We have a couple of loops that deal with short reads/EINTR from read(2)
and pread(2), and upcoming changes would need to add more. Add some
wrappers to abstract this away.
drgn_read_memory_file() still needs the loop so it can fault on the
exact offset that returns EIO.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
The call to min() in drgn_read_memory_file() results in the following
warning on 32-bit architectures that I missed on review:
In file included from ../../libdrgn/memory_reader.c:10:
../../libdrgn/memory_reader.c: In function 'drgn_read_memory_file':
../../libdrgn/minmax.h:36:26: warning: comparison of distinct pointer types lacks a cast
36 | (void)(&unique_x == &unique_y); \
| ^~
../../libdrgn/minmax.h:28:19: note: in expansion of macro 'cmp_once_impl'
28 | #define min(x, y) cmp_once_impl(x, y, PP_UNIQUE(_x), PP_UNIQUE(_y), <)
| ^~~~~~~~~~~~~
../../libdrgn/memory_reader.c:284:34: note: in expansion of macro 'min'
284 | size_t readlen = min(file_end - file_offset, count);
| ^~~
We can fix it with a cast, and additionally do the call to min() earlier
and rework the logic a bit.
Fixes: 9684771d61 ("libdrgn: Zero fill excluded pages in kernel core dumps rather than FaultError")
Signed-off-by: Omar Sandoval <osandov@osandov.com>
There's a lot more context here that we should write down. It's also
worth noting that it appears that GDB always zero fills the range
between p_filesz and p_memsz, so if we end up having any other issues
because of this, we might have to concede and go back to the behavior
before commit 02912ca7d0 ("libdrgn: fix handling of p_filesz < p_memsz
in core dumps").
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Something changed recently in PackIt and it no longer generates a
changelog if the rpmautospec macro is present. This ends up breaking
EPEL 8 builds, which apparently don't support rpmautospec properly yet
(see https://pagure.io/fedora-infra/rpmautospec/issue/204).
Signed-off-by: Davide Cavalca <dcavalca@fb.com>
Since _repr_pretty_() uses output of str(), and the latter is already
heavily tested in tests/test_language_c.py, we can simply test whether
p.text() is called instead of duplicating all the test cases.
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Add pretty printing support in Jupyter notebook for Object, Type,
StackFrame, and StackTrace; it will print out their representation in
programming language syntax with str(), similar to what's being done in
interactive mode.
Link: https://ipython.readthedocs.io/en/stable/api/generated/IPython.lib.pretty.html#extending
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Apparently Sphinx doesn't like it when you use the same link text for
two different links. Fix it by adding an extra underscore, which makes
it an anonymous reference.
Fixes: 9c69d2dd4b ("README: update libkdumpfile installation instructions")
Signed-off-by: Omar Sandoval <osandov@osandov.com>
makedumpfile will exclude zero pages. We found a core file where a
structure straddled a page boundary and the end of the structure
was all zeros so the page was excluded and we were generating a
FaultError trying to access the structure.
This change reverts a portion of that behaviour such that when we are
debugging a kernel core we go back to the zero fill behaviour. To do this
we go back to creating segments based on memsz instead of filesz and
handling the filesz->memsz gap in drgn_read_memory_file.
Fixes: 02912ca7d0 ("libdrgn: fix handling of p_filesz < p_memsz in core dumps")
Signed-off-by: Glen McCready <gkm@mysteryinc.ca>
Replace the old "Scriptable debugger library" and
"Debugger-as-a-library" taglines with the one we're using on GitHub,
"Programmable debugger". Make up for it by emphasizing that drgn can
also be used as a library a tiny bit more in the README.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Now that we're documenting parameter and return types with annotations,
we can use only one line for the overload of functions that can take
either an object or a program and an integer.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Instead of adding type information to directive descriptions with the
:type:, :rtype:, and :vartype: fields, document types with type
annotations. For functions and methods, we add the type annotations to
the signature. For variables and attributes, we use the :type: option.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
There are a bunch of page flag getters in the kernel like
PageUptodate(), PageLocked(), etc., that kernel developers are
accustomed to using. Most of them are simple bit tests. Let's add
helpers for all of those. These are generated from
include/linux/page-flags.h in the Linux kernel source tree as of Linux
v6.0-rc1.
More complicated getters that need to do more than a simple flag check
(e.g., PageCompound()) will need to be added manually.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
drgn is now packaged for openSUSE. Add instructions for installing with
zypper or from source. Also reindent the Arch Linux instructions
correctly.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
PyErr_SetObject() takes a reference on the exception value, so we need
to drop the reference we got when we created the value. Issue #196 ran
into this by reading tons of unmapped addresses.
Fixes: 80fef04c70 ("Add address attribute to FaultError exception")
Signed-off-by: Omar Sandoval <osandov@osandov.com>
This helper function identifies the slab cache (if any) the object at
the given address belongs to. This will be useful for a future helper
function which prints the stack trace with more information about each
item on the stack.
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Modify how the test page is allocated to ensure we have a directly
mapped address which is not slab allocated for testing the negative case
of find_containing_slab_cache.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
The config option is and always has been CONFIG_FW_CFG_SYSFS, not
CONFIG_FW_CFG. Also suggest the user-visible CONFIG_KEXEC instead of the
internal CONFIG_CRASH_CORE.
Fixes: 2bd861f719 ("libdrgn: program: detect QEMU guest memory dumps without VMCOREINFO")
Signed-off-by: Omar Sandoval <osandov@osandov.com>
cgroup_bpf_prog_for_each() needed a minor update, but after fixing that,
all of the flavors pass all tests.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
If we only have the stack trace available, it's useful to get the
program it came from. This'll be used eventually for helpers that take a
stack trace.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Kernel makes use of several lockless singly lists (free_ipc_list,
delayed_mntput_list etc.) so having some helpers to traverse
these lists can be useful.
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
We don't specifically need BusyBox; we just need a reasonable Linux
userspace, which we can assume is already available on the host, whether
it's coreutils+util-linux, BusyBox, or something else.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
The test command does this, and I always end up doing it when I'm doing
manual testing with the vmtest.vm CLI, so let's just do it by default.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Just picking up the newest version. Also fix the following warning:
WARNING: extlinks: Sphinx-6.0 will require a caption string to contain exactly one '%s' and all other '%' need to be escaped as '%%'.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
"Object finder" was renamed from "symbol finder" awhile ago, but we
forgot to update the advanced usage documentation.
Fixes: 0c5df56fba ("libdrgn: replace symbol index with object index")
Signed-off-by: Omar Sandoval <osandov@osandov.com>
We're currently checking whether the iterator has entered the
non-canonical range when fetching the last level of the page table, but
the cutover actually happens while we're in the last level. Fix it by
doing the check unconditionally.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Similarly to the helpers available to iterate over eBPF programs and
maps, add helpers for links and BTF objects. The implementation is very
straightforward.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
[Omar: add kernel version comments]
Signed-off-by: Omar Sandoval <osandov@osandov.com>
The helpers only work since Linux v4.15, but it's easy to make them work
before that. We can also easily handle kernels without cgroup BPF
programs (either before Linux v4.10 or without CONFIG_CGROUP_BPF) and
yield nothing.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
This is the same idea as commit 4da28ba0a1 ("helpers: only lookup type
once for for_each_entry helpers").
Signed-off-by: Omar Sandoval <osandov@osandov.com>
These currently only work on Linux v5.13 and newer, and it's not worth
the effort to support older versions. Let's at least document it.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
We currently don't have any tests for the BPF helpers or the
bpf_inspect.py tool. As a result, the latter is broken on newer kernel
versions. Before we can add tests, we need the vmtest kernel to support
BPF.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
A path is the most convenient way to find a cgroup if we don't already
have a pointer to it from another structure.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
I originally thought this would be too difficult, but it's fairly
straightforward to parse /proc/mounts and allows us to avoid some setup
and cleanup.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
This looks up a kernfs node from a path. It will be used to look up
cgroups by path. This is based on kernfs_walk_ns() from the Linux
kernel, but it doesn't handle namespaced kernfs nodes yet.
kernfs_walk_ns() in the kernel is actually built on another function,
kernfs_find_ns(), but I don't think the latter is very useful as a
helper.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
drgn_debug_info_find_complete() looks up the name of the incomplete type
in the global namespace. This is incorrect for C++: we need to look it
up in the namespace that the DIE is in.
To find the containing namespace, we need to do a DIE ancestor walk. We
don't want to do this for C, so add a flag indicating whether a language
has namespaces to struct drgn_language. If it's true, then we do the
ancestor walk and then look up the name in the appropriate namespace.
Signed-off-by: Jay Kamat <jaygkamat@gmail.com>
Currently, DIE references are specified as an index into the list of the
unit DIE's children. This has a few issues:
* It's hard to figure out what references what at a glance.
* Changes to tests sometimes need to renumber these indices.
* DIEs at lower levels in the tree cannot be referenced.
Replace it with explicit "labels" which are referred to by name.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Now that we made the other memory management helpers generic, the last
thing to implement for AArch64 is page table walking. This looks a lot
like the x86-64 equivalent but has to support the various page and
virtual address sizes that can be configured for AArch64.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
This is always 0 on x86-64, but on AArch64, the start of physical memory
can be at a much higher address.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
AArch64 has changed the location of vmemmap multiple times, and not all
of these can be easily distinguished. Rather than restorting to kernel
version checks, this replaces the vmemmap architecture callback with a
generic approach that gets the vmemmap address directly from the
mem_section table.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
On x86-64, the difference between virtual addresses in the direct map
and the corresponding physical addresses is called PAGE_OFFSET, so we
exposed that via an architecture callback and the Linux kernel object
finder. However, this doesn't translate to other architectures. Namely,
on AArch64, the difference is PAGE_OFFSET - PHYS_OFFSET, and both
PAGE_OFFSET and PHYS_OFFSET have varied over time and between
configurations.
We can remove the architecture callback and avoid version-specific logic
by letting the page table tell us the offset. We just need an address in
the direct map, which is easy to find since this includes kmalloc and
memblock allocations.
Signed-off-by: Omar Sandoval <osandov@osandov.com>
