Building a kpatch for a module with this Makefile:
The Makefile is as follow:
obj-m += m_hello.o
m_hello-y = hello.o
default:
$(MAKE) -C /lib/modules/4.4.21-69-default/build M=$(shell pwd) modules
clean:
$(MAKE) -C /lib/modules/4.4.21-69-default/build M=$(shell pwd) clean
results in kpatch-build "ERROR: two parent matches for hello.o".
The problem is that find_parent_obj() looks for filenames like so:
% grep -l hello.o ./.*.cmd | grep -Fv hello.o
.m_hello.ko.cmd
.m_hello.o.cmd
where .m_hello.ko.cmd is the parant for m_hello.o, and .m_hello.o.cmd is the
parant for hello.o, but because the "hello.o" is a substring of "m_hello.o",
it will cause "m_hello.o" to be matched for the "hello.o" as well.
Fix this by using grep's -w|--word-regexp option to force it to match
whole words instead of substrings.
Signed-off-by: chenzefeng <chenzefeng2@huawei.com>
When these from internal depths of Red Hat upstream paths changed and
now we are one level deeper in directory tree.
The issue probably also exist in rhel8.0 rebase pr #993.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
If the symbol associated with a relocation does not have a section set,
nothing is done for that relocation.
Skip iterating through all the symbols of the ELF file in such a case.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
rela_insn() only retrieves information about an instruction and does not
modify sections or relocations.
Add const to make this explicit.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
There is no point inspecting through the symbols of the ELF files
(original and patched) when the ELF headers do not meet requirements.
Check ELF headers as soon as the files are mapped.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
We are seeing the following error on a real world patch:
unsupported reference to special section __barrier_nospec_fixup
The kpatch commit bb444c2168 ("create-diff-object: Check for *_fixup
sections changes") created this error because we were trying to be
future proof. However, that may have been overly paranoid, as it
doesn't seem likely that those fixup sections will need relocations
anytime soon, because the replacement instructions are manually
generated in code. And anyway that "future proof" commit breaks the
present.
Also we decided at LPC that we are going to remove .klp.arch sections
anyway, so once that happens we will be fully future-proof anyway.
This reverts commit bb444c2168.
Fixes#974.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Somewhere starting with 5.3 (probably with 9f69a496f100 "kbuild: split
out *.mod out of {single,multi}-used-m rules", but that is not
confirmed) .mod and correcponding .mod.cmd files started showing up
during module builds throwing off kpatch-build's find_parent_obj() func.
Filter out any files ending with .mod.cmd as they are definitely not the
parent.
Signed-off-by: Artem Savkov <artem.savkov@gmail.com>
Not every distro out there supports /etc/os-release file.
This file is useful for obtaining given distro defaults, but not
essential for the script to work (when all parameters are passed
on a command line).
To avoid warnings or unwanted errors, make sourcing of this file
conditional.
Signed-off-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Run the input patch(es) through lsdiff and then verify that no obviously
unsupported files are directly modified (e.g. assembly .S files).
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Make sure we don't set HAVE_SIMPLE_ENABLE on rhel8 before rhel8.2
Fixes: b913b4b ("livepatch-patch-hook: skip klp_(un)register_patch() for RHEL-7.8+ kernels")
Fixes: #1031
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Increment version to v0.8.0 due to manual signaling logic being removed
from kpatch util. Full list of changes:
- kpatch.ko atomic replace fixes
- Fixes for potential problems found by covscan
- Remove manual signaling logic from kpatch utility
- Don't strip callback symbols
- Allow dynamic debug static keys
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Recent distros don't require you to set 'ulimit -c unlimited'. Instead
they place core files in a distro-specific location. Update the SIGSEGV
error message accordingly.
Fixes: #1025
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
While static keys (jump labels) are currently broken in livepatch, a
broken dynamic debug static key is harmless since it just disables
dynamically enabled debug printks in the patched code.
Fixes: #1021
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
We saw the following panic on ppc64le when loading the macro-callbacks
integration test:
livepatch: enabling patch 'kpatch_macro_callbacks'
Oops: Exception in kernel mode, sig: 4 [#1]
LE SMP NR_CPUS=2048 NUMA pSeries
Modules linked in: kpatch_macro_callbacks(OEK+) rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace fscache sunrpc sg pseries_rng xts vmx_crypto xfs libcrc32c sd_mod ibmvscsi scsi_transport_srp ibmveth dm_mirror dm_region_hash dm_log dm_mod [last unloaded: kpatch_gcc_static_local_var_6]
CPU: 2 PID: 17445 Comm: insmod Kdump: loaded Tainted: G OE K --------- - - 4.18.0-128.el8.ppc64le #1
NIP: d00000000bb708e0 LR: c0000000001fd610 CTR: d00000000bb708e0
REGS: c00000040e98f640 TRAP: 0700 Tainted: G OE K --------- - - (4.18.0-128.el8.ppc64le)
MSR: 800000000288b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 28008228 XER: 20040003
CFAR: c0000000001fd60c IRQMASK: 0
GPR00: c0000000001fd5c0 c00000040e98f8c0 c000000001662a00 c000000733525400
GPR04: 0000000000000800 0000000000000800 c0000000015e2c00 c0000007335254a8
GPR08: 0000000000000001 d00000000bb708e0 c0000007eeb68400 0000000000000000
GPR12: d00000000bb708e0 c000000007fad600 0000000000000001 aaaaaaaaaaaaaaab
GPR16: 000000000000ff20 000000000000fff1 000000000000fff2 d00000000bb90000
GPR20: 00000000000000a9 c00000040e98fc00 c000000000d8a728 c00000040e98fc00
GPR24: d00000000bb73f88 00000000006080c0 d00000000bb73a38 c000000733525400
GPR28: 0000000000000001 c000000733525400 ffffffffffffffed c0000007eeb60900
NIP [d00000000bb708e0] callback_info.isra.0+0x7c/0x66c [kpatch_macro_callbacks]
LR [c0000000001fd610] __klp_enable_patch+0x130/0x230
Call Trace:
[c00000040e98f8c0] [c0000000001fd5c0] __klp_enable_patch+0xe0/0x230 (unreliable)
[c00000040e98f940] [c0000000001fd7d8] klp_enable_patch+0xc8/0x100
[c00000040e98f980] [d00000000bb7079c] patch_init+0x460/0x4cc [kpatch_macro_callbacks]
[c00000040e98fa20] [c000000000010108] do_one_initcall+0x58/0x248
[c00000040e98fae0] [c00000000023b860] do_init_module+0x80/0x330
[c00000040e98fb70] [c0000000002416a4] load_module+0x3994/0x3d00
[c00000040e98fd30] [c000000000241cf4] sys_finit_module+0xc4/0x130
[c00000040e98fe30] [c00000000000b388] system_call+0x5c/0x70
Instruction dump:
7cea482a 48000235 e8410018 48000014 3c620000 e8638160 48000221 e8410018
38210060 e8010010 7c0803a6 4e800020 <0000ae18> 00000000 3c4c0001 3842ae18
The problem was introduced by a recent fix:
e8f7f2dfe8 ("create-diff-object/ppc64le: Fix replace_sections_syms() for bundled symbols")
We didn't notice the fact that there's a hack in
kpatch_include_callback_elements() which reverts the work of
kpatch_replace_sections_syms() for callback function symbols.
The problem is that that revert is only partial, causing the callback
pointers to point to the .TOC data which is located 8 bytes before the
start of the function code. This happens because
kpatch_include_callback_elements() makes the same assumption that
kpatch_replace_sections_syms() had previously made: that bundled symbols
are always located at the start of their corresponding sections.
kpatch_include_callback_elements() mysteriously strips references to the
callback function symbols, replacing them with section symbols. In this
case it replaced a 'pre_patch_callback' function reference with a
'.text.unlikely.pre_patch_callback' section reference. But it didn't
adjust the rela->addend accordingly.
Joe discovered the reasoning for why kpatch_include_callback_elements()
removes function symbol references in the commit log for 7dfad2fb76
("fix dynrela corruption in load/unload hooks"):
In the case of the hook functions, we strip the FUNC symbol to prevent
it from being added to the kpatch.funcs section as a patched function.
But that justification doesn't really make sense, at least not with the
current code. Callbacks aren't added to .kpatch.funcs anyway. They're
classifed as NEW. Only CHANGED functions are added to .kpatch.funcs.
So remove that hack, fixing this bug in the process.
This does have a side effect of showing the callback functions as new
functions, because their symbols are now included.
Before:
aio.o: found callback: post_unpatch_callback
aio.o: found callback: pre_patch_callback
aio.o: found callback: pre_unpatch_callback
aio.o: new function: callback_info.isra.0
After:
aio.o: found callback: post_unpatch_callback
aio.o: found callback: pre_patch_callback
aio.o: found callback: pre_unpatch_callback
aio.o: new function: callback_info.isra.0
aio.o: new function: pre_patch_callback
aio.o: new function: post_patch_callback
aio.o: new function: pre_unpatch_callback
aio.o: new function: post_unpatch_callback
But anyway they _are_ new functions, so the new output seems more
correct to me.
Fixes: e8f7f2dfe8 ("create-diff-object/ppc64le: Fix replace_sections_syms() for bundled symbols")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
The existing comment is wrong. It confusingly conflates the function's
offset, which is 8 bytes from the beginning of the section, with the
function's localentry offset which is 8 bytes from the beginning of the
function.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Ever since upstream v5.1 (specifically commits 0b3d52790e1c ("livepatch:
Remove signal sysfs attribute") and cba82dea3061 ("livepatch: Send a
fake signal periodically") the kpatch utility script's
signal_stalled_processes() functionality has been redundant.
Remove code from the script that manually signals stalled processes. If
the sysfs signal interface is still present, use that, otherwise let
(newer) kernels handle the fake signals on their own.
Fixes: #1022
Signed-off-by: Joe Lawrence joe.lawrence@redhat.com
RHEL-7.8 backported upstream kernel commit 958ef1e39d24 ("livepatch:
Simplify API by removing registration step"), so add it to the kernels
using the simple registration API.
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Standard centos7 repos don't contain ccache so we have to install it
from epel just like we do on rhel7.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
group_size variable is assigned right after we enter for loop without
ever being read so there is no need to initialize it to 0 beforehand.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
"funcs" in kpatch_create_patches_sections() and "entries" in
kpatch_create_kpatch_arch_section() were only used by sizeof, replaced
those with corresponding types.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Actually exit on strdup error instead of just printing a warning message
in make_modname().
Found by covscan, see issue #984 for full log.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
There were 2 insances where return value of find_section_by_name wasn't
checked before dereference.
Found by covscan, see issue #984 for full log.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Make sure symtab section was found before dereferencing it.
Found by covscan, see issue #984 for full log.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
