diff options
Diffstat (limited to 'src/runtime/internal')
| -rw-r--r-- | src/runtime/internal/syscall/asm_linux_amd64.s | 44 | ||||
| -rw-r--r-- | src/runtime/internal/syscall/syscall_linux.go | 27 |
2 files changed, 56 insertions, 15 deletions
diff --git a/src/runtime/internal/syscall/asm_linux_amd64.s b/src/runtime/internal/syscall/asm_linux_amd64.s index 961d9bd6402..3740ef1beb5 100644 --- a/src/runtime/internal/syscall/asm_linux_amd64.s +++ b/src/runtime/internal/syscall/asm_linux_amd64.s @@ -6,28 +6,42 @@ // func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr) // -// Syscall # in AX, args in DI SI DX R10 R8 R9, return in AX DX. +// We need to convert to the syscall ABI. +// +// arg | ABIInternal | Syscall +// --------------------------- +// num | AX | AX +// a1 | BX | DI +// a2 | CX | SI +// a3 | DI | DX +// a4 | SI | R10 +// a5 | R8 | R8 +// a6 | R9 | R9 +// +// r1 | AX | AX +// r2 | BX | DX +// err | CX | part of AX // // Note that this differs from "standard" ABI convention, which would pass 4th // arg in CX, not R10. -TEXT ·Syscall6(SB),NOSPLIT,$0-80 - MOVQ num+0(FP), AX // syscall entry - MOVQ a1+8(FP), DI - MOVQ a2+16(FP), SI - MOVQ a3+24(FP), DX - MOVQ a4+32(FP), R10 - MOVQ a5+40(FP), R8 - MOVQ a6+48(FP), R9 +TEXT ·Syscall6<ABIInternal>(SB),NOSPLIT,$0 + // a6 already in R9. + // a5 already in R8. + MOVQ SI, R10 // a4 + MOVQ DI, DX // a3 + MOVQ CX, SI // a2 + MOVQ BX, DI // a1 + // num already in AX. SYSCALL CMPQ AX, $0xfffffffffffff001 JLS ok - MOVQ $-1, r1+56(FP) - MOVQ $0, r2+64(FP) NEGQ AX - MOVQ AX, errno+72(FP) + MOVQ AX, CX // errno + MOVQ $-1, AX // r1 + MOVQ $0, BX // r2 RET ok: - MOVQ AX, r1+56(FP) - MOVQ DX, r2+64(FP) - MOVQ $0, errno+72(FP) + // r1 already in AX. + MOVQ DX, BX // r2 + MOVQ $0, CX // errno RET diff --git a/src/runtime/internal/syscall/syscall_linux.go b/src/runtime/internal/syscall/syscall_linux.go index 06d5f21e7c4..7f268e8fba1 100644 --- a/src/runtime/internal/syscall/syscall_linux.go +++ b/src/runtime/internal/syscall/syscall_linux.go @@ -5,8 +5,35 @@ // Package syscall provides the syscall primitives required for the runtime. package syscall +import ( + _ "unsafe" // for go:linkname +) + // TODO(https://go.dev/issue/51087): This package is incomplete and currently // only contains very minimal support for Linux. // Syscall6 calls system call number 'num' with arguments a1-6. func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr) + +// syscall_RawSyscall6 is a push linkname to export Syscall6 as +// syscall.RawSyscall6. +// +// //go:uintptrkeepalive because the uintptr argument may be converted pointers +// that need to be kept alive in the caller (this is implied for Syscall6 since +// it has no body). +// +// //go:nosplit because stack copying does not account for uintptrkeepalive, so +// the stack must not grow. Stack copying cannot blindly assume that all +// uintptr arguments are pointers, because some values may look like pointers, +// but not really be pointers, and adjusting their value would break the call. +// +// This is a separate wrapper because we can't export one function as two +// names. The assembly implementations name themselves Syscall6 would not be +// affected by a linkname. +// +//go:uintptrkeepalive +//go:nosplit +//go:linkname syscall_RawSyscall6 syscall.RawSyscall6 +func syscall_RawSyscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr) { + return Syscall6(num, a1, a2, a3, a4, a5, a6) +} |