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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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f7c34874f0
Implement atomic primitives using exclusive access opcodes available in the recent xtensa cores. Since l32ex/s32ex don't have any memory ordering guarantees don't define __smp_mb__before_atomic/__smp_mb__after_atomic to make them use memw. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
168 lines
3.9 KiB
C
168 lines
3.9 KiB
C
/*
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* Atomic futex routines
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*
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* Based on the PowerPC implementataion
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Copyright (C) 2013 TangoTec Ltd.
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*
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* Baruch Siach <baruch@tkos.co.il>
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*/
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#ifndef _ASM_XTENSA_FUTEX_H
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#define _ASM_XTENSA_FUTEX_H
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#include <linux/futex.h>
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#include <linux/uaccess.h>
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#include <linux/errno.h>
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#if XCHAL_HAVE_EXCLUSIVE
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#define __futex_atomic_op(insn, ret, old, uaddr, arg) \
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__asm__ __volatile( \
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"1: l32ex %[oldval], %[addr]\n" \
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insn "\n" \
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"2: s32ex %[newval], %[addr]\n" \
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" getex %[newval]\n" \
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" beqz %[newval], 1b\n" \
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" movi %[newval], 0\n" \
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"3:\n" \
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" .section .fixup,\"ax\"\n" \
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" .align 4\n" \
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" .literal_position\n" \
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"5: movi %[oldval], 3b\n" \
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" movi %[newval], %[fault]\n" \
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" jx %[oldval]\n" \
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" .previous\n" \
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" .section __ex_table,\"a\"\n" \
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" .long 1b, 5b, 2b, 5b\n" \
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" .previous\n" \
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: [oldval] "=&r" (old), [newval] "=&r" (ret) \
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: [addr] "r" (uaddr), [oparg] "r" (arg), \
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[fault] "I" (-EFAULT) \
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: "memory")
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#elif XCHAL_HAVE_S32C1I
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#define __futex_atomic_op(insn, ret, old, uaddr, arg) \
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__asm__ __volatile( \
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"1: l32i %[oldval], %[addr], 0\n" \
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insn "\n" \
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" wsr %[oldval], scompare1\n" \
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"2: s32c1i %[newval], %[addr], 0\n" \
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" bne %[newval], %[oldval], 1b\n" \
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" movi %[newval], 0\n" \
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"3:\n" \
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" .section .fixup,\"ax\"\n" \
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" .align 4\n" \
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" .literal_position\n" \
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"5: movi %[oldval], 3b\n" \
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" movi %[newval], %[fault]\n" \
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" jx %[oldval]\n" \
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" .previous\n" \
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" .section __ex_table,\"a\"\n" \
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" .long 1b, 5b, 2b, 5b\n" \
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" .previous\n" \
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: [oldval] "=&r" (old), [newval] "=&r" (ret) \
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: [addr] "r" (uaddr), [oparg] "r" (arg), \
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[fault] "I" (-EFAULT) \
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: "memory")
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#endif
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static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
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u32 __user *uaddr)
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{
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#if XCHAL_HAVE_S32C1I || XCHAL_HAVE_EXCLUSIVE
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int oldval = 0, ret;
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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 %[newval], %[oparg]",
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ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_ADD:
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__futex_atomic_op("add %[newval], %[oldval], %[oparg]",
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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 %[newval], %[oldval], %[oparg]",
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ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_ANDN:
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__futex_atomic_op("and %[newval], %[oldval], %[oparg]",
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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 %[newval], %[oldval], %[oparg]",
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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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*oval = oldval;
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return ret;
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#else
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return -ENOSYS;
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#endif
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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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#if XCHAL_HAVE_S32C1I || XCHAL_HAVE_EXCLUSIVE
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unsigned long tmp;
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int ret = 0;
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if (!access_ok(uaddr, sizeof(u32)))
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return -EFAULT;
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__asm__ __volatile__ (
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" # futex_atomic_cmpxchg_inatomic\n"
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#if XCHAL_HAVE_EXCLUSIVE
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"1: l32ex %[tmp], %[addr]\n"
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" s32i %[tmp], %[uval], 0\n"
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" bne %[tmp], %[oldval], 2f\n"
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" mov %[tmp], %[newval]\n"
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"3: s32ex %[tmp], %[addr]\n"
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" getex %[tmp]\n"
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" beqz %[tmp], 1b\n"
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#elif XCHAL_HAVE_S32C1I
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" wsr %[oldval], scompare1\n"
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"1: s32c1i %[newval], %[addr], 0\n"
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" s32i %[newval], %[uval], 0\n"
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#endif
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"2:\n"
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" .section .fixup,\"ax\"\n"
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" .align 4\n"
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" .literal_position\n"
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"4: movi %[tmp], 2b\n"
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" movi %[ret], %[fault]\n"
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" jx %[tmp]\n"
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" .previous\n"
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" .section __ex_table,\"a\"\n"
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" .long 1b, 4b\n"
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#if XCHAL_HAVE_EXCLUSIVE
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" .long 3b, 4b\n"
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#endif
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" .previous\n"
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: [ret] "+r" (ret), [newval] "+r" (newval), [tmp] "=&r" (tmp)
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: [addr] "r" (uaddr), [oldval] "r" (oldval), [uval] "r" (uval),
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[fault] "I" (-EFAULT)
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: "memory");
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return ret;
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#else
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return -ENOSYS;
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#endif
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}
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#endif /* _ASM_XTENSA_FUTEX_H */
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