Re: Update syscall lists for Linux 5.19

[Aurelien Jarno <aurelien@aurel32.net>]

On 2022-08-05 10:28, Palmer Dabbelt wrote:
> On Fri, 05 Aug 2022 07:42:48 PDT (-0700), aurelien@aurel32.net wrote:
> > On 2022-08-03 17:36, Palmer Dabbelt wrote:
> > > On Tue, 02 Aug 2022 12:23:42 PDT (-0700), joseph@codesourcery.com wrote:
> > > > Linux 5.19 has no new syscalls, but enables memfd_secret in the uapi
> > > > headers for RISC-V.  Update the version number in syscall-names.list
> > > > to reflect that it is still current for 5.19 and regenerate the
> > > > arch-syscall.h headers with build-many-glibcs.py update-syscalls.
> > > >
> > > > Tested with build-many-glibcs.py.
> > > >
> > > > diff --git a/sysdeps/unix/sysv/linux/riscv/rv32/arch-syscall.h b/sysdeps/unix/sysv/linux/riscv/rv32/arch-syscall.h
> > > > index bf4be80..202520e 100644
> > > > --- a/sysdeps/unix/sysv/linux/riscv/rv32/arch-syscall.h
> > > > +++ b/sysdeps/unix/sysv/linux/riscv/rv32/arch-syscall.h
> > > > @@ -122,6 +122,7 @@
> > > >  #define __NR_mbind 235
> > > >  #define __NR_membarrier 283
> > > >  #define __NR_memfd_create 279
> > > > +#define __NR_memfd_secret 447
> > > >  #define __NR_migrate_pages 238
> > > >  #define __NR_mincore 232
> > > >  #define __NR_mkdirat 34
> > > > diff --git a/sysdeps/unix/sysv/linux/riscv/rv64/arch-syscall.h b/sysdeps/unix/sysv/linux/riscv/rv64/arch-syscall.h
> > > > index d656aed..4e65f33 100644
> > > > --- a/sysdeps/unix/sysv/linux/riscv/rv64/arch-syscall.h
> > > > +++ b/sysdeps/unix/sysv/linux/riscv/rv64/arch-syscall.h
> > > > @@ -127,6 +127,7 @@
> > > >  #define __NR_mbind 235
> > > >  #define __NR_membarrier 283
> > > >  #define __NR_memfd_create 279
> > > > +#define __NR_memfd_secret 447
> > > >  #define __NR_migrate_pages 238
> > > >  #define __NR_mincore 232
> > > >  #define __NR_mkdirat 34
> > > > diff --git a/sysdeps/unix/sysv/linux/syscall-names.list b/sysdeps/unix/sysv/linux/syscall-names.list
> > > > index 6c7b2f7..028ad31 100644
> > > > --- a/sysdeps/unix/sysv/linux/syscall-names.list
> > > > +++ b/sysdeps/unix/sysv/linux/syscall-names.list
> > > > @@ -21,8 +21,8 @@
> > > >  # This file can list all potential system calls.  The names are only
> > > >  # used if the installed kernel headers also provide them.
> > > >
> > > > -# The list of system calls is current as of Linux 5.18.
> > > > -kernel 5.18
> > > > +# The list of system calls is current as of Linux 5.19.
> > > > +kernel 5.19
> > > >
> > > >  FAST_atomic_update
> > > >  FAST_cmpxchg
> > > 
> > > Thanks, this was just a bug in the uapi headers: the syscall itself was has
> > > been implemented since 7bb7f2ac24a0 ("arch, mm: wire up memfd_secret system
> > > call where relevant"), which IIUC was first released in 5.14.  The fix
> > > should get backported.
> > 
> > It got backported in 5.18.3.
> 
> Sorry if that was the wrong thing to do, I thought this was safe because it
> was just making the number availiable in the headers.
> 
> > > I don't think any of that matters so much here, though.
> > 
> > The backport causes the misc/tst-glibcsyscalls test to fail on the
> > stable branches (tested on 2.35, but I guess it's the same on 2.36):
> > 
> > | original exit status 1
> > | error: kernel syscall 'memfd_secret' (447) not known to glibc
> > | info: glibc tables are based on kernel version 5.18
> > | info: installed kernel headers are version 5.18
> > 
> > So I wonder if we should just backport this commit to the stable
> > branches to fix this failure.
> 
> That works for me.  Another option would be to revert the backport in Linux.
> Either way we're stuck with some combination of releases that fail, so I'm
> not sure which is better.

No I do not think it is so bad. Errors are only reported when glibc
headers version >= kernel version (otherwise they are just warnings). So
if we increase glibc headers version to 5.18 by backporting this patch,
they won't be errors anymore with kernel headers 5.18.y or older.

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                 http://www.aurel32.net