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| author |   Jason A. Donenfeld <Jason@zx2c4.com> | 2021-11-05 00:59:07 +0100 |
|---|---|---|
| committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2021-11-06 14:36:57 +0100 |
| commit | 6144b4844252806b36a76147677b14b234cb2ade (patch) | |
| tree | 3a64ceb1524a2d0aba8a278ce633b9a99e44d0a3 | |
| parent | go-patches: read nanotime in 1 instruction on 64bit (diff) | |
| download | wireguard-windows-6144b4844252806b36a76147677b14b234cb2ade.tar.xz wireguard-windows-6144b4844252806b36a76147677b14b234cb2ade.zip | |
go-patches: return correct nanosec param on arm64
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
| -rw-r--r-- | go-patches/0004-runtime-use-correct-constant-when-computing-nsec-rem.patch | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/go-patches/0004-runtime-use-correct-constant-when-computing-nsec-rem.patch b/go-patches/0004-runtime-use-correct-constant-when-computing-nsec-rem.patch new file mode 100644 index 00000000..4a826068 --- /dev/null +++ b/go-patches/0004-runtime-use-correct-constant-when-computing-nsec-rem.patch @@ -0,0 +1,81 @@ +From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 +From: "Jason A. Donenfeld" <Jason@zx2c4.com> +Date: Fri, 5 Nov 2021 00:10:31 +0100 +Subject: [PATCH] runtime: use correct constant when computing nsec remainder + +A code comment on amd64 for windows and plan9 contained a snippet for +splitting apart the sec and nsec components of a unix timestamp, with +produced assembly below, which was then cleaned up by hand. When arm64 +was ported, that code snippet in the comment went through the compiler +to produce some code that was then pasted and cleaned up. Unfortunately, +the comment had a typo in it, containing 8 zeros instead of 9. + +This resulted in the constant used in the assembly being wrong, spotted +by @bufflig's eagle eyes. So, this commit fixes the comment on all three +platforms, and the assembly on windows/arm64. + +Fixes #48072. + +Change-Id: I786fe89147328b0d25544f52c927ddfdb9f6f1cf +Reviewed-on: https://go-review.googlesource.com/c/go/+/361474 +Trust: Jason A. Donenfeld <Jason@zx2c4.com> +Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com> +Reviewed-by: Patrik Nyblom <pnyb@google.com> +TryBot-Result: Go Bot <gobot@golang.org> +--- + src/runtime/sys_plan9_amd64.s | 2 +- + src/runtime/time_windows_amd64.s | 2 +- + src/runtime/time_windows_arm64.s | 9 +++------ + 3 files changed, 5 insertions(+), 8 deletions(-) + +diff --git a/src/runtime/sys_plan9_amd64.s b/src/runtime/sys_plan9_amd64.s +index 731306ab44..068200b7f3 100644 +--- a/src/runtime/sys_plan9_amd64.s ++++ b/src/runtime/sys_plan9_amd64.s +@@ -94,7 +94,7 @@ TEXT runtime·walltime(SB),NOSPLIT,$8-12 + MOVQ 0(SP), AX + + // generated code for +- // func f(x uint64) (uint64, uint64) { return x/1000000000, x%100000000 } ++ // func f(x uint64) (uint64, uint64) { return x/1000000000, x%1000000000 } + // adapted to reduce duplication + MOVQ AX, CX + MOVQ $1360296554856532783, AX +diff --git a/src/runtime/time_windows_amd64.s b/src/runtime/time_windows_amd64.s +index 045f64eb46..70f6a008cd 100644 +--- a/src/runtime/time_windows_amd64.s ++++ b/src/runtime/time_windows_amd64.s +@@ -25,7 +25,7 @@ TEXT time·now(SB),NOSPLIT,$0-24 + IMULQ $100, AX + + // generated code for +- // func f(x uint64) (uint64, uint64) { return x/1000000000, x%100000000 } ++ // func f(x uint64) (uint64, uint64) { return x/1000000000, x%1000000000 } + // adapted to reduce duplication + MOVQ AX, CX + MOVQ $1360296554856532783, AX +diff --git a/src/runtime/time_windows_arm64.s b/src/runtime/time_windows_arm64.s +index e8a0eb2f93..ef5b848473 100644 +--- a/src/runtime/time_windows_arm64.s ++++ b/src/runtime/time_windows_arm64.s +@@ -32,17 +32,14 @@ TEXT time·now(SB),NOSPLIT|NOFRAME,$0-24 + // Code stolen from compiler output for: + // + // var x uint64 +- // func f() (sec uint64, nsec uint32) { return x / 1000000000, uint32(x % 100000000) } ++ // func f() (sec uint64, nsec uint32) { return x / 1000000000, uint32(x % 1000000000) } + // + LSR $1, R0, R1 + MOVD $-8543223759426509416, R2 +- UMULH R2, R1, R1 ++ UMULH R1, R2, R1 + LSR $28, R1, R1 + MOVD R1, sec+0(FP) +- MOVD $-6067343680855748867, R1 +- UMULH R0, R1, R1 +- LSR $26, R1, R1 +- MOVD $100000000, R2 ++ MOVD $1000000000, R2 + MSUB R1, R0, R2, R0 + MOVW R0, nsec+8(FP) + RET |