drgn_object_init() is available in drgh.h file and seems to a required
call before calling drgn_program_find_object().
Without this, trying to call drgn_object_init() from an external C
application results in undefined reference.
Signed-off-by: Aditya Sarwade <asarwade@fb.com>
This picks up a newer version of QEMU and lets us use udevadm trigger
-w. Let's also explicitly add "os: linux" to silence the config
validation.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
As of QEMU commit a5804fcf7b22 ("9pfs: local: ignore O_NOATIME if we
don't have permissions") (in v5.1.0), QEMU handles O_NOATIME sanely, so
we don't need the LD_PRELOAD hack. Since we're adding a version check,
make the multidevs check based on the version, too.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Now that drgndoc can handle overloads and we have the IntegerLike and
Path aliases, we can add type annotations to all helpers. There are also
a couple of functional changes that snuck in here to make annotating
easier.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
One of the blockers for adding type annotations to helpers is that some
helpers need to be overloaded, but drgndoc doesn't support that. This
adds support. Each function now tracks all of its overloaded signature,
each of which may be documented separately. The formatted output (for
functions/methods and classes with __init__()) combines all of the
documented overloads.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
We can get rid of the :include: and :exclude: options by deciding solely
based on whether a node has a docstring. Empty docstrings can be used to
indicate nodes that should be included with no additional content. The
__init__() method must now also have a docstring in order to be
documented. Additionally, the directives are now fully formatted by the
Formatter rather than being split between the Formatter and
DrgnDocDirective.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
The helpers implemented in C have Python wrappers only for the purpose
of documentation. This is because drgndoc ignores all imports when
recursively documenting attributes. However, mypy uses the convention
that aliased imports (i.e., import ... as ... or from ... import ... as
...) are considered re-exported, so we can follow that convention and
include aliased imports. (mypy also considered attributes in __all__ as
re-exported, so we should probably follow that in the future, too, but
for now aliased imports are enough). This lets us get rid of the Python
wrappers.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Rather than duplicating Union[str, bytes, os.PathLike] everywhere, add
an alias. Also make it explicitly os.PathLike[str] or os.PathLike[bytes]
to get rid of some mypy --strict errors.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Lots if interfaces in drgn transparently turn an integer Object into an
int by using __index__(), so add an IntegerLike protocol for this and
use it everywhere applicable.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
The __init_subclass__ and __class_getitem__ methods are always class
methods even if not decorated as such, so format them accordingly.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Every few builds or so, a vmtest VM crashes after printing "x86: Booting
SMP configuration:". After some difficult debugging, I determined that
the crash happens in arch/x86/realmode/rm/trampoline_64.S (the code that
initializes secondary CPUs) at the ljmp from startup_32 to startup_64.
The real problem happens earlier in startup_32:
movl $pa_trampoline_pgd, %eax
movl %eax, %cr3
Sometimes, the store to CR3 "fails" and CR3 remains zero, which causes
the later ljmp to triple fault.
This can be reproduced by the following script:
#!/bin/sh
curl -L 'https://www.dropbox.com/sh/2mcf2xvg319qdaw/AABFKsISWRpndNZ1gz60O-qSa/x86_64/vmlinuz-5.8.0-rc7-vmtest1?dl=1' -o vmlinuz
cat > commands.gdb << "EOF"
set confirm off
target remote :1234
# arch/x86/realmode/rm/trampoline_64.S:startup_32 after CR3 store.
hbreak *0x9ae09 if $cr3 == 0
command
info registers eax cr3
quit 1
end
# kernel/smp.c:smp_init() after all CPUs have been brought up. If we get here,
# the bug wasn't triggered.
hbreak *0xffffffff81ed4484
command
kill
quit 0
end
continue
EOF
while true; do
qemu-system-x86_64 -cpu host -enable-kvm -smp 64 -m 128M \
-nodefaults -display none -serial file:/dev/stdout -no-reboot \
-kernel vmlinuz -append 'console=0,115200 panic=-1 nokaslr' \
-s -S &
gdb -batch -x commands.gdb || exit 1
done
This seems to be a problem with nested virtualization that was fixed by
Linux kernel commit b4d185175bc1 ("KVM: VMX: give unrestricted guest
full control of CR3") (in v4.17). Apparently, the Google Cloud hosts
that Travis runs on are missing this fix. We obviously can't patch those
hosts, but we can work around it. Disabling unrestricted guest support
in the Travis VM causes CR3 stores in the nested vmtest VM to be
emulated, bypassing the bug.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
PyPI's RST parser apparently doesn't know the highlight directive, which
snuck into the README in commit 4de147e478 ("Add CONTRIBUTING.rst").
Use code-block instead.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Make the KASLR offset available to Python in a new
drgn.helpers.linux.boot module, and move pgtable_l5_enabled() there,
too.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
My work VPN is apparently closing HTTP connections prematurely, which
exposed that urllib won't catch incomplete reads if copied through
shutil.copyfileobj(). Check it explicitly.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
drgn.h is generated from drgn.h.in since commit d60c6a1d68 ("libdrgn:
add register information to platform").
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Clean up the coding style of the remaining few places that the last
couple of changes didn't rewrite.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
The folly F14 implementation provides 3 storage policies: value, node,
and vector. The default F14FastMap/F14FastSet chooses between the value
and vector policies based on the value size.
We currently only implement the value policy, as the node policy is easy
to emulate and the vector policy would've added more complexity. This
adds support for the vector policy (adding even more C abuse :) and
automatically chooses the policy the same way as folly. It'd be easy to
add a way to choose the policy if needed.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
The only major change to the folly F14 implementation since I originally
ported it is commit 3d169f4365cf ("memory savings for F14 tables with
explicit reserve()"). That is a small improvement for small tables and a
large improvement for vector tables, which are about to be added.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
posix_memalign() doesn't have the restriction that the size must be a
multiple of the alignment like aligned_alloc() does in C11.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Compile-time constants have DW_AT_const_value instead of DW_AT_location.
We can translate those to a value object.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Really it's more of a test program than an example program. It's useful
for benchmarking, testing with valgrind, etc. It's not built by default,
but it can be built manually with:
$ make -C build/temp.* examples/load_debug_info
And run with:
$ ./build/temp.*/examples/load_debug_info
Signed-off-by: Omar Sandoval <osandov@osandov.com>
GCC 10 doesn't generate a DIE for union thread_union, which breaks our
THREAD_SIZE object finder. The previous change removed our internal
dependency on THREAD_SIZE, so disable this test while I investigate why
GCC changed.
Commit eea5422546 ("libdrgn: make Linux kernel stack unwinding more
robust") overlooked that if the task is running in userspace, the stack
pointer in PRSTATUS obviously won't match the kernel stack pointer.
Let's bite the bullet and use the PID. If the race shows up in practice,
we can try to come up with another workaround.
This documents best practices for contributing to drgn. We now require a
DCO sign-off.
Also clean up some related areas in the documentation.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
I once tried to implement a generic arithmetic right shift macro without
relying on any implementation-defined behavior, but this turned out to
be really hard. drgn is fairly tied to GCC and GCC-compatible compilers
(like Clang), so let's just assume GCC's model [1]: modular conversion
to signed types, two's complement signed bitwise operators, and sign
extension for signed right shift.
1: https://gcc.gnu.org/onlinedocs/gcc/Integers-implementation.html
Declaring a local vector or hash table and separately initializing it
with vector_init()/hash_table_init() is annoying. Add macros that can be
used as initializers.
This exposes several places where the C89 style of placing all
declarations at the beginning of a block is awkward. I adopted this
style from the Linux kernel, which uses C89 and thus requires this
style. I'm now convinced that it's usually nicer to declare variables
where they're used. So let's officially adopt the style of mixing
declarations and code (and ditch the blank line after declarations) and
update the functions touched by this change.
We were forgetting to mask away the extra bits. There are two places
that we use the tag without converting it to a uint8_t:
hash_table_probe_delta(), which is mostly benign since we mask it by the
chunk mask anyways; and table_chunk_match() without SSE 2, which
completely breaks.
While we're here, let's align the comments better.
After thinking about it some more, I realized that "libdwfl: simplify
activation frame logic" breaks the case where during unwinding someone
queries isactivation for reasons other than knowing whether to decrement
program counter. Revert the patch and refactor "libdwfl: add interface
for getting Dwfl_Module and Dwarf_Frame for Dwfl_Frame" to handle it
differently.
Based on:
c95081596 size: Also obey radix printing for bsd format.
With the following patches:
configure: Add --disable-programs
configure: Add --disable-shared
libdwfl: add interface for attaching to/detaching from threads
libdwfl: export __libdwfl_frame_reg_get as dwfl_frame_register
libdwfl: add interface for getting Dwfl_Module and Dwarf_Frame for Dwfl_Frame
libdwfl: add interface for evaluating DWARF expressions in a frame
