diff options
Diffstat (limited to 'pkg/ring0/lib_amd64.s')
| -rw-r--r-- | pkg/ring0/lib_amd64.s | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/pkg/ring0/lib_amd64.s b/pkg/ring0/lib_amd64.s index 70a43e79e..8ed98fc84 100644 --- a/pkg/ring0/lib_amd64.s +++ b/pkg/ring0/lib_amd64.s @@ -80,6 +80,29 @@ TEXT ·xsaveopt(SB),NOSPLIT,$0-8 BYTE $0x48; BYTE $0x0f; BYTE $0xae; BYTE $0x37; RET +// writeFS writes to the FS base. +// +// This is written in assembly because it must be safe to call before the Go +// environment is set up. See comment on start(). +// +// Preconditions: must be running in the lower address space, as it accesses +// global data. +TEXT ·writeFS(SB),NOSPLIT,$8-8 + MOVQ addr+0(FP), AX + + CMPB ·hasFSGSBASE(SB), $1 + JNE msr + + PUSHQ AX + CALL ·wrfsbase(SB) + POPQ AX + RET +msr: + PUSHQ AX + CALL ·wrfsmsr(SB) + POPQ AX + RET + // wrfsbase writes to the FS base. // // The code corresponds to: |