Messages in this thread | | | Subject | Re: [RESEND PATCH v2] bus: arm-cci: use asm unreachable | From | Robin Murphy <> | Date | Tue, 8 May 2018 13:19:30 +0100 |
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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The commit title is a bit out-of-date now (I guess it could just be something like "remove unnecessary unreachable()" now), but the rest looks OK to me - even GCC clearly doesn't expect anything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(); > } > > /** >
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