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Re: [PATCH 02/15] powerpc: Use Linux kABI for syscall return
On 11/02/2020 09:31, Florian Weimer wrote:
> * Adhemerval Zanella:
>
>> On 11/02/2020 08:18, Florian Weimer wrote:
>>> * Adhemerval Zanella:
>>>
>>>> diff --git a/sysdeps/unix/sysv/linux/powerpc/sysdep.h b/sysdeps/unix/sysv/linux/powerpc/sysdep.h
>>>> index 01c26be24b..abdcfd4a63 100644
>>>> --- a/sysdeps/unix/sysv/linux/powerpc/sysdep.h
>>>> +++ b/sysdeps/unix/sysv/linux/powerpc/sysdep.h
>>>> @@ -60,9 +60,8 @@
>>>> : "+r" (r0), "+r" (r3), "+r" (r4), "+r" (r5), "+r" (r6), \
>>>> "+r" (r7), "+r" (r8) \
>>>> : : "r9", "r10", "r11", "r12", "cr0", "ctr", "lr", "memory"); \
>>>> - err = (long int) r0; \
>>>> __asm__ __volatile__ ("" : "=r" (rval) : "r" (r3)); \
>>>> - rval; \
>>>> + (long int) r0 & (1 << 28) ? -rval : rval; \
>>>> })
>>>>
>>>> #define INTERNAL_VSYSCALL_CALL(funcptr, err, nr, args...) \
>>>> @@ -110,21 +109,20 @@
>>>> : ASM_INPUT_##nr \
>>>> : "r9", "r10", "r11", "r12", \
>>>> "cr0", "ctr", "memory"); \
>>>> - err = r0; \
>>>> - r3; \
>>>> + r0 & (1 << 28) ? -r3 : r3; \
>>>> })
>>>> #define INTERNAL_SYSCALL(name, err, nr, args...) \
>>>> INTERNAL_SYSCALL_NCS (__NR_##name, err, nr, args)
>>>>
>>>> #undef INTERNAL_SYSCALL_DECL
>>>> -#define INTERNAL_SYSCALL_DECL(err) long int err __attribute__ ((unused))
>>>> +#define INTERNAL_SYSCALL_DECL(err) do { } while (0)
>>>>
>>>> #undef INTERNAL_SYSCALL_ERROR_P
>>>> #define INTERNAL_SYSCALL_ERROR_P(val, err) \
>>>> - ((void) (val), __builtin_expect ((err) & (1 << 28), 0))
>>>> + ((unsigned long) (val) >= (unsigned long) -4095)
>>>>
>>>> #undef INTERNAL_SYSCALL_ERRNO
>>>> -#define INTERNAL_SYSCALL_ERRNO(val, err) (val)
>>>> +#define INTERNAL_SYSCALL_ERRNO(val, err) (-(val))
>>>>
>>>> #if defined(__PPC64__) || defined(__powerpc64__)
>>>> # define SYSCALL_ARG_SIZE 8
>>>
>>> What's the baseline for this patch?
>>
>> To simplify the Linux syscall handling on all architectures by using the
>> already set kABI interface (where returns values from
>> 0xfffffffffffff000 to 0xffffffffffffffff indicates an error). The idea
>> is initially to consolidate the INLINE_SYSCALL macro and remove the
>> INTERNAL_SYSCALL_DECL macro.
>>
>> This refactoring is an initial one, my long-term goal is twofold:
>>
>> 1. Remove the assembly macros to define syscall and only use the
>> C interface. It simplifies ports, requires less hackery to handle
>> all its subtitles in C generations (static/pic/etc), and most likely
>> would play nice on a possible LTO build.
>>
>> 2. Rework the syscall interfaces to use static inline instead of
>> macros. It will avoid the argument handling that led to the
>> subtle BZ#25523 bug and it defines a proper kABI interface.
>
> I meant that the patch doesn't seem to be against master.
Hum I just rebase against master (eb948facd8) and it does apply. Why
do you think it does not seem to be apply against master?
>
> I don't have the object 01c26be24b locally.
>
> Thanks,
> Florian
>