
--
2.17.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* [RESEND PATCH v2] bus: arm-cci: use asm unreachable
@ 2018-05-08 11:32 ` Stefan Agner
0 siblings, 0 replies; 6+ messages in thread
From: Stefan Agner @ 2018-05-08 11:32 UTC (permalink / raw)
To: linux-arm-kernel
Mixing asm and C code is not recommended in a naked function by
gcc and leads to an error when using clang:
drivers/bus/arm-cci.c:2107:2: error: non-ASM statement in naked
function is not supported
unreachable();
^
While the function is marked __naked it actually properly return
in asm. There is no need for the unreachable() call.
Suggested-by: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Nicolas Pitre <nico@linaro.org>
---
drivers/bus/arm-cci.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index 443e4c3fd357..b8184a903583 100644
--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -371,8 +371,6 @@ asmlinkage void __naked cci_enable_port_for_self(void)
[sizeof_struct_cpu_port] "i" (sizeof(struct cpu_port)),
[sizeof_struct_ace_port] "i" (sizeof(struct cci_ace_port)),
[offsetof_port_phys] "i" (offsetof(struct cci_ace_port, phys)) );
-
- unreachable();
}
/**
--
2.17.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [RESEND PATCH v2] bus: arm-cci: use asm unreachable
2018-05-08 11:32 ` Stefan Agner
@ 2018-05-08 12:19 ` Robin Murphy
-1 siblings, 0 replies; 6+ messages in thread
From: Robin Murphy @ 2018-05-08 12:19 UTC (permalink / raw)
To: Stefan Agner, arm, arnd
Cc: linux, ard.biesheuvel, nicolas.pitre, marc.zyngier, behanw,
keescook, Bernhard.Rosenkranzer, mka, linux-arm-kernel,
linux-kernel
On 08/05/18 12:32, Stefan Agner wrote:
> Mixing asm and C code is not recommended in a naked function by
> gcc and leads to an error when using clang:
> drivers/bus/arm-cci.c:2107:2: error: non-ASM statement in naked
> function is not supported
> unreachable();
> ^
>
> While the function is marked __naked it actually properly return
> in asm. There is no need for the unreachable() call.
The commit title is a bit out-of-date now (I guess it could just be
something like "remove unnecessary unreachable()" now), but the rest
looks OK to me - even GCC clearly doesn't expect anything beyond the asm
to be reachable anyway since the lack of epilogue includes the lack of
any compiler-generated return. I've checked that GCC 7.2 generates
identical object files before and after, other than (for obvious
reasons) the line numbers generated by WANT_WARN_ON_SLOWPATH for all the
WARN()s appearing later in the file.
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> Suggested-by: Russell King <linux@arm.linux.org.uk>
> Signed-off-by: Stefan Agner <stefan@agner.ch>
> Acked-by: Nicolas Pitre <nico@linaro.org>
> ---
> drivers/bus/arm-cci.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
> index 443e4c3fd357..b8184a903583 100644
> --- a/drivers/bus/arm-cci.c
> +++ b/drivers/bus/arm-cci.c
> @@ -371,8 +371,6 @@ asmlinkage void __naked cci_enable_port_for_self(void)
> [sizeof_struct_cpu_port] "i" (sizeof(struct cpu_port)),
> [sizeof_struct_ace_port] "i" (sizeof(struct cci_ace_port)),
> [offsetof_port_phys] "i" (offsetof(struct cci_ace_port, phys)) );
> -
> - unreachable();
> }
>
> /**
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* [RESEND PATCH v2] bus: arm-cci: use asm unreachable
@ 2018-05-08 12:19 ` Robin Murphy
0 siblings, 0 replies; 6+ messages in thread
From: Robin Murphy @ 2018-05-08 12:19 UTC (permalink / raw)
To: linux-arm-kernel
On 08/05/18 12:32, Stefan Agner wrote:
> Mixing asm and C code is not recommended in a naked function by
> gcc and leads to an error when using clang:
> drivers/bus/arm-cci.c:2107:2: error: non-ASM statement in naked
> function is not supported
> unreachable();
> ^
>
> While the function is marked __naked it actually properly return
> in asm. There is no need for the unreachable() call.
The commit title is a bit out-of-date now (I guess it could just be
something like "remove unnecessary unreachable()" now), but the rest
looks OK to me - even GCC clearly doesn't expect anything beyond the asm
to be reachable anyway since the lack of epilogue includes the lack of
any compiler-generated return. I've checked that GCC 7.2 generates
identical object files before and after, other than (for obvious
reasons) the line numbers generated by WANT_WARN_ON_SLOWPATH for all the
WARN()s appearing later in the file.
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> Suggested-by: Russell King <linux@arm.linux.org.uk>
> Signed-off-by: Stefan Agner <stefan@agner.ch>
> Acked-by: Nicolas Pitre <nico@linaro.org>
> ---
> drivers/bus/arm-cci.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
> index 443e4c3fd357..b8184a903583 100644
> --- a/drivers/bus/arm-cci.c
> +++ b/drivers/bus/arm-cci.c
> @@ -371,8 +371,6 @@ asmlinkage void __naked cci_enable_port_for_self(void)
> [sizeof_struct_cpu_port] "i" (sizeof(struct cpu_port)),
> [sizeof_struct_ace_port] "i" (sizeof(struct cci_ace_port)),
> [offsetof_port_phys] "i" (offsetof(struct cci_ace_port, phys)) );
> -
> - unreachable();
> }
>
> /**
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [RESEND PATCH v2] bus: arm-cci: use asm unreachable
2018-05-08 12:19 ` Robin Murphy
@ 2018-05-08 13:01 ` Stefan Agner
-1 siblings, 0 replies; 6+ messages in thread
From: Stefan Agner @ 2018-05-08 13:01 UTC (permalink / raw)
To: Robin Murphy
Cc: arm, arnd, linux, ard.biesheuvel, nicolas.pitre, marc.zyngier,
behanw, keescook, Bernhard.Rosenkranzer, mka, linux-arm-kernel,
linux-kernel
On 08.05.2018 14:19, Robin Murphy wrote:
> On 08/05/18 12:32, Stefan Agner wrote:
>> Mixing asm and C code is not recommended in a naked function by
>> gcc and leads to an error when using clang:
>> drivers/bus/arm-cci.c:2107:2: error: non-ASM statement in naked
>> function is not supported
>> unreachable();
>> ^
>>
>> While the function is marked __naked it actually properly return
>> in asm. There is no need for the unreachable() call.
>
> The commit title is a bit out-of-date now (I guess it could just be
> something like "remove unnecessary unreachable()" now), but the rest
> looks OK to me - even GCC clearly doesn't expect anything beyond the
> asm to be reachable anyway since the lack of epilogue includes the
> lack of any compiler-generated return. I've checked that GCC 7.2
> generates identical object files before and after, other than (for
> obvious reasons) the line numbers generated by WANT_WARN_ON_SLOWPATH
> for all the WARN()s appearing later in the file.
Title: Oops, good catch! Will send a v3.
Thanks for checking gcc.
--
Stefan
>
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
>
>> Suggested-by: Russell King <linux@arm.linux.org.uk>
>> Signed-off-by: Stefan Agner <stefan@agner.ch>
>> Acked-by: Nicolas Pitre <nico@linaro.org>
>> ---
>> drivers/bus/arm-cci.c | 2 --
>> 1 file changed, 2 deletions(-)
>>
>> diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
>> index 443e4c3fd357..b8184a903583 100644
>> --- a/drivers/bus/arm-cci.c
>> +++ b/drivers/bus/arm-cci.c
>> @@ -371,8 +371,6 @@ asmlinkage void __naked cci_enable_port_for_self(void)
>> [sizeof_struct_cpu_port] "i" (sizeof(struct cpu_port)),
>> [sizeof_struct_ace_port] "i" (sizeof(struct cci_ace_port)),
>> [offsetof_port_phys] "i" (offsetof(struct cci_ace_port, phys)) );
>> -
>> - unreachable();
>> }
>> /**
>>
^ permalink raw reply [flat|nested] 6+ messages in thread
* [RESEND PATCH v2] bus: arm-cci: use asm unreachable
@ 2018-05-08 13:01 ` Stefan Agner
0 siblings, 0 replies; 6+ messages in thread
From: Stefan Agner @ 2018-05-08 13:01 UTC (permalink / raw)
To: linux-arm-kernel
On 08.05.2018 14:19, Robin Murphy wrote:
> On 08/05/18 12:32, Stefan Agner wrote:
>> Mixing asm and C code is not recommended in a naked function by
>> gcc and leads to an error when using clang:
>> drivers/bus/arm-cci.c:2107:2: error: non-ASM statement in naked
>> function is not supported
>> unreachable();
>> ^
>>
>> While the function is marked __naked it actually properly return
>> in asm. There is no need for the unreachable() call.
>
> The commit title is a bit out-of-date now (I guess it could just be
> something like "remove unnecessary unreachable()" now), but the rest
> looks OK to me - even GCC clearly doesn't expect anything beyond the
> asm to be reachable anyway since the lack of epilogue includes the
> lack of any compiler-generated return. I've checked that GCC 7.2
> generates identical object files before and after, other than (for
> obvious reasons) the line numbers generated by WANT_WARN_ON_SLOWPATH
> for all the WARN()s appearing later in the file.
Title: Oops, good catch! Will send a v3.
Thanks for checking gcc.
--
Stefan
>
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
>
>> Suggested-by: Russell King <linux@arm.linux.org.uk>
>> Signed-off-by: Stefan Agner <stefan@agner.ch>
>> Acked-by: Nicolas Pitre <nico@linaro.org>
>> ---
>> drivers/bus/arm-cci.c | 2 --
>> 1 file changed, 2 deletions(-)
>>
>> diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
>> index 443e4c3fd357..b8184a903583 100644
>> --- a/drivers/bus/arm-cci.c
>> +++ b/drivers/bus/arm-cci.c
>> @@ -371,8 +371,6 @@ asmlinkage void __naked cci_enable_port_for_self(void)
>> [sizeof_struct_cpu_port] "i" (sizeof(struct cpu_port)),
>> [sizeof_struct_ace_port] "i" (sizeof(struct cci_ace_port)),
>> [offsetof_port_phys] "i" (offsetof(struct cci_ace_port, phys)) );
>> -
>> - unreachable();
>> }
>> /**
>>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2018-05-08 13:01 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2018-05-08 11:32 [RESEND PATCH v2] bus: arm-cci: use asm unreachable Stefan Agner
2018-05-08 11:32 ` Stefan Agner
2018-05-08 12:19 ` Robin Murphy
2018-05-08 12:19 ` Robin Murphy
2018-05-08 13:01 ` Stefan Agner
2018-05-08 13:01 ` Stefan Agner
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