| Message ID | 20180320230206.25289-2-stefan@agner.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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.) > > 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 >
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 >>
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(); } /**
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. Signed-off-by: Stefan Agner <stefan@agner.ch> --- drivers/bus/arm-cci.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)