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96 lines
2.3 KiB
Go
96 lines
2.3 KiB
Go
package frame
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import (
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"encoding/binary"
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"fmt"
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"sort"
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)
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// Represents a Common Information Entry in
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// the Dwarf .debug_frame section.
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type CommonInformationEntry struct {
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Length uint32
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CIE_id uint32
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Version uint8
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Augmentation string
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CodeAlignmentFactor uint64
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DataAlignmentFactor int64
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ReturnAddressRegister uint64
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InitialInstructions []byte
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}
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// Represents a Frame Descriptor Entry in the
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// Dwarf .debug_frame section.
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type FrameDescriptionEntry struct {
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Length uint32
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CIE *CommonInformationEntry
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Instructions []byte
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begin, end uint64
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order binary.ByteOrder
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}
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// Returns whether or not the given address is within the
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// bounds of this frame.
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func (fde *FrameDescriptionEntry) Cover(addr uint64) bool {
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if (addr - fde.begin) < fde.end {
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return true
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}
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return false
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}
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// Address of first location for this frame.
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func (fde *FrameDescriptionEntry) Begin() uint64 {
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return fde.begin
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}
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// Address of last location for this frame.
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func (fde *FrameDescriptionEntry) End() uint64 {
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return fde.begin + fde.end
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}
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// Set up frame for the given PC.
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func (fde *FrameDescriptionEntry) EstablishFrame(pc uint64) *FrameContext {
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return executeDwarfProgramUntilPC(fde, pc)
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}
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// Return the offset from the current SP that the return address is stored at.
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func (fde *FrameDescriptionEntry) ReturnAddressOffset(pc uint64) (frameOffset, returnAddressOffset int64) {
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frame := fde.EstablishFrame(pc)
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return frame.cfa.offset, frame.regs[fde.CIE.ReturnAddressRegister].offset
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}
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type FrameDescriptionEntries []*FrameDescriptionEntry
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func NewFrameIndex() FrameDescriptionEntries {
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return make(FrameDescriptionEntries, 0, 1000)
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}
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type NoFDEForPCError struct {
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PC uint64
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}
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func (err *NoFDEForPCError) Error() string {
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return fmt.Sprintf("could not find FDE for PC %#v", err.PC)
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}
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// Returns the Frame Description Entry for the given PC.
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func (fdes FrameDescriptionEntries) FDEForPC(pc uint64) (*FrameDescriptionEntry, error) {
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idx := sort.Search(len(fdes), func(i int) bool {
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if fdes[i].Cover(pc) {
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return true
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}
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if fdes[i].LessThan(pc) {
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return false
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}
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return true
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})
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if idx == len(fdes) {
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return nil, &NoFDEForPCError{pc}
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}
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return fdes[idx], nil
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}
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func (frame *FrameDescriptionEntry) LessThan(pc uint64) bool {
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return frame.End() <= pc
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}
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