Re: [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to ilp32

From	Catalin Marinas <catalin.marinas@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to ilp32
Date	2015-12-23 14:40 +0100
Message-ID	<qIRO2-1P2-29@gated-at.bofh.it> (permalink)
References	<qG5DP-1iE-3@gated-at.bofh.it> <qG5DQ-1iE-25@gated-at.bofh.it> <qIueK-3Tt-5@gated-at.bofh.it> <qICYG-QF-35@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Tue, Dec 22, 2015 at 10:44:14PM +0100, Arnd Bergmann wrote:
> On Tuesday 22 December 2015, Catalin Marinas wrote:
> > > +
> > > +ENTRY(compat_sys_statfs64_wrapper)
> > > +     mov     w3, #84
> > > +     cmp     w1, #88
> > > +     csel    w1, w3, w1, eq
> > > +     b       compat_sys_statfs64
> > > +ENDPROC(compat_sys_statfs64_wrapper)
> > > +
> > > +ENTRY(compat_sys_fstatfs64_wrapper)
> > > +     mov     w3, #84
> > > +     cmp     w1, #88
> > > +     csel    w1, w3, w1, eq
> > > +     b       compat_sys_fstatfs64
> > > +ENDPROC(compat_sys_fstatfs64_wrapper)
> > 
> > I'm not convinced we need these wrappers for ILP32. They've been
> > introduced on arch/arm many years ago by commit Fixes: 713c481519f1
> > ([ARM] 3108/2: old ABI compat: statfs64 and fstatfs64) to deal with user
> > space passing a size of 88 (the EABI size of struct compat_statfs64
> > without the packing and alignment attribute). Since that commit, the
> > sizeof(struct compat_statfs64) is 84 already. This should be the case
> > with the new ILP32 exported headers (no backwards compatibility), so
> > user space should never pass 88 as size. Therefore we could call
> > compat_sys_(f)statfs64 directly without wrappers.
> 
> That means we have to set ARCH_PACK_STATFS64 in the arm64 header files
> though, and propagate the OABI alignment to arm64/ilp32 as well, rather
> than using the 88-byte version that every other 32-bit architecture
> except for x86-32 and arm32 has.

Yuri replied that for EABI glibc, sizeof(struct statfs64) is already 88.
If that's correct and the packing attribute is ignored by glibc, we
could drop ARCH_PACK_COMPAT_STATFS64 as well (OABI not supported by
arm64). But I would be slightly worried since glibc is not the only user
of the kernel ABI.

For ILP32, I think we can skip defining ARCH_PACK_STATFS64 (of course,
only if __ILP32__) and state that sizeof(struct statfs64) is 88
(unpacked). In which case we need the wrappers above to be able to reuse
the compat_sys_statfs64 code.

> Another option would be to set "#define __statfs_word __u64" and use
> the 64-bit statfs call, instead of compat_sys_statfs64, but that in turn
> requires special-casing statfs in libc.

I wouldn't go this route as we kind of agreed that ILP32 should look
like any other 32-bit ABI.

-- 
Catalin
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Thread

[RFC3 PATCH v6 00/20] ILP32 for ARM64 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 22:50 +0100
  [PATCH v6 10/20] arm64:ilp32 use the native LP64 'start_thread' for ILP32 threads Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 22:50 +0100
    Re: [PATCH v6 10/20] arm64:ilp32 use the native LP64 'start_thread' for ILP32 threads Arnd Bergmann <arnd@arndb.de> - 2015-12-16 17:00 +0100
      Re: [PATCH v6 10/20] arm64:ilp32 use the native LP64 'start_thread'  for ILP32 threads Yury Norov <ynorov@caviumnetworks.com> - 2015-12-18 15:00 +0100
  [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 22:50 +0100
    Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-12-16 17:10 +0100
    Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate  table (in entry.S) to use it Catalin Marinas <catalin.marinas@arm.com> - 2015-12-17 19:30 +0100
      Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-12-17 21:20 +0100
        Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate  table (in entry.S) to use it Andrew Pinski <pinskia@gmail.com> - 2015-12-17 21:20 +0100
          Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-12-17 22:00 +0100
          Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate  table (in entry.S) to use it Catalin Marinas <catalin.marinas@arm.com> - 2015-12-18 12:50 +0100
            Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-12-18 14:00 +0100
              Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate  table (in entry.S) to use it Catalin Marinas <catalin.marinas@arm.com> - 2015-12-21 19:40 +0100
                Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-12-21 23:30 +0100
              Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it "Dr. Philipp Tomsich" <philipp.tomsich@theobroma-systems.com> - 2015-12-21 19:50 +0100
                Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-12-21 23:20 +0100
    Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-12-21 23:40 +0100
      Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate  table (in entry.S) to use it Yury Norov <ynorov@caviumnetworks.com> - 2015-12-23 19:40 +0100
        Re: [PATCH v6 12/20] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Arnd Bergmann <arnd@arndb.de> - 2015-12-23 22:50 +0100
  [PATCH v6 02/20] arm64: ensure the kernel is compiled for LP64 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 22:50 +0100
  [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to ilp32 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 22:50 +0100
    Re: [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to ilp32 Andreas Schwab <schwab@suse.de> - 2015-12-17 15:40 +0100
      Re: [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to  ilp32 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-18 15:00 +0100
    Re: [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to  ilp32 Catalin Marinas <catalin.marinas@arm.com> - 2015-12-22 13:30 +0100
      Re: [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to ilp32 Arnd Bergmann <arnd@arndb.de> - 2015-12-22 22:50 +0100
        Re: [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to  ilp32 Catalin Marinas <catalin.marinas@arm.com> - 2015-12-23 14:40 +0100
          Re: [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to ilp32 Arnd Bergmann <arnd@arndb.de> - 2015-12-23 21:50 +0100
            Re: [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to  ilp32 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-30 18:30 +0100
              Re: [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to ilp32 Arnd Bergmann <arnd@arndb.de> - 2015-12-30 23:40 +0100
      Re: [PATCH v6 13/20] arm64: ilp32: share aarch32 syscall wrappers to  ilp32 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-23 05:30 +0100
  [PATCH v6 08/20] arm64: ilp32: add is_ilp32_compat_{task,thread} and TIF_32BIT_AARCH64 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 22:50 +0100
    Re: [PATCH v6 08/20] arm64: ilp32: add is_ilp32_compat_{task,  thread} and TIF_32BIT_AARCH64 Catalin Marinas <catalin.marinas@arm.com> - 2015-12-17 12:50 +0100
      Re: [PATCH v6 08/20] arm64: ilp32: add is_ilp32_compat_{task,  thread} and TIF_32BIT_AARCH64 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-18 15:20 +0100
        Re: [PATCH v6 08/20] arm64: ilp32: add is_ilp32_compat_{task,  thread} and TIF_32BIT_AARCH64 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-18 15:50 +0100
          Re: [PATCH v6 08/20] arm64: ilp32: add is_ilp32_compat_{task,  thread} and TIF_32BIT_AARCH64 Catalin Marinas <catalin.marinas@arm.com> - 2015-12-21 18:50 +0100
  [PATCH v6 04/20] arm64: change some CONFIG_COMPAT over to use CONFIG_AARCH32_EL0 instead Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 22:50 +0100
    Re: [PATCH v6 04/20] arm64: change some CONFIG_COMPAT over to use  CONFIG_AARCH32_EL0 instead Yury Norov <ynorov@caviumnetworks.com> - 2015-12-23 15:20 +0100
    > diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile Bamvor Jian Zhang <bamvor.zhangjian@linaro.org> - 2015-12-28 09:50 +0100
      Re: [PATCH v6 04/20] arm64: change some CONFIG_COMPAT over to use  CONFIG_AARCH32_EL0 instead "Zhangjian (Bamvor)" <bamvor.zhangjian@huawei.com> - 2015-12-28 10:10 +0100
        Re: [PATCH v6 04/20] arm64: change some CONFIG_COMPAT over to use  CONFIG_AARCH32_EL0 instead Yury Norov <ynorov@caviumnetworks.com> - 2015-12-29 13:40 +0100
          [PATCH] arm64: compat: fix wrong dependency Bamvor Jian Zhang <bamvor.zhangjian@linaro.org> - 2015-12-29 16:10 +0100
        Re: [PATCH v6 04/20] arm64: change some CONFIG_COMPAT over to use  CONFIG_AARCH32_EL0 instead Yury Norov <ynorov@caviumnetworks.com> - 2015-12-29 14:20 +0100
  [PATCH v6 01/20] arm64: ilp32: add documentation on the ILP32 ABI for ARM64 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 22:50 +0100
  [PATCH v6 09/20] arm64:ilp32: share HWCAP between LP64 and ILP32 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 22:50 +0100
    Re: [PATCH v6 09/20] arm64:ilp32: share HWCAP between LP64 and ILP32 Arnd Bergmann <arnd@arndb.de> - 2015-12-16 17:00 +0100
      Re: [PATCH v6 09/20] arm64:ilp32: share HWCAP between LP64 and ILP32 Catalin Marinas <catalin.marinas@arm.com> - 2015-12-16 18:00 +0100
        Re: [PATCH v6 09/20] arm64:ilp32: share HWCAP between LP64 and ILP32 Catalin Marinas <catalin.marinas@arm.com> - 2015-12-16 18:20 +0100
          Re: [PATCH v6 09/20] arm64:ilp32: share HWCAP between LP64 and ILP32 Arnd Bergmann <arnd@arndb.de> - 2015-12-16 20:20 +0100
            Re: [PATCH v6 09/20] arm64:ilp32: share HWCAP between LP64 and ILP32 Catalin Marinas <catalin.marinas@arm.com> - 2015-12-17 12:00 +0100
              Re: [PATCH v6 09/20] arm64:ilp32: share HWCAP between LP64 and ILP32 Arnd Bergmann <arnd@arndb.de> - 2015-12-17 15:00 +0100
  [PATCH v6 07/20] arm64: introduce is_a32_task and is_a32_thread (for AArch32 compat) Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 22:50 +0100
    Re: [PATCH v6 07/20] arm64: introduce is_a32_task and is_a32_thread  (for AArch32 compat) Catalin Marinas <catalin.marinas@arm.com> - 2015-12-17 12:40 +0100
  [PATCH v6 05/20] arm64:uapi: set __BITS_PER_LONG correctly for ILP32 and LP64 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 22:50 +0100
  [PATCH v6 11/20] arm64:ilp32: support core dump generation for ILP32 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 22:50 +0100
    Re: [PATCH v6 11/20] arm64:ilp32: support core dump generation for  ILP32 Catalin Marinas <catalin.marinas@arm.com> - 2015-12-17 15:10 +0100
  [PATCH v6 15/20] arm64: signal: move ilp32 and lp64 common code to separated file Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 22:50 +0100
    Re: [PATCH v6 15/20] arm64: signal: move ilp32 and lp64 common code to separated file Arnd Bergmann <arnd@arndb.de> - 2015-12-16 17:10 +0100
      Re: [PATCH v6 15/20] arm64: signal: move ilp32 and lp64 common code  to separated file Yury Norov <ynorov@caviumnetworks.com> - 2015-12-18 14:50 +0100
        Re: [PATCH v6 15/20] arm64: signal: move ilp32 and lp64 common code to separated file Arnd Bergmann <arnd@arndb.de> - 2015-12-18 15:20 +0100
    Re: [PATCH v6 15/20] arm64: signal: move ilp32 and lp64 common code  to separated file Catalin Marinas <catalin.marinas@arm.com> - 2015-12-22 18:20 +0100
  [PATCH v6 17/20] arm64: ilp32: introduce ilp32-specific handlers for sigframe Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 23:00 +0100
    Re: [PATCH v6 17/20] arm64: ilp32: introduce ilp32-specific handlers  for sigframe Catalin Marinas <catalin.marinas@arm.com> - 2015-12-22 18:20 +0100
  [PATCH v6 18/20] arm64:ilp32: add vdso-ilp32 and use for signal return Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 23:00 +0100
  [PATCH v6 19/20] arm64:ilp32: change COMPAT_ELF_PLATFORM to report a a subplatform for ILP32 Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 23:00 +0100
  [PATCH v6 20/20] arm64:ilp32: add ARM64_ILP32 to Kconfig Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 23:00 +0100
  [PATCH v6 16/20] arm64: signal32: move ilp32 and aarch32 common code to separated file Yury Norov <ynorov@caviumnetworks.com> - 2015-12-15 23:00 +0100
    Re: [PATCH v6 16/20] arm64: signal32: move ilp32 and aarch32 common  code to separated file Catalin Marinas <catalin.marinas@arm.com> - 2015-12-22 15:30 +0100
  Re: [RFC3 PATCH v6 00/20] ILP32 for ARM64 Arnd Bergmann <arnd@arndb.de> - 2015-12-16 17:30 +0100

csiph-web