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2019-07-18objtool: Refactor jump table codeJosh Poimboeuf3-40/+46
Now that C jump tables are supported, call them "jump tables" instead of "switch tables". Also rename some other variables, add comments, and simplify the code flow a bit. Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/cf951b0c0641628e0b9b81f7ceccd9bcabcb4bd8.1563413318.git.jpoimboe@redhat.com
2019-07-18objtool: Refactor sibling call detection logicJosh Poimboeuf1-32/+33
Simplify the sibling call detection logic a bit. Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/8357dbef9e7f5512e76bf83a76c81722fc09eb5e.1563413318.git.jpoimboe@redhat.com
2019-07-18objtool: Do frame pointer check before dead end checkJosh Poimboeuf1-9/+9
Even calls to __noreturn functions need the frame pointer setup first. Such functions often dump the stack. Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/aed62fbd60e239280218be623f751a433658e896.1563413318.git.jpoimboe@redhat.com
2019-07-18objtool: Change dead_end_function() to return booleanJosh Poimboeuf1-22/+14
dead_end_function() can no longer return an error. Simplify its interface by making it return boolean. Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/9e6679610768fb6e6c51dca23f7d4d0c03b0c910.1563413318.git.jpoimboe@redhat.com
2019-07-18objtool: Warn on zero-length functionsJosh Poimboeuf1-0/+6
All callable functions should have an ELF size. Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/03d429c4fa87829c61c5dc0e89652f4d9efb62f1.1563413318.git.jpoimboe@redhat.com
2019-07-18objtool: Refactor function alias logicJosh Poimboeuf2-8/+10
- Add an alias check in validate_functions(). With this change, aliases no longer need uaccess_safe set. - Add an alias check in decode_instructions(). With this change, the "if (!insn->func)" check is no longer needed. - Don't create aliases for zero-length functions, as it can have unexpected results. The next patch will spit out a warning for zero-length functions anyway. Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/26a99c31426540f19c9a58b9e10727c385a147bc.1563413318.git.jpoimboe@redhat.com
2019-07-18objtool: Track original function across branchesJosh Poimboeuf1-16/+12
If 'insn->func' is NULL, objtool skips some important checks, including sibling call validation. So if some .fixup code does an invalid sibling call, objtool ignores it. Treat all code branches (including alts) as part of the original function by keeping track of the original func value from validate_functions(). This improves the usefulness of some clang function fallthrough warnings, and exposes some additional kernel bugs in the process. Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/505df630f33c9717e1ccde6e4b64c5303135c25f.1563413318.git.jpoimboe@redhat.com
2019-07-18objtool: Add mcsafe_handle_tail() to the uaccess safe listJosh Poimboeuf1-0/+1
After an objtool improvement, it's reporting that __memcpy_mcsafe() is calling mcsafe_handle_tail() with AC=1: arch/x86/lib/memcpy_64.o: warning: objtool: .fixup+0x13: call to mcsafe_handle_tail() with UACCESS enabled arch/x86/lib/memcpy_64.o: warning: objtool: __memcpy_mcsafe()+0x34: (alt) arch/x86/lib/memcpy_64.o: warning: objtool: __memcpy_mcsafe()+0xb: (branch) arch/x86/lib/memcpy_64.o: warning: objtool: __memcpy_mcsafe()+0x0: <=== (func) mcsafe_handle_tail() is basically an extension of __memcpy_mcsafe(), so AC=1 is supposed to be set. Add mcsafe_handle_tail() to the uaccess safe list. Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/035c38f7eac845281d3c3d36749144982e06e58c.1563413318.git.jpoimboe@redhat.com
2019-07-18Merge branch 'x86/debug' into core/urgentThomas Gleixner1-7/+20
Pick up the two pending objtool patches as the next round of objtool fixes depend on them.
2019-07-18objtool: Rename elf_open() to prevent conflict with libelf from elftoolchainMichael Forney3-3/+3
The elftoolchain version of libelf has a function named elf_open(). The function name isn't quite accurate anyway, since it also reads all the ELF data. Rename it to elf_read(), which is more accurate. [ jpoimboe: rename to elf_read(); write commit description ] Signed-off-by: Michael Forney <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Link: https://lkml.kernel.org/r/7ce2d1b35665edf19fd0eb6fbc0b17b81a48e62f.1562793604.git.jpoimboe@redhat.com
2019-07-18objtool: Use Elf_Scn typedef instead of assuming struct nameMichael Forney1-1/+1
The libelf implementation might use a different struct name, and the Elf_Scn typedef is already used throughout the rest of objtool. Signed-off-by: Michael Forney <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Link: https://lkml.kernel.org/r/d270e1be2835fc2a10acf67535ff2ebd2145bf43.1562793448.git.jpoimboe@redhat.com
2019-07-09Merge tag 'docs-5.3' of git://git.lwn.net/linuxLinus Torvalds1-2/+2
Pull Documentation updates from Jonathan Corbet: "It's been a relatively busy cycle for docs: - A fair pile of RST conversions, many from Mauro. These create more than the usual number of simple but annoying merge conflicts with other trees, unfortunately. He has a lot more of these waiting on the wings that, I think, will go to you directly later on. - A new document on how to use merges and rebases in kernel repos, and one on Spectre vulnerabilities. - Various improvements to the build system, including automatic markup of function() references because some people, for reasons I will never understand, were of the opinion that :c:func:``function()`` is unattractive and not fun to type. - We now recommend using sphinx 1.7, but still support back to 1.4. - Lots of smaller improvements, warning fixes, typo fixes, etc" * tag 'docs-5.3' of git://git.lwn.net/linux: (129 commits) docs: automarkup.py: ignore exceptions when seeking for xrefs docs: Move binderfs to admin-guide Disable Sphinx SmartyPants in HTML output doc: RCU callback locks need only _bh, not necessarily _irq docs: format kernel-parameters -- as code Doc : doc-guide : Fix a typo platform: x86: get rid of a non-existent document Add the RCU docs to the core-api manual Documentation: RCU: Add TOC tree hooks Documentation: RCU: Rename txt files to rst Documentation: RCU: Convert RCU UP systems to reST Documentation: RCU: Convert RCU linked list to reST Documentation: RCU: Convert RCU basic concepts to reST docs: filesystems: Remove uneeded .rst extension on toctables scripts/sphinx-pre-install: fix out-of-tree build docs: zh_CN: submitting-drivers.rst: Remove a duplicated Documentation/ Documentation: PGP: update for newer HW devices Documentation: Add section about CPU vulnerabilities for Spectre Documentation: platform: Delete x86-laptop-drivers.txt docs: Note that :c:func: should no longer be used ...
2019-07-09objtool: Add support for C jump tablesJosh Poimboeuf1-7/+20
Objtool doesn't know how to read C jump tables, so it has to whitelist functions which use them, causing missing ORC unwinder data for such functions, e.g. ___bpf_prog_run(). C jump tables are very similar to GCC switch jump tables, which objtool already knows how to read. So adding support for C jump tables is easy. It just needs to be able to find the tables and distinguish them from other data. To allow the jump tables to be found, create an __annotate_jump_table macro which can be used to annotate them. The annotation is done by placing the jump table in an .rodata..c_jump_table section. The '.rodata' prefix ensures that the data will be placed in the rodata section by the vmlinux linker script. The double periods are part of an existing convention which distinguishes kernel sections from GCC sections. Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Song Liu <[email protected]> Cc: Kairui Song <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Alexei Starovoitov <[email protected]> Cc: Daniel Borkmann <[email protected]> Link: https://lkml.kernel.org/r/0ba2ca30442b16b97165992381ce643dc27b3d1a.1561685471.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <[email protected]>
2019-07-02objtool: Fix build by linking against tools/lib/ctype.o sourcesJiri Olsa1-0/+5
Fix objtool build, because it adds _ctype dependency via isspace call patch. Signed-off-by: Jiri Olsa <[email protected]> Cc: Adrian Hunter <[email protected]> Cc: André Goddard Rosa <[email protected]> Cc: Clark Williams <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Thomas Gleixner <[email protected]> Fixes: 7bd330de43fd ("tools lib: Adopt skip_spaces() from the kernel sources") Link: http://lkml.kernel.org/r/20190702121240.GB12694@krava Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
2019-06-14Merge tag 'v5.2-rc4' into mauroJonathan Corbet23-307/+23
We need to pick up post-rc1 changes to various document files so they don't get lost in Mauro's massive RST conversion push.
2019-06-08docs: fix broken documentation linksMauro Carvalho Chehab1-2/+2
Mostly due to x86 and acpi conversion, several documentation links are still pointing to the old file. Fix them. Signed-off-by: Mauro Carvalho Chehab <[email protected]> Reviewed-by: Wolfram Sang <[email protected]> Reviewed-by: Sven Van Asbroeck <[email protected]> Reviewed-by: Bhupesh Sharma <[email protected]> Acked-by: Mark Brown <[email protected]> Signed-off-by: Jonathan Corbet <[email protected]>
2019-05-30treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156Thomas Gleixner5-73/+5
Based on 1 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 write to the free software foundation inc 59 temple place suite 330 boston ma 02111 1307 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 1334 file(s). Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Allison Randal <[email protected]> Reviewed-by: Richard Fontana <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
2019-05-21treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13Thomas Gleixner18-234/+18
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 <[email protected]> Reviewed-by: Kate Stewart <[email protected]> Reviewed-by: Jilayne Lovejoy <[email protected]> Reviewed-by: Steve Winslow <[email protected]> Reviewed-by: Allison Randal <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
2019-05-19Merge branch 'core-urgent-for-linus' of ↵Linus Torvalds1-1/+2
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull core fixes from Ingo Molnar: "This fixes a particularly thorny munmap() bug with MPX, plus fixes a host build environment assumption in objtool" * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Allow AR to be overridden with HOSTAR x86/mpx, mm/core: Fix recursive munmap() corruption
2019-05-17objtool: Allow AR to be overridden with HOSTARNathan Chancellor1-1/+2
Currently, this Makefile hardcodes GNU ar, meaning that if it is not available, there is no way to supply a different one and the build will fail. $ make AR=llvm-ar CC=clang LD=ld.lld HOSTAR=llvm-ar HOSTCC=clang \ HOSTLD=ld.lld HOSTLDFLAGS=-fuse-ld=lld defconfig modules_prepare ... AR /out/tools/objtool/libsubcmd.a /bin/sh: 1: ar: not found ... Follow the logic of HOST{CC,LD} and allow the user to specify a different ar tool via HOSTAR (which is used elsewhere in other tools/ Makefiles). Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Reviewed-by: Nick Desaulniers <[email protected]> Reviewed-by: Mukesh Ojha <[email protected]> Cc: <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/80822a9353926c38fd7a152991c6292491a9d0e8.1558028966.git.jpoimboe@redhat.com Link: https://github.com/ClangBuiltLinux/linux/issues/481 Signed-off-by: Ingo Molnar <[email protected]>
2019-05-16Merge branch 'core-urgent-for-linus' of ↵Linus Torvalds2-5/+8
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull core fixes from Ingo Molnar: "A handful of objtool updates, plus a documentation addition for __ab_c_size()" * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Fix whitelist documentation typo objtool: Fix function fallthrough detection objtool: Don't use ignore flag for fake jumps overflow.h: Add comment documenting __ab_c_size()
2019-05-15objtool: Fix whitelist documentation typoRaphael Gault1-1/+1
The directive specified in the documentation to add an exception for a single file in a Makefile was inverted. Signed-off-by: Raphael Gault <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/522362a1b934ee39d0af0abb231f68e160ecf1a8.1557874043.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <[email protected]>
2019-05-13objtool: Fix function fallthrough detectionJosh Poimboeuf1-1/+2
When a function falls through to the next function due to a compiler bug, objtool prints some obscure warnings. For example: drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x95: return with modified stack frame drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x0: stack state mismatch: cfa1=7+32 cfa2=7+8 Instead it should be printing: drivers/regulator/core.o: warning: objtool: regulator_supply_is_couple() falls through to next function regulator_count_voltages() This used to work, but was broken by the following commit: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") The padding nops at the end of a function aren't actually part of the function, as defined by the symbol table. So the 'func' variable in validate_branch() is getting cleared to NULL when a padding nop is encountered, breaking the fallthrough detection. If the current instruction doesn't have a function associated with it, just consider it to be part of the previously detected function by not overwriting the previous value of 'func'. Reported-by: kbuild test robot <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: <[email protected]> Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") Link: http://lkml.kernel.org/r/546d143820cd08a46624ae8440d093dd6c902cae.1557766718.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <[email protected]>
2019-05-13objtool: Don't use ignore flag for fake jumpsJosh Poimboeuf1-3/+5
The ignore flag is set on fake jumps in order to keep add_jump_destinations() from setting their jump_dest, since it already got set when the fake jump was created. But using the ignore flag is a bit of a hack. It's normally used to skip validation of an instruction, which doesn't really make sense for fake jumps. Also, after the next patch, using the ignore flag for fake jumps can trigger a false "why am I validating an ignored function?" warning. Instead just add an explicit check in add_jump_destinations() to skip fake jumps. Signed-off-by: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/71abc072ff48b2feccc197723a9c52859476c068.1557766718.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <[email protected]>
2019-05-08Merge tag 'docs-5.2' of git://git.lwn.net/linuxLinus Torvalds1-1/+1
Pull documentation updates from Jonathan Corbet: "A reasonably busy cycle for docs, including: - Lots of work on the Chinese and Italian translations - Some license-rules clarifications from Christoph - Various build-script fixes - A new document on memory models - RST conversion of the live-patching docs - The usual collection of typo fixes and corrections" * tag 'docs-5.2' of git://git.lwn.net/linux: (140 commits) docs/livepatch: Unify style of livepatch documentation in the ReST format docs: livepatch: convert docs to ReST and rename to *.rst scripts/documentation-file-ref-check: detect broken :doc:`foo` scripts/documentation-file-ref-check: don't parse Next/ dir LICENSES: Rename other to deprecated LICENSES: Clearly mark dual license only licenses docs: Don't reference the ZLib license in license-rules.rst docs/vm: Minor editorial changes in the THP and hugetlbfs docs/vm: add documentation of memory models doc:it_IT: translation alignment doc: fix typo in PGP guide dontdiff: update with Kconfig build artifacts docs/zh_CN: fix typos in 1.Intro.rst file docs/zh_CN: redirect CoC docs to Chinese version doc: mm: migration doesn't use FOLL_SPLIT anymore docs: doc-guide: remove the extension from .rst files doc: kselftest: Fix KBUILD_OUTPUT usage instructions docs: trace: fix some Sphinx warnings docs: speculation.txt: mark example blocks as such docs: ntb.txt: add blank lines to clean up some Sphinx warnings ...
2019-05-07docs: livepatch: convert docs to ReST and rename to *.rstMauro Carvalho Chehab1-1/+1
Convert livepatch documentation to ReST format. The changes are mostly trivial, as the documents are already on a good shape. Just a few markup changes are needed for Sphinx to properly parse the docs. The conversion is actually: - add blank lines and identation in order to identify paragraphs; - fix tables markups; - add some lists markups; - mark literal blocks; - The in-file TOC becomes a comment, in order to skip it from the output, as Sphinx already generates an index there. - adjust title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <[email protected]> Signed-off-by: Petr Mladek <[email protected]> Acked-by: Miroslav Benes <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Acked-by: Joe Lawrence <[email protected]> Reviewed-by: Kamalesh Babulal <[email protected]> Signed-off-by: Jonathan Corbet <[email protected]>
2019-05-06Merge branch 'core-objtool-for-linus' of ↵Linus Torvalds11-102/+382
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull objtool updates from Ingo Molnar: "This is a series from Peter Zijlstra that adds x86 build-time uaccess validation of SMAP to objtool, which will detect and warn about the following uaccess API usage bugs and weirdnesses: - call to %s() with UACCESS enabled - return with UACCESS enabled - return with UACCESS disabled from a UACCESS-safe function - recursive UACCESS enable - redundant UACCESS disable - UACCESS-safe disables UACCESS As it turns out not leaking uaccess permissions outside the intended uaccess functionality is hard when the interfaces are complex and when such bugs are mostly dormant. As a bonus we now also check the DF flag. We had at least one high-profile bug in that area in the early days of Linux, and the checking is fairly simple. The checks performed and warnings emitted are: - call to %s() with DF set - return with DF set - return with modified stack frame - recursive STD - redundant CLD It's all x86-only for now, but later on this can also be used for PAN on ARM and objtool is fairly cross-platform in principle. While all warnings emitted by this new checking facility that got reported to us were fixed, there might be GCC version dependent warnings that were not reported yet - which we'll address, should they trigger. The warnings are non-fatal build warnings" * 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions x86/uaccess: Dont leak the AC flag into __put_user() argument evaluation sched/x86_64: Don't save flags on context switch objtool: Add Direction Flag validation objtool: Add UACCESS validation objtool: Fix sibling call detection objtool: Rewrite alt->skip_orig objtool: Add --backtrace support objtool: Rewrite add_ignores() objtool: Handle function aliases objtool: Set insn->func for alternatives x86/uaccess, kcov: Disable stack protector x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP x86/uaccess, ubsan: Fix UBSAN vs. SMAP x86/uaccess, kasan: Fix KASAN vs SMAP x86/smap: Ditch __stringify() x86/uaccess: Introduce user_access_{save,restore}() x86/uaccess, signal: Fix AC=1 bloat x86/uaccess: Always inline user_access_begin() x86/uaccess, xen: Suppress SMAP warnings ...
2019-04-05objtool: Add rewind_stack_do_exit() to the noreturn listJosh Poimboeuf1-0/+1
This fixes the following warning seen on GCC 7.3: arch/x86/kernel/dumpstack.o: warning: objtool: oops_end() falls through to next function show_regs() Reported-by: kbuild test robot <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Cc: Peter Zijlstra <[email protected]> Link: https://lkml.kernel.org/r/3418ebf5a5a9f6ed7e80954c741c0b904b67b5dc.1554398240.git.jpoimboe@redhat.com
2019-04-03objtool: Add Direction Flag validationPeter Zijlstra4-2/+37
Having DF escape is BAD(tm). Linus; you suggested this one, but since DF really is only used from ASM and the failure case is fairly obvious, do we really need this? OTOH the patch is fairly small and simple, so let's just do this to demonstrate objtool's superior awesomeness. Suggested-by: Linus Torvalds <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2019-04-03objtool: Add UACCESS validationPeter Zijlstra9-21/+223
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) <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2019-04-03objtool: Fix sibling call detectionPeter Zijlstra1-31/+55
It turned out that we failed to detect some sibling calls; specifically those without relocation records; like: $ ./objdump-func.sh defconfig-build/mm/kasan/generic.o __asan_loadN 0000 0000000000000840 <__asan_loadN>: 0000 840: 48 8b 0c 24 mov (%rsp),%rcx 0004 844: 31 d2 xor %edx,%edx 0006 846: e9 45 fe ff ff jmpq 690 <check_memory_region> So extend the cross-function jump to also consider those that are not between known (or newly detected) parent/child functions, as sibling-cals when they jump to the start of the function. The second part of that condition is to deal with random jumps to the middle of other function, as can be found in arch/x86/lib/copy_user_64.S for example. This then (with later patches applied) makes the above recognise the sibling call: mm/kasan/generic.o: warning: objtool: __asan_loadN()+0x6: call to check_memory_region() with UACCESS enabled Also make sure to set insn->call_dest for sibling calls so we can know who we're calling. This is useful information when printing validation warnings later. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2019-04-03objtool: Rewrite alt->skip_origPeter Zijlstra1-6/+10
Really skip the original instruction flow, instead of letting it continue with NOPs. Since the alternative code flow already continues after the original instructions, only the alt-original is skipped. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2019-04-03objtool: Add --backtrace supportPeter Zijlstra4-6/+25
For when you want to know the path that reached your fail state: $ ./objtool check --no-fp --backtrace arch/x86/lib/usercopy_64.o arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0x3: UACCESS disable without MEMOPs: __clear_user() arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x3a: (alt) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x2e: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x18: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0xffffffffffffffff: (branch) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x5: (alt) arch/x86/lib/usercopy_64.o: warning: objtool: __clear_user()+0x0: <=== (func) 0000000000000000 <__clear_user>: 0: e8 00 00 00 00 callq 5 <__clear_user+0x5> 1: R_X86_64_PLT32 __fentry__-0x4 5: 90 nop 6: 90 nop 7: 90 nop 8: 48 89 f0 mov %rsi,%rax b: 48 c1 ee 03 shr $0x3,%rsi f: 83 e0 07 and $0x7,%eax 12: 48 89 f1 mov %rsi,%rcx 15: 48 85 c9 test %rcx,%rcx 18: 74 0f je 29 <__clear_user+0x29> 1a: 48 c7 07 00 00 00 00 movq $0x0,(%rdi) 21: 48 83 c7 08 add $0x8,%rdi 25: ff c9 dec %ecx 27: 75 f1 jne 1a <__clear_user+0x1a> 29: 48 89 c1 mov %rax,%rcx 2c: 85 c9 test %ecx,%ecx 2e: 74 0a je 3a <__clear_user+0x3a> 30: c6 07 00 movb $0x0,(%rdi) 33: 48 ff c7 inc %rdi 36: ff c9 dec %ecx 38: 75 f6 jne 30 <__clear_user+0x30> 3a: 90 nop 3b: 90 nop 3c: 90 nop 3d: 48 89 c8 mov %rcx,%rax 40: c3 retq Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2019-04-03objtool: Rewrite add_ignores()Peter Zijlstra2-32/+20
The whole add_ignores() thing was wildly weird; rewrite it according to 'modern' ways. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2019-04-03objtool: Handle function aliasesPeter Zijlstra2-5/+12
Function aliases result in different symbols for the same set of instructions; track a canonical symbol so there is a unique point of access. This again prepares the way for function attributes. And in particular the need for aliases comes from how KASAN uses them. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2019-04-03objtool: Set insn->func for alternativesPeter Zijlstra1-0/+1
In preparation of function attributes, we need each instruction to have a valid link back to its function. Therefore make sure we set the function association for alternative instruction sequences; they are, after all, still part of the function. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2019-04-03x86/nospec, objtool: Introduce ANNOTATE_IGNORE_ALTERNATIVEPeter Zijlstra1-4/+4
To facillitate other usage of ignoring alternatives; rename ANNOTATE_NOSPEC_IGNORE to ANNOTATE_IGNORE_ALTERNATIVE. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2019-03-28objtool: Query pkg-config for libelf locationRolf Eike Beer1-2/+5
If it is not in the default location, compilation fails at several points. Signed-off-by: Rolf Eike Beer <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/91a25e992566a7968fedc89ec80e7f4c83ad0548.1553622500.git.jpoimboe@redhat.com
2019-03-21objtool: Move objtool_file struct off the stackJosh Poimboeuf1-1/+2
Objtool uses over 512k of stack, thanks to the hash table embedded in the objtool_file struct. This causes an unnecessarily large stack allocation and breaks users with low stack limits. Move the struct off the stack. Fixes: 042ba73fe7eb ("objtool: Add several performance improvements") Reported-by: Vassili Karpov <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/df92dcbc4b84b02ffa252f46876df125fb56e2d7.1552954176.git.jpoimboe@redhat.com
2018-11-20objtool: Fix segfault in .cold detection with -ffunction-sectionsArtem Savkov1-3/+14
Because find_symbol_by_name() traverses the same lists as read_symbols(), changing sym->name in place without copying it affects the result of find_symbol_by_name(). In the case where a ".cold" function precedes its parent in sec->symbol_list, it can result in a function being considered a parent of itself. This leads to function length being set to 0 and other consequent side-effects including a segfault in add_switch_table(). The effects of this bug are only visible when building with -ffunction-sections in KCFLAGS. Fix by copying the search string instead of modifying it in place. Signed-off-by: Artem Savkov <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") Link: http://lkml.kernel.org/r/910abd6b5a4945130fd44f787c24e07b9e07c8da.1542736240.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <[email protected]>
2018-11-20objtool: Fix double-free in .cold detection error pathArtem Savkov1-1/+1
If read_symbols() fails during second list traversal (the one dealing with ".cold" subfunctions) it frees the symbol, but never deletes it from the list/hash_table resulting in symbol being freed again in elf_close(). Fix it by just returning an error, leaving cleanup to elf_close(). Signed-off-by: Artem Savkov <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") Link: http://lkml.kernel.org/r/beac5a9b7da9e8be90223459dcbe07766ae437dd.1542736240.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <[email protected]>
2018-11-03Merge branch 'core/urgent' into x86/urgent, to pick up objtool fixIngo Molnar1-1/+1
Signed-off-by: Ingo Molnar <[email protected]>
2018-11-01objtool: Support GCC 9 cold subfunction naming schemeJosh Poimboeuf1-1/+1
Starting with GCC 8, a lot of unlikely code was moved out of line to "cold" subfunctions in .text.unlikely. For example, the unlikely bits of: irq_do_set_affinity() are moved out to the following subfunction: irq_do_set_affinity.cold.49() Starting with GCC 9, the numbered suffix has been removed. So in the above example, the cold subfunction is instead: irq_do_set_affinity.cold() Tweak the objtool subfunction detection logic so that it detects both GCC 8 and GCC 9 naming schemes. Reported-by: Peter Zijlstra (Intel) <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Peter Zijlstra (Intel) <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/015e9544b1f188d36a7f02fa31e9e95629aa5f50.1541040800.git.jpoimboe@redhat.com
2018-10-29Merge branches 'x86/early-printk', 'x86/microcode' and 'core/objtool' into ↵Ingo Molnar4-9/+37
x86/urgent, to pick up simple topic branches Signed-off-by: Ingo Molnar <[email protected]>
2018-09-27x86/jump_table: Use relative referencesArd Biesheuvel1-2/+2
Similar to the arm64 case, 64-bit x86 can benefit from using relative references rather than absolute ones when emitting struct jump_entry instances. Not only does this reduce the memory footprint of the entries themselves by 33%, it also removes the need for carrying relocation metadata on relocatable builds (i.e., for KASLR) which saves a fair chunk of .init space as well (although the savings are not as dramatic as on arm64) Signed-off-by: Ard Biesheuvel <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Cc: [email protected] Cc: [email protected] Cc: Arnd Bergmann <[email protected]> Cc: Heiko Carstens <[email protected]> Cc: Kees Cook <[email protected]> Cc: Will Deacon <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Martin Schwidefsky <[email protected]> Cc: Jessica Yu <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2018-09-08objtool: Support per-function rodata sectionsAllan Xavier4-9/+37
Add support for processing switch jump tables in objects with multiple .rodata sections, such as those created by '-ffunction-sections' and '-fdata-sections'. Currently, objtool always looks in .rodata for jump table information, which results in many "sibling call from callable instruction with modified stack frame" warnings with objects compiled using those flags. The fix is comprised of three parts: 1. Flagging all .rodata sections when importing ELF information for easier checking later. 2. Keeping a reference to the section each relocation is from in order to get the list_head for the other relocations in that section. 3. Finding jump tables by following relocations to .rodata sections, rather than always referencing a single global .rodata section. The patch has been tested without data sections enabled and no differences in the resulting orc unwind information were seen. Note that as objtool adds terminators to end of each .text section the unwind information generated between a function+data sections build and a normal build aren't directly comparable. Manual inspection suggests that objtool is now generating the correct information, or at least making more of an effort to do so than it did previously. Signed-off-by: Allan Xavier <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com
2018-08-15Merge tag 'kbuild-v4.19' of ↵Linus Torvalds1-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: - verify depmod is installed before modules_install - support build salt in case build ids must be unique between builds - allow users to specify additional host compiler flags via HOST*FLAGS, and rename internal variables to KBUILD_HOST*FLAGS - update buildtar script to drop vax support, add arm64 support - update builddeb script for better debarch support - document the pit-fall of if_changed usage - fix parallel build of UML with O= option - make 'samples' target depend on headers_install to fix build errors - remove deprecated host-progs variable - add a new coccinelle script for refcount_t vs atomic_t check - improve double-test coccinelle script - misc cleanups and fixes * tag 'kbuild-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (41 commits) coccicheck: return proper error code on fail Coccinelle: doubletest: reduce side effect false positives kbuild: remove deprecated host-progs variable kbuild: make samples really depend on headers_install um: clean up archheaders recipe kbuild: add %asm-generic to no-dot-config-targets um: fix parallel building with O= option scripts: Add Python 3 support to tracing/draw_functrace.py builddeb: Add automatic support for sh{3,4}{,eb} architectures builddeb: Add automatic support for riscv* architectures builddeb: Add automatic support for m68k architecture builddeb: Add automatic support for or1k architecture builddeb: Add automatic support for sparc64 architecture builddeb: Add automatic support for mips{,64}r6{,el} architectures builddeb: Add automatic support for mips64el architecture builddeb: Add automatic support for ppc64 and powerpcspe architectures builddeb: Introduce functions to simplify kconfig tests in set_debarch builddeb: Drop check for 32-bit s390 builddeb: Change architecture detection fallback to use dpkg-architecture builddeb: Skip architecture detection when KBUILD_DEBARCH is set ...
2018-08-13Merge branch 'x86-asm-for-linus' of ↵Linus Torvalds5-2/+8
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 asm updates from Thomas Gleixner: "The lowlevel and ASM code updates for x86: - Make stack trace unwinding more reliable - ASM instruction updates for better code generation - Various cleanups" * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/entry/64: Add two more instruction suffixes x86/asm/64: Use 32-bit XOR to zero registers x86/build/vdso: Simplify 'cmd_vdso2c' x86/build/vdso: Remove unused vdso-syms.lds x86/stacktrace: Enable HAVE_RELIABLE_STACKTRACE for the ORC unwinder x86/unwind/orc: Detect the end of the stack x86/stacktrace: Do not fail for ORC with regs on stack x86/stacktrace: Clarify the reliable success paths x86/stacktrace: Remove STACKTRACE_DUMP_ONCE x86/stacktrace: Do not unwind after user regs x86/asm: Use CC_SET/CC_OUT in percpu_cmpxchg8b_double() to micro-optimize code generation
2018-07-18kbuild: Rename HOSTLDFLAGS to KBUILD_HOSTLDFLAGSLaura Abbott1-1/+1
In preparation for enabling command line LDFLAGS, re-name HOSTLDFLAGS to KBUILD_HOSTLDFLAGS as the internal use only flags. This should not have any visible effects. Signed-off-by: Laura Abbott <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]>
2018-07-18kbuild: Rename HOSTCFLAGS to KBUILD_HOSTCFLAGSLaura Abbott1-1/+1
In preparation for enabling command line CFLAGS, re-name HOSTCFLAGS to KBUILD_HOSTCFLAGS as the internal use only flags. This should not have any visible effects. Signed-off-by: Laura Abbott <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]>
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