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SubjectRe: [PATCH 01/19] compat ABI: use non-compat openat and open_by_handle_at variants
On Mon, Jun 27, 2016 at 09:47:38AM +0200, Andreas Schwab wrote:
> Yury Norov <ynorov@caviumnetworks.com> writes:
>
> > The only difference is that non-compat version forces O_LARGEFILE,
> > and it should be the default behaviour for all architectures, as
> > we don't support 32-bit off_t. The only exception is tile32, that
> > continues with compat version of syscalls.
> >
> > Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
> > Acked-by: Arnd Bergmann <arnd@arndb.de>
> > Acked-by: Chris Metcalf <cmetcalf@ezchip.com> [for tile]
> > ---
> > arch/tile/kernel/compat.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/arch/tile/kernel/compat.c b/arch/tile/kernel/compat.c
> > index 4912084..489ae19 100644
> > --- a/arch/tile/kernel/compat.c
> > +++ b/arch/tile/kernel/compat.c
> > @@ -94,6 +94,9 @@ COMPAT_SYSCALL_DEFINE5(llseek, unsigned int, fd, unsigned int, offset_high,
> > #define compat_sys_readahead sys32_readahead
> > #define sys_llseek compat_sys_llseek
> >
> > +#define sys_openat compat_sys_openat
> > +#define sys_open_by_handle_at compat_sys_open_by_handle_at
> > +
> > /* Call the assembly trampolines where necessary. */
> > #define compat_sys_rt_sigreturn _compat_sys_rt_sigreturn
> > #define sys_clone _sys_clone
>
> This is a no-op. Did you mean to add this? Without that the testsuite
> of tar fails on ILP32.

The change you suggest below is what I originally sent at the end of
December, but that chunk was lost after one of numerous rebases probably.

http://lkml.iu.edu/hypermail/linux/kernel/1512.3/00510.html

IIRC, the only difference between this couple of syscalls and their
compat versions is that non-compat syscalls set O_LARGEFILE depending
on (BITS_PER_LONG != 32). Next patch of this series introduces
ARCH_32BIT_OFF_T config option to force O_LARGEFILE for 64-bit arches,
and all new 32-bit arches, as ARCH_32BIT_OFF_T is enabled for existing
32-bit arches explicitly.

O_LARGEFILE is controlled like this:
-#define force_o_largefile() (BITS_PER_LONG != 32)
+#define force_o_largefile() (!IS_ENABLED(CONFIG_ARCH_32BIT_OFF_T))

So if I restore original patch, everything will work. But my question
is: if ARCH_32BIT_OFF_T disables O_LARGEFILE for tile32 anyway, what
for we redirect native syscall handlers to compat ones? They are
looking identical...

If my understanding is correct, we can drop the change in
arch/tile/kernel/compat.c and join this patch with next one in this
series.

Chris, Arnd?

>
> diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
> index a26415b..4dcc38d 100644
> --- a/include/uapi/asm-generic/unistd.h
> +++ b/include/uapi/asm-generic/unistd.h
> @@ -178,7 +178,7 @@ __SYSCALL(__NR_fchownat, sys_fchownat)
> #define __NR_fchown 55
> __SYSCALL(__NR_fchown, sys_fchown)
> #define __NR_openat 56
> -__SC_COMP(__NR_openat, sys_openat, compat_sys_openat)
> +__SYSCALL(__NR_openat, sys_openat)
> #define __NR_close 57
> __SYSCALL(__NR_close, sys_close)
> #define __NR_vhangup 58
> @@ -676,8 +676,7 @@ __SYSCALL(__NR_fanotify_mark, sys_fanotify_mark)
> #define __NR_name_to_handle_at 264
> __SYSCALL(__NR_name_to_handle_at, sys_name_to_handle_at)
> #define __NR_open_by_handle_at 265
> -__SC_COMP(__NR_open_by_handle_at, sys_open_by_handle_at, \
> - compat_sys_open_by_handle_at)
> +__SYSCALL(__NR_open_by_handle_at, sys_open_by_handle_at)
> #define __NR_clock_adjtime 266
> __SC_COMP(__NR_clock_adjtime, sys_clock_adjtime, compat_sys_clock_adjtime)
> #define __NR_syncfs 267
> --
> 2.9.0
>
>
> Andreas.
>
> --
> Andreas Schwab, SUSE Labs, schwab@suse.de
> GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
> "And now for something completely different."

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