This adds a port to Linux on the IBM Z platform (a.k.a s390x). It only
supports the 64-bit ABI. Most functionality is working and all the tests
pass with the exception of the coredump tests*.
Unwinding is only supported if DWARF unwind information is present.
libunwind can't currently make use of the backchain (if present).
The getcontext/setcontext functions only preserve/restore a subset of
registers. Currently this only consists of callee-saved registers and
some parameter registers.
Vector registers and access registers are not saved (and aren't callee-
saved) by getcontext and cannot currently be modified. They will however
be restored unmodified after resuming a context from a signal handler.
There is no special libunwind support for setjmp, the functionality is
emulated using glibc (I think all the ports do this for modern Linux
kernels).
* Unwinding on s390x requires floating point register access which the
coredump library doesn't currently support.
(At least on x86(_32),) `unw_resume` will call `setcontext` which will modify the signal masks
based on the value in the context. Since the signal mask is not being initialized by
`unw_getcontext`, this cause the signal mask to be set to a random (uninitialized) value after
`unw_resume` which cause the test to fail since it relies on the signal mask for SIGUSR2 being
cleared.
The proper fix is likely to either make `unw_resume` not touch the signal mask if the context
wasn't initialized with a signal ucontext, or to make `unw_getcontext` record the signal mask too.
It's unclear to me which approach should be taken...
In the mean time, the intermittent failure can be fixed simply by zero initialing the context first
which would clear all the signal masks.
When siginfo is available, a more reliable way is to use the `ucontext` passed in
to the signal handler directly and rely on `sigreturn` to reset it.
Unfortunately, this is currently not implemented on all archs either.
* Add `SA_SIGINFO` flag
This is needed to guarantee the availability of the `ucontext` argument
* Mark the `NULL` pointer load as `volatile`
Further prevent any compiler optimization on the load.
The calls to mincore() or msync() are not checking for actual accessibility
this could lead to SIGSEGV if the address from a mapped page with the
PROT_NONE property occurs on the stack.
Hence an attempt to write one byte from the checked address to a pipe will
fail if the address is not readable.
We've tried to run slightly modified test-coredump-unwind.c built with
tcmalloc, and it promptly crashed. Attached patch fixes the heap buffer
overflow bug which caused it.
Add interface for configurable dwarf cache size
* Use item size and round up to nearest power of 2.
* Initial cache still exists in BSS. Without this, it means we would fail
backtrace when out of memory. The test-mem test fails without this
Currently setcontext for x86_64 restores the signal mask, even
though it is never saved anywhere. This means the signal mask
is often garbage after an unw_resume.
(changed in commit f8a15e9679)
It looks like this was a fix for the Gtest-resume-sig function -
testing if signal masks are restored across signal frames. The
root issue looks like that x86_64 only uses sigreturn for the exact
signal frame, and not for any decedant frames as well (as i64 does).
Instead, modify Gresume to use sigreturn if *any* frame on the stack
is a signal frame, so that we correct fixup the signal mask and any
sigaltstacks. The sigreturn os-specific functions are changed slightly
to copy in the saved ucontext structure if we are jumping farther
up the stack.
This should fix sigprocmask reported issues such as
https://github.com/dropbox/pyston/blob/master/libunwind_patches/0002-pyston-stop-x86_64-setcontext-restoring-uninitialize.patch
Tests pass on freebsd, linux
Read the address using strtoul(). If strtol() is used and the number is
bigger than LONG_MAX, LONG_MAX is returned instead, which leads to a failure
if the mapping address is 0x80000000 or larger on 32-bit platforms (and
similarly for 64-bit platforms).
If we don't link to libexecinfo, as detected by the
AC_SEARCH_LIBS(backtrace, execinfo) configure probe, we get
```
test-coredump-unwind.o: In function `handle_sigsegv':
/home/libunwind/tests/test-coredump-unwind.c:246: undefined reference to
`backtrace_symbols_fd'
collect2: error: ld returned 1 exit status
Makefile:1187: recipe for target 'test-coredump-unwind' failed
```
and
```
Gtest-init.o: In function `do_backtrace()':
Gtest-init.cxx:(.text+0x2f): undefined reference to `_Ux86_64_getcontext'
Gtest-init.cxx:(.text+0x48): undefined reference to `_Ux86_64_init_local'
Gtest-init.cxx:(.text+0x63): undefined reference to `_Ux86_64_get_reg'
Gtest-init.cxx:(.text+0x96): undefined reference to `_Ux86_64_get_proc_name'
Gtest-init.cxx:(.text+0x171): undefined reference to `_Ux86_64_step'
collect2: error: ld returned 1 exit status
Makefile:1063: recipe for target 'Gtest-init' failed
```
There are 2 XFAIL and 6 FAIL tests, but it's a start
Add dummy assign statements at the top so we don't have to trace all
the different if paths to see where the value is initially assigned.
Now all code paths just append it.
It looks like the dynamic frame support isn't fully baked on
non-ia64, leading to lots of mailing list comments about broken
tests (even though they're marked as supposed to fail, it's still
confusing).
This is similar to commit c90a2e02b3
"Mark run-ptrace-mapper and run-ptrace-misc as XFAIL on MIPS".
Starting with 2.6.39, ARM Linux returns -EIO for PTRACE_SINGLESTEP, so
we need to mark this as XFAIL for ARM too.
The Linux commit that changed this is
commit 425fc47adb5bb69f76285be77a09a3341a30799e
Author: Will Deacon <will.deacon@arm.com>
Date: Mon Feb 14 14:31:09 2011 +0100
ARM: 6668/1: ptrace: remove single-step emulation code
see: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=425fc47adb5bb69f76285be77a09a3341a30799e
Signed-off-by: Gregory Fong <gregory.0xf0@gmail.com>
Though PTRACE_SINGLESTEP is defined on MIPS Linux, the kernel does
not support that kind of request. The ptrace call failed and sets
errno to EIO and paused process is not resumed. In case of
run-ptrace-mapper and run-ptrace-misc this leads to hanged execution
because next call to wait4 never returns.
This change adds run-ptrace-mapper and run-ptrace-misc to the list
of 'expected failed' tests on MIPS targets.
Signed-off-by: Simon Atanasyan <simon@atanasyan.com>
On systems where the system compiler supports Altivec by default,
the libunwind Makefile will attempt to build an extra test case
ppc64-test-altivec. Unfortunately, the link step will fail since
the Makefile does not actually link against the libunwind library.
Fixed by adding the appropriate LDADD macro.
Signed-off-by: Ulrich Weigand <uweigand@de.ibm.com>
The crasher test is used as part of the coredump test suite,
but is being built regardless of whether that support has been
configured or not. This patch changes the build so that it is
only built when coredump support is enabled.
Currently, libunwind-setjmp is built whenever local unwinding is
built. This patch adds an explicit flag to control it instead.
The default if not specified is to follow the old behavior.
This change adds a manual override to control building of the ptrace
library, similar to the existing --enable-coredump option. The
default is set based on the existence of sys/ptrace.h, allowing it
to be automatically disabled for platforms that do not have ptrace.
We do not really need to care if the system provides `backtrace()',
since we will want to test the one provided in libunwind, not the one
that is provided by the system. The `backtrace()' calls should already
be aliased to `unw_backtrace()', but if that is not working for whatever
reason, we can call `unw_backtrace()' explicitly.
