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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: : : : :8d7718aa08is the first bad commit : : commit8d7718aa08: : Author: Michel Lespinasse <walken@google.com> : : 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. Michael said: : This fixes the glibc test suite failures and the pulseaudio related : crashes, but it does not fix the java compiiler lockups that I was (and : are still) observing. That is some other problem. Reported-by: Michael Cree <mcree@orcon.net.nz> Tested-by: Michael Cree <mcree@orcon.net.nz> Acked-by: Phil Carmody <ext-phil.2.carmody@nokia.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Michel Lespinasse <walken@google.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Reviewed-by: Matt Turner <mattst88@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
120 lines
2.8 KiB
C
120 lines
2.8 KiB
C
#ifndef _ASM_ALPHA_FUTEX_H
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#define _ASM_ALPHA_FUTEX_H
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#ifdef __KERNEL__
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#include <linux/futex.h>
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#include <linux/uaccess.h>
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#include <asm/errno.h>
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#include <asm/barrier.h>
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#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
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__asm__ __volatile__( \
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__ASM_SMP_MB \
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"1: ldl_l %0,0(%2)\n" \
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insn \
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"2: stl_c %1,0(%2)\n" \
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" beq %1,4f\n" \
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" mov $31,%1\n" \
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"3: .subsection 2\n" \
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"4: br 1b\n" \
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" .previous\n" \
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" .section __ex_table,\"a\"\n" \
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" .long 1b-.\n" \
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" lda $31,3b-1b(%1)\n" \
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" .long 2b-.\n" \
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" lda $31,3b-2b(%1)\n" \
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" .previous\n" \
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: "=&r" (oldval), "=&r"(ret) \
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: "r" (uaddr), "r"(oparg) \
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: "memory")
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static inline int futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
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{
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int op = (encoded_op >> 28) & 7;
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int cmp = (encoded_op >> 24) & 15;
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int oparg = (encoded_op << 8) >> 20;
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int cmparg = (encoded_op << 20) >> 20;
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int oldval = 0, ret;
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if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
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oparg = 1 << oparg;
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if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
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return -EFAULT;
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pagefault_disable();
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switch (op) {
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case FUTEX_OP_SET:
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__futex_atomic_op("mov %3,%1\n", ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_ADD:
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__futex_atomic_op("addl %0,%3,%1\n", ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_OR:
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__futex_atomic_op("or %0,%3,%1\n", ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_ANDN:
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__futex_atomic_op("andnot %0,%3,%1\n", ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_XOR:
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__futex_atomic_op("xor %0,%3,%1\n", ret, oldval, uaddr, oparg);
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break;
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default:
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ret = -ENOSYS;
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}
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pagefault_enable();
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if (!ret) {
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switch (cmp) {
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case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
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case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
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case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
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case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
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case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
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case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
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default: ret = -ENOSYS;
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}
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}
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return ret;
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}
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static inline int
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futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
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u32 oldval, u32 newval)
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{
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int ret = 0, cmp;
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u32 prev;
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if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
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return -EFAULT;
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__asm__ __volatile__ (
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__ASM_SMP_MB
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"1: ldl_l %1,0(%3)\n"
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" cmpeq %1,%4,%2\n"
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" beq %2,3f\n"
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" mov %5,%2\n"
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"2: stl_c %2,0(%3)\n"
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" beq %2,4f\n"
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"3: .subsection 2\n"
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"4: br 1b\n"
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" .previous\n"
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" .section __ex_table,\"a\"\n"
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" .long 1b-.\n"
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" lda $31,3b-1b(%0)\n"
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" .long 2b-.\n"
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" lda $31,3b-2b(%0)\n"
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" .previous\n"
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: "+r"(ret), "=&r"(prev), "=&r"(cmp)
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: "r"(uaddr), "r"((long)(int)oldval), "r"(newval)
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: "memory");
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*uval = prev;
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return ret;
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}
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#endif /* __KERNEL__ */
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#endif /* _ASM_ALPHA_FUTEX_H */
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