54 lines
1.3 KiB
Go
54 lines
1.3 KiB
Go
// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
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// SPDX-License-Identifier: BSD-3-Clause
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//go:build riscv64
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package verify
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import (
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"encoding/binary"
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"fmt"
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"reflect"
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"syscall"
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"unsafe"
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)
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//go:nosplit
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func enterJIT(fn uintptr, stack uintptr)
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//go:nosplit
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func leaveJIT()
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var leaveJITAddr uintptr
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func init() {
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leaveJITAddr = reflect.ValueOf(leaveJIT).Pointer()
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}
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const stackPad = 64
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// Call invokes the assembled function at fnAddr with the given ABI0 argument block.
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//
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// Not safe for concurrent use: only one JIT call may be in flight at a
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// time, the trampolines keep the saved registers in package globals.
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func Call(fnAddr uintptr, args []byte) ([]byte, error) {
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stackSize := stackPad + 8 + len(args) + 64
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stackMem, err := syscall.Mmap(-1, 0, stackSize,
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syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_PRIVATE|syscall.MAP_ANON)
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if err != nil {
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return nil, fmt.Errorf("verify: stack mmap: %w", err)
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}
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defer syscall.Munmap(stackMem)
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retOff := stackPad
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binary.LittleEndian.PutUint64(stackMem[retOff:retOff+8], uint64(leaveJITAddr))
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copy(stackMem[retOff+8:], args)
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stackBase := uintptr(unsafe.Pointer(&stackMem[retOff]))
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enterJIT(fnAddr, stackBase)
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out := make([]byte, len(args))
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copy(out, stackMem[retOff+8:retOff+8+len(args)])
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return out, nil
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}
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