By separating the Unwind table into a different file, this functionality
can be a part of the DWARF library with no dependency on MC, which makes
it usable in the MC layer.
This is a continuation of
[PR#14520](https://github.com/llvm/llvm-project/pull/142520).
Reapply "[NFC][DebugInfo][DWARF] Create new low-level dwarf library (#…
(#145959)
This reapplies cbf781f0bdf2f680abbe784faedeefd6f84c246e, with fixes for
the shared-library build and the unconventional sanitizer-runtime build.
Original Description:
This is the culmination of a series of changes described in [1].
Although somewhat large by line count, it is almost entirely mechanical,
creating a new library in DebugInfo/DWARF/LowLevel. This new library has
very minimal dependencies, allowing it to be used from more places than
the normal DebugInfo/DWARF library--in particular from MC.
1.
https://discourse.llvm.org/t/rfc-debuginfo-dwarf-refactor-into-to-lower-and-higher-level-libraries/86665/2
This is the culmination of a series of changes described in [1].
Although somewhat large by line count, it is almost entirely mechanical,
creating a new library in DebugInfo/DWARF/LowLevel. This new library has
very minimal dependencies, allowing it to be used from more places than
the normal DebugInfo/DWARF library--in particular from MC.
I am happy to put it in another location, or to structure it differently
if that makes sense. Some have suggested in BinaryFormat, but it is not
a great fit there. But if that makes more sense to the reviewers, I can
do that.
Another possibility would be to use pass-through headers to allow
clients who don't care to depend only on DebugInfo/DWARF. This would be
a much less invasive change, and perhaps easier for clients. But also a
system that hides details.
Either way, I'm open.
1.
https://discourse.llvm.org/t/rfc-debuginfo-dwarf-refactor-into-to-lower-and-higher-level-libraries/86665/2
CFIPrograms' most common uses are within debug frames, but it is not
their only use. For example, some assembly writers encode them by hand
into .cfi_escape directives. This PR extracts printing code for them
into its own files, which avoids the need for the main class to depend
on DWARFUnit, sections, and similar.
One in a series of NFC DebugInfo/DWARF refactoring changes to layer it
more cleanly, so that binary CFI parsing can be used from low-level
code, (such as byte strings created via .cfi_escape) without circular
dependencies. The final goal is to make a more limited dwarf library
usable from lower-level code.
More information can be found at
https://discourse.llvm.org/t/rfc-debuginfo-dwarf-refactor-into-to-lower-and-higher-level-libraries/86665
(Revised version of a previous, unreviewed, PR.)
Move all expression verification into its only client: DWARFVerifier.
Move all printing code (which was a mix of static and member functions)
into a separate class.
This is one in a series of refactoring PRs to separate dwarf
functionality into lower-level pieces usable without object files and
sections at build time. The code is already written this way via various
"if (section == nullptr)" and similar conditionals. So the functionality
itself is needed and exists, but only as a runtime feature. The goal of
these refactors is to remove the build-time dependencies, which will
allow the existing functionality to be used from lower-level parts of
the compiler. Particularly from lib/MC/.... More information at:
https://discourse.llvm.org/t/rfc-debuginfo-dwarf-refactor-into-to-lower-and-higher-level-libraries/86665
CFIPrograms' most common uses are within debug frames, but it is not
their only use. For example, some assembly writers encode them by hand
into .cfi_escape directives. This PR extracts code for them into its own
files, setting them up to be evaluated from outside debug frames
themselves.
One in a series of NFC DebugInfo/DWARF refactoring changes to layer it
more cleanly, so that binary CFI parsing can be used from low-level
code, (such as byte strings created via .cfi_escape) without circular
dependencies. The final goal is to make a more limited dwarf library
usable from lower-level code.
As part of FEAT_PAuthLR, a new DWARF Frame Instruction was introduced,
`DW_CFA_AARCH64_negate_ra_state_with_pc`. This instructs Libunwind that
the PC has been used with the signing instruction. This change includes
three commits
- Libunwind support for the newly introduced DWARF Instruction
- CodeGen Support for the DWARF Instructions
- Reversing the changes made in #96377. Due to
`DW_CFA_AARCH64_negate_ra_state_with_pc`'s requirements to be placed
immediately after the signing instruction, this would mean the CFI
Instruction location was not consistent with the generated location when
not using FEAT_PAuthLR. The commit reverses the changes and makes the
location consistent across the different branch protection options.
While this does have a code size effect, this is a negligible one.
For the ABI information, see here:
853286c7ab/aadwarf64/aadwarf64.rst (id23)
When dumping FDEs, `readelf` prints new location values after
`DW_CFA_advance_loc(*)` instructions, which looks quite convenient:
```
> readelf -wf test.o
...
... FDE ... pc=0000000000000030..0000000000000064
DW_CFA_advance_loc: 4 to 0000000000000034
...
DW_CFA_advance_loc: 4 to 0000000000000038
...
```
This patch makes `llvm-dwarfdump` and `llvm-readobj` do the same.
Previously, CFA_remember_state stored only the register locations but ignored the CFA value. This needs also to be remembered and restored for correct behavior. The problem occurs, e.g., on functions with multiple epilogues, where the CFA value after the first epilogue is becomes wrong.
Reviewed By: #debug-info, MaskRay
Differential Revision: https://reviews.llvm.org/D140338
This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
This patch had to be reverted because on gcc 7.5.0 we see an error converting from std::unique_ptr<MCRegisterInfo> to Expected<std::unique_ptr<MCRegisterInfo>> as the return type for the function createRegInfo. This has now been fixed.
As usual with that header cleanup series, some implicit dependencies now need to
be explicit:
llvm/DebugInfo/DWARF/DWARFContext.h no longer includes:
- "llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h"
- "llvm/DebugInfo/DWARF/DWARFCompileUnit.h"
- "llvm/DebugInfo/DWARF/DWARFDebugAbbrev.h"
- "llvm/DebugInfo/DWARF/DWARFDebugAranges.h"
- "llvm/DebugInfo/DWARF/DWARFDebugFrame.h"
- "llvm/DebugInfo/DWARF/DWARFDebugLoc.h"
- "llvm/DebugInfo/DWARF/DWARFDebugMacro.h"
- "llvm/DebugInfo/DWARF/DWARFGdbIndex.h"
- "llvm/DebugInfo/DWARF/DWARFSection.h"
- "llvm/DebugInfo/DWARF/DWARFTypeUnit.h"
- "llvm/DebugInfo/DWARF/DWARFUnitIndex.h"
Plus llvm/Support/Errc.h not included by a bunch of llvm/DebugInfo/DWARF/DWARF*.h files
Preprocessed lines to build llvm on my setup:
after: 1065629059
before: 1066621848
Which is a great diff!
Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D119723
UnwindTable::parseRows() may return successfully if the CFIProgram has either
no CFI instructions or only DW_CFA_nop instructions and the UnwindRow return
argument will be empty. But currently, the callers are not checking for this case
which is leading to incorrect dumps in the unwind tables in such cases i.e.
CFA=unspecified
Reviewed By: clayborg
Differential Revision: https://reviews.llvm.org/D101892
D81469 introduced a check to error on CIE version different
than 1 for eh_frame, but older compilers mistakenly create binaries
with this version set to 3 for DWARF4 or 4 to DWARF5. Move the check
to dump time instead of eh_frame parse time, so we can be tolerant
with older binaries.
Reviewed By: aprantl
Differential Revision: https://reviews.llvm.org/D97830
GCC warning:
```
/llvm-project/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp: In member function ‘llvm::Expected<long unsigned int> llvm::dwarf::CFIProgram::Instruction::getOperandAsUnsigned(const llvm::dwarf::CFIProgram&, uint32_t) const’:
/llvm-project/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp:425:1: warning: control reaches end of non-void function [-Wreturn-type]
425 | }
| ^
/llvm-project/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp: In member function ‘llvm::Expected<long int> llvm::dwarf::CFIProgram::Instruction::getOperandAsSigned(const llvm::dwarf::CFIProgram&, uint32_t) const’:
/llvm-project/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp:477:1: warning: control reaches end of non-void function [-Wreturn-type]
477 | }
| ^
```
This patch adds the ability to evaluate the state machine for CIE and FDE unwind objects and produce a UnwindTable with all UnwindRow objects needed to unwind registers. It will also dump the UnwindTable for each CIE and FDE when dumping DWARF .debug_frame or .eh_frame sections in llvm-dwarfdump or llvm-objdump. This allows users to see what the unwind rows actually look like for a given CIE or FDE instead of just seeing a list of opcodes.
This patch adds new classes: UnwindLocation, RegisterLocations, UnwindRow, and UnwindTable.
UnwindLocation is a class that describes how to unwind a register or Call Frame Address (CFA).
RegisterLocations is a class that tracks registers and their UnwindLocations. It gets populated when parsing the DWARF call frame instruction opcodes for a unwind row. The registers are mapped from their register numbers to the UnwindLocation in a map.
UnwindRow contains the result of evaluating a row of DWARF call frame instructions for the CIE, or a row from a FDE. The CIE can produce a set of initial instructions that each FDE that points to that CIE will use as the seed for the state machine when parsing FDE opcodes. A UnwindRow for a CIE will not have a valid address, whille a UnwindRow for a FDE will have a valid address.
The UnwindTable is a class that contains a sorted (by address) vector of UnwindRow objects and is the result of parsing all opcodes in a CIE, or FDE. Parsing a CIE should produce a UnwindTable with a single row. Parsing a FDE will produce a UnwindTable with one or more UnwindRow objects where all UnwindRow objects have valid addresses. The rows in the UnwindTable will be sorted from lowest Address to highest after parsing the state machine, or an error will be returned if the table isn't sorted. To parse a UnwindTable clients can use the following methods:
static Expected<UnwindTable> UnwindTable::create(const CIE *Cie);
static Expected<UnwindTable> UnwindTable::create(const FDE *Fde);
A valid table will be returned if the DWARF call frame instruction opcodes have no encoding errors. There are a few things that can go wrong during the evaluation of the state machine and these create functions will catch and return them.
Differential Revision: https://reviews.llvm.org/D89845
Register context information was already being passed into the DWARFDebugFrame code that dumps unwind information but it wasn't being used. This change adds the ability to dump registers names of a valid MC register context was passed in and if it knows about the register. Updated the tests to use the newly returned register names.
Differential Revision: https://reviews.llvm.org/D88767
There are following issues with `CFIProgram::parse` code:
1) Invalid CFI opcodes were never tested. And currently a test would fail
when the `LLVM_ENABLE_ABI_BREAKING_CHECKS` is enabled. It happens because
the `DataExtractor::Cursor C` remains unchecked when the
"Invalid extended CFI opcode" error is reported:
```
.eh_frame section at offset 0x1128 address 0x0:
Program aborted due to an unhandled Error:
Error value was Success. (Note: Success values must still be checked prior to being destroyed).
```
2) It is impossible to reach the "Invalid primary CFI opcode" error with the current code.
There are 3 possible primary opcode values and all of them are handled. Hence this error
should be replaced with llvm_unreachable.
3) Errors currently reported are upper-case.
This patch refines the code in the `CFIProgram::parse` method to fix all issues mentioned
and adds unit tests for all possible invalid extended CFI opcodes.
Differential revision: https://reviews.llvm.org/D82868
Currently when the .eh_frame section is truncated so that
CFI instructions can't be read, it is possible to enter
an infinite loop.
It happens because `CFIProgram::parse` does not handle errors properly.
This patch fixes the issue.
Differential revision: https://reviews.llvm.org/D82017
A CIE with the Length == 0 is a terminator:
https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html
And GNU objdump recognizes them and prints the following for such entries:
"00000000 ZERO terminator"
This patch teaches llvm-objdump to do the same. I had to update tests to use
"CHECK-NEXT" too.
(Note: it looks perhaps not right that printing is done inside the DebugInfo library,
I'd expect to see the change in the llvm-objdump's code somewhere instead,
but that is how it done atm).
Differential revision: https://reviews.llvm.org/D80476
I've noticed an issue with "Data.getRelocatedValue(...)" call.
it might silently ignore an error when a content is truncated.
That leads to an infinite loop in the code (e.g. llvm-readobj hangs).
After fixing the issue I've found that actually we always tried
to read past the end of a section, even when a content was valid.
It happened because the terminator CIE (a CIE with the length == 0)
was never handled. At first I've tried just to stop adding the terminator
entry (and return), but it does not seem to be correct, because tools like
llvm-objdump might want to print something for such entries
(see comments in the code and test cases).
This patch fixes issues mentioned, provides new test cases for
both llvm-readobj and lib/DebugInfo and adds FIXMEs to existent
test cases related.
Differential revision: https://reviews.llvm.org/D80299
Imagine we have a broken .eh_frame.
Below is a possible sample output of llvm-readelf:
```
...
entry 2 {
initial_location: 0x10f5
address: 0x2080
}
}
}
.eh_frame section at offset 0x2028 address 0x2028:
LLVM ERROR: Parsing entry instructions at 0 failed
PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace.
Stack dump:
0. Program arguments: /home/umb/LLVM/LLVM/llvm-project/build/bin/llvm-readelf -a 1
#0 0x000055f4a2ff5a1a llvm::sys::PrintStackTrace(llvm::raw_ostream&) (/home/umb/LLVM/LLVM/llvm-project/build/bin/llvm-readelf+0x2b9a1a)
...
#15 0x00007fdae5dc209b __libc_start_main /build/glibc-B9XfQf/glibc-2.28/csu/../csu/libc-start.c:342:3
#16 0x000055f4a2db746a _start (/home/umb/LLVM/LLVM/llvm-project/build/bin/llvm-readelf+0x7b46a)
Aborted
```
I.e. it calls abort(), suggests to submit a bug report and exits with the code 134.
This patch changes the logic to propagate errors to callers.
This fixes the behavior for llvm-dwarfdump, llvm-readobj and other possible tools.
Differential revision: https://reviews.llvm.org/D79165
With a fix to uninitialized EndOffset.
DW_OP_call_ref is the only operation that has an operand which depends
on the DWARF format. The patch fixes handling that operation in DWARF64
units.
Differential Revision: https://reviews.llvm.org/D79501
