[libunwind][SystemZ] Unwind out of signal handlers

Unwinding out of signal handlers currently does not work since
the sigreturn trampoline is not annotated with CFI data.

Fix this by detecting the

[libunwind][SystemZ] Unwind out of signal handlers

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

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[libc++] Add a CI job running MSAN

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 unnot

[libc++] Add a CI job running MSAN

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

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[libunwind] Fix unwind_leaffunction test

It's possible for this test not to pass if the libc used does not provide
unwind info for raise. We can replace it with __builtin_cast, which can lead
to a S

[libunwind] Fix unwind_leaffunction test

It's possible for this test not to pass if the libc used does not provide
unwind info for raise. We can replace it with __builtin_cast, which can lead
to a SIGTRAP on x86_64 and a SIGILL on aarch64.

Using this alternative, a nop is needed before the __builtin_cast. This is
because libunwind incorrectly decrements pc, which can cause pc to jump into
the previous function and use the incorrect FDE.

Differential Revision: https://reviews.llvm.org/D114818

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[libunwind] Fix testing with sanitizers enabled

When testing with sanitizers enabled, we need to link against a plethora
of system libraries. Using `-nodefaultlibs` like we used to breaks this,
and

[libunwind] Fix testing with sanitizers enabled

When testing with sanitizers enabled, we need to link against a plethora
of system libraries. Using `-nodefaultlibs` like we used to breaks this,
and we would have to add all these system libraries manually, which is
not portable and error prone. Instead, stop using `-nodefaultlibs` so
that we get the libraries added by default by the compiler.

The only caveat with this approach is that we are now relying on the
fact that `-L <path-to-local-libunwind>` will cause the just built
libunwind to be selected before the system implementation (either of
libunwind or libgcc_s.so), which is somewhat fragile.

This patch also turns the 32 bit multilib build into a soft failure
since we are in the process of removing it anyway, see D114473 for
details. This patch is incompatible with the 32 bit multilib build
because Ubuntu does not provide a proper libstdc++ for 32 bits, and
that is required when running with sanitizers enabled.

Differential Revision: https://reviews.llvm.org/D114385

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[libunwind] Add a from-scratch config for running libunwind tests

Running tests for libunwind is a lot simpler than running tests for
libc++, so a simple Lit config file is sufficient. The benefit i

[libunwind] Add a from-scratch config for running libunwind tests

Running tests for libunwind is a lot simpler than running tests for
libc++, so a simple Lit config file is sufficient. The benefit is that
we disentangle the libunwind test configuration from the libc++ and
libc++abi test configuration. The setup was too complicated, which led
to some bugs (notably we were running against the system libunwind on
Apple platforms).

Differential Revision: https://reviews.llvm.org/D111664

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[runtimes][ci] Run the tests for libunwind in the CI

We should arguably have always been doing that. The state of libunwind
is quite sad, so this commit adds several XFAILs to make the CI pass.
We n

[runtimes][ci] Run the tests for libunwind in the CI

We should arguably have always been doing that. The state of libunwind
is quite sad, so this commit adds several XFAILs to make the CI pass.
We need to investigate why so many tests are not passing in some
configurations, but I'll defer that to folks who actually work on
libunwind for lack of bandwidth.

Differential Revision: https://reviews.llvm.org/D110872

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[runtimes] Simplify how we specify XFAIL & friends based on the triple

Now that Lit supports regular expressions inside XFAIL & friends, it is
much easier to write Lit annotations based on the tripl

[runtimes] Simplify how we specify XFAIL & friends based on the triple

Now that Lit supports regular expressions inside XFAIL & friends, it is
much easier to write Lit annotations based on the triple.

Differential Revision: https://reviews.llvm.org/D104747

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[libunwind] Unwind through aarch64/Linux sigreturn frame

An AArch64 sigreturn trampoline frame can't currently be described
in a DWARF .eh_frame section, because the AArch64 DWARF spec currently
doe

[libunwind] Unwind through aarch64/Linux sigreturn frame

An AArch64 sigreturn trampoline frame can't currently be described
in a DWARF .eh_frame section, because the AArch64 DWARF spec currently
doesn't define a constant for the PC register. (PC and LR may need to
be restored to different values.)

Instead, use the same technique as libgcc or github.com/libunwind and
detect the sigreturn frame by looking for the sigreturn instructions:

mov x8, #0x8b
svc #0x0

If a sigreturn frame is detected, libunwind restores all the GPRs by
assuming that sp points at an rt_sigframe Linux kernel struct. This
behavior is a fallback mode that is only used if there is no ordinary
unwind info for sigreturn.

If libunwind can't find unwind info for a PC, it assumes that the PC is
readable, and would crash if it isn't. This could happen if:
- The PC points at a function compiled without unwind info, and which
is part of an execute-only mapping (e.g. using -Wl,--execute-only).
- The PC is invalid and happens to point to unreadable or unmapped
memory.

In the tests, ignore a failed dladdr call so that the tests can run on
user-mode qemu for AArch64, which uses a stack-allocated trampoline
instead of a vDSO.

Reviewed By: danielkiss, compnerd, #libunwind

Differential Revision: https://reviews.llvm.org/D90898

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[runtimes] Use int main(int, char**) consistently in tests

This is needed when running the tests in Freestanding mode, where main()
isn't treated specially. In Freestanding, main() doesn't get mangl

[runtimes] Use int main(int, char**) consistently in tests

This is needed when running the tests in Freestanding mode, where main()
isn't treated specially. In Freestanding, main() doesn't get mangled as
extern "C", so whatever runtime we're using fails to find the entry point.

One way to solve this problem is to define a symbol alias from __Z4mainiPPc
to _main, however this requires all definitions of main() to have the same
mangling. Hence this commit.

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[libunwind] Support for leaf function unwinding.

Unwinding leaf function is useful in cases when the backtrace finds a
leaf function for example when it caused a signal.
This patch also add the supp

[libunwind] Support for leaf function unwinding.

Unwinding leaf function is useful in cases when the backtrace finds a
leaf function for example when it caused a signal.
This patch also add the support for the DW_CFA_undefined because it marks
the end of the frames.

Ryan Prichard provided code for the tests.

Reviewed By: #libunwind, mstorsjo

Differential Revision: https://reviews.llvm.org/D83573

Reland with limit the test to the x86_64-linux target.

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[libunwind] Support for leaf function unwinding.

Unwinding leaf function is useful in cases when the backtrace finds a
leaf function for example when it caused a signal.
This patch also add the supp

[libunwind] Support for leaf function unwinding.

Unwinding leaf function is useful in cases when the backtrace finds a
leaf function for example when it caused a signal.
This patch also add the support for the DW_CFA_undefined because it marks
the end of the frames.

Ryan Prichard provided code for the tests.

Reviewed By: #libunwind, mstorsjo

Differential Revision: https://reviews.llvm.org/D83573

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