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ELF: Add .eh_frame 'P', 'R' and 'L' augmentation characters. 

This basically reverts commit r260073 because it is found that
augmentation strings don't always start with "zR". It is reported
as https://llvm.org/bugs/show_bug.cgi?id=26541.

llvm-svn: 260294
This commit is contained in:
Rui Ueyama 2016-02-09 21:41:01 +00:00
parent a0ff556aa1
commit 6448f8ae5d
1 changed files with 48 additions and 7 deletions
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55
lld/ELF/OutputSections.cpp
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@ -881,6 +881,34 @@ static void skipLeb128(ArrayRef<uint8_t> &D) {
fatal("corrupted or unsupported CIE information");
}
template <class ELFT> static size_t getAugPSize(unsigned Enc) {
switch (Enc & 0x0f) {
case dwarf::DW_EH_PE_absptr:
case dwarf::DW_EH_PE_signed:
return ELFT::Is64Bits ? 8 : 4;
case dwarf::DW_EH_PE_udata2:
case dwarf::DW_EH_PE_sdata2:
return 2;
case dwarf::DW_EH_PE_udata4:
case dwarf::DW_EH_PE_sdata4:
return 4;
case dwarf::DW_EH_PE_udata8:
case dwarf::DW_EH_PE_sdata8:
return 8;
}
fatal("unknown FDE encoding");
}
template <class ELFT> static void skipAugP(ArrayRef<uint8_t> &D) {
uint8_t Enc = readByte(D);
if ((Enc & 0xf0) == dwarf::DW_EH_PE_aligned)
fatal("DW_EH_PE_aligned encoding is not supported");
size_t Size = getAugPSize<ELFT>(Enc);
if (Size < D.size())
fatal("corrupted CIE");
D = D.slice(Size);
}
template <class ELFT>
uint8_t EHOutputSection<ELFT>::getFdeEncoding(ArrayRef<uint8_t> D) {
if (D.size() < 8)
@ -911,13 +939,26 @@ uint8_t EHOutputSection<ELFT>::getFdeEncoding(ArrayRef<uint8_t> D) {
else
skipLeb128(D);
// We assume that the augmentation string always starts with 'z'
// (which specifies the size of the CIE field) and 'R' (which
// specifies the FDE encoding.)
if (!Aug.startswith("zR"))
fatal("unknown .eh_frame augmentation string: " + Aug);
skipLeb128(D);
return readByte(D);
// We only care about an 'R' value, but other records may precede an 'R'
// record. Records are not in TLV (type-length-value) format, so we need
// to teach the linker how to skip records for each type.
for (; !Aug.empty(); Aug = Aug.substr(1)) {
switch (Aug[0]) {
case 'z':
skipLeb128(D);
break;
case 'R':
return readByte(D);
case 'P':
skipAugP<ELFT>(D);
break;
case 'L':
break;
default:
fatal("unknown .eh_frame augmentation string: " + Aug);
}
}
return dwarf::DW_EH_PE_absptr;
}
template <class ELFT>