Re: [PATCH 06/13] arc: define syscall_get_arch()

Andy Lutomirski
2018-11-09T15:56:17Z

> On Nov 9, 2018, at 7:27 AM, Alexey Brodkin <alexey.brodkin@synopsys.com> wrote:
>
> Hi Andy,
>
>> On Fri, 2018-11-09 at 07:17 -0800, Andy Lutomirski wrote:
>> On Fri, Nov 9, 2018 at 6:22 AM Alexey Brodkin
>> <alexey.brodkin@synopsys.com> wrote:
>>> Hi Dmitry,
>>>
>>>> On Fri, 2018-11-09 at 06:16 +0300, Dmitry V. Levin wrote:
>>>> syscall_get_arch() is required to be implemented on all architectures
>>>> that use tracehook_report_syscall_entry() in order to extend
>>>> the generic ptrace API with PTRACE_GET_SYSCALL_INFO request.
>>>>
>>>> Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
>>>> ---
>>>> arch/arc/include/asm/syscall.h | 6 ++++++
>>>> include/uapi/linux/audit.h | 1 +
>>>> 2 files changed, 7 insertions(+)
>>>
>>> [snip]
>>>
>>>> diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
>>>> index 818ae690ab79..a7149ceb5b98 100644
>>>> --- a/include/uapi/linux/audit.h
>>>> +++ b/include/uapi/linux/audit.h
>>>> @@ -375,6 +375,7 @@ enum {
>>>>
>>>> #define AUDIT_ARCH_AARCH64 (EM_AARCH64|__AUDIT_ARCH_64BIT|__AUDIT_ARCH_LE)
>>>> #define AUDIT_ARCH_ALPHA (EM_ALPHA|__AUDIT_ARCH_64BIT|__AUDIT_ARCH_LE)
>>>> +#define AUDIT_ARCH_ARC (EM_ARC)
>>>
>>> Similarly here we need to have:
>>> ---------------------------->8-----------------------------
>>> +#define AUDIT_ARCH_ARC (EM_ARC|EM_ARCV2)
>>> ---------------------------->8-----------------------------
>>>
>>
>> Huh? How does the bitwise or of two ELF machine codes make any sense?
>
> Oops... I didn't read examples of AUDIT_ARCH_ALPHA above :(
> Indeed that was stupid.
>
> But what would be a proper fix then?
>
> Something like that?
> ---------------------------->8-----------------------------
> #define AUDIT_ARCH_ARC (EM_ARC)
> #define AUDIT_ARCH_ARCV2 (EM_ARCV2)
>
>
> static inline int syscall_get_arch(void)
> {
> #ifdef __ARC700__
> return AUDIT_ARCH_ARC;
> #else
> return AUDIT_ARCH_ARCV2;
> #endif
> }
> ---------------------------->8-----------------------------
>

Maybe, but I know basically nothing about ARC. Is the syscall numbering or calling convention different on ARC vs ARCv2?