According to EHABI32 §8.5.2, the PAC for the return address of a
function described in an exception table is supposed to be addressed
in the _Unwind_VRS_{Get,Set} API by setting regclass=_UVRSC_PSEUDO and
regno=0. (The space of 'regno' values is independent for each
regclass, and for _UVRSC_PSEUDO, there is only one valid regno so far.)
That is indeed what libunwind's _Unwind_VRS_{Get,Set} functions expect
to receive. But at two call sites, the wrong values are passed in:
regno is being set to UNW_ARM_RA_AUTH_CODE (0x8F) instead of 0, and in
one case, regclass is _UVRSC_CORE instead of _UVRSC_PSEUDO.
As a result, those calls to _Unwind_VRS_{Get,Set} return
_UVRSR_FAILED, which their callers ignore. So if you compile in the
AUTG instruction that actually validates the PAC, it will try to
validate what's effectively an uninitialised register as an
authentication code, and trigger a CPU fault even on correct exception
unwinding.
Reviewed By: danielkiss
Differential Revision: https://reviews.llvm.org/D128522
By adding noinline and calling fprintf before returning we ensure that
every function will have a distinct call frame and that the return address
will always be saved instead of saving the target in main as the result.
Before this change all backtraces were always backtrace -> main -> _start,
i.e. always exactly three entries. This happenend because all calls were
inlined in main() and the test just happenend to pass because there is at
least _start before main.
I found this while fixing some bugs in libunwind for CHERI and noticed that
the test was passing even though the code was completely broken.
Obtained from: https://github.com/CTSRD-CHERI/llvm-project
Reviewed By: #libunwind, ldionne, MaskRay
Differential Revision: https://reviews.llvm.org/D126611
This fixes unwinding in boundary cases on ARM with SEH.
In the case of ARM/Thumb, disp->ControlPc points at the following
instruction, with the thumb bit set. Thus by decrementing 1,
it still points at the next instruction. To achieve the desired
effect of pointing at the previous instruction, one first has to strip
out the thumb bit, then do the decrement by 1 to reach the previous
instruction.
When libcxxabi looks for call site ranges, it already does
`_Unwind_GetIP(context) - 1` (in `scan_eh_tab` in
libcxxabi/src/cxa_personality.cpp), so we shouldn't do the
corresponding `- 1` multiple times.
In the case of libcxxabi on Thumb, `funcStart` (still in `scan_eh_tab`)
may have the thumb bit set. If the program counter address is
decremented both in libunwind (first removing the thumb bit, then
decremented), and then libcxxabi decrements it further, and compares
with a `funcStart` with the thumb bit set, it could point to one byte
before the start of the call site.
Thus: This modification makes libunwind with SEH work with libcxxabi
on Thumb, in settings where libunwind and libcxxabi worked fine with
Dwarf before.
For existing cases with libunwind with SEH (on x86_64 and aarch64),
this modification doesn't break any of my testcases.
Differential Revision: https://reviews.llvm.org/D126869
There's no such corresponding code for ARM64 (which has been working
in production for years). The SEH version of the Unwind functions
(e.g. `_Unwind_GetLanguageSpecificData`) doesn't use these fields.
The `_Unwind_ForcedUnwind` function would need these bits though,
but that's not used in normal C++ exception unwinding.
Differential Revision: https://reviews.llvm.org/D126868
Check `__SEH__` when checking if ARM EHABI should be implied,
similarly to 4a3722a2c3 / D126866.
Fix a warning by using the right format specifier (PRIxPTR instead
of PRIx64), and add a double->float cast in a codepath that hasn't
been built so far.
This is enough to make SEH unwinding of itanium ABI exceptions on
ARM mostly work - one specific issue is fixed in a separate follow-up
patch.
Differential Revision: https://reviews.llvm.org/D126867
Summary:
This patch changes scripts to add libunwind CI on AIX. Test config file ibm-libunwind-shared.cfg.in is introduced for testing on AIX.
Reviewed by: ldionne, MaskRay, libunwind, ibc++abi
Differential Revision: https://reviews.llvm.org/D126017
Add a warning and tweak the release note to explain that the deprecation
targets libc++, libc++abi and libuwnind as well.
Also, as a fly-by, ensure that our CI runs the legacy testing configuration
for libc++, libc++abi and libunwind. This doesn't matter too much since
it's deprecated, but we might as well test it properly.
Differential Revision: https://reviews.llvm.org/D126478
The CMake variable LIBUNWIND_SUPPORTS_NODEFAULTLIBS_FLAG has been renamed
into C_SUPPORTS_NODEFAULTLIBS_FLAG because the last one is used in the
confix-ix.cmake file while the variable with the original name is not used
at al.
Differential Revision: https://reviews.llvm.org/D126466
Start testing Apple backdeployment with older libunwinds, and stop
explicitly specifying the libunwind testing config, since it is
already selected correctly by default.
Differential Revision: https://reviews.llvm.org/D126470
We've observed segfaults in libunwind when attempting to check for the
Linux aarch64 sigreturn frame, presumably because of bad unwind info
leading to an incorrect PC that we attempt to read from. Use
process_vm_readv to read the memory safely instead.
The s390x code path should likely follow suit, but I don't have the
hardware to be able to test that, so I didn't modify it here either.
Reviewed By: MaskRay, rprichard, #libunwind
Differential Revision: https://reviews.llvm.org/D126343
Create a macro for this instead of duplicating the architecture checks
everywhere. (It's a little redundant to use it when we're checking for a
specific architecture, but I'm also applying it there for consistency.)
Reviewed By: rprichard, MaskRay, #libunwind
Differential Revision: https://reviews.llvm.org/D126342
The _LIBUNWIND_HAS_NO_THREADS macro is only picked up by libunwind
inside its sources, so it is only required when it builds. It doesn't
need to be defined when running the tests.
Also, add a CI job that tests this configuration. The exact configuration
is that we build a shared libc++ and merge objects for the ABI library
and the unwinder library into it.
Differential Revision: https://reviews.llvm.org/D125903
(In the case of libunwind, the cmake option is called
LIBUNWIND_HIDE_SYMBOLS, but it has the same effect as
LIBCXX_HERMETIC_STATIC_LIBRARY and
LIBCXXABI_HERMETIC_STATIC_LIBRARY.)
Previously, the same issue was dealt with by setting a project wide
define (_LIBUNWIND_HIDE_SYMBOLS,
_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS and
_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS) if only building a static
library. If building both static and shared at the same time, this
wasn't set, and the static library would contain dllexport directives.
The LIB*_HERMETIC_STATIC_LIBRARY and LIBUNWIND_HIDE_SYMBOLS cmake
options only apply the defines to the static library in the build,
even if building both static and shared at the same time.
(This could only be done use after the object libraries were
enabled, as a shared libcxx needs libcxxabi object files built
with dllexports included.)
This allows removing inelegant code for deciding how to build the
libcxxabi static library and a TODO comment that suggested that
users should need to start setting an option, which they shouldn't
need to. Finally, this gets rid of two XFAILs in tests.
Differential Revision: https://reviews.llvm.org/D125715
Program may set the RA_SIGN_STATE pseudo register by expressions.
Libunwind expected only the DW_CFA_AARCH64_negate_ra_state could change the value
of the register which leads to runtime errors on PAC enabled systems.
In the recent version of the aadwarf64[1] a limitation is added[2] to forbid the mixing the
DW_CFA_AARCH64_negate_ra_state with other DWARF Register Rule Instructions.
[1] https://github.com/ARM-software/abi-aa/releases/tag/2022Q1
[2] https://github.com/ARM-software/abi-aa/pull/129
Reviewed By: #libunwind, MaskRay
Differential Revision: https://reviews.llvm.org/D123692
Reland: test moved because it depends on exceptions.
This is a variant of D116689 rebased on top of the new (proposed) ABI
refactoring in D120727. It should conserve the basic properties of the
original patch by @phosek, except it also allows cleaning up the merging
of libc++abi into libc++ from the libc++ side.
Differential Revision: https://reviews.llvm.org/D125393
Standalone builds have been deprecated and then removed for a while now.
Trying to use standalone builds leads to a fatal CMake error, so this
code is all dead. Remove it to clean things up.
Differential Revision: https://reviews.llvm.org/D125561
Program may set the RA_SIGN_STATE pseudo register by expressions.
Libunwind expected only the DW_CFA_AARCH64_negate_ra_state could change the value
of the register which leads to runtime errors on PAC enabled systems.
In the recent version of the aadwarf64[1] a limitation is added[2] to forbid the mixing the
DW_CFA_AARCH64_negate_ra_state with other DWARF Register Rule Instructions.
[1] https://github.com/ARM-software/abi-aa/releases/tag/2022Q1
[2] https://github.com/ARM-software/abi-aa/pull/129
Reviewed By: #libunwind, MaskRay
Differential Revision: https://reviews.llvm.org/D123692
We add `--unwindlib=none` to `CMAKE_REQUIRED_FLAGS`
to make sure that builds with a yet-incomplete toolchain succeed,
to avoid linker failures about missing unwindlib.
When this option is added to `CMAKE_REQUIRED_FLAGS`, it gets added to
both compile and link commands in CMake compile tests. If
`--unwindlib=none` is included in compilation commands, it causes
warnings about unused arguments, as the flag only is relevant for
linking.
Due to the warnings in CMake tests, the later CMake test for the
`-Werror` option failed (as the tested `-Werror` option caused the
preexisting warning due to unused `--unwindlib=none` to become a
hard error). Therefore, most CI configurations that build with
`LIBCXX_ENABLE_WERROR` didn't actually end up enabling `-Werror`
after all.
When looking at the CI build log of recent CI builds, they do
end up printing:
-- Performing Test LIBCXX_SUPPORTS_WERROR_FLAG
-- Performing Test LIBCXX_SUPPORTS_WERROR_FLAG - Failed
-- Performing Test LIBCXX_SUPPORTS_WX_FLAG
-- Performing Test LIBCXX_SUPPORTS_WX_FLAG - Failed
Thus while the configurations are meant to error out on warnings,
they actually haven't done that, due to the interaction of these
options.
To fix this, remove the individual cases of adding `--unwindlib=none`
into `CMAKE_REQUIRED_FLAGS` in libcxx and libunwind.
`runtimes/CMakeLists.txt` still adds `--unwindlib=none` if needed, but
not otherwise. (The same issue with enabling `-Werror` does remain
if `--unwindlib=none` strictly is needed though - that can be fixed
separately afterwards.)
These individual cases in libunwind and libcxx were added while
standalone builds of the runtimes still were supported - but no longer
are necessary now.
Differential Revision: https://reviews.llvm.org/D124375
This makes sure to include libunwind log messages in the build if
LIBUNWIND_ENABLE_ASSERTIONS is set (which it is by default), when
building in RelWithDebInfo configurations.
Differential Revision: https://reviews.llvm.org/D124912
Unwinding out of signal handlers currently does not work since
the sigreturn trampoline is not annotated with CFI data.
Fix this by detecting the sigreturn trampoline during unwinding
and providing appropriate unwind data manually. This follows
closely the approach used by existing code for the AArch64 target.
Reviewed by: MaskRay
Differential Revision: https://reviews.llvm.org/D124765
Add support for the SystemZ (s390x) architecture to libunwind.
Support should be feature-complete with the exception of
unwinding from signal handlers (to be added later).
Reviewed by: MaskRay
Differential Revision: https://reviews.llvm.org/D124248
When the sigreturn trampoline is found the unw_proc_info_t.end_ip need to be set to
indicate a stack frame is found.
Reviewed By: cjdb, #libunwind, MaskRay
Differential Revision: https://reviews.llvm.org/D124522
Avoid repeating CMake checks across runtimes by unifying names of
variables used for results to leverage CMake caching.
Differential Revision: https://reviews.llvm.org/D110005
Summary:
This is an add-on patch to address comments.
- Replace #elif in file <assembly.h> with #else as suggested;
- Reversed the indentation changes in the main patch.
Differential Revision: https://reviews.llvm.org/D100132
Summary:
This patch contains the implementation of the unwinder for IBM AIX.
AIX does not support the eh_frame section. Instead, the traceback table located at the end of each function provides the information for stack unwinding and EH. In this patch macro _LIBUNWIND_SUPPORT_TBTAB_UNWIND is used to guard code for AIX traceback table based unwinding. Function getInfoFromTBTable() and stepWithTBTable() are added to get the EH information from the traceback table and to step up the stack respectively.
There are two kinds of LSDA information for EH on AIX, the state table and the range table. The state table is used by the previous version of the IBM XL compiler, i.e., xlC and xlclang++. The DWARF based range table is used by AIX clang++. The traceback table has flags to differentiate these cases. For the range table, relative addresses are calculated using a base of DW_EH_PE_datarel, which is the TOC base of the module where the function of the current frame belongs.
Two personality routines are employed to handle these two different LSDAs, __xlcxx_personality_v0() for the state table and __xlcxx_personality_v1() for the range table. Since the traceback table does not have the information of the personality for the state table approach, its personality __xlcxx_personality_v0() is dynamically resolved as the handler for the state table. For the range table, the locations of the LSDA and its associated personality routine are found in the traceback table.
Assembly code for 32- and 64-bit PowerPC in UnwindRegistersRestore.S and UnwindRegistersSave.S are modified so that it can be consumed by the GNU flavor assembler and the AIX assembler. The restoration of vector registers does not check VRSAVE on AIX because VRSAVE is not used in the AIX ABI.
Reviewed by: MaskRay, compnerd, cebowleratibm, sfertile, libunwind
Differential Revision: https://reviews.llvm.org/D100132
For some reason, we've been going without a MSAN CI job, even though
even run-buildbot defined a generic-msan job. This must have been an
oversight that went unnoticed. Thanks to @EricWF for the catch.
Differential Revision: https://reviews.llvm.org/D120851
This allows us to detect whether we're being compiled with LLVM's libunwind
more easily, without CMake having to set explicit variables.
As discussed in https://llvm.org/D119538.
Differential Revision: https://reviews.llvm.org/D121015
Instead, folks can use the equivalent variables provided by CMake
to set those. This removal aims to reduce complexity and potential
for confusion when setting the target triple for building the runtimes,
and make it correct when `CMAKE_OSX_ARCHITECTURES` is used (right now
both `-arch` and `--target=` will end up being passed, which is downright
incorrect).
Differential Revision: https://reviews.llvm.org/D112155
We should not assume that the cet.h header exists just because
we're on x86 linux. Only include it if __CET__ is defined. This
makes the code more similar to what compiler-rt does in
ee423d93ea/compiler-rt/lib/builtins/assembly.h (L17)
(though that one also has a __has_include() check -- I've not found
that to be necessary).
Differential Revision: https://reviews.llvm.org/D119697
Simon Tatham