Add DWARF unwinding, and an external debug info loader for ELF #15823

Some distributions (ie. Ubuntu) have their libc debug info in separate files. This change allows the stack walking code to read that debug info. - add support for reading compressed ELF sections - support reading the build-id from the elf headers in order to lookup external debug info - support reading the .gnu_debuglink section to look up external debug info

- add register printing

- change read apis to use a stream - add register formatters

- implement def_cfa_register

- implement restore_state, restore_extended, offset_extended

- fixup eh pointer decoding

- add abi routines for getting register values - unwding is working!

- add dwarf.abi.RegisterContext to handle register numbers changing based on DWARF format

- move register formatting code to zig-dwardump

…raceFromBase, update crash_report to use this for exceptions

- increase test-std max_rss to 1.1 above the CI observed amount

- .eh_frame_hdr contains a binary-searchable data structure for finding an FDE. If present, we can use this section to avoid having to parse the entire FDE/CIE list in the binary, instead only entries that are actually required for unwinding are read. - rework the inputs pc-relative pointer decoding to support both already-mapped sections as well as sections mapped from a file - store the VirtualMachine on UnwindContext so the allocations can be reused

…Entry

…when available

- Fix unwindFrame using the previous FDE row instead of the current one - Handle unwinding through noreturn functions - Add x86-linux getcontext - Fixup x86_64-linux getcontext not restoring the fp env - Fix start_addr filtering on x86-windows

…SP match the state after it would return) debug: fixup ucontext_t check

I had accidentally regressed support for -gdwarf in 461fb49 when I changed the logic to use the already-mapped exe/dll image instead of loading it from disk. The string table is mapped as all zeroes by the loader, so if a section header's name is longer than 8 bytes (like the ones generated by -gdwarf), then the name can't be read. Now, if any section headers require the string table, the file is mapped from disk. windows: Add NtCreateSection/NtMapViewOfSection/NtUnmapViewOfSection

debug: make getContext public

…in that case

debug: supports_context -> have_ucontext, supports_getcontext -> have_getcontext test: rework dwarf_unwind test case to also test the non-libc path

…angeIterator Some DWARF5 subprograms have non-contiguous instruction ranges. An example of such a function is `puts` in Ubuntu's libc. This change fixes name lookups for functions that use DW_AT_range in their DIE.

…up for linux This change enhances stack trace output to include a note that debug info was missing, and therefore the stack trace may not be accurate. For example, if the user is using a libc compiled with -fomit-frame-pointer and doesn't have debug symbols installed, any traces that begin in a libc function may not unwind correctly. This allows the user to notice this and potentially install debug symbols to improve the output.

…pped sections dwarf: const-correctness fixups dwarf: implement the remaining register rules dwarf: start implmenting the DWARF expression stack machine

dwarf: fixup x86 register mapping logic dwarf: change the register context update to update in-place instead of copying debug: always print the unwind error type

…xt when writing expressions

dwarf: use ThreadContext instead of os.ucontext_t dwarf: add regBytes impl for windows dwarf: fixup expression types for non-native

… UnwindContext

expressions: add more tests, fix tests for mipsel debug: add lookupModuleName implementation for macos

…w tests

…type convesions debug: dupeContext -> copyContext

… to infer it dwarf: implement OP.entry_value, add tests

…nd_info section dwarf: fixup missing error

dwarf: fixup tests that used a ThreadContext

dwarf: map the V registers in abi.regBytes test: add test case that exercises the stack-indirect __unwind_info mode in x86_64

dwarf: documentation fixups target: enable unwind tables on macho

…e IP register

…he test code

…ch64-macos

Renamed dwarf_unwinding -> stack_iterator to better reflect that it's not just DWARF unwinding. Added a test for unwinding with a frame pointer.

debug: handle the possibility of eh_frame / debug_frame being mapped in memory or loaded from disk

…dwarf lookups

…m the __unwind_info directly

… itself is updated by a column rule

…in cases

dwarf: handle signal frame CIE flag

dwarf: fixup unchecked .eh_frame CIE offset subtraction

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Add DWARF unwinding, and an external debug info loader for ELF #15823

Add DWARF unwinding, and an external debug info loader for ELF #15823

Commits on Jul 21, 2023