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https://github.com/edk2-porting/linux-next.git
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0ea366f5e1
The cost of changing a cacheline from shared to exclusive state can be significant, especially when this is triggered by an exclusive store, since it may result in having to retry the transaction. This patch makes use of prfm to prefetch cachelines for write prior to ldxr/stxr loops when using the ll/sc atomic routines. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
77 lines
1.9 KiB
ArmAsm
77 lines
1.9 KiB
ArmAsm
/*
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* Based on arch/arm/lib/bitops.h
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*
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* Copyright (C) 2013 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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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/lse.h>
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/*
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* x0: bits 5:0 bit offset
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* bits 31:6 word offset
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* x1: address
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*/
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.macro bitop, name, llsc, lse
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ENTRY( \name )
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and w3, w0, #63 // Get bit offset
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eor w0, w0, w3 // Clear low bits
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mov x2, #1
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add x1, x1, x0, lsr #3 // Get word offset
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alt_lse " prfm pstl1strm, [x1]", "nop"
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lsl x3, x2, x3 // Create mask
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alt_lse "1: ldxr x2, [x1]", "\lse x3, [x1]"
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alt_lse " \llsc x2, x2, x3", "nop"
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alt_lse " stxr w0, x2, [x1]", "nop"
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alt_lse " cbnz w0, 1b", "nop"
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ret
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ENDPROC(\name )
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.endm
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.macro testop, name, llsc, lse
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ENTRY( \name )
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and w3, w0, #63 // Get bit offset
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eor w0, w0, w3 // Clear low bits
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mov x2, #1
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add x1, x1, x0, lsr #3 // Get word offset
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alt_lse " prfm pstl1strm, [x1]", "nop"
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lsl x4, x2, x3 // Create mask
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alt_lse "1: ldxr x2, [x1]", "\lse x4, x2, [x1]"
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lsr x0, x2, x3
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alt_lse " \llsc x2, x2, x4", "nop"
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alt_lse " stlxr w5, x2, [x1]", "nop"
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alt_lse " cbnz w5, 1b", "nop"
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alt_lse " dmb ish", "nop"
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and x0, x0, #1
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ret
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ENDPROC(\name )
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.endm
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/*
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* Atomic bit operations.
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*/
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bitop change_bit, eor, steor
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bitop clear_bit, bic, stclr
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bitop set_bit, orr, stset
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testop test_and_change_bit, eor, ldeoral
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testop test_and_clear_bit, bic, ldclral
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testop test_and_set_bit, orr, ldsetal
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