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| author | Roland Shoemaker <roland@golang.org> | 2025-12-04 13:26:52 -0800 |
|---|---|---|
| committer | Roland Shoemaker <roland@golang.org> | 2025-12-05 10:22:34 -0800 |
| commit | 2244bd7eeb17cb3d361908d3a441ecfc2c4a82b5 (patch) | |
| tree | 6442e9a749e929668196e85fc13b1f21e9db50d0 | |
| parent | f84f8d86beb08631217e77d725a4b6528ed91dc2 (diff) | |
| download | go-2244bd7eeb17cb3d361908d3a441ecfc2c4a82b5.tar.xz | |
crypto/subtle: add speculation barrier after DIT
When enabling DIT on ARM64, add speculation barrier instructions to
ensure that subsequent instructions are executed using the updated
DIT state.
See https://developer.apple.com/documentation/xcode/writing-arm64-code-for-apple-platforms#Enable-DIT-for-constant-time-cryptographic-operations
which recommends doing this. The Arm documentation for DIT doesn't tell
you to do this, but it seems prudent.
Change-Id: Idbc87b332650a77b8cb3509c11377bf5c724f3cf
Reviewed-on: https://go-review.googlesource.com/c/go/+/726980
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
| -rw-r--r-- | src/internal/runtime/sys/dit_arm64.s | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/src/internal/runtime/sys/dit_arm64.s b/src/internal/runtime/sys/dit_arm64.s index c27dfc9af3..408b60c8c0 100644 --- a/src/internal/runtime/sys/dit_arm64.s +++ b/src/internal/runtime/sys/dit_arm64.s @@ -9,6 +9,11 @@ TEXT ·EnableDIT(SB),$0-1 UBFX $24, R0, $1, R1 MOVB R1, ret+0(FP) MSR $1, DIT + // TODO(roland): the SB instruction is significantly more + // performant when available. We should detect its availability + // and use it when we can. + DSB $7 // nsh + ISB $15 // sy RET TEXT ·DITEnabled(SB),$0-1 |