50d504cfdd
This narrows to what the `internal/platform` package supports, which is currently bound by Go SDK source that include `Mprotect` or windows. Ex. `zsyscall_linux_amd64.go` includes `Mprotect`, but `zsyscall_freebsd_amd64.go` does not. This should prevent errors like below, by allowing `wazero.NewRuntime()` to properly fallback to the interpreter. ``` .../mmap.go:74:16: undefined: syscall.Mprotect ``` A later change will implement FreeBSD. This is just here to ensure users don't crash on unexpected OS. See #607 Signed-off-by: Adrian Cole <adrian@tetrate.io>
57 lines
1.7 KiB
Go
57 lines
1.7 KiB
Go
// This uses syscall.Mprotect. Go's SDK only supports this on darwin and linux.
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//go:build darwin || linux
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package platform
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import "syscall"
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func munmapCodeSegment(code []byte) error {
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return syscall.Munmap(code)
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}
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// mmapCodeSegmentAMD64 gives all read-write-exec permission to the mmap region
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// to enter the function. Otherwise, segmentation fault exception is raised.
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func mmapCodeSegmentAMD64(code []byte) ([]byte, error) {
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mmapFunc, err := syscall.Mmap(
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-1,
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0,
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len(code),
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// The region must be RWX: RW for writing native codes, X for executing the region.
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syscall.PROT_READ|syscall.PROT_WRITE|syscall.PROT_EXEC,
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// Anonymous as this is not an actual file, but a memory,
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// Private as this is in-process memory region.
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syscall.MAP_ANON|syscall.MAP_PRIVATE,
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)
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if err != nil {
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return nil, err
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}
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copy(mmapFunc, code)
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return mmapFunc, nil
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}
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// mmapCodeSegmentARM64 cannot give all read-write-exec permission to the mmap region.
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// Otherwise, the mmap systemcall would raise an error. Here we give read-write
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// to the region at first, write the native code and then change the perm to
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// read-exec so we can execute the native code.
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func mmapCodeSegmentARM64(code []byte) ([]byte, error) {
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mmapFunc, err := syscall.Mmap(
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-1,
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0,
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len(code),
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// The region must be RW: RW for writing native codes.
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syscall.PROT_READ|syscall.PROT_WRITE,
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// Anonymous as this is not an actual file, but a memory,
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// Private as this is in-process memory region.
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syscall.MAP_ANON|syscall.MAP_PRIVATE,
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)
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if err != nil {
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return nil, err
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}
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copy(mmapFunc, code)
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// Then we're done with writing code, change the permission to RX.
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err = syscall.Mprotect(mmapFunc, syscall.PROT_READ|syscall.PROT_EXEC)
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return mmapFunc, err
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}
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