On 1/16/19 3:41 AM, Arnd Bergmann wrote:
> On Tue, Jan 15, 2019 at 3:55 AM Jens Axboe <axboe@xxxxxxxxx> wrote:
>>
>> diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
>> index 3cf7b533b3d1..194e79c0032e 100644
>> --- a/arch/x86/entry/syscalls/syscall_32.tbl
>> +++ b/arch/x86/entry/syscalls/syscall_32.tbl
>> @@ -398,3 +398,5 @@
>> 384 i386 arch_prctl sys_arch_prctl __ia32_compat_sys_arch_prctl
>> 385 i386 io_pgetevents sys_io_pgetevents __ia32_compat_sys_io_pgetevents
>> 386 i386 rseq sys_rseq __ia32_sys_rseq
>> +387 i386 io_uring_setup sys_io_uring_setup __ia32_compat_sys_io_uring_setup
>> +388 i386 io_uring_enter sys_io_uring_enter __ia32_sys_io_uring_enter
>> diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
>> index f0b1709a5ffb..453ff7a79002 100644
>> --- a/arch/x86/entry/syscalls/syscall_64.tbl
>> +++ b/arch/x86/entry/syscalls/syscall_64.tbl
>> @@ -343,6 +343,8 @@
>> 332 common statx __x64_sys_statx
>> 333 common io_pgetevents __x64_sys_io_pgetevents
>> 334 common rseq __x64_sys_rseq
>> +335 common io_uring_setup __x64_sys_io_uring_setup
>> +336 common io_uring_enter __x64_sys_io_uring_enter
>
> In my series for the y2038 system calls, I'm trying to move to having the
> same numbers across all architectures. Unfortunately, that clashes
> with newly assigned numbers here, so one of us needs to pick new
> numbers.
>
> If my series gets merged without other changes to the numbers, the next
> available numbers on all architectures become 424 and 425.
>
> Could you use those here?
Yeah that's totally fine, I don't really care what the numbers end up
being, that side isn't fixed for me.
>> +SYSCALL_DEFINE2(io_uring_setup, u32, entries,
>> + struct io_uring_params __user *, params)
>> +{
>> + return io_uring_setup(entries, params, false);
>> +}
>> +
>> +#ifdef CONFIG_COMPAT
>> +COMPAT_SYSCALL_DEFINE2(io_uring_setup, u32, entries,
>> + struct io_uring_params __user *, params)
>> +{
>> + return io_uring_setup(entries, params, true);
>> +}
>> +#endif
>
> The compat syscall has the same calling conventions as the
> native one here, so I think you can just use that directly.
Not sure I understand what you mean here. I need to know if it's the
compat one, hence 'true' vs 'false', so I know what the size of the user
pointers/structs are.
>> +/*
>> + * IO submission data structure (Submission Queue Entry)
>> + */
>> +struct io_uring_sqe {
>> + __u8 opcode; /* type of operation for this sqe */
>> + __u8 flags; /* as of now unused */
>> + __u16 ioprio; /* ioprio for the request */
>> + __s32 fd; /* file descriptor to do IO on */
>> + __u64 off; /* offset into file */
>> + union {
>> + void *addr; /* buffer or iovecs */
>> + __u64 __pad;
>> + };
>
> It seems a bit unfortunate to keep the pointer field only
> almost compatible between 32-bit and 64-bit big-endian
> architectures, as that requires an in_compat_syscall()
> check whenever we access the pointer from the kernel.
>
> Could you use a __u64 field to store the pointer itself
> instead?
I feel like I'm missing something here, we'll still need the compat code
on the kernel side for 32-bit app on 64-bit kernel, so what would we
solve by making this an __u64?
>> diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
>> index ab9d0e3c6d50..ee5e523564bb 100644
>> --- a/kernel/sys_ni.c
>> +++ b/kernel/sys_ni.c
>> @@ -46,6 +46,8 @@ COND_SYSCALL(io_getevents);
>> COND_SYSCALL(io_pgetevents);
>> COND_SYSCALL_COMPAT(io_getevents);
>> COND_SYSCALL_COMPAT(io_pgetevents);
>> +COND_SYSCALL(io_uring_setup);
>> +COND_SYSCALL(io_uring_enter);
>
> Unless you remove the compat_sys_io_uring_setup() definition,
> this should also have a corresponding COND_SYSCALL_COMPAT()
> entry.
Gotcha, thanks! I'll make that change.
--
Jens Axboe
