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Re: [PATCH 02/15] powerpc: Use Linux kABI for syscall return
* 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.
I don't have the object 01c26be24b locally.
Thanks,
Florian