On Mon, 27 Feb 2012 19:48:28 +1300 Michael Cree <mcree@xxxxxxxxxxxx> wrote: > > There is no 32-bit compare instruction. These are implemented by > > consistently extending the values to a 64-bit type. Since the > > load instruction sign-extends, we want to sign-extend the other > > quantity as well (despite the fact it's logically unsigned). > > > > So: > > > > - : "r"(uaddr), "r"((long)oldval), "r"(newval) > > + : "r"(uaddr), "r"((long)(int)oldval), "r"(newval) > > > > should do the trick. > > Thanks, that fixes it. Will you formally submit a patch with commit > message or should I? > > You can have at least a Reviewed-by, or even an > Acked-by: Phil Carmody <ext-phil.2.carmody@xxxxxxxxx> > who correctly analysed the problem in response to when I suggested the > fix on the debian-alpha email list without explanation. Seems that I am an alpha hacker! This? From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Subject: alpha: fix 32/64-bit bug in futex support Michael Cree said: : : I have noticed some user space problems (pulseaudio crashes in pthread : : code, glibc/nptl test suite failures, java compiler freezes on SMP alpha : : systems) that arise when using a 2.6.39 or later kernel on Alpha. : : Bisecting between 2.6.38 and 2.6.39 (using glibc/nptl test suite as : : criterion for good/bad kernel) eventually leads to: : : : : 8d7718aa082aaf30a0b4989e1f04858952f941bc is the first bad commit : : commit 8d7718aa082aaf30a0b4989e1f04858952f941bc : : Author: Michel Lespinasse <walken@xxxxxxxxxx> : : Date: Thu Mar 10 18:50:58 2011 -0800 : : : : futex: Sanitize futex ops argument types : : : : Change futex_atomic_op_inuser and futex_atomic_cmpxchg_inatomic : : prototypes to use u32 types for the futex as this is the data type the : : futex core code uses all over the place. : : : : Looking at the commit I see there is a change of the uaddr argument in : : the Alpha architecture specific code for futexes from int to u32, but I : : don't see why this should cause a problem. Richard Henderson said: : futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, : u32 oldval, u32 newval) : ... : : "r"(uaddr), "r"((long)oldval), "r"(newval) : : : There is no 32-bit compare instruction. These are implemented by : consistently extending the values to a 64-bit type. Since the : load instruction sign-extends, we want to sign-extend the other : quantity as well (despite the fact it's logically unsigned). : : So: : : - : "r"(uaddr), "r"((long)oldval), "r"(newval) : + : "r"(uaddr), "r"((long)(int)oldval), "r"(newval) : : should do the trick. Reported-by: Michael Cree <mcree@xxxxxxxxxxxx> Tested-by: Michael Cree <mcree@xxxxxxxxxxxx> Acked-by: Phil Carmody <ext-phil.2.carmody@xxxxxxxxx> Cc: Richard Henderson <rth@xxxxxxxxxxx> Cc: Michel Lespinasse <walken@xxxxxxxxxx> Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx> Cc: Matt Turner <mattst88@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/alpha/include/asm/futex.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN arch/alpha/include/asm/futex.h~alpha-fix-32-64-bit-bug-in-futex-support arch/alpha/include/asm/futex.h --- a/arch/alpha/include/asm/futex.h~alpha-fix-32-64-bit-bug-in-futex-support +++ a/arch/alpha/include/asm/futex.h @@ -108,7 +108,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, " lda $31,3b-2b(%0)\n" " .previous\n" : "+r"(ret), "=&r"(prev), "=&r"(cmp) - : "r"(uaddr), "r"((long)oldval), "r"(newval) + : "r"(uaddr), "r"((long)(int)oldval), "r"(newval) : "memory"); *uval = prev; _ -- To unsubscribe from this list: send the line "unsubscribe linux-alpha" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
