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Re: [tcf-dev] TCF agent problem with DWARF containing .debug_loc section

Hi Andreas,

 

Yes, this does look bad.

I have changed the code to use Addr1 – Addr0 instead of second mapping.

 

Thanks,

Eugene

 

From: tcf-dev-bounces@xxxxxxxxxxx [mailto:tcf-dev-bounces@xxxxxxxxxxx] On Behalf Of Ragnerstam, Andreas
Sent: Wednesday, October 19, 2016 7:32 AM
To: tcf-dev@xxxxxxxxxxx
Subject: [tcf-dev] TCF agent problem with DWARF containing .debug_loc section

 

Hi,

I am working with TCF as a developer of Wind River Simics and have found an issue with the DWARF service in the TCF agent with an ELF file that contains a .debug_loc section.

 

In dwarfexpr.c:76 in dwarf_get_expression_list there is an issue when converting the end address (Addr1) to a run-time address:

 

    if (!errno) RT_Addr1 = elf_map_to_run_time_address(Value->mContext, Unit->mFile, S1, Base + Addr1);

 

The end address (Addr1) for the location in debug_loc is an exclusive address, containing the first address past the end of the address range, and that address is being translated to a run-time address using elf_map_to_run_time_address (in tcf_elf.c). For the case when the region in the ELF-file has its last byte at Base + Addr1 – 1 the translation will fail as elf_run_time_address_in_region() will fail (check is “addr >= p->address + p->mem_size”). This mapping (if necessary) should be done for the last address included in the address range, not the first address outside of the range.

Something like:

 

    if (!errno) RT_Addr1 = elf_map_to_run_time_address(Value->mContext, Unit->mFile, S1, Base + Addr1 - 1) + 1;

 

An alternative might be to determine Info->code_size from Addr1 – Addr0 instead of converting the upper address.

 

I ran into this issue with a ppc64 binary compiled with gcc4.1.0.

 

Regards,

Andreas Ragnerstam

 

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