PenaDevops/delve
2
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

dwarf/frame: discard indirect flag reading personality func in eh_frame (#3032)

Browse Source 
We don't do anything with the personality function so there is no point
in complaining that we don't fully support the pointer encoding flags
used to describe it.

This matches the current level of support of pointer encodings in gdb
(they are discarded when reading the personality function and not
supported for FDEs because gcc doesn't generate them).

Fixes #3015
This commit is contained in:
Alessandro Arzilli 2022-06-24 15:49:18 +02:00 committed by GitHub
parent 76ecc53293
commit 2d09ea65bc
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 11 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
pkg/dwarf/frame/entries.go
View File

@ -108,8 +108,8 @@ func (fdes FrameDescriptionEntries) Append(otherFDEs FrameDescriptionEntries) Fr
// ptrEnc represents a pointer encoding value, used during eh_frame decoding
// to determine how pointers were encoded.
// Least significant 4 (0xf) bytes encode the size as well as its
// signed-ness, most significant 4 bytes (0xf0) are flags describing how
// the value should be interpreted (absolute, relative...)
// signed-ness, most significant 4 bytes (0xf0 == ptrEncFlagsMask) are flags
// describing how the value should be interpreted (absolute, relative...)
// See https://www.airs.com/blog/archives/460.
type ptrEnc uint8
@ -126,12 +126,16 @@ const (
ptrEncSdata4 ptrEnc = 0x0b // 4 bytes, signed
ptrEncSdata8 ptrEnc = 0x0c // 8 bytes, signed
ptrEncFlagsMask ptrEnc = 0xf0
ptrEncPCRel ptrEnc = 0x10 // value is relative to the memory address where it appears
ptrEncTextRel ptrEnc = 0x20 // value is relative to the address of the text section
ptrEncDataRel ptrEnc = 0x30 // value is relative to the address of the data section
ptrEncFuncRel ptrEnc = 0x40 // value is relative to the start of the function
ptrEncAligned ptrEnc = 0x50 // value should be aligned
ptrEncIndirect ptrEnc = 0x80 // value is an address where the real value of the pointer is stored
ptrEncSupportedFlags = ptrEncPCRel
)
// Supported returns true if this pointer encoding is supported.
@ -142,7 +146,7 @@ func (ptrEnc ptrEnc) Supported() bool {
// These values aren't defined at the moment
return false
}
if ptrEnc&0xf0 != ptrEncPCRel {
if (ptrEnc&ptrEncFlagsMask)&^ptrEncSupportedFlags != 0 {
// Currently only the PC relative flag is supported
return false
}

7
pkg/dwarf/frame/parser.go
View File

@ -201,12 +201,13 @@ func parseCIE(ctx *parseContext) parsefunc {
// the pointer to the personality function encoded as specified by the
// pointer encoding.
// We don't support this but have to read it anyway.
e, _ := buf.ReadByte()
if !ptrEnc(e).Supported() {
b, _ := buf.ReadByte()
e := ptrEnc(b) &^ ptrEncIndirect
if !e.Supported() {
ctx.err = fmt.Errorf("pointer encoding not supported %#x at %#x", e, ctx.offset())
return nil
}
ctx.readEncodedPtr(0, buf, ptrEnc(e))
ctx.readEncodedPtr(0, buf, e)
default:
ctx.err = fmt.Errorf("unsupported augmentation character %c at %#x", ctx.common.Augmentation[i], ctx.offset())
return nil