Messages in this thread | | | Date | Wed, 21 Mar 2018 09:22:47 +0100 | From | Stefan Agner <> | Subject | Re: [PATCH 1/5] bus: arm-cci: use asm unreachable |
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On 21.03.2018 00:30, Russell King - ARM Linux wrote: > On Wed, Mar 21, 2018 at 12:02:02AM +0100, 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(); >> ^ >> >> Instead of using the unreachable() macro use the assember variant >> ASM_UNREACHABLE. This will no longer emit __builtin_unreachable(), >> but since the function is naked and its return type is void it seems >> not to have aversive effects. > > I think that unreachable() there is rather silly - this function > *does* return, and the comments say as much. Just delete the silly > "unreachable()", there's no need to put an ASM_UNREACHABLE in there. > > The function is not declared as not returning, and nothing in this > file uses it anyway - it's called from the mcpm code, which also > _does_ expect this function to return (if it doesn't, then we're > basically saying the CPU that called it is dead.) >
Hm, that makes sense. Will just drop unreachable() in the next revision.
Thanks for reviewing!
-- Stefan
>> >> Signed-off-by: Stefan Agner <stefan@agner.ch> >> --- >> drivers/bus/arm-cci.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c >> index 5426c04fe24b..ee9da86fec47 100644 >> --- a/drivers/bus/arm-cci.c >> +++ b/drivers/bus/arm-cci.c >> @@ -2084,6 +2084,7 @@ asmlinkage void __naked cci_enable_port_for_self(void) >> >> " mov r0, #0 \n" >> " bx lr \n" >> + ASM_UNREACHABLE >> >> " .align 2 \n" >> "5: .word cpu_port - . \n" >> @@ -2103,8 +2104,6 @@ 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(); >> } >> >> /** >> -- >> 2.16.2 >>
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