2016-09-15 1:08 GMT+03:00 Kyle Huey <m...@kylehuey.com>:
> On Wed, Sep 14, 2016 at 2:59 PM, Dmitry Safonov <0x7f454...@gmail.com> wrote:
>> 2016-09-15 0:08 GMT+03:00 Kyle Huey <m...@kylehuey.com>:
>>> Signed-off-by: Kyle Huey <kh...@kylehuey.com>
>>> ---
>>> arch/x86/entry/syscalls/syscall_32.tbl | 1 +
>>> arch/x86/kernel/process.c | 80
>>> ++++++++++++++++++++++++++++++++++
>>> arch/x86/kernel/process_64.c | 66 ----------------------------
>>> 3 files changed, 81 insertions(+), 66 deletions(-)
>>>
>>> diff --git a/arch/x86/entry/syscalls/syscall_32.tbl
>>> b/arch/x86/entry/syscalls/syscall_32.tbl
>>> index f848572..3b6965b 100644
>>> --- a/arch/x86/entry/syscalls/syscall_32.tbl
>>> +++ b/arch/x86/entry/syscalls/syscall_32.tbl
>>> @@ -386,3 +386,4 @@
>>> 377 i386 copy_file_range sys_copy_file_range
>>> 378 i386 preadv2 sys_preadv2
>>> compat_sys_preadv2
>>> 379 i386 pwritev2 sys_pwritev2
>>> compat_sys_pwritev2
>>> +380 i386 arch_prctl sys_arch_prctl
>>
>> Why not define it as other 32-bit syscalls with compat_sys_ prefix
>> with the help of COMPAT_SYSCALL_DEFINE() macro?
>> Then you could omit code moving, drop is_32 helper.
>> I miss something obvious?
>
> The code will have to move regardless, because right now do_arch_prctl
> is in process-64.c which is only compiled on a 64 bit kernel.
Why? This code will not work anyway for 32-bit in your patches
by obscuring it with is_32.
> As I told Dave Hansen in the non-RESEND thread (not sure why
> git-send-email didn't put him in this one ...) I considered doing a
> compat_sys_arch_prctl that would reject the relevant arch_prctls that
> don't apply on 32 bit but I didn't see any prior art for it (in my
> admittedly non-exhaustive search).
Well, you could just add to 64-bit do_arch_prctl() new cases for your
prctls - that would be just a two-lines for each new prctl.
Also add compat_sys_ and define *only* what's needed there for you,
do not add there ARCH_{SET,GET}_{FS,GS}.
Does this make sense?
--
Dmitry
