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Diffstat (limited to 'src/pkg/sync/atomic/asm_arm.s')
| -rw-r--r-- | src/pkg/sync/atomic/asm_arm.s | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/src/pkg/sync/atomic/asm_arm.s b/src/pkg/sync/atomic/asm_arm.s new file mode 100644 index 000000000..95e2f5be4 --- /dev/null +++ b/src/pkg/sync/atomic/asm_arm.s @@ -0,0 +1,122 @@ +// Copyright 2011 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// ARM atomic operations, for use by asm_$(GOOS)_arm.s. + +TEXT ·armCompareAndSwapUint32(SB),7,$0 + MOVW valptr+0(FP), R1 + MOVW old+4(FP), R2 + MOVW new+8(FP), R3 +casloop: + // LDREX and STREX were introduced in ARM 6. + LDREX (R1), R0 + CMP R0, R2 + BNE casfail + STREX R3, (R1), R0 + CMP $0, R0 + BNE casloop + MOVW $1, R0 + MOVBU R0, ret+12(FP) + RET +casfail: + MOVW $0, R0 + MOVBU R0, ret+12(FP) + RET + +TEXT ·armCompareAndSwapUint64(SB),7,$0 + BL fastCheck64<>(SB) + MOVW valptr+0(FP), R1 + MOVW oldlo+4(FP), R2 + MOVW oldhi+8(FP), R3 + MOVW newlo+12(FP), R4 + MOVW newhi+16(FP), R5 +cas64loop: + // LDREXD and STREXD were introduced in ARM 11. + LDREXD (R1), R6 // loads R6 and R7 + CMP R2, R6 + BNE cas64fail + CMP R3, R7 + BNE cas64fail + STREXD R4, (R1), R0 // stores R4 and R5 + CMP $0, R0 + BNE cas64loop + MOVW $1, R0 + MOVBU R0, ret+20(FP) + RET +cas64fail: + MOVW $0, R0 + MOVBU R0, ret+20(FP) + RET + +TEXT ·armAddUint32(SB),7,$0 + MOVW valptr+0(FP), R1 + MOVW delta+4(FP), R2 +addloop: + // LDREX and STREX were introduced in ARM 6. + LDREX (R1), R3 + ADD R2, R3 + STREX R3, (R1), R0 + CMP $0, R0 + BNE addloop + MOVW R3, ret+8(FP) + RET + +TEXT ·armAddUint64(SB),7,$0 + BL fastCheck64<>(SB) + MOVW valptr+0(FP), R1 + MOVW deltalo+4(FP), R2 + MOVW deltahi+8(FP), R3 +add64loop: + // LDREXD and STREXD were introduced in ARM 11. + LDREXD (R1), R4 // loads R4 and R5 + ADD.S R2, R4 + ADC R3, R5 + STREXD R4, (R1), R0 // stores R4 and R5 + CMP $0, R0 + BNE add64loop + MOVW R4, retlo+12(FP) + MOVW R5, rethi+16(FP) + RET + +// Check for broken 64-bit LDREXD as found in QEMU. +// LDREXD followed by immediate STREXD should succeed. +// If it fails, try a few times just to be sure (maybe our thread got +// rescheduled between the two instructions) and then panic. +// A bug in some copies of QEMU makes STREXD never succeed, +// which will make uses of the 64-bit atomic operations loop forever. +// If things are working, set okLDREXD to avoid future checks. +// https://bugs.launchpad.net/qemu/+bug/670883. +TEXT check64<>(SB),7,$16 + MOVW $10, R1 + // 8-aligned stack address scratch space. + MOVW $8(R13), R5 + AND $~7, R5 +loop: + LDREXD (R5), R2 + STREXD R2, (R5), R0 + CMP $0, R0 + BEQ ok + SUB $1, R1 + CMP $0, R1 + BNE loop + // Must be buggy QEMU. + BL ·panic64(SB) +ok: + RET + +// Fast, cached version of check. No frame, just MOVW CMP RET after first time. +TEXT fastCheck64<>(SB),7,$-4 + MOVW ok64<>(SB), R0 + CMP $0, R0 // have we been here before? + RET.NE + B slowCheck64<>(SB) + +TEXT slowCheck64<>(SB),7,$0 + BL check64<>(SB) + // Still here, must be okay. + MOVW $1, R0 + MOVW R0, ok64<>(SB) + RET + +GLOBL ok64<>(SB), $4 |