> On Feb 16, 2017, at 3:51 AM, Ramana via lldb-dev <lldb-dev@lists.llvm.org>
> wrote:
>
> It looks like LLDB doesn't like ELF relocatable files for debugging
> and asserts with the following message when tried
>
> <path to>/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp:2228:
> unsigned int ObjectFileELF::RelocateSection(.....): Assertion `false
> && "unexpected relocation type"' failed.
>
> Are we not supposed to debug ELF relocatable files on LLDB or am I
> missing something?
>
> If we cannot debug the relocatable files, is it _simply_ because those
> files lack program headers (program memory map) and relocations are
> yet to be processed (for debug info) or there are other reasons?
>
> For our target, the assembler output itself is a self contained ELF
> and hence will not have external references (both code and data). I am
> wondering if I can debug these ELF files on LLDB with minimal changes
> which does not require a full (or proper) linking step and would
> appreciate any pointers on that.
>
> Thanks,
> Ramana
Looks like you just need to add support for the 32 bit relocations:
if (hdr->Is32Bit()) {
switch (reloc_type(rel)) {
case R_386_32:
case R_386_PC32:
default:
assert(false && "unexpected relocation type");
}
} else {
switch (reloc_type(rel)) {
case R_X86_64_64: {
symbol = symtab->FindSymbolByID(reloc_symbol(rel));
if (symbol) {
addr_t value = symbol->GetAddressRef().GetFileAddress();
DataBufferSP &data_buffer_sp = debug_data.GetSharedDataBuffer();
uint64_t *dst = reinterpret_cast<uint64_t *>(
data_buffer_sp->GetBytes() + rel_section->GetFileOffset() +
ELFRelocation::RelocOffset64(rel));
*dst = value + ELFRelocation::RelocAddend64(rel);
}
break;
}
case R_X86_64_32:
case R_X86_64_32S: {
symbol = symtab->FindSymbolByID(reloc_symbol(rel));
if (symbol) {
addr_t value = symbol->GetAddressRef().GetFileAddress();
value += ELFRelocation::RelocAddend32(rel);
assert(
(reloc_type(rel) == R_X86_64_32 && (value <= UINT32_MAX)) ||
(reloc_type(rel) == R_X86_64_32S &&
((int64_t)value <= INT32_MAX && (int64_t)value >= INT32_MIN)));
uint32_t truncated_addr = (value & 0xFFFFFFFF);
DataBufferSP &data_buffer_sp = debug_data.GetSharedDataBuffer();
uint32_t *dst = reinterpret_cast<uint32_t *>(
data_buffer_sp->GetBytes() + rel_section->GetFileOffset() +
ELFRelocation::RelocOffset32(rel));
*dst = truncated_addr;
}
break;
}
case R_X86_64_PC32:
default:
assert(false && "unexpected relocation type");
}
}
I am guessing you will do something similar to the x86-64 stuff.
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