| Message ID | 20220808114908.240813-3-sv@linux.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | objtool: Enable and implement --mcount option on powerpc | expand |
Le 08/08/2022 à 13:48, Sathvika Vasireddy a écrit : > Since we need an alignment of 4 bytes, override > __ALIGN() and __ALIGN_STR() accordingly. Why/When do we now need an alignment of 4 bytes ? Please explain the reason in the commit message. > > Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com> > --- > arch/powerpc/include/asm/linkage.h | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/arch/powerpc/include/asm/linkage.h b/arch/powerpc/include/asm/linkage.h > index b71b9582e754..8df88fe61438 100644 > --- a/arch/powerpc/include/asm/linkage.h > +++ b/arch/powerpc/include/asm/linkage.h > @@ -2,8 +2,12 @@ > #ifndef _ASM_POWERPC_LINKAGE_H > #define _ASM_POWERPC_LINKAGE_H > > +#include <linux/stringify.h> > #include <asm/types.h> > > +#define __ALIGN .align 2 > +#define __ALIGN_STR __stringify(__ALIGN) Why do you need to use __stringify ? ARM64 does: #define __ALIGN .align 2 #define __ALIGN_STR ".align 2" > + > #ifdef CONFIG_PPC64_ELF_ABI_V1 > #define cond_syscall(x) \ > asm ("\t.weak " #x "\n\t.set " #x ", sys_ni_syscall\n" \
Hi Christophe, On 10/08/22 14:01, Christophe Leroy wrote: > > Le 08/08/2022 à 13:48, Sathvika Vasireddy a écrit : >> Since we need an alignment of 4 bytes, override >> __ALIGN() and __ALIGN_STR() accordingly. > Why/When do we now need an alignment of 4 bytes ? Please explain the > reason in the commit message. Powerpc instructions must be word-aligned. Currently, there is an alignment of 16 bytes (by default), and it is much more than what is required for powerpc (4 bytes). The default expansion of these macros are: #define __ALIGN .align 4,0x90 #define __ALIGN_STR ".align 4,0x90" Since Powerpc Linux does not require a 16 byte alignment, override _ALIGN() and __ALIGN_STR() macros to use required 4 byte alignment. Sure, I'll explain the reason in commit message. > >> Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com> >> --- >> arch/powerpc/include/asm/linkage.h | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/arch/powerpc/include/asm/linkage.h b/arch/powerpc/include/asm/linkage.h >> index b71b9582e754..8df88fe61438 100644 >> --- a/arch/powerpc/include/asm/linkage.h >> +++ b/arch/powerpc/include/asm/linkage.h >> @@ -2,8 +2,12 @@ >> #ifndef _ASM_POWERPC_LINKAGE_H >> #define _ASM_POWERPC_LINKAGE_H >> >> +#include <linux/stringify.h> >> #include <asm/types.h> >> >> +#define __ALIGN .align 2 >> +#define __ALIGN_STR __stringify(__ALIGN) > Why do you need to use __stringify ? > > ARM64 does: > > #define __ALIGN .align 2 > #define __ALIGN_STR ".align 2" We could use either __stringify() or quotes, both do the same thing. While arm64 does ".align 2", x86 does: #define __ALIGN .p2align 4, 0x90 #define __ALIGN_STR __stringify(__ALIGN) > > > > >> + >> #ifdef CONFIG_PPC64_ELF_ABI_V1 >> #define cond_syscall(x) \ >> asm ("\t.weak " #x "\n\t.set " #x ", sys_ni_syscall\n" \ Thanks for reviewing! - Sathvika
diff --git a/arch/powerpc/include/asm/linkage.h b/arch/powerpc/include/asm/linkage.h index b71b9582e754..8df88fe61438 100644 --- a/arch/powerpc/include/asm/linkage.h +++ b/arch/powerpc/include/asm/linkage.h @@ -2,8 +2,12 @@ #ifndef _ASM_POWERPC_LINKAGE_H #define _ASM_POWERPC_LINKAGE_H +#include <linux/stringify.h> #include <asm/types.h> +#define __ALIGN .align 2 +#define __ALIGN_STR __stringify(__ALIGN) + #ifdef CONFIG_PPC64_ELF_ABI_V1 #define cond_syscall(x) \ asm ("\t.weak " #x "\n\t.set " #x ", sys_ni_syscall\n" \
Since we need an alignment of 4 bytes, override __ALIGN() and __ALIGN_STR() accordingly. Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com> --- arch/powerpc/include/asm/linkage.h | 4 ++++ 1 file changed, 4 insertions(+)