path: root/kernel/compat.c
diff options
authorakpm@osdl.org <akpm@osdl.org>2006-06-25 05:48:35 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-25 10:01:15 -0700
commit838cd153a5250a79a302f6c5d68a4794b70c4ccb (patch)
tree9122d37d7521c9345779aa84e2ca8d754d997475 /kernel/compat.c
parent92eeccd8badbfebe12383b6e5326b27dc707601d (diff)
[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 'kernel/compat.c')
1 files changed, 0 insertions, 7 deletions
diff --git a/kernel/compat.c b/kernel/compat.c
index 2f672332430f..126dee9530aa 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -730,17 +730,10 @@ void
sigset_from_compat (sigset_t *set, compat_sigset_t *compat)
switch (_NSIG_WORDS) {
-#if defined (__COMPAT_ENDIAN_SWAP__)
- case 4: set->sig[3] = compat->sig[7] | (((long)compat->sig[6]) << 32 );
- case 3: set->sig[2] = compat->sig[5] | (((long)compat->sig[4]) << 32 );
- case 2: set->sig[1] = compat->sig[3] | (((long)compat->sig[2]) << 32 );
- case 1: set->sig[0] = compat->sig[1] | (((long)compat->sig[0]) << 32 );
case 4: set->sig[3] = compat->sig[6] | (((long)compat->sig[7]) << 32 );
case 3: set->sig[2] = compat->sig[4] | (((long)compat->sig[5]) << 32 );
case 2: set->sig[1] = compat->sig[2] | (((long)compat->sig[3]) << 32 );
case 1: set->sig[0] = compat->sig[0] | (((long)compat->sig[1]) << 32 );

Privacy Policy