JIRA: https://issues.redhat.com/browse/RHEL-25415
Conflicts: The handling of objtool args is different in RHEL9 than it is
upstream. The scripts/Makefile.lib chunk is correctly applied to
scripts/link-vmlinux.sh in RHEL9.
commit 280981d6994e0700abd36647b141e73059851e66
Author: Sathvika Vasireddy <sv@linux.ibm.com>
Date: Mon Nov 14 23:27:49 2022 +0530
objtool: Add --mnop as an option to --mcount
Some architectures (powerpc) may not support ftrace locations being nop'ed
out at build time. Introduce CONFIG_HAVE_OBJTOOL_NOP_MCOUNT for objtool, as
a means for architectures to enable nop'ing of ftrace locations. Add --mnop
as an option to objtool --mcount, to indicate support for the same.
Also, make sure that --mnop can be passed as an option to objtool only when
--mcount is passed.
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221114175754.1131267-12-sv@linux.ibm.com
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2190342
Conflicts: The scripts/Makefile.lib hunk is applied with modification to
scripts/Makefile.build and scripts/link-vmlinux.sh due
to missing upstream commit 9ec6ab6ee5ca ("kbuild: use
objtool-args-y to clean up objtool arguments") & other
related commits.
commit 0c0a6d8934e2081df93ba0bfc0cf615cc9c06988
Author: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 15 Sep 2022 13:11:10 +0200
objtool: Add --hacks=skylake
Make the call/func sections selectable via the --hacks option.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111146.120821440@infradead.org
Signed-off-by: Waiman Long <longman@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-255
commit 9f2899fe36a623885d8576604cb582328ad32b3c
Author: Peter Zijlstra <peterz@infradead.org>
Date: Fri Oct 28 15:50:42 2022 +0200
objtool: Add option to generate prefix symbols
When code is compiled with:
-fpatchable-function-entry=${PADDING_BYTES},${PADDING_BYTES}
functions will have PADDING_BYTES of NOP in front of them. Unwinders
and other things that symbolize code locations will typically
attribute these bytes to the preceding function.
Given that these bytes nominally belong to the following symbol this
mis-attribution is confusing.
Inspired by the fact that CFI_CLANG emits __cfi_##name symbols to
claim these bytes, allow objtool to emit __pfx_##name symbols to do
the same.
Therefore add the objtool --prefix=N argument, to conditionally place
a __pfx_##name symbol at N bytes ahead of symbol 'name' when: all
these preceding bytes are NOP and name-N is an instruction boundary.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Yujie Liu <yujie.liu@intel.com>
Link: https://lkml.kernel.org/r/20221028194453.526899822@infradead.org
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-255
Conflicts:
arch/x86/include/asm/nospec-branch.h
- cs-9 already has upstream f43b9876e857 ("x86/retbleed: Add
fine grained Kconfig knobs"), check for CONFIG_CPU_UNRET_ENTRY
or CONFIG_CPU_IBPB_ENTRY instead of CONFIG_RETPOLINE
tools/objtool/builtin-check.c
tools/objtool/include/objtool/builtin.h
- c9-9 already has upstream f43b9876e857 ("x86/retbleed: Add
fine grained Kconfig knobs")
include/linux/objtool.h
tools/include/linux/objtool.h
- cs-9 already has upstream 8faea26e6111 ("objtool: Re-add
UNWIND_HINT_{SAVE_RESTORE}"), insert UNWIND_HINT_TYPE_ENTRY
into the available 4th enum
tools/objtool/check.c
- cs-9 already has upstream 8faea26e6111 ("objtool: Re-add
UNWIND_HINT_{SAVE_RESTORE}"), apply
UNWIND_HINT_TYPE_REGS_PARTIAL hunk in read_unwind_hints()
manually
tools/objtool/include/objtool/check.h
- cs-9 already has upstream 8faea26e6111 ("objtool: Re-add
UNWIND_HINT_{SAVE_RESTORE}"), which added save and restore
values to struct instruction. While we're here, fix the
alignment of the bitfields that said omitted.
scripts/Makefile.vmlinux_o
- cs-9 doesn't have upstream 5d45950dfbb1 ("kbuild: move
vmlinux.o link to scripts/Makefile.vmlinux_o") or b42d23065024
("kbuild: factor out the common objtool arguments"), so add
objtool --unret option in scripts/link-vmlinux.sh
commit a09a6e2399ba0595c3042b3164f3ca68a3cff33e
Author: Peter Zijlstra <peterz@infradead.org>
Date: Tue Jun 14 23:16:03 2022 +0200
objtool: Add entry UNRET validation
Since entry asm is tricky, add a validation pass that ensures the
retbleed mitigation has been done before the first actual RET
instruction.
Entry points are those that either have UNWIND_HINT_ENTRY, which acts
as UNWIND_HINT_EMPTY but marks the instruction as an entry point, or
those that have UWIND_HINT_IRET_REGS at +0.
This is basically a variant of validate_branch() that is
intra-function and it will simply follow all branches from marked
entry points and ensures that all paths lead to ANNOTATE_UNRET_END.
If a path hits RET or an indirection the path is a fail and will be
reported.
There are 3 ANNOTATE_UNRET_END instances:
- UNTRAIN_RET itself
- exception from-kernel; this path doesn't need UNTRAIN_RET
- all early exceptions; these also don't need UNTRAIN_RET
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2121207
Conflicts:
scripts/Makefile.build
- rhel9 doesn't have d31ed5d767c0 ("kbuild: Fixup the IBT kbuild
changes")
commit 753da4179d08b625d8df72e97724e22749969fd3
Author: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Mon Apr 18 09:50:43 2022 -0700
objtool: Remove --lto and --vmlinux in favor of --link
The '--lto' option is a confusing way of telling objtool to do stack
validation despite it being a linked object. It's no longer needed now
that an explicit '--stackval' option exists. The '--vmlinux' option is
also redundant.
Remove both options in favor of a straightforward '--link' option which
identifies a linked object.
Also, implicitly set '--link' with a warning if the user forgets to do
so and we can tell that it's a linked object. This makes it easier for
manual vmlinux runs.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/dcd3ceffd15a54822c6183e5766d21ad06082b45.1650300597.git.jpoimboe@redhat.com
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2121207
Conflicts:
lib/Kconfig.debug
- rhel9 doesn't have upstream bece04b5b41d ("kcov: fix generic
Kconfig dependencies if ARCH_WANTS_NO_INSTR")
lib/Kconfig.kcsan
- rhel9 doesn't have upstream 69562e4983d9 ("kcsan: Add core
support for a subset of weak memory modeling"), so can't
update KCSAN_WEAK_MEMORY dependencies
commit 22102f4559beaabcea614b29ee090c6a214f002f
Author: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Mon Apr 18 09:50:40 2022 -0700
objtool: Make noinstr hacks optional
Objtool has some hacks in place to workaround toolchain limitations
which otherwise would break no-instrumentation rules. Make the hacks
explicit (and optional for other arches) by turning it into a cmdline
option and kernel config option.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/b326eeb9c33231b9dfbb925f194ed7ee40edcd7c.1650300597.git.jpoimboe@redhat.com
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2121207
commit 4ab7674f5951ac6a8ac4fa8828090edb64a4771f
Author: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Mon Apr 18 09:50:39 2022 -0700
objtool: Make jump label hack optional
Objtool secretly does a jump label hack to overcome the limitations of
the toolchain. Make the hack explicit (and optional for other arches)
by turning it into a cmdline option and kernel config option.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/3bdcbfdd27ecb01ddec13c04bdf756a583b13d24.1650300597.git.jpoimboe@redhat.com
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2121207
Conflicts:
scripts/Makefile.build
tools/objtool/builtin-check.c
tools/objtool/include/objtool/builtin.h
- (diff context) rhel9 already has upstream f43b9876e857
("x86/retbleed: Add fine grained Kconfig knobs"), which added
--rethunk option
commit 26e176896a5bb9222ae3433da902edd2566a61a4
Author: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Mon Apr 18 09:50:38 2022 -0700
objtool: Make static call annotation optional
As part of making objtool more modular, put the existing static call
code behind a new '--static-call' option.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/d59ac57ef3d6d8380cdce20322314c9e2e556750.1650300597.git.jpoimboe@redhat.com
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2121207
commit 72064474964724c59ddff58a581a31b1ede75cf9
Author: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Mon Apr 18 09:50:37 2022 -0700
objtool: Make stack validation frame-pointer-specific
Now that CONFIG_STACK_VALIDATION is frame-pointer specific, do the same
for the '--stackval' option. Now the '--no-fp' option is redundant and
can be removed.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/f563fa064b3b63d528de250c72012d49e14742a3.1650300597.git.jpoimboe@redhat.com
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2121207
commit 7dce62041ac34b613a5ed1bd937117e492e06dc8
Author: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Mon Apr 18 09:50:33 2022 -0700
objtool: Make stack validation optional
Make stack validation an explicit cmdline option so that individual
objtool features can be enabled individually by other arches.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/52da143699574d756e65ca4c9d4acaffe9b0fe5f.1650300597.git.jpoimboe@redhat.com
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
squash with 3158d8573495d
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2121207
commit 99c0beb547a3e0ec3a63edeba0960c6ddf2226b0
Author: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Mon Apr 18 09:50:31 2022 -0700
objtool: Add option to print section addresses
To help prevent objtool users from having to do math to convert function
addresses to section addresses, and to help out with finding data
addresses reported by IBT validation, add an option to print the section
address in addition to the function address.
Normal:
vmlinux.o: warning: objtool: fixup_exception()+0x2d1: unreachable instruction
With '--sec-address':
vmlinux.o: warning: objtool: fixup_exception()+0x2d1 (.text+0x76c51): unreachable instruction
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/2cea4d5299d53d1a4c09212a6ad7820aa46fda7a.1650300597.git.jpoimboe@redhat.com
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2121207
Conflicts:
scripts/Makefile.build
tools/objtool/builtin-check.c
tools/objtool/include/objtool/builtin.h
- (diff context) rhel9 already has upstream f43b9876e857
("x86/retbleed: Add fine grained Kconfig knobs"),
which added --rethunk option and CONFIG_RETHUNK
commit b51277eb9775ce916f9efd2c51533e481180c1e8
Author: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Mon Apr 18 09:50:27 2022 -0700
objtool: Ditch subcommands
Objtool has a fairly singular focus. It runs on object files and does
validations and transformations which can be combined in various ways.
The subcommand model has never been a good fit, making it awkward to
combine and remove options.
Remove the "check" and "orc" subcommands in favor of a more traditional
cmdline option model. This makes it much more flexible to use, and
easier to port individual features to other arches.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/5c61ebf805e90aefc5fa62bc63468ffae53b9df6.1650300597.git.jpoimboe@redhat.com
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2121207
Conflicts:
scripts/Makefile.build
- rhel9 already has CONFIG_RETHUNK from upstream f43b9876e857
("x86/retbleed: Add fine grained Kconfig knobs")
tools/objtool/builtin-check.c
- rhel9 already has upstream f43b9876e857 ("x86/retbleed: Add fine
grained Kconfig knobs"), which added --rethunk option
tools/objtool/check.c
tools/objtool/include/objtool/builtin.h
- rhel9 already has upstream f43b9876e857 ("x86/retbleed: Add fine
grained Kconfig knobs"), account for rethunk code
commit 2daf7faba7ded8703e4b4ebc8b161f22272fc91a
Author: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Mon Apr 18 09:50:26 2022 -0700
objtool: Reorganize cmdline options
Split the existing options into two groups: actions, which actually do
something; and options, which modify the actions in some way.
Also there's no need to have short flags for all the non-action options.
Reserve short flags for the more important actions.
While at it:
- change a few of the short flags to be more intuitive
- make option descriptions more consistently descriptive
- sort options in the source like they are when printed
- move options to a global struct
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/9dcaa752f83aca24b1b21f0b0eeb28a0c181c0b0.1650300597.git.jpoimboe@redhat.com
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2121207
Conflicts:
tools/objtool/builtin-check.c
tools/objtool/include/objtool/builtin.h
- rhel9 already contains backport of upstream f43b9876e857
("x86/retbleed: Add fine grained Kconfig knobs"), which added
rethunk option
tools/objtool/check.c
- rhel9 already contains upstream 8faea26e6111 ("objtool: Re-add
UNWIND_HINT_{SAVE_RESTORE}"), which added save and restore
checks to read_unwind_hints()
- rhel9 already contains upstream d9e9d2300681 ("x86,objtool:
Create .return_sites"), changing the diff context when adding
same_function() and is_first_func_insn()
commit 08f87a93c8ec709698edba66a5167077181fc978
Author: Peter Zijlstra <peterz@infradead.org>
Date: Tue Mar 8 16:30:54 2022 +0100
objtool: Validate IBT assumptions
Intel IBT requires that every indirect JMP/CALL targets an ENDBR
instructions, failing this #CP happens and we die. Similarly, all
exception entries should be ENDBR.
Find all code relocations and ensure they're either an ENDBR
instruction or ANNOTATE_NOENDBR. For the exceptions look for
UNWIND_HINT_IRET_REGS at sym+0 not being ENDBR.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154319.705110141@infradead.org
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2121207
Conflicts:
tools/objtool/builtin-check.c
tools/objtool/include/objtool/builtin.h
- rhel9 already contains backport of upstream f43b9876e857
("x86/retbleed: Add fine grained Kconfig knobs"), which added
rethunk option
commit 53f7109ef957315ab53205ba3a3f4f48874c0428
Author: Peter Zijlstra <peterz@infradead.org>
Date: Tue Mar 8 16:30:45 2022 +0100
objtool: Rename --duplicate to --lto
In order to prepare for LTO like objtool runs for modules, rename the
duplicate argument to lto.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154319.172584233@infradead.org
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2090231
CVE: CVE-2022-23816
CVE: CVE-2022-23825
CVE: CVE-2022-29900
CVE: CVE-2022-29901
Conflicts:
1) A merge conflict in the removal hunk of arch/x86/Kconfig due to
missing upstream commit 03f16cd020eb ("objtool: Add CONFIG_OBJTOOL")
that introduces OBJTOOL. The addition hunk is adjusted accordingly.
2) A merge conflict in the UNTRAIN_RET hunk of
arch/x86/include/asm/nospec-branch.h due to missing upstream commit
a09a6e2399ba ("objtool: Add entry UNRET validation").
3) A merge conflict in the apply_returns() else hunk of
arch/x86/kernel/alternative.c. due to missing upstream commit
03f16cd020eb ("objtool: Add CONFIG_OBJTOOL").
4) The scripts/Makefile.lib hunk is applied to scripts/Makefile.build
instead due to missing upstream commit b42d23065024 ("kbuild:
factor out the common objtool arguments"). A rethunk variable is
manually added due to missing upstream commit ("objtool: Reorganize
cmdline options").
5) A merge conflict in the first hunk of tools/objtool/builtin-check.c
due to missing upstream commit a09a6e2399ba ("objtool: Add entry
UNRET validation"). The remaining opts_valid() hunks are dropped
because of missing this commit and commit b51277eb9775 ("objtool:
Ditch subcommands").
6) A merge conflict in tools/objtool/include/objtool/builtin.h due
to missing upstream commit 2daf7faba7de ("objtool: Reorganize cmdline
options"). The new rethunk variable is manually applied.
commit f43b9876e857c739d407bc56df288b0ebe1a9164
Author: Peter Zijlstra <peterz@infradead.org>
Date: Mon, 27 Jun 2022 22:21:17 +0000
x86/retbleed: Add fine grained Kconfig knobs
Do fine-grained Kconfig for all the various retbleed parts.
NOTE: if your compiler doesn't support return thunks this will
silently 'upgrade' your mitigation to IBPB, you might not like this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Waiman Long <longman@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2090231
commit 1cc1e4c8aab4213bd4e6353dec2620476a233d6d
Author: Peter Zijlstra <peterz@infradead.org>
Date: Sat, 4 Dec 2021 14:43:42 +0100
objtool: Add straight-line-speculation validation
Teach objtool to validate the straight-line-speculation constraints:
- speculation trap after indirect calls
- speculation trap after RET
Notable: when an instruction is annotated RETPOLINE_SAFE, indicating
speculation isn't a problem, also don't care about sls for that
instruction.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211204134908.023037659@infradead.org
Signed-off-by: Waiman Long <longman@redhat.com>
Teach objtool to parse options from the OBJTOOL_ARGS environment
variable.
This enables things like:
$ OBJTOOL_ARGS="--backup" make O=defconfig-build/ kernel/ponies.o
to obtain both defconfig-build/kernel/ponies.o{,.orig} and easily
inspect what objtool actually did.
Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20210226110004.252553847@infradead.org
Ensure there's a single place that parses check_options, in
preparation for extending where to get options from.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20210226110004.193108106@infradead.org
Teach objtool to write backups files, such that it becomes easier to
see what objtool did to the object file.
Backup files will be ${name}.orig.
Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/YD4obT3aoXPWl7Ax@hirez.programming.kicks-ass.net
- Generate __mcount_loc in objtool (Peter Zijlstra)
- Support running objtool against vmlinux.o (Sami Tolvanen)
- Clang LTO enablement for x86 (Sami Tolvanen)
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Merge tag 'clang-lto-v5.12-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull more clang LTO updates from Kees Cook:
"Clang LTO x86 enablement.
Full disclosure: while this has _not_ been in linux-next (since it
initially looked like the objtool dependencies weren't going to make
v5.12), it has been under daily build and runtime testing by Sami for
quite some time. These x86 portions have been discussed on lkml, with
Peter, Josh, and others helping nail things down.
The bulk of the changes are to get objtool working happily. The rest
of the x86 enablement is very small.
Summary:
- Generate __mcount_loc in objtool (Peter Zijlstra)
- Support running objtool against vmlinux.o (Sami Tolvanen)
- Clang LTO enablement for x86 (Sami Tolvanen)"
Link: https://lore.kernel.org/lkml/20201013003203.4168817-26-samitolvanen@google.com/
Link: https://lore.kernel.org/lkml/cover.1611263461.git.jpoimboe@redhat.com/
* tag 'clang-lto-v5.12-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
kbuild: lto: force rebuilds when switching CONFIG_LTO
x86, build: allow LTO to be selected
x86, cpu: disable LTO for cpu.c
x86, vdso: disable LTO only for vDSO
kbuild: lto: postpone objtool
objtool: Split noinstr validation from --vmlinux
x86, build: use objtool mcount
tracing: add support for objtool mcount
objtool: Don't autodetect vmlinux.o
objtool: Fix __mcount_loc generation with Clang's assembler
objtool: Add a pass for generating __mcount_loc
This change adds a --noinstr flag to objtool to allow us to specify
that we're processing vmlinux.o without also enabling noinstr
validation. This is needed to avoid false positives with LTO when we
run objtool on vmlinux.o without CONFIG_DEBUG_ENTRY.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
With LTO, we run objtool on vmlinux.o, but don't want noinstr
validation. This change requires --vmlinux to be passed to objtool
explicitly.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Add the --mcount option for generating __mcount_loc sections
needed for dynamic ftrace. Using this pass requires the kernel to
be compiled with -mfentry and CC_USING_NOP_MCOUNT to be defined
in Makefile.
Link: https://lore.kernel.org/lkml/20200625200235.GQ4781@hirez.programming.kicks-ass.net/
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
[Sami: rebased, dropped config changes, fixed to actually use --mcount,
and wrote a commit message.]
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Currently objtool headers are being included either by their base name
or included via ../ from a parent directory. In case of a base name usage:
#include "warn.h"
#include "arch_elf.h"
it does not make it apparent from which directory the file comes from.
To make it slightly better, and actually to avoid name clashes some arch
specific files have "arch_" suffix. And files from an arch folder have
to revert to including via ../ e.g:
#include "../../elf.h"
With additional architectures support and the code base growth there is
a need for clearer headers naming scheme for multiple reasons:
1. to make it instantly obvious where these files come from (objtool
itself / objtool arch|generic folders / some other external files),
2. to avoid name clashes of objtool arch specific headers, potential
obtool arch generic headers and the system header files (there is
/usr/include/elf.h already),
3. to avoid ../ includes and improve code readability.
4. to give a warm fuzzy feeling to developers who are mostly kernel
developers and are accustomed to linux kernel headers arranging
scheme.
Doesn't this make it instantly obvious where are these files come from?
#include <objtool/warn.h>
#include <arch/elf.h>
And doesn't it look nicer to avoid ugly ../ includes? Which also
guarantees this is elf.h from the objtool and not /usr/include/elf.h.
#include <objtool/elf.h>
This patch defines and implements new objtool headers arranging
scheme. Which is:
- all generic headers go to include/objtool (similar to include/linux)
- all arch headers go to arch/$(SRCARCH)/include/arch (to get arch
prefix). This is similar to linux arch specific "asm/*" headers but we
are not abusing "asm" name and calling it what it is. This also helps
to prevent name clashes (arch is not used in system headers or kernel
exports).
To bring objtool to this state the following things are done:
1. current top level tools/objtool/ headers are moved into
include/objtool/ subdirectory,
2. arch specific headers, currently only arch/x86/include/ are moved into
arch/x86/include/arch/ and were stripped of "arch_" suffix,
3. new -I$(srctree)/tools/objtool/include include path to make
includes like <objtool/warn.h> possible,
4. rewriting file includes,
5. make git not to ignore include/objtool/ subdirectory.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Now that the objtool_file can be obtained outside of the check function,
orc generation builtin no longer requires check to explicitly call its
orc related functions.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Structure objtool_file can be used by different subcommands. In fact
it already is, by check and orc.
Provide a function that allows to initialize objtool_file, that builtin
can call, without relying on check to do the correct setup for them and
explicitly hand the objtool_file to them.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Objtool currently only compiles for x86 architectures. This is
fine as it presently does not support tooling for other
architectures. However, we would like to be able to convert other
kernel tools to run as objtool sub commands because they too
process ELF object files. This will allow us to convert tools
such as recordmcount to use objtool's ELF code.
Since much of recordmcount's ELF code is copy-paste code to/from
a variety of other kernel tools (look at modpost for example) this
means that if we can convert recordmcount we can convert more.
We define weak definitions for subcommand entry functions and other weak
definitions for shared functions critical to building existing
subcommands. These return 127 when the command is missing which signify
tools that do not exist on all architectures. In this case the "check"
and "orc" tools do not exist on all architectures so we only add them
for x86. Future changes adding support for "check", to arm64 for
example, can then modify the SUBCMD_CHECK variable when building for
arm64.
Objtool is not currently wired in to KConfig to be built for other
architectures because it's not needed for those architectures and
there are no commands it supports other than those for x86. As more
command support is enabled on various architectures the necessary
KConfig changes can be made (e.g. adding "STACK_VALIDATION") to
trigger building objtool.
[ jpoimboe: remove aliases, add __weak macro, add error messages ]
Cc: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Validate that any call out of .noinstr.text is in between
instr_begin() and instr_end() annotations.
This annotation is useful to ensure correct behaviour wrt tracing
sensitive code like entry/exit and idle code. When we run code in a
sensitive context we want a guarantee no unknown code is ran.
Since this validation relies on knowing the section of call
destination symbols, we must run it on vmlinux.o instead of on
individual object files.
Add two options:
-d/--duplicate "duplicate validation for vmlinux"
-l/--vmlinux "vmlinux.o validation"
Where the latter auto-detects when objname ends with "vmlinux.o" and
the former will force all validations, also those already done on
!vmlinux object files.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.106268040@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Have it print a few numbers which can be used to size the hashtables.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.321381240@infradead.org
Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not see http www gnu org licenses
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details [based]
[from] [clk] [highbank] [c] you should have received a copy of the
gnu general public license along with this program if not see http
www gnu org licenses
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 355 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190519154041.837383322@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It is important that UACCESS regions are as small as possible;
furthermore the UACCESS state is not scheduled, so doing anything that
might directly call into the scheduler will cause random code to be
ran with UACCESS enabled.
Teach objtool too track UACCESS state and warn about any CALL made
while UACCESS is enabled. This very much includes the __fentry__()
and __preempt_schedule() calls.
Note that exceptions _do_ save/restore the UACCESS state, and therefore
they can drive preemption. This also means that all exception handlers
must have an otherwise redundant UACCESS disable instruction;
therefore ignore this warning for !STT_FUNC code (exception handlers
are not normal functions).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
David allowed retpolines in .init.text, except for modules, which will
trip up objtool retpoline validation, fix that.
Requested-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
David requested a objtool validation pass for CONFIG_RETPOLINE=y enabled
builds, where it validates no unannotated indirect jumps or calls are
left.
Add an additional .discard.retpoline_safe section to allow annotating
the few indirect sites that are required and safe.
Requested-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use the existing global variables instead of passing them around and
creating duplicate global variables.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Objtool tries to silence 'unreachable instruction' warnings when it
detects gcov is enabled, because gcov produces a lot of unreachable
instructions and they don't really matter.
However, the 0-day bot is still reporting some unreachable instruction
warnings with CONFIG_GCOV_KERNEL=y on GCC 4.6.4.
As it turns out, objtool's gcov detection doesn't work with older
versions of GCC because they don't create a bunch of symbols with the
'gcov.' prefix like newer versions of GCC do.
Move the gcov check out of objtool and instead just create a new
'--no-unreachable' flag which can be passed in by the kernel Makefile
when CONFIG_GCOV_KERNEL is defined.
Also rename the 'nofp' variable to 'no_fp' for consistency with the new
'no_unreachable' variable.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 9cfffb1168 ("objtool: Skip all "unreachable instruction" warnings for gcov kernels")
Link: http://lkml.kernel.org/r/c243dc78eb2ffdabb6e927844dea39b6033cd395.1500939244.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that objtool knows the states of all registers on the stack for each
instruction, it's straightforward to generate debuginfo for an unwinder
to use.
Instead of generating DWARF, generate a new format called ORC, which is
more suitable for an in-kernel unwinder. See
Documentation/x86/orc-unwinder.txt for a more detailed description of
this new debuginfo format and why it's preferable to DWARF.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/c9b9f01ba6c5ed2bdc9bb0957b78167fdbf9632e.1499786555.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In preparation for the new 'objtool undwarf generate' command, which
will rely on 'objtool check', move the checking code from
builtin-check.c to check.c where it can be used by other commands.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Jiri Slaby <jslaby@suse.cz>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/294c5c695fd73c1a5000bbe5960a7c9bec4ee6b4.1498659915.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
CONFIG_FORTIFY_SOURCE=y implements fortify_panic() as a __noreturn function,
so objtool needs to know about it too.
Suggested-by: Daniel Micay <danielmicay@gmail.com>
Tested-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1497532835-32704-1-git-send-email-jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
And with the goodies present in the kernel.h counterpart, i.e. checking
that the parameter is an array at build time.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-roiwxwgwgld4kygn65if60wa@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Arnd Bergmann reported a (false positive) objtool warning:
drivers/infiniband/sw/rxe/rxe_resp.o: warning: objtool: rxe_responder()+0xfe: sibling call from callable instruction with changed frame pointer
The issue is in find_switch_table(). It tries to find a switch
statement's jump table by walking backwards from an indirect jump
instruction, looking for a relocation to the .rodata section. In this
case it stopped walking prematurely: the first .rodata relocation it
encountered was for a variable (resp_state_name) instead of a jump
table, so it just assumed there wasn't a jump table.
The fix is to ignore any .rodata relocation which refers to an ELF
object symbol. This works because the jump tables are anonymous and
have no symbols associated with them.
Reported-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 3732710ff6 ("objtool: Improve rare switch jump table pattern detection")
Link: http://lkml.kernel.org/r/20170302225723.3ndbsnl4hkqbne7a@treble
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The '__unreachable' and '__func_stack_frame_non_standard' sections are
only used at compile time. They're discarded for vmlinux but they
should also be discarded for modules.
Since this is a recurring pattern, prefix the section names with
".discard.". It's a nice convention and vmlinux.lds.h already discards
such sections.
Also remove the 'a' (allocatable) flag from the __unreachable section
since it doesn't make sense for a discarded section.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jessica Yu <jeyu@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: d1091c7fa3 ("objtool: Improve detection of BUG() and other dead ends")
Link: http://lkml.kernel.org/r/20170301180444.lhd53c5tibc4ns77@treble
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The BUG() macro's use of __builtin_unreachable() via the unreachable()
macro tells gcc that the instruction is a dead end, and that it's safe
to assume the current code path will not execute past the previous
instruction.
On x86, the BUG() macro is implemented with the 'ud2' instruction. When
objtool's branch analysis sees that instruction, it knows the current
code path has come to a dead end.
Peter Zijlstra has been working on a patch to change the WARN macros to
use 'ud2'. That patch will break objtool's assumption that 'ud2' is
always a dead end.
Generally it's best for objtool to avoid making those kinds of
assumptions anyway. The more ignorant it is of kernel code internals,
the better.
So create a more generic way for objtool to detect dead ends by adding
an annotation to the unreachable() macro. The annotation stores a
pointer to the end of the unreachable code path in an '__unreachable'
section. Objtool can read that section to find the dead ends.
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/41a6d33971462ebd944a1c60ad4bf5be86c17b77.1487712920.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The following commit:
3732710ff6 ("objtool: Improve rare switch jump table pattern detection")
... improved objtool's ability to detect GCC switch statement jump
tables for GCC 6. However the check to allow short jumps with the
scanned range of instructions wasn't quite right. The pattern detection
should allow jumps to the indirect jump instruction itself.
This fixes the following warning:
drivers/infiniband/sw/rxe/rxe_comp.o: warning: objtool: rxe_completer()+0x315: sibling call from callable instruction with changed frame pointer
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 3732710ff6 ("objtool: Improve rare switch jump table pattern detection")
Link: http://lkml.kernel.org/r/20161026153408.2rifnw7bvoc5sex7@treble
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Recently objtool has started reporting a few "unreachable instruction"
warnings when CONFIG_GCOV is enabled for newer versions of GCC. Usually
this warning means there's some new control flow that objtool doesn't
understand. But in this case, objtool is correct and the instructions
really are inaccessible. It's an annoying quirk of gcov, but it's
harmless, so it's ok to just silence the warnings.
With older versions of GCC, it was relatively easy to detect
gcov-specific instructions and to skip any unreachable warnings produced
by them. But GCC 6 has gotten craftier.
Instead of continuing to play whack-a-mole with gcov, just use a bigger,
more permanent hammer and disable unreachable warnings for the whole
file when gcov is enabled. This is fine to do because a) unreachable
warnings are usually of questionable value; and b) gcov isn't used for
production kernels and we can relax the checks a bit there.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/38d5c87d61d9cd46486dd2c86f46603dff0df86f.1476393584.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
GCC 6 added a new switch statement jump table optimization which makes
objtool's life harder. It looks like:
mov [rodata addr],%reg1
... some instructions ...
jmpq *(%reg1,%reg2,8)
The optimization is quite rare, but objtool still needs to be able to
identify the pattern so that it can follow all possible control flow
paths related to the switch statement.
In order to detect the pattern, objtool starts from the indirect jump
and scans backwards through the function until it finds the first
instruction in the pattern. If it encounters an unconditional jump
along the way, it stops and considers the pattern to be not found.
As it turns out, unconditional jumps can happen, as long as they are
small forward jumps within the range being scanned.
This fixes the following warnings:
drivers/infiniband/sw/rxe/rxe_comp.o: warning: objtool: rxe_completer()+0x2f4: sibling call from callable instruction with changed frame pointer
drivers/infiniband/sw/rxe/rxe_resp.o: warning: objtool: rxe_responder()+0x10f: sibling call from callable instruction with changed frame pointer
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/8a9ed68ae1780e8d3963e4ee13f2f257fe3a3c33.1476393584.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
objtool reports the following new warning:
kernel/exit.o: warning: objtool: do_exit() falls through to next function complete_and_exit()
The warning is caused by do_exit()'s new call to do_task_dead(), which
is a new "noreturn" function which objtool doesn't know about yet,
introduced by:
9af6528ee9 ("sched/core: Optimize __schedule()")
( objtool has to know all the global noreturn functions so it can follow
the control flow of any functions which call them. Unfortunately they
need to be hard-coded because there's no automated way to detect them. )
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kbuild-all@01.org
Cc: tipbuild@zytor.com
Link: http://lkml.kernel.org/r/20160922212125.zbuewckqll4yur25@treble
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This fixes some false positive objtool warnings seen with gcc 6.1.1:
kernel/trace/ring_buffer.o: warning: objtool: ring_buffer_read_page()+0x36c: sibling call from callable instruction with changed frame pointer
arch/x86/kernel/reboot.o: warning: objtool: native_machine_emergency_restart()+0x139: sibling call from callable instruction with changed frame pointer
lib/xz/xz_dec_stream.o: warning: objtool: xz_dec_run()+0xc2: sibling call from callable instruction with changed frame pointer
With GCC 6, a new code pattern is sometimes used to access a switch
statement jump table in .rodata, which objtool doesn't yet recognize:
mov [rodata addr],%reg1
... some instructions ...
jmpq *(%reg1,%reg2,8)
Add support for detecting that pattern. The detection code is rather
crude, but it's still effective at weeding out false positives and
catching real warnings. It can be refined later once objtool starts
reading DWARF CFI.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/b8c9503b4ad8c8a827cc5400db4c1b40a3ea07bc.1469751119.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Prarit Bhargava
Waiman Long
Joe Lawrence
Peter Zijlstra
Linus Torvalds
Sami Tolvanen
Vasily Gorbik
Julien Thierry
Matt Helsley
Thomas Gleixner
Josh Poimboeuf
Kees Cook
Arnaldo Carvalho de Melo