forked from luck/tmp_suning_uos_patched
ARM: 6889/1: futex: add SMP futex support when !CPU_USE_DOMAINS
This patch uses the load/store exclusive instructions to add SMP futex support for ARM. Since the ARM architecture does not provide instructions for unprivileged exclusive memory accesses, we can only provide SMP futexes when CPU domain support is disabled. Cc: Nicolas Pitre <nico@fluxnic.net> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Will Deacon
Russell King
parent
af3e4fd37a
commit
c1b0db5660
@ -3,16 +3,74 @@
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#ifdef __KERNEL__
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#if defined(CONFIG_CPU_USE_DOMAINS) && defined(CONFIG_SMP)
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/* ARM doesn't provide unprivileged exclusive memory accessors */
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#include <asm-generic/futex.h>
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#else
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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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#define __futex_atomic_ex_table(err_reg) \
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"3:\n" \
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" .pushsection __ex_table,\"a\"\n" \
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" .align 3\n" \
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" .long 1b, 4f, 2b, 4f\n" \
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" .popsection\n" \
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" .pushsection .fixup,\"ax\"\n" \
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"4: mov %0, " err_reg "\n" \
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" b 3b\n" \
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" .popsection"
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#ifdef CONFIG_SMP
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#include <asm-generic/futex.h>
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#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
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smp_mb(); \
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__asm__ __volatile__( \
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"1: ldrex %1, [%2]\n" \
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" " insn "\n" \
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"2: strex %1, %0, [%2]\n" \
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" teq %1, #0\n" \
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" bne 1b\n" \
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" mov %0, #0\n" \
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__futex_atomic_ex_table("%4") \
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: "=&r" (ret), "=&r" (oldval) \
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: "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
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: "cc", "memory")
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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;
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u32 val;
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if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
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return -EFAULT;
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smp_mb();
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__asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
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"1: ldrex %1, [%4]\n"
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" teq %1, %2\n"
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" ite eq @ explicit IT needed for the 2b label\n"
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"2: strexeq %0, %3, [%4]\n"
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" movne %0, #0\n"
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" teq %0, #0\n"
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" bne 1b\n"
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__futex_atomic_ex_table("%5")
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: "=&r" (ret), "=&r" (val)
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: "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
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: "cc", "memory");
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smp_mb();
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*uval = val;
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return ret;
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}
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#else /* !SMP, we can work around lack of atomic ops by disabling preemption */
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#include <linux/futex.h>
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#include <linux/preempt.h>
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#include <linux/uaccess.h>
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#include <asm/errno.h>
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#include <asm/domain.h>
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#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
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@ -21,19 +79,37 @@
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" " insn "\n" \
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"2: " T(str) " %0, [%2]\n" \
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" mov %0, #0\n" \
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"3:\n" \
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" .pushsection __ex_table,\"a\"\n" \
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" .align 3\n" \
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" .long 1b, 4f, 2b, 4f\n" \
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" .popsection\n" \
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" .pushsection .fixup,\"ax\"\n" \
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"4: mov %0, %4\n" \
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" b 3b\n" \
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" .popsection" \
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__futex_atomic_ex_table("%4") \
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: "=&r" (ret), "=&r" (oldval) \
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: "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
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: "cc", "memory")
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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;
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u32 val;
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if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
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return -EFAULT;
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__asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
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"1: " T(ldr) " %1, [%4]\n"
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" teq %1, %2\n"
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" it eq @ explicit IT needed for the 2b label\n"
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"2: " T(streq) " %3, [%4]\n"
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__futex_atomic_ex_table("%5")
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: "+r" (ret), "=&r" (val)
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: "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
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: "cc", "memory");
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*uval = val;
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return ret;
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}
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#endif /* !SMP */
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static inline int
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futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
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{
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@ -87,39 +163,6 @@ futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
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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;
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u32 val;
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if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
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return -EFAULT;
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__asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
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"1: " T(ldr) " %1, [%4]\n"
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" teq %1, %2\n"
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" it eq @ explicit IT needed for the 2b label\n"
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"2: " T(streq) " %3, [%4]\n"
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"3:\n"
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" .pushsection __ex_table,\"a\"\n"
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" .align 3\n"
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" .long 1b, 4f, 2b, 4f\n"
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" .popsection\n"
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" .pushsection .fixup,\"ax\"\n"
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"4: mov %0, %5\n"
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" b 3b\n"
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" .popsection"
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: "+r" (ret), "=&r" (val)
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: "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
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: "cc", "memory");
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*uval = val;
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return ret;
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}
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#endif /* !SMP */
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#endif /* !(CPU_USE_DOMAINS && SMP) */
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#endif /* __KERNEL__ */
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#endif /* _ASM_ARM_FUTEX_H */
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