Re: [PATCH v2] signal: add procfd_signal() syscall

On November 30, 2018 5:54:18 AM GMT+13:00, Andy Lutomirski [off-list ref] wrote:

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On Nov 29, 2018, at 4:28 AM, Florian Weimer [off-list ref]

wrote:

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Disclaimer: I'm looking at this patch because Christian requested it.
I'm not a kernel developer.

* Christian Brauner:

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diff --git a/arch/x86/entry/syscalls/syscall_32.tbl

b/arch/x86/entry/syscalls/syscall_32.tbl

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index 3cf7b533b3d1..3f27ffd8ae87 100644

--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl

@@ -398,3 +398,4 @@

384    i386    arch_prctl        sys_arch_prctl           

__ia32_compat_sys_arch_prctl

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385    i386    io_pgetevents        sys_io_pgetevents       

__ia32_compat_sys_io_pgetevents

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386    i386    rseq            sys_rseq            __ia32_sys_rseq
+387    i386    procfd_signal        sys_procfd_signal       

__ia32_compat_sys_procfd_signal

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diff --git a/arch/x86/entry/syscalls/syscall_64.tbl

b/arch/x86/entry/syscalls/syscall_64.tbl

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index f0b1709a5ffb..8a30cde82450 100644

--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl

@@ -343,6 +343,7 @@

332    common    statx            __x64_sys_statx
333    common    io_pgetevents        __x64_sys_io_pgetevents
334    common    rseq            __x64_sys_rseq
+335    64    procfd_signal        __x64_sys_procfd_signal

#
# x32-specific system call numbers start at 512 to avoid cache

impact

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@@ -386,3 +387,4 @@

545    x32    execveat        __x32_compat_sys_execveat/ptregs
546    x32    preadv2            __x32_compat_sys_preadv64v2
547    x32    pwritev2        __x32_compat_sys_pwritev64v2
+548    x32    procfd_signal        __x32_compat_sys_procfd_signal

Is there a reason why these numbers have to be different?

(See the recent discussion with Andy Lutomirski.)

Hah, I missed this part of the patch.  Let’s not add new x32 syscall
numbers.

Also, can we perhaps rework this a bit to get rid of the compat entry
point?  The easier way would be to check in_compat_syscall(). The nicer
way IMO would be to use the 64-bit structure for 32-bit as well.

Do you have a syscall which set precedence/did this before I could look at?
Just if you happen to remember one.
Fwiw, I followed the other signal syscalls.
They all introduce compat syscalls.