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022620eed3
Provide an optimised, assembly implementation of array_index_mask_nospec() for arm64 so that the compiler is not in a position to transform the code in ways which affect its ability to inhibit speculation (e.g. by introducing conditional branches). This is similar to the sequence used by x86, modulo architectural differences in the carry/borrow flags. Reviewed-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
149 lines
3.8 KiB
C
149 lines
3.8 KiB
C
/*
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* Based on arch/arm/include/asm/barrier.h
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*
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* Copyright (C) 2012 ARM Ltd.
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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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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __ASM_BARRIER_H
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#define __ASM_BARRIER_H
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#ifndef __ASSEMBLY__
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#define __nops(n) ".rept " #n "\nnop\n.endr\n"
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#define nops(n) asm volatile(__nops(n))
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#define sev() asm volatile("sev" : : : "memory")
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#define wfe() asm volatile("wfe" : : : "memory")
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#define wfi() asm volatile("wfi" : : : "memory")
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#define isb() asm volatile("isb" : : : "memory")
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#define dmb(opt) asm volatile("dmb " #opt : : : "memory")
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#define dsb(opt) asm volatile("dsb " #opt : : : "memory")
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#define psb_csync() asm volatile("hint #17" : : : "memory")
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#define csdb() asm volatile("hint #20" : : : "memory")
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#define mb() dsb(sy)
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#define rmb() dsb(ld)
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#define wmb() dsb(st)
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#define dma_rmb() dmb(oshld)
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#define dma_wmb() dmb(oshst)
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/*
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* Generate a mask for array_index__nospec() that is ~0UL when 0 <= idx < sz
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* and 0 otherwise.
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*/
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#define array_index_mask_nospec array_index_mask_nospec
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static inline unsigned long array_index_mask_nospec(unsigned long idx,
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unsigned long sz)
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{
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unsigned long mask;
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asm volatile(
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" cmp %1, %2\n"
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" sbc %0, xzr, xzr\n"
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: "=r" (mask)
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: "r" (idx), "Ir" (sz)
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: "cc");
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csdb();
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return mask;
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}
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#define __smp_mb() dmb(ish)
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#define __smp_rmb() dmb(ishld)
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#define __smp_wmb() dmb(ishst)
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#define __smp_store_release(p, v) \
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do { \
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union { typeof(*p) __val; char __c[1]; } __u = \
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{ .__val = (__force typeof(*p)) (v) }; \
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compiletime_assert_atomic_type(*p); \
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switch (sizeof(*p)) { \
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case 1: \
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asm volatile ("stlrb %w1, %0" \
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: "=Q" (*p) \
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: "r" (*(__u8 *)__u.__c) \
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: "memory"); \
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break; \
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case 2: \
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asm volatile ("stlrh %w1, %0" \
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: "=Q" (*p) \
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: "r" (*(__u16 *)__u.__c) \
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: "memory"); \
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break; \
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case 4: \
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asm volatile ("stlr %w1, %0" \
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: "=Q" (*p) \
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: "r" (*(__u32 *)__u.__c) \
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: "memory"); \
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break; \
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case 8: \
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asm volatile ("stlr %1, %0" \
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: "=Q" (*p) \
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: "r" (*(__u64 *)__u.__c) \
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: "memory"); \
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break; \
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} \
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} while (0)
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#define __smp_load_acquire(p) \
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({ \
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union { typeof(*p) __val; char __c[1]; } __u; \
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compiletime_assert_atomic_type(*p); \
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switch (sizeof(*p)) { \
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case 1: \
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asm volatile ("ldarb %w0, %1" \
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: "=r" (*(__u8 *)__u.__c) \
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: "Q" (*p) : "memory"); \
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break; \
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case 2: \
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asm volatile ("ldarh %w0, %1" \
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: "=r" (*(__u16 *)__u.__c) \
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: "Q" (*p) : "memory"); \
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break; \
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case 4: \
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asm volatile ("ldar %w0, %1" \
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: "=r" (*(__u32 *)__u.__c) \
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: "Q" (*p) : "memory"); \
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break; \
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case 8: \
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asm volatile ("ldar %0, %1" \
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: "=r" (*(__u64 *)__u.__c) \
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: "Q" (*p) : "memory"); \
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break; \
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} \
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__u.__val; \
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})
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#define smp_cond_load_acquire(ptr, cond_expr) \
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({ \
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typeof(ptr) __PTR = (ptr); \
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typeof(*ptr) VAL; \
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for (;;) { \
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VAL = smp_load_acquire(__PTR); \
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if (cond_expr) \
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break; \
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__cmpwait_relaxed(__PTR, VAL); \
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} \
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VAL; \
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})
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#include <asm-generic/barrier.h>
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#endif /* __ASSEMBLY__ */
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#endif /* __ASM_BARRIER_H */
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