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Re: [PATCH] mips/o32: fix internal_syscall5/6/7

• From: Aurelien Jarno <aurelien at aurel32 dot net>
• To: "Maciej W. Rozycki" <macro at imgtec dot com>
• Cc: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>,Joseph Myers <joseph at codesourcery dot com>, libc-alpha at sourceware dot org
• Date: Sat, 19 Aug 2017 14:44:45 +0200
• Subject: Re: [PATCH] mips/o32: fix internal_syscall5/6/7
• Authentication-results: sourceware.org; auth=none
• References: <alpine.DEB.2.00.1708171313580.17596@tp.orcam.me.uk> <bfef7321-0a07-13bf-a153-431c244bab0a@linaro.org> <alpine.DEB.2.00.1708172114340.17596@tp.orcam.me.uk> <39ca6099-2a86-f5f4-30fe-e86bb4cd736b@linaro.org> <20170817212022.nz6wv6d55xlvubez@aurel32.net> <alpine.DEB.2.00.1708172250280.17596@tp.orcam.me.uk> <20170818071616.vk4i25nd2fkkk5ij@aurel32.net> <alpine.DEB.2.00.1708181015550.17596@tp.orcam.me.uk> <20170818174451.hhdfihr266nvpwqs@aurel32.net> <alpine.DEB.2.00.1708182212340.17596@tp.orcam.me.uk>

On 2017-08-18 23:27, Maciej W. Rozycki wrote:> On Fri, 18 Aug 2017, Aurelien Jarno wrote:> > > > > I am using GCC 6, so if the fix went in GCC 7, that's normal the issue> > > > is present.> > > > > >  OK then; you can use the workaround I suggested to verify MIPS16 > > > compilation then.> > > > The workaround didn't work.> >  Hmm, that means there's something wrong with binutils which needs fixing.  > Can you please send me the failing .s file and the command line used to > assemble it (from `gcc -v')?Please find that attached.> > > > That's an interesting idea. If we use a different stub depending on the> > > > number of arguments, we can actually pass the syscall number last, which> > > > is probably more readable. Could also be used for mips16 in all cases?> > > > > >  MIPS16 wrappers do that already, which is also why there is an individual > > > one for each syscall argument count.> > > > Please find below a new patch implementing that. It started to be> > complicated to get the MIPS16 related defines used to build the > > equivalent code through GCC to work, so I decided to also implement> > __libc_do_syscall0 to __libc_do_syscall4 in libc-do-syscall.S. I looked> > at the original code generated by GCC, it's very similar to what I used,> > sometimes just a bit longer (sometimes GCC saves the syscall number to> > the stack to reload it just after).> >  The MIPS16 wrappers were split into individual files so that only ones > that are actually used by `ld.so' are pulled.  I think it would be good if > we preserved that.  I'll see if I can experiment with keeping the original > MIPS16 0-3 wrappers.For what I have seen, ld.so already uses syscalls with 1 to 4 arguments.It doesn't use any syscall without argument though. So it's only 4instructions overhead.Aurelien-- Aurelien Jarno                          GPG: 4096R/1DDD8C9Baurelien@aurel32.nethttp://www.aurel32.net

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• Follow-Ups:
  • Re: [PATCH] mips/o32: fix internal_syscall5/6/7
    • From: Maciej W. Rozycki

• References:
  • Re: [PATCH] mips/o32: fix internal_syscall5/6/7
    • From: Maciej W. Rozycki
  • Re: [PATCH] mips/o32: fix internal_syscall5/6/7
    • From: Adhemerval Zanella
  • Re: [PATCH] mips/o32: fix internal_syscall5/6/7
    • From: Maciej W. Rozycki
  • Re: [PATCH] mips/o32: fix internal_syscall5/6/7
    • From: Adhemerval Zanella
  • Re: [PATCH] mips/o32: fix internal_syscall5/6/7
    • From: Aurelien Jarno
  • Re: [PATCH] mips/o32: fix internal_syscall5/6/7
    • From: Maciej W. Rozycki
  • Re: [PATCH] mips/o32: fix internal_syscall5/6/7
    • From: Aurelien Jarno
  • Re: [PATCH] mips/o32: fix internal_syscall5/6/7
    • From: Maciej W. Rozycki
  • Re: [PATCH] mips/o32: fix internal_syscall5/6/7
    • From: Aurelien Jarno
  • Re: [PATCH] mips/o32: fix internal_syscall5/6/7
    • From: Maciej W. Rozycki