130 lines
3.6 KiB
Go
130 lines
3.6 KiB
Go
package amd64
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import (
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"encoding/binary"
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"reflect"
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"unsafe"
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"github.com/tetratelabs/wazero/internal/wasmdebug"
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)
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func stackView(rbp, top uintptr) []byte {
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l := int(top - rbp)
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var stackBuf []byte
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{
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hdr := (*reflect.SliceHeader)(unsafe.Pointer(&stackBuf))
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hdr.Data = rbp
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hdr.Len = l
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hdr.Cap = l
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}
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return stackBuf
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}
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// UnwindStack implements wazevo.unwindStack.
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func UnwindStack(_, rbp, top uintptr, returnAddresses []uintptr) []uintptr {
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stackBuf := stackView(rbp, top)
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for i := uint64(0); i < uint64(len(stackBuf)); {
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// (high address)
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// +-----------------+
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// | ....... |
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// | ret Y |
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// | ....... |
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// | ret 0 |
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// | arg X |
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// | ....... |
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// | arg 1 |
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// | arg 0 |
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// | ReturnAddress |
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// | Caller_RBP |
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// +-----------------+ <---- Caller_RBP
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// | ........... |
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// | clobbered M |
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// | ............ |
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// | clobbered 0 |
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// | spill slot N |
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// | ............ |
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// | spill slot 0 |
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// | ReturnAddress |
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// | Caller_RBP |
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// +-----------------+ <---- RBP
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// (low address)
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callerRBP := binary.LittleEndian.Uint64(stackBuf[i:])
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retAddr := binary.LittleEndian.Uint64(stackBuf[i+8:])
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returnAddresses = append(returnAddresses, uintptr(retAddr))
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i = callerRBP - uint64(rbp)
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if len(returnAddresses) == wasmdebug.MaxFrames {
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break
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}
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}
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return returnAddresses
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}
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// GoCallStackView implements wazevo.goCallStackView.
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func GoCallStackView(stackPointerBeforeGoCall *uint64) []uint64 {
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// (high address)
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// +-----------------+ <----+
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// | xxxxxxxxxxx | | ;; optional unused space to make it 16-byte aligned.
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// ^ | arg[N]/ret[M] | |
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// sliceSize | | ............ | | SizeInBytes/8
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// | | arg[1]/ret[1] | |
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// v | arg[0]/ret[0] | <----+
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// | SizeInBytes |
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// +-----------------+ <---- stackPointerBeforeGoCall
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// (low address)
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data := unsafe.Add(unsafe.Pointer(stackPointerBeforeGoCall), 8)
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size := *stackPointerBeforeGoCall / 8
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return unsafe.Slice((*uint64)(data), int(size))
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}
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func AdjustClonedStack(oldRsp, oldTop, rsp, rbp, top uintptr) {
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diff := uint64(rsp - oldRsp)
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newBuf := stackView(rbp, top)
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for i := uint64(0); i < uint64(len(newBuf)); {
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// (high address)
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// +-----------------+
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// | ....... |
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// | ret Y |
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// | ....... |
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// | ret 0 |
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// | arg X |
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// | ....... |
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// | arg 1 |
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// | arg 0 |
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// | ReturnAddress |
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// | Caller_RBP |
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// +-----------------+ <---- Caller_RBP
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// | ........... |
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// | clobbered M |
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// | ............ |
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// | clobbered 0 |
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// | spill slot N |
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// | ............ |
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// | spill slot 0 |
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// | ReturnAddress |
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// | Caller_RBP |
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// +-----------------+ <---- RBP
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// (low address)
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callerRBP := binary.LittleEndian.Uint64(newBuf[i:])
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if callerRBP == 0 {
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// End of stack.
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break
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}
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if i64 := int64(callerRBP); i64 < int64(oldRsp) || i64 >= int64(oldTop) {
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panic("BUG: callerRBP is out of range")
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}
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if int(callerRBP) < 0 {
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panic("BUG: callerRBP is negative")
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}
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adjustedCallerRBP := callerRBP + diff
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if int(adjustedCallerRBP) < 0 {
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panic("BUG: adjustedCallerRBP is negative")
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}
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binary.LittleEndian.PutUint64(newBuf[i:], adjustedCallerRBP)
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i = adjustedCallerRBP - uint64(rbp)
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}
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}
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