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author | akpm@osdl.org <akpm@osdl.org> | 2006-06-25 05:48:35 -0700 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-25 10:01:15 -0700 |
commit | 838cd153a5250a79a302f6c5d68a4794b70c4ccb (patch) | |
tree | 9122d37d7521c9345779aa84e2ca8d754d997475 /include | |
parent | 92eeccd8badbfebe12383b6e5326b27dc707601d (diff) | |
download | op-kernel-dev-838cd153a5250a79a302f6c5d68a4794b70c4ccb.zip op-kernel-dev-838cd153a5250a79a302f6c5d68a4794b70c4ccb.tar.gz |
[PATCH] N32 sigset and __COMPAT_ENDIAN_SWAP__
I'm testing glibc on MIPS64, little-endian, N32, O32 and N64 multilibs.
Among the NPTL test failures seen are some arising from sigsuspend problems
for N32: it blocks the wrong signals, so SIGCANCEL (SIGRTMIN) is blocked
despite glibc's carefully excluding it from sets of signals to block.
Specifically, testing suggests it blocks signal N^32 instead of signal N,
so (in the example tested) blocking SIGUSR1 (17) blocks signal 49 instead.
glibc's sigset_t uses an array of unsigned long, as does the kernel.
In both cases, signal N+1 is represented as
(1UL << (N % (8 * sizeof (unsigned long)))) in word number
(N / (8 * sizeof (unsigned long))).
Thus the N32 glibc uses an array of 32-bit words and the N64 kernel uses an
array of 64-bit words. For little-endian, the layout is the same, with
signals 1-32 in the first 4 bytes, signals 33-64 in the second, etc.; for
big-endian, userspace has that layout while in the kernel each 8 bytes have
the two halves swapped from the userspace layout.
The N32 sigsuspend syscall uses sigset_from_compat to convert the userspace
sigset to kernel format. If __COMPAT_ENDIAN_SWAP__ is *not* set, this uses
logic of the form
set->sig[0] = compat->sig[0] | (((long)compat->sig[1]) << 32 )
to convert the userspace sigset to a kernel one. This looks correct to me
for both big and little endian, given that in userspace compat->sig[1] will
represent signals 33-64, and so will the high 32 bits of set->sig[0] in the
kernel. If however __COMPAT_ENDIAN_SWAP__ *is* set, as it is for
__MIPSEL__, it uses
set->sig[0] = compat->sig[1] | (((long)compat->sig[0]) << 32 );
which seems incorrect for both big and little endian, and would
explain the observed symptoms.
This code is the only use of __COMPAT_ENDIAN_SWAP__, so if incorrect
then that macro serves no purpose, in which case something like the
following patch would seem appropriate to remove it.
Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/asm-mips/compat.h | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/include/asm-mips/compat.h b/include/asm-mips/compat.h index 986511d..900f472 100644 --- a/include/asm-mips/compat.h +++ b/include/asm-mips/compat.h @@ -145,8 +145,5 @@ static inline void __user *compat_alloc_user_space(long len) return (void __user *) (regs->regs[29] - len); } -#if defined (__MIPSEL__) -#define __COMPAT_ENDIAN_SWAP__ 1 -#endif #endif /* _ASM_COMPAT_H */ |