From: Michel Lespinasse Date: Fri, 11 Mar 2011 02:48:51 +0000 (-0800) Subject: futex: Sanitize cmpxchg_futex_value_locked API X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=37a9d912b24f;p=linux-beck.git futex: Sanitize cmpxchg_futex_value_locked API The cmpxchg_futex_value_locked API was funny in that it returned either the original, user-exposed futex value OR an error code such as -EFAULT. This was confusing at best, and could be a source of livelocks in places that retry the cmpxchg_futex_value_locked after trying to fix the issue by running fault_in_user_writeable(). This change makes the cmpxchg_futex_value_locked API more similar to the get_futex_value_locked one, returning an error code and updating the original value through a reference argument. Signed-off-by: Michel Lespinasse Acked-by: Chris Metcalf [tile] Acked-by: Tony Luck [ia64] Acked-by: Thomas Gleixner Tested-by: Michal Simek [microblaze] Acked-by: David Howells [frv] Cc: Darren Hart Cc: Peter Zijlstra Cc: Matt Turner Cc: Russell King Cc: Ralf Baechle Cc: "James E.J. Bottomley" Cc: Benjamin Herrenschmidt Cc: Martin Schwidefsky Cc: Paul Mundt Cc: "David S. Miller" Cc: Linus Torvalds LKML-Reference: <20110311024851.GC26122@google.com> Signed-off-by: Thomas Gleixner --- diff --git a/arch/alpha/include/asm/futex.h b/arch/alpha/include/asm/futex.h index 945de222ab91..c4e5c2850cce 100644 --- a/arch/alpha/include/asm/futex.h +++ b/arch/alpha/include/asm/futex.h @@ -81,21 +81,22 @@ static inline int futex_atomic_op_inuser (int encoded_op, int __user *uaddr) } static inline int -futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) +futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { - int prev, cmp; + int ret = 0, prev, cmp; if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) return -EFAULT; __asm__ __volatile__ ( __ASM_SMP_MB - "1: ldl_l %0,0(%2)\n" - " cmpeq %0,%3,%1\n" - " beq %1,3f\n" - " mov %4,%1\n" - "2: stl_c %1,0(%2)\n" - " beq %1,4f\n" + "1: ldl_l %1,0(%3)\n" + " cmpeq %1,%4,%2\n" + " beq %2,3f\n" + " mov %5,%2\n" + "2: stl_c %2,0(%3)\n" + " beq %2,4f\n" "3: .subsection 2\n" "4: br 1b\n" " .previous\n" @@ -105,11 +106,12 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) " .long 2b-.\n" " lda $31,3b-2b(%0)\n" " .previous\n" - : "=&r"(prev), "=&r"(cmp) + : "+r"(ret), "=&r"(prev), "=&r"(cmp) : "r"(uaddr), "r"((long)oldval), "r"(newval) : "memory"); - return prev; + *uval = prev; + return ret; } #endif /* __KERNEL__ */ diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h index 7133a8620830..d20b78fce758 100644 --- a/arch/arm/include/asm/futex.h +++ b/arch/arm/include/asm/futex.h @@ -88,9 +88,10 @@ futex_atomic_op_inuser (int encoded_op, int __user *uaddr) } static inline int -futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) +futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { - int val; + int ret = 0, val; if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) return -EFAULT; @@ -99,24 +100,25 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) * call sites. */ __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n" - "1: " T(ldr) " %0, [%3]\n" - " teq %0, %1\n" + "1: " T(ldr) " %1, [%4]\n" + " teq %1, %2\n" " it eq @ explicit IT needed for the 2b label\n" - "2: " T(streq) " %2, [%3]\n" + "2: " T(streq) " %3, [%4]\n" "3:\n" " .pushsection __ex_table,\"a\"\n" " .align 3\n" " .long 1b, 4f, 2b, 4f\n" " .popsection\n" " .pushsection .fixup,\"ax\"\n" - "4: mov %0, %4\n" + "4: mov %0, %5\n" " b 3b\n" " .popsection" - : "=&r" (val) + : "+r" (ret), "=&r" (val) : "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT) : "cc", "memory"); - return val; + *uval = val; + return ret; } #endif /* !SMP */ diff --git a/arch/frv/include/asm/futex.h b/arch/frv/include/asm/futex.h index 08b3d1da3583..0548f8e4d11e 100644 --- a/arch/frv/include/asm/futex.h +++ b/arch/frv/include/asm/futex.h @@ -10,7 +10,8 @@ extern int futex_atomic_op_inuser(int encoded_op, int __user *uaddr); static inline int -futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) +futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { return -ENOSYS; } diff --git a/arch/ia64/include/asm/futex.h b/arch/ia64/include/asm/futex.h index c7f0f062239c..b0728404dad0 100644 --- a/arch/ia64/include/asm/futex.h +++ b/arch/ia64/include/asm/futex.h @@ -100,23 +100,26 @@ futex_atomic_op_inuser (int encoded_op, int __user *uaddr) } static inline int -futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) +futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) return -EFAULT; { - register unsigned long r8 __asm ("r8"); + register unsigned long r8 __asm ("r8") = 0; + unsigned long prev; __asm__ __volatile__( " mf;; \n" " mov ar.ccv=%3;; \n" "[1:] cmpxchg4.acq %0=[%1],%2,ar.ccv \n" " .xdata4 \"__ex_table\", 1b-., 2f-. \n" "[2:]" - : "=r" (r8) + : "=r" (prev) : "r" (uaddr), "r" (newval), "rO" ((long) (unsigned) oldval) : "memory"); + *uval = prev; return r8; } } diff --git a/arch/microblaze/include/asm/futex.h b/arch/microblaze/include/asm/futex.h index ad3fd61b2fe7..fa019ed65dfb 100644 --- a/arch/microblaze/include/asm/futex.h +++ b/arch/microblaze/include/asm/futex.h @@ -94,31 +94,33 @@ futex_atomic_op_inuser(int encoded_op, int __user *uaddr) } static inline int -futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) +futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { - int prev, cmp; + int ret = 0, prev, cmp; if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) return -EFAULT; - __asm__ __volatile__ ("1: lwx %0, %2, r0; \ - cmp %1, %0, %3; \ - beqi %1, 3f; \ - 2: swx %4, %2, r0; \ - addic %1, r0, 0; \ - bnei %1, 1b; \ + __asm__ __volatile__ ("1: lwx %1, %3, r0; \ + cmp %2, %1, %4; \ + beqi %2, 3f; \ + 2: swx %5, %3, r0; \ + addic %2, r0, 0; \ + bnei %2, 1b; \ 3: \ .section .fixup,\"ax\"; \ 4: brid 3b; \ - addik %0, r0, %5; \ + addik %0, r0, %6; \ .previous; \ .section __ex_table,\"a\"; \ .word 1b,4b,2b,4b; \ .previous;" \ - : "=&r" (prev), "=&r"(cmp) \ + : "+r" (ret), "=&r" (prev), "=&r"(cmp) \ : "r" (uaddr), "r" (oldval), "r" (newval), "i" (-EFAULT)); - return prev; + *uval = prev; + return ret; } #endif /* __KERNEL__ */ diff --git a/arch/mips/include/asm/futex.h b/arch/mips/include/asm/futex.h index b9cce90346cf..692a24bd83b7 100644 --- a/arch/mips/include/asm/futex.h +++ b/arch/mips/include/asm/futex.h @@ -132,9 +132,10 @@ futex_atomic_op_inuser(int encoded_op, int __user *uaddr) } static inline int -futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) +futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { - int retval; + int ret = 0, val; if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) return -EFAULT; @@ -145,25 +146,25 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) " .set push \n" " .set noat \n" " .set mips3 \n" - "1: ll %0, %2 \n" - " bne %0, %z3, 3f \n" + "1: ll %1, %3 \n" + " bne %1, %z4, 3f \n" " .set mips0 \n" - " move $1, %z4 \n" + " move $1, %z5 \n" " .set mips3 \n" - "2: sc $1, %1 \n" + "2: sc $1, %2 \n" " beqzl $1, 1b \n" __WEAK_LLSC_MB "3: \n" " .set pop \n" " .section .fixup,\"ax\" \n" - "4: li %0, %5 \n" + "4: li %0, %6 \n" " j 3b \n" " .previous \n" " .section __ex_table,\"a\" \n" " "__UA_ADDR "\t1b, 4b \n" " "__UA_ADDR "\t2b, 4b \n" " .previous \n" - : "=&r" (retval), "=R" (*uaddr) + : "+r" (ret), "=&r" (val), "=R" (*uaddr) : "R" (*uaddr), "Jr" (oldval), "Jr" (newval), "i" (-EFAULT) : "memory"); } else if (cpu_has_llsc) { @@ -172,31 +173,32 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) " .set push \n" " .set noat \n" " .set mips3 \n" - "1: ll %0, %2 \n" - " bne %0, %z3, 3f \n" + "1: ll %1, %3 \n" + " bne %1, %z4, 3f \n" " .set mips0 \n" - " move $1, %z4 \n" + " move $1, %z5 \n" " .set mips3 \n" - "2: sc $1, %1 \n" + "2: sc $1, %2 \n" " beqz $1, 1b \n" __WEAK_LLSC_MB "3: \n" " .set pop \n" " .section .fixup,\"ax\" \n" - "4: li %0, %5 \n" + "4: li %0, %6 \n" " j 3b \n" " .previous \n" " .section __ex_table,\"a\" \n" " "__UA_ADDR "\t1b, 4b \n" " "__UA_ADDR "\t2b, 4b \n" " .previous \n" - : "=&r" (retval), "=R" (*uaddr) + : "+r" (ret), "=&r" (val), "=R" (*uaddr) : "R" (*uaddr), "Jr" (oldval), "Jr" (newval), "i" (-EFAULT) : "memory"); } else return -ENOSYS; - return retval; + *uval = val; + return ret; } #endif diff --git a/arch/parisc/include/asm/futex.h b/arch/parisc/include/asm/futex.h index 0c705c3a55ef..4c6d8672325b 100644 --- a/arch/parisc/include/asm/futex.h +++ b/arch/parisc/include/asm/futex.h @@ -51,10 +51,10 @@ futex_atomic_op_inuser (int encoded_op, int __user *uaddr) /* Non-atomic version */ static inline int -futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) +futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { - int err = 0; - int uval; + int val; /* futex.c wants to do a cmpxchg_inatomic on kernel NULL, which is * our gateway page, and causes no end of trouble... @@ -65,12 +65,12 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) return -EFAULT; - err = get_user(uval, uaddr); - if (err) return -EFAULT; - if (uval == oldval) - err = put_user(newval, uaddr); - if (err) return -EFAULT; - return uval; + if (get_user(val, uaddr)) + return -EFAULT; + if (val == oldval && put_user(newval, uaddr)) + return -EFAULT; + *uval = val; + return 0; } #endif /*__KERNEL__*/ diff --git a/arch/powerpc/include/asm/futex.h b/arch/powerpc/include/asm/futex.h index 7c589ef81fb0..631e8da60064 100644 --- a/arch/powerpc/include/asm/futex.h +++ b/arch/powerpc/include/asm/futex.h @@ -82,35 +82,37 @@ static inline int futex_atomic_op_inuser (int encoded_op, int __user *uaddr) } static inline int -futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) +futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { - int prev; + int ret = 0, prev; if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) return -EFAULT; __asm__ __volatile__ ( PPC_RELEASE_BARRIER -"1: lwarx %0,0,%2 # futex_atomic_cmpxchg_inatomic\n\ - cmpw 0,%0,%3\n\ +"1: lwarx %1,0,%3 # futex_atomic_cmpxchg_inatomic\n\ + cmpw 0,%1,%4\n\ bne- 3f\n" - PPC405_ERR77(0,%2) -"2: stwcx. %4,0,%2\n\ + PPC405_ERR77(0,%3) +"2: stwcx. %5,0,%3\n\ bne- 1b\n" PPC_ACQUIRE_BARRIER "3: .section .fixup,\"ax\"\n\ -4: li %0,%5\n\ +4: li %0,%6\n\ b 3b\n\ .previous\n\ .section __ex_table,\"a\"\n\ .align 3\n\ " PPC_LONG "1b,4b,2b,4b\n\ .previous" \ - : "=&r" (prev), "+m" (*uaddr) + : "+r" (ret), "=&r" (prev), "+m" (*uaddr) : "r" (uaddr), "r" (oldval), "r" (newval), "i" (-EFAULT) : "cc", "memory"); - return prev; + *uval = prev; + return ret; } #endif /* __KERNEL__ */ diff --git a/arch/s390/include/asm/futex.h b/arch/s390/include/asm/futex.h index 5c5d02de49e9..27ac515ef59c 100644 --- a/arch/s390/include/asm/futex.h +++ b/arch/s390/include/asm/futex.h @@ -39,13 +39,13 @@ static inline int futex_atomic_op_inuser (int encoded_op, int __user *uaddr) return ret; } -static inline int futex_atomic_cmpxchg_inatomic(int __user *uaddr, +static inline int futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, int oldval, int newval) { if (! access_ok (VERIFY_WRITE, uaddr, sizeof(int))) return -EFAULT; - return uaccess.futex_atomic_cmpxchg(uaddr, oldval, newval); + return uaccess.futex_atomic_cmpxchg(uval, uaddr, oldval, newval); } #endif /* __KERNEL__ */ diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h index d6b1ed0ec52b..549adf6a9b8b 100644 --- a/arch/s390/include/asm/uaccess.h +++ b/arch/s390/include/asm/uaccess.h @@ -84,7 +84,7 @@ struct uaccess_ops { size_t (*strnlen_user)(size_t, const char __user *); size_t (*strncpy_from_user)(size_t, const char __user *, char *); int (*futex_atomic_op)(int op, int __user *, int oparg, int *old); - int (*futex_atomic_cmpxchg)(int __user *, int old, int new); + int (*futex_atomic_cmpxchg)(int *, int __user *, int old, int new); }; extern struct uaccess_ops uaccess; diff --git a/arch/s390/lib/uaccess.h b/arch/s390/lib/uaccess.h index 126011df14f1..89a80674e44b 100644 --- a/arch/s390/lib/uaccess.h +++ b/arch/s390/lib/uaccess.h @@ -12,12 +12,12 @@ extern size_t copy_from_user_std(size_t, const void __user *, void *); extern size_t copy_to_user_std(size_t, void __user *, const void *); extern size_t strnlen_user_std(size_t, const char __user *); extern size_t strncpy_from_user_std(size_t, const char __user *, char *); -extern int futex_atomic_cmpxchg_std(int __user *, int, int); +extern int futex_atomic_cmpxchg_std(int *, int __user *, int, int); extern int futex_atomic_op_std(int, int __user *, int, int *); extern size_t copy_from_user_pt(size_t, const void __user *, void *); extern size_t copy_to_user_pt(size_t, void __user *, const void *); extern int futex_atomic_op_pt(int, int __user *, int, int *); -extern int futex_atomic_cmpxchg_pt(int __user *, int, int); +extern int futex_atomic_cmpxchg_pt(int *, int __user *, int, int); #endif /* __ARCH_S390_LIB_UACCESS_H */ diff --git a/arch/s390/lib/uaccess_pt.c b/arch/s390/lib/uaccess_pt.c index 404f2de296dc..b3cebcd52f5c 100644 --- a/arch/s390/lib/uaccess_pt.c +++ b/arch/s390/lib/uaccess_pt.c @@ -354,26 +354,29 @@ int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old) return ret; } -static int __futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval) +static int __futex_atomic_cmpxchg_pt(int *uval, int __user *uaddr, + int oldval, int newval) { int ret; asm volatile("0: cs %1,%4,0(%5)\n" - "1: lr %0,%1\n" + "1: la %0,0\n" "2:\n" EX_TABLE(0b,2b) EX_TABLE(1b,2b) : "=d" (ret), "+d" (oldval), "=m" (*uaddr) : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr) : "cc", "memory" ); + *uval = oldval; return ret; } -int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval) +int futex_atomic_cmpxchg_pt(int *uval, int __user *uaddr, + int oldval, int newval) { int ret; if (segment_eq(get_fs(), KERNEL_DS)) - return __futex_atomic_cmpxchg_pt(uaddr, oldval, newval); + return __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval); spin_lock(¤t->mm->page_table_lock); uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr); if (!uaddr) { @@ -382,7 +385,7 @@ int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval) } get_page(virt_to_page(uaddr)); spin_unlock(¤t->mm->page_table_lock); - ret = __futex_atomic_cmpxchg_pt(uaddr, oldval, newval); + ret = __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval); put_page(virt_to_page(uaddr)); return ret; } diff --git a/arch/s390/lib/uaccess_std.c b/arch/s390/lib/uaccess_std.c index a6c4f7ed24a4..1d6643c0b95f 100644 --- a/arch/s390/lib/uaccess_std.c +++ b/arch/s390/lib/uaccess_std.c @@ -287,19 +287,21 @@ int futex_atomic_op_std(int op, int __user *uaddr, int oparg, int *old) return ret; } -int futex_atomic_cmpxchg_std(int __user *uaddr, int oldval, int newval) +int futex_atomic_cmpxchg_std(int *uval, int __user *uaddr, + int oldval, int newval) { int ret; asm volatile( " sacf 256\n" "0: cs %1,%4,0(%5)\n" - "1: lr %0,%1\n" + "1: la %0,0\n" "2: sacf 0\n" EX_TABLE(0b,2b) EX_TABLE(1b,2b) : "=d" (ret), "+d" (oldval), "=m" (*uaddr) : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr) : "cc", "memory" ); + *uval = oldval; return ret; } diff --git a/arch/sh/include/asm/futex-irq.h b/arch/sh/include/asm/futex-irq.h index a9f16a7f9aea..7b701cbd1e84 100644 --- a/arch/sh/include/asm/futex-irq.h +++ b/arch/sh/include/asm/futex-irq.h @@ -88,7 +88,8 @@ static inline int atomic_futex_op_xchg_xor(int oparg, int __user *uaddr, return ret; } -static inline int atomic_futex_op_cmpxchg_inatomic(int __user *uaddr, +static inline int atomic_futex_op_cmpxchg_inatomic(int *uval, + int __user *uaddr, int oldval, int newval) { unsigned long flags; @@ -102,10 +103,8 @@ static inline int atomic_futex_op_cmpxchg_inatomic(int __user *uaddr, local_irq_restore(flags); - if (ret) - return ret; - - return prev; + *uval = prev; + return ret; } #endif /* __ASM_SH_FUTEX_IRQ_H */ diff --git a/arch/sh/include/asm/futex.h b/arch/sh/include/asm/futex.h index 68256ec5fa35..a8a5125dc9b4 100644 --- a/arch/sh/include/asm/futex.h +++ b/arch/sh/include/asm/futex.h @@ -65,12 +65,13 @@ static inline int futex_atomic_op_inuser(int encoded_op, int __user *uaddr) } static inline int -futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) +futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) return -EFAULT; - return atomic_futex_op_cmpxchg_inatomic(uaddr, oldval, newval); + return atomic_futex_op_cmpxchg_inatomic(uval, uaddr, oldval, newval); } #endif /* __KERNEL__ */ diff --git a/arch/sparc/include/asm/futex_64.h b/arch/sparc/include/asm/futex_64.h index 47f95839dc69..e0862200d6a1 100644 --- a/arch/sparc/include/asm/futex_64.h +++ b/arch/sparc/include/asm/futex_64.h @@ -85,26 +85,30 @@ static inline int futex_atomic_op_inuser(int encoded_op, int __user *uaddr) } static inline int -futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) +futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { + int ret = 0; + __asm__ __volatile__( - "\n1: casa [%3] %%asi, %2, %0\n" + "\n1: casa [%4] %%asi, %3, %1\n" "2:\n" " .section .fixup,#alloc,#execinstr\n" " .align 4\n" "3: sethi %%hi(2b), %0\n" " jmpl %0 + %%lo(2b), %%g0\n" - " mov %4, %0\n" + " mov %5, %0\n" " .previous\n" " .section __ex_table,\"a\"\n" " .align 4\n" " .word 1b, 3b\n" " .previous\n" - : "=r" (newval) - : "0" (newval), "r" (oldval), "r" (uaddr), "i" (-EFAULT) + : "+r" (ret), "=r" (newval) + : "1" (newval), "r" (oldval), "r" (uaddr), "i" (-EFAULT) : "memory"); - return newval; + *uval = newval; + return ret; } #endif /* !(_SPARC64_FUTEX_H) */ diff --git a/arch/tile/include/asm/futex.h b/arch/tile/include/asm/futex.h index fe0d10dcae57..664b20aa2584 100644 --- a/arch/tile/include/asm/futex.h +++ b/arch/tile/include/asm/futex.h @@ -119,8 +119,8 @@ static inline int futex_atomic_op_inuser(int encoded_op, int __user *uaddr) return ret; } -static inline int futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, - int newval) +static inline int futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { struct __get_user asm_ret; @@ -128,7 +128,8 @@ static inline int futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, return -EFAULT; asm_ret = futex_cmpxchg(uaddr, oldval, newval); - return asm_ret.err ? asm_ret.err : asm_ret.val; + *uval = asm_ret.val; + return asm_ret.err; } #ifndef __tilegx__ diff --git a/arch/x86/include/asm/futex.h b/arch/x86/include/asm/futex.h index 1f11ce44e956..884c0b5676f4 100644 --- a/arch/x86/include/asm/futex.h +++ b/arch/x86/include/asm/futex.h @@ -109,9 +109,10 @@ static inline int futex_atomic_op_inuser(int encoded_op, int __user *uaddr) return ret; } -static inline int futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, - int newval) +static inline int futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { + int ret = 0; #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_BSWAP) /* Real i386 machines have no cmpxchg instruction */ @@ -122,18 +123,19 @@ static inline int futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) return -EFAULT; - asm volatile("1:\t" LOCK_PREFIX "cmpxchgl %3, %1\n" + asm volatile("1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n" "2:\t.section .fixup, \"ax\"\n" - "3:\tmov %2, %0\n" + "3:\tmov %3, %0\n" "\tjmp 2b\n" "\t.previous\n" _ASM_EXTABLE(1b, 3b) - : "=a" (oldval), "+m" (*uaddr) - : "i" (-EFAULT), "r" (newval), "0" (oldval) + : "+r" (ret), "=a" (oldval), "+m" (*uaddr) + : "i" (-EFAULT), "r" (newval), "1" (oldval) : "memory" ); - return oldval; + *uval = oldval; + return ret; } #endif diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h index 3c2344f48136..132bf5227b44 100644 --- a/include/asm-generic/futex.h +++ b/include/asm-generic/futex.h @@ -48,7 +48,8 @@ futex_atomic_op_inuser (int encoded_op, int __user *uaddr) } static inline int -futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) +futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr, + int oldval, int newval) { return -ENOSYS; } diff --git a/kernel/futex.c b/kernel/futex.c index 773815465bac..237f14bfc022 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -381,15 +381,16 @@ static struct futex_q *futex_top_waiter(struct futex_hash_bucket *hb, return NULL; } -static u32 cmpxchg_futex_value_locked(u32 __user *uaddr, u32 uval, u32 newval) +static int cmpxchg_futex_value_locked(u32 *curval, u32 __user *uaddr, + u32 uval, u32 newval) { - u32 curval; + int ret; pagefault_disable(); - curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval); + ret = futex_atomic_cmpxchg_inatomic(curval, uaddr, uval, newval); pagefault_enable(); - return curval; + return ret; } static int get_futex_value_locked(u32 *dest, u32 __user *from) @@ -688,9 +689,7 @@ retry: if (set_waiters) newval |= FUTEX_WAITERS; - curval = cmpxchg_futex_value_locked(uaddr, 0, newval); - - if (unlikely(curval == -EFAULT)) + if (unlikely(cmpxchg_futex_value_locked(&curval, uaddr, 0, newval))) return -EFAULT; /* @@ -728,9 +727,7 @@ retry: lock_taken = 1; } - curval = cmpxchg_futex_value_locked(uaddr, uval, newval); - - if (unlikely(curval == -EFAULT)) + if (unlikely(cmpxchg_futex_value_locked(&curval, uaddr, uval, newval))) return -EFAULT; if (unlikely(curval != uval)) goto retry; @@ -843,9 +840,7 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this) newval = FUTEX_WAITERS | task_pid_vnr(new_owner); - curval = cmpxchg_futex_value_locked(uaddr, uval, newval); - - if (curval == -EFAULT) + if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval)) ret = -EFAULT; else if (curval != uval) ret = -EINVAL; @@ -880,10 +875,8 @@ static int unlock_futex_pi(u32 __user *uaddr, u32 uval) * There is no waiter, so we unlock the futex. The owner died * bit has not to be preserved here. We are the owner: */ - oldval = cmpxchg_futex_value_locked(uaddr, uval, 0); - - if (oldval == -EFAULT) - return oldval; + if (cmpxchg_futex_value_locked(&oldval, uaddr, uval, 0)) + return -EFAULT; if (oldval != uval) return -EAGAIN; @@ -1578,9 +1571,7 @@ retry: while (1) { newval = (uval & FUTEX_OWNER_DIED) | newtid; - curval = cmpxchg_futex_value_locked(uaddr, uval, newval); - - if (curval == -EFAULT) + if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval)) goto handle_fault; if (curval == uval) break; @@ -2073,11 +2064,8 @@ retry: * again. If it succeeds then we can return without waking * anyone else up: */ - if (!(uval & FUTEX_OWNER_DIED)) - uval = cmpxchg_futex_value_locked(uaddr, vpid, 0); - - - if (unlikely(uval == -EFAULT)) + if (!(uval & FUTEX_OWNER_DIED) && + cmpxchg_futex_value_locked(&uval, uaddr, vpid, 0)) goto pi_faulted; /* * Rare case: we managed to release the lock atomically, @@ -2464,9 +2452,7 @@ retry: * userspace. */ mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; - nval = futex_atomic_cmpxchg_inatomic(uaddr, uval, mval); - - if (nval == -EFAULT) + if (futex_atomic_cmpxchg_inatomic(&nval, uaddr, uval, mval)) return -1; if (nval != uval) @@ -2679,8 +2665,7 @@ static int __init futex_init(void) * implementation, the non-functional ones will return * -ENOSYS. */ - curval = cmpxchg_futex_value_locked(NULL, 0, 0); - if (curval == -EFAULT) + if (cmpxchg_futex_value_locked(&curval, NULL, 0, 0) == -EFAULT) futex_cmpxchg_enabled = 1; for (i = 0; i < ARRAY_SIZE(futex_queues); i++) {