forked from OSchip/llvm-project
f0ee69f75d
Summary: First part of a fix for JITed code debugging. This has been a regression from 5.0 to 6.0 and it's is still reproducible on current master: https://bugs.llvm.org/show_bug.cgi?id=36209 The address of the breakpoint site is corrupt: the 0x4 value we end up with, looks like an offset on a zero base address. When we parse the ELF section headers from the JIT descriptor, the load address for the text section we find in `header.sh_addr` is correct. The bug manifests in `VMAddressProvider::GetVMRange(const ELFSectionHeader &)` (follow it from `ObjectFileELF::CreateSections()`). Here we think the object type was `eTypeObjectFile` and unleash some extra logic [1] which essentially overwrites the address with a zero value. The object type is deduced from the ELF header's `e_type` in `ObjectFileELF::CalculateType()`. It never returns `eTypeJIT`, because the ELF header has no representation for it [2]. Instead the in-memory ELF object states `ET_REL`, which leads to `eTypeObjectFile`. This is what we get from `lli` at least since 3.x. (Might it be better to write `ET_EXEC` on the JIT side instead? In fact, relocations were already applied at this point, so "Relocatable" is not quite exact.) So, this patch proposes to set `eTypeJIT` explicitly whenever we read from a JIT descriptor. In `ObjectFileELF::CreateSections()` we can then call `GetType()`, which returns the explicit value or otherwise falls back to `CalculateType()`. LLDB then sets the breakpoint successfully. Next step: debug info. ``` Process 1056 stopped * thread #1, name = 'lli', stop reason = breakpoint 1.2 frame #0: 0x00007ffff7ff7000 JIT(0x3ba2030)`jitbp() JIT(0x3ba2030)`jitbp: -> 0x7ffff7ff7000 <+0>: pushq %rbp 0x7ffff7ff7001 <+1>: movq %rsp, %rbp 0x7ffff7ff7004 <+4>: movabsq $0x7ffff7ff6000, %rdi ; imm = 0x7FFFF7FF6000 0x7ffff7ff700e <+14>: movabsq $0x7ffff6697e80, %rcx ; imm = 0x7FFFF6697E80 ``` [1] It was first introduced with https://reviews.llvm.org/D38142#change-lF6csxV8HdlL, which has also been the original breaking change. The code has changed a lot since then. [2] ELF object types: https://github.com/llvm/llvm-project/blob/2d2277f5/llvm/include/llvm/BinaryFormat/ELF.h#L110 Reviewers: labath, JDevlieghere, bkoropoff, clayborg, espindola, alexshap, stella.stamenova Reviewed By: labath, clayborg Subscribers: probinson, emaste, aprantl, arichardson, MaskRay, AlexDenisov, yurydelendik, lldb-commits Tags: #lldb Differential Revision: https://reviews.llvm.org/D61611 llvm-svn: 360354 |
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| .. | ||
| case-sensitive.c | ||
| debug_addrx.yaml | ||
| debug_rnglist_basic.yaml | ||
| debug_rnglist_offset_pair.yaml | ||
| debug_rnglist_rlestartend.yaml | ||
| debug_rnglistx_rlex.yaml | ||
| implicit_const_form_support.yaml | ||
| jitbp.cpp | ||
| ppc64-localentry.s | ||
| single-file-split-dwarf.o.yaml | ||
| single-file-split-dwarf.yaml | ||
| split-dwarf-5-addrbase.dwo.yaml | ||
| split-dwarf-5-addrbase.yaml | ||
| split-dwarf5-debug-stroffsets-file1.dwo.yaml | ||
| split-dwarf5-debug-stroffsets-file2.dwo.yaml | ||
| split-dwarf5-debug-stroffsets-main.yaml | ||