From 7b4df8f018ec01df3ecbd9961c769e7199853363 Mon Sep 17 00:00:00 2001 From: Russ Cox Date: Mon, 22 Dec 2014 22:50:42 -0500 Subject: runtime, sync/atomic: add write barrier for atomic write of pointer Add write barrier to atomic operations manipulating pointers. In general an atomic write of a pointer word may indicate racy accesses, so there is no strictly safe way to attempt to keep the shadow copy in sync with the real one. Instead, mark the shadow copy as not used. Redirect sync/atomic pointer routines back to the runtime ones, so that there is only one copy of the write barrier and shadow logic. In time we might consider doing this for most of the sync/atomic functions, but for now only the pointer routines need that treatment. Found with GODEBUG=wbshadow=1 mode. Eventually that will run automatically, but right now it still detects other missing write barriers. Change-Id: I852936b9a111a6cb9079cfaf6bd78b43016c0242 Reviewed-on: https://go-review.googlesource.com/2066 Reviewed-by: Rick Hudson Reviewed-by: Austin Clements --- src/sync/atomic/asm_386.s | 9 --------- src/sync/atomic/asm_amd64.s | 14 +------------- src/sync/atomic/asm_amd64p32.s | 14 +------------- src/sync/atomic/asm_freebsd_arm.s | 9 --------- src/sync/atomic/asm_linux_arm.s | 9 --------- src/sync/atomic/asm_nacl_arm.s | 9 --------- src/sync/atomic/asm_netbsd_arm.s | 9 --------- src/sync/atomic/asm_ppc64x.s | 9 --------- 8 files changed, 2 insertions(+), 80 deletions(-) (limited to 'src/sync') diff --git a/src/sync/atomic/asm_386.s b/src/sync/atomic/asm_386.s index 740dfe76ba..383d759ae7 100644 --- a/src/sync/atomic/asm_386.s +++ b/src/sync/atomic/asm_386.s @@ -50,9 +50,6 @@ swaploop: TEXT ·SwapUintptr(SB),NOSPLIT,$0-12 JMP ·SwapUint32(SB) -TEXT ·SwapPointer(SB),NOSPLIT,$0-12 - JMP ·SwapUint32(SB) - TEXT ·CompareAndSwapInt32(SB),NOSPLIT,$0-13 JMP ·CompareAndSwapUint32(SB) @@ -69,9 +66,6 @@ TEXT ·CompareAndSwapUint32(SB),NOSPLIT,$0-13 TEXT ·CompareAndSwapUintptr(SB),NOSPLIT,$0-13 JMP ·CompareAndSwapUint32(SB) -TEXT ·CompareAndSwapPointer(SB),NOSPLIT,$0-13 - JMP ·CompareAndSwapUint32(SB) - TEXT ·CompareAndSwapInt64(SB),NOSPLIT,$0-21 JMP ·CompareAndSwapUint64(SB) @@ -209,6 +203,3 @@ TEXT ·StoreUint64(SB),NOSPLIT,$0-12 TEXT ·StoreUintptr(SB),NOSPLIT,$0-8 JMP ·StoreUint32(SB) - -TEXT ·StorePointer(SB),NOSPLIT,$0-8 - JMP ·StoreUint32(SB) diff --git a/src/sync/atomic/asm_amd64.s b/src/sync/atomic/asm_amd64.s index 6e53ebedd2..551c002674 100644 --- a/src/sync/atomic/asm_amd64.s +++ b/src/sync/atomic/asm_amd64.s @@ -29,9 +29,6 @@ TEXT ·SwapUint64(SB),NOSPLIT,$0-24 TEXT ·SwapUintptr(SB),NOSPLIT,$0-24 JMP ·SwapUint64(SB) -TEXT ·SwapPointer(SB),NOSPLIT,$0-24 - JMP ·SwapUint64(SB) - TEXT ·CompareAndSwapInt32(SB),NOSPLIT,$0-17 JMP ·CompareAndSwapUint32(SB) @@ -47,9 +44,6 @@ TEXT ·CompareAndSwapUint32(SB),NOSPLIT,$0-17 TEXT ·CompareAndSwapUintptr(SB),NOSPLIT,$0-25 JMP ·CompareAndSwapUint64(SB) -TEXT ·CompareAndSwapPointer(SB),NOSPLIT,$0-25 - JMP ·CompareAndSwapUint64(SB) - TEXT ·CompareAndSwapInt64(SB),NOSPLIT,$0-25 JMP ·CompareAndSwapUint64(SB) @@ -137,10 +131,4 @@ TEXT ·StoreUint64(SB),NOSPLIT,$0-16 RET TEXT ·StoreUintptr(SB),NOSPLIT,$0-16 - JMP ·StorePointer(SB) - -TEXT ·StorePointer(SB),NOSPLIT,$0-16 - MOVQ addr+0(FP), BP - MOVQ val+8(FP), AX - XCHGQ AX, 0(BP) - RET + JMP ·StoreUint64(SB) diff --git a/src/sync/atomic/asm_amd64p32.s b/src/sync/atomic/asm_amd64p32.s index d77cc2c088..b4e19ee257 100644 --- a/src/sync/atomic/asm_amd64p32.s +++ b/src/sync/atomic/asm_amd64p32.s @@ -30,9 +30,6 @@ TEXT ·SwapUint64(SB),NOSPLIT,$0-24 TEXT ·SwapUintptr(SB),NOSPLIT,$0-12 JMP ·SwapUint32(SB) -TEXT ·SwapPointer(SB),NOSPLIT,$0-12 - JMP ·SwapUint32(SB) - TEXT ·CompareAndSwapInt32(SB),NOSPLIT,$0-17 JMP ·CompareAndSwapUint32(SB) @@ -48,9 +45,6 @@ TEXT ·CompareAndSwapUint32(SB),NOSPLIT,$0-17 TEXT ·CompareAndSwapUintptr(SB),NOSPLIT,$0-17 JMP ·CompareAndSwapUint32(SB) -TEXT ·CompareAndSwapPointer(SB),NOSPLIT,$0-17 - JMP ·CompareAndSwapUint32(SB) - TEXT ·CompareAndSwapInt64(SB),NOSPLIT,$0-25 JMP ·CompareAndSwapUint64(SB) @@ -150,10 +144,4 @@ TEXT ·StoreUint64(SB),NOSPLIT,$0-16 RET TEXT ·StoreUintptr(SB),NOSPLIT,$0-8 - JMP ·StorePointer(SB) - -TEXT ·StorePointer(SB),NOSPLIT,$0-8 - MOVL addr+0(FP), BX - MOVL val+4(FP), AX - XCHGL AX, 0(BX) - RET + JMP ·StoreUint32(SB) diff --git a/src/sync/atomic/asm_freebsd_arm.s b/src/sync/atomic/asm_freebsd_arm.s index 06b975e897..46710eab01 100644 --- a/src/sync/atomic/asm_freebsd_arm.s +++ b/src/sync/atomic/asm_freebsd_arm.s @@ -16,9 +16,6 @@ TEXT ·CompareAndSwapUint32(SB),NOSPLIT,$0 TEXT ·CompareAndSwapUintptr(SB),NOSPLIT,$0 B ·CompareAndSwapUint32(SB) -TEXT ·CompareAndSwapPointer(SB),NOSPLIT,$0 - B ·CompareAndSwapUint32(SB) - TEXT ·AddInt32(SB),NOSPLIT,$0 B ·AddUint32(SB) @@ -37,9 +34,6 @@ TEXT ·SwapUint32(SB),NOSPLIT,$0 TEXT ·SwapUintptr(SB),NOSPLIT,$0 B ·SwapUint32(SB) -TEXT ·SwapPointer(SB),NOSPLIT,$0 - B ·SwapUint32(SB) - TEXT ·CompareAndSwapInt64(SB),NOSPLIT,$0 B ·CompareAndSwapUint64(SB) @@ -104,6 +98,3 @@ TEXT ·StoreUint64(SB),NOSPLIT,$0 TEXT ·StoreUintptr(SB),NOSPLIT,$0 B ·StoreUint32(SB) - -TEXT ·StorePointer(SB),NOSPLIT,$0 - B ·StoreUint32(SB) diff --git a/src/sync/atomic/asm_linux_arm.s b/src/sync/atomic/asm_linux_arm.s index 944758441a..b388e4c550 100644 --- a/src/sync/atomic/asm_linux_arm.s +++ b/src/sync/atomic/asm_linux_arm.s @@ -57,9 +57,6 @@ cascheck: TEXT ·CompareAndSwapUintptr(SB),NOSPLIT,$0 B ·CompareAndSwapUint32(SB) -TEXT ·CompareAndSwapPointer(SB),NOSPLIT,$0 - B ·CompareAndSwapUint32(SB) - TEXT ·AddInt32(SB),NOSPLIT,$0 B ·AddUint32(SB) @@ -97,9 +94,6 @@ swaploop1: TEXT ·SwapUintptr(SB),NOSPLIT,$0 B ·SwapUint32(SB) -TEXT ·SwapPointer(SB),NOSPLIT,$0 - B ·SwapUint32(SB) - TEXT cas64<>(SB),NOSPLIT,$0 MOVW $0xffff0f60, PC // __kuser_cmpxchg64: Linux-3.1 and above @@ -211,6 +205,3 @@ TEXT ·StoreUint64(SB),NOSPLIT,$0 TEXT ·StoreUintptr(SB),NOSPLIT,$0 B ·StoreUint32(SB) - -TEXT ·StorePointer(SB),NOSPLIT,$0 - B ·StoreUint32(SB) diff --git a/src/sync/atomic/asm_nacl_arm.s b/src/sync/atomic/asm_nacl_arm.s index 76f6233364..8b4b6872a6 100644 --- a/src/sync/atomic/asm_nacl_arm.s +++ b/src/sync/atomic/asm_nacl_arm.s @@ -16,9 +16,6 @@ TEXT ·CompareAndSwapUint32(SB),NOSPLIT,$0 TEXT ·CompareAndSwapUintptr(SB),NOSPLIT,$0 B ·CompareAndSwapUint32(SB) -TEXT ·CompareAndSwapPointer(SB),NOSPLIT,$0 - B ·CompareAndSwapUint32(SB) - TEXT ·AddInt32(SB),NOSPLIT,$0 B ·AddUint32(SB) @@ -37,9 +34,6 @@ TEXT ·SwapUint32(SB),NOSPLIT,$0 TEXT ·SwapUintptr(SB),NOSPLIT,$0 B ·SwapUint32(SB) -TEXT ·SwapPointer(SB),NOSPLIT,$0 - B ·SwapUint32(SB) - TEXT ·CompareAndSwapInt64(SB),NOSPLIT,$0 B ·CompareAndSwapUint64(SB) @@ -104,6 +98,3 @@ TEXT ·StoreUint64(SB),NOSPLIT,$0 TEXT ·StoreUintptr(SB),NOSPLIT,$0 B ·StoreUint32(SB) - -TEXT ·StorePointer(SB),NOSPLIT,$0 - B ·StoreUint32(SB) diff --git a/src/sync/atomic/asm_netbsd_arm.s b/src/sync/atomic/asm_netbsd_arm.s index dbe80898fd..5c98de33c6 100644 --- a/src/sync/atomic/asm_netbsd_arm.s +++ b/src/sync/atomic/asm_netbsd_arm.s @@ -16,9 +16,6 @@ TEXT ·CompareAndSwapUint32(SB),NOSPLIT,$0 TEXT ·CompareAndSwapUintptr(SB),NOSPLIT,$0 B ·CompareAndSwapUint32(SB) -TEXT ·CompareAndSwapPointer(SB),NOSPLIT,$0 - B ·CompareAndSwapUint32(SB) - TEXT ·AddInt32(SB),NOSPLIT,$0 B ·AddUint32(SB) @@ -37,9 +34,6 @@ TEXT ·SwapUint32(SB),NOSPLIT,$0 TEXT ·SwapUintptr(SB),NOSPLIT,$0 B ·SwapUint32(SB) -TEXT ·SwapPointer(SB),NOSPLIT,$0 - B ·SwapUint32(SB) - TEXT ·CompareAndSwapInt64(SB),NOSPLIT,$0 B ·CompareAndSwapUint64(SB) @@ -104,6 +98,3 @@ TEXT ·StoreUint64(SB),NOSPLIT,$0 TEXT ·StoreUintptr(SB),NOSPLIT,$0 B ·StoreUint32(SB) - -TEXT ·StorePointer(SB),NOSPLIT,$0 - B ·StoreUint32(SB) diff --git a/src/sync/atomic/asm_ppc64x.s b/src/sync/atomic/asm_ppc64x.s index bcd46c5cff..00e1afb78f 100644 --- a/src/sync/atomic/asm_ppc64x.s +++ b/src/sync/atomic/asm_ppc64x.s @@ -39,9 +39,6 @@ TEXT ·SwapUint64(SB),NOSPLIT,$0-24 TEXT ·SwapUintptr(SB),NOSPLIT,$0-24 BR ·SwapUint64(SB) -TEXT ·SwapPointer(SB),NOSPLIT,$0-24 - BR ·SwapUint64(SB) - TEXT ·CompareAndSwapInt32(SB),NOSPLIT,$0-17 BR ·CompareAndSwapUint32(SB) @@ -66,9 +63,6 @@ TEXT ·CompareAndSwapUint32(SB),NOSPLIT,$0-17 TEXT ·CompareAndSwapUintptr(SB),NOSPLIT,$0-25 BR ·CompareAndSwapUint64(SB) -TEXT ·CompareAndSwapPointer(SB),NOSPLIT,$0-25 - BR ·CompareAndSwapUint64(SB) - TEXT ·CompareAndSwapInt64(SB),NOSPLIT,$0-25 BR ·CompareAndSwapUint64(SB) @@ -178,7 +172,4 @@ TEXT ·StoreUint64(SB),NOSPLIT,$0-16 RETURN TEXT ·StoreUintptr(SB),NOSPLIT,$0-16 - BR ·StorePointer(SB) - -TEXT ·StorePointer(SB),NOSPLIT,$0-16 BR ·StoreUint64(SB) -- cgit v1.3-5-g9baa