1. 06 Dec, 2017 1 commit
    • Mikulas Patocka's avatar
      objtool: Fix 64-bit build on 32-bit host · 14c47b54
      Mikulas Patocka authored
      The new ORC unwinder breaks the build of a 64-bit kernel on a 32-bit
      host.  Building the kernel on a i386 or x32 host fails with:
      
        orc_dump.c: In function 'orc_dump':
        orc_dump.c:105:26: error: passing argument 2 of 'elf_getshdrnum' from incompatible pointer type [-Werror=incompatible-pointer-types]
          if (elf_getshdrnum(elf, &nr_sections)) {
                                  ^
        In file included from /usr/local/include/gelf.h:32:0,
                         from elf.h:22,
                         from warn.h:26,
                         from orc_dump.c:20:
        /usr/local/include/libelf.h:304:12: note: expected 'size_t * {aka unsigned int *}' but argument is of type 'long unsigned int *'
         extern int elf_getshdrnum (Elf *__elf, size_t *__dst);
                    ^~~~~~~~~~~~~~
        orc_dump.c:190:17: error: format '%lx' expects argument of type 'long unsigned int', but argument 3 has type 'Elf64_Sxword {aka long long int}' [-Werror=format=]
            printf("%s+%lx:", name, rela.r_addend);
                       ~~^          ~~~~~~~~~~~~~
                       %llx
      
      Fix the build failure.
      
      Another problem is that if the user specifies HOSTCC or HOSTLD
      variables, they are ignored in the objtool makefile.  Change the
      Makefile to respect these variables.
      Signed-off-by: 's avatarMikulas Patocka <mpatocka@redhat.com>
      Signed-off-by: 's avatarJosh Poimboeuf <jpoimboe@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Sven Joachim <svenjoac@gmx.de>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Fixes: 627fce14 ("objtool: Add ORC unwind table generation")
      Link: http://lkml.kernel.org/r/19f0e64d8e07e30a7b307cd010eb780c404fe08d.1512252895.git.jpoimboe@redhat.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      14c47b54
  2. 14 Nov, 2017 1 commit
    • Ingo Molnar's avatar
      tools/headers: Sync objtool UAPI header · a356d2ae
      Ingo Molnar authored
      objtool grew this new warning:
      
        Warning: synced file at 'tools/objtool/arch/x86/include/asm/inat.h' differs from latest kernel version at 'arch/x86/include/asm/inat.h'
      
      which upstream header grew new INAT_SEG_* definitions.
      
      Sync up the tooling version of the header.
      Reported-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      a356d2ae
  3. 08 Nov, 2017 1 commit
  4. 07 Nov, 2017 2 commits
  5. 04 Nov, 2017 1 commit
  6. 02 Nov, 2017 1 commit
    • Greg Kroah-Hartman's avatar
      License cleanup: add SPDX GPL-2.0 license identifier to files with no license · b2441318
      Greg Kroah-Hartman authored
      Many source files in the tree are missing licensing information, which
      makes it harder for compliance tools to determine the correct license.
      
      By default all files without license information are under the default
      license of the kernel, which is GPL version 2.
      
      Update the files which contain no license information with the 'GPL-2.0'
      SPDX license identifier.  The SPDX identifier is a legally binding
      shorthand, which can be used instead of the full boiler plate text.
      
      This patch is based on work done by Thomas Gleixner and Kate Stewart and
      Philippe Ombredanne.
      
      How this work was done:
      
      Patches were generated and checked against linux-4.14-rc6 for a subset of
      the use cases:
       - file had no licensing information it it.
       - file was a */uapi/* one with no licensing information in it,
       - file was a */uapi/* one with existing licensing information,
      
      Further patches will be generated in subsequent months to fix up cases
      where non-standard license headers were used, and references to license
      had to be inferred by heuristics based on keywords.
      
      The analysis to determine which SPDX License Identifier to be applied to
      a file was done in a spreadsheet of side by side results from of the
      output of two independent scanners (ScanCode & Windriver) producing SPDX
      tag:value files created by Philippe Ombredanne.  Philippe prepared the
      base worksheet, and did an initial spot review of a few 1000 files.
      
      The 4.13 kernel was the starting point of the analysis with 60,537 files
      assessed.  Kate Stewart did a file by file comparison of the scanner
      results in the spreadsheet to determine which SPDX license identifier(s)
      to be applied to the file. She confirmed any determination that was not
      immediately clear with lawyers working with the Linux Foundation.
      
      Criteria used to select files for SPDX license identifier tagging was:
       - Files considered eligible had to be source code files.
       - Make and config files were included as candidates if they contained >5
         lines of source
       - File already had some variant of a license header in it (even if <5
         lines).
      
      All documentation files were explicitly excluded.
      
      The following heuristics were used to determine which SPDX license
      identifiers to apply.
      
       - when both scanners couldn't find any license traces, file was
         considered to have no license information in it, and the top level
         COPYING file license applied.
      
         For non */uapi/* files that summary was:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|-------
         GPL-2.0                                              11139
      
         and resulted in the first patch in this series.
      
         If that file was a */uapi/* path one, it was "GPL-2.0 WITH
         Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|-------
         GPL-2.0 WITH Linux-syscall-note                        930
      
         and resulted in the second patch in this series.
      
       - if a file had some form of licensing information in it, and was one
         of the */uapi/* ones, it was denoted with the Linux-syscall-note if
         any GPL family license was found in the file or had no licensing in
         it (per prior point).  Results summary:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|------
         GPL-2.0 WITH Linux-syscall-note                       270
         GPL-2.0+ WITH Linux-syscall-note                      169
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
         LGPL-2.1+ WITH Linux-syscall-note                      15
         GPL-1.0+ WITH Linux-syscall-note                       14
         ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
         LGPL-2.0+ WITH Linux-syscall-note                       4
         LGPL-2.1 WITH Linux-syscall-note                        3
         ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
         ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1
      
         and that resulted in the third patch in this series.
      
       - when the two scanners agreed on the detected license(s), that became
         the concluded license(s).
      
       - when there was disagreement between the two scanners (one detected a
         license but the other didn't, or they both detected different
         licenses) a manual inspection of the file occurred.
      
       - In most cases a manual inspection of the information in the file
         resulted in a clear resolution of the license that should apply (and
         which scanner probably needed to revisit its heuristics).
      
       - When it was not immediately clear, the license identifier was
         confirmed with lawyers working with the Linux Foundation.
      
       - If there was any question as to the appropriate license identifier,
         the file was flagged for further research and to be revisited later
         in time.
      
      In total, over 70 hours of logged manual review was done on the
      spreadsheet to determine the SPDX license identifiers to apply to the
      source files by Kate, Philippe, Thomas and, in some cases, confirmation
      by lawyers working with the Linux Foundation.
      
      Kate also obtained a third independent scan of the 4.13 code base from
      FOSSology, and compared selected files where the other two scanners
      disagreed against that SPDX file, to see if there was new insights.  The
      Windriver scanner is based on an older version of FOSSology in part, so
      they are related.
      
      Thomas did random spot checks in about 500 files from the spreadsheets
      for the uapi headers and agreed with SPDX license identifier in the
      files he inspected. For the non-uapi files Thomas did random spot checks
      in about 15000 files.
      
      In initial set of patches against 4.14-rc6, 3 files were found to have
      copy/paste license identifier errors, and have been fixed to reflect the
      correct identifier.
      
      Additionally Philippe spent 10 hours this week doing a detailed manual
      inspection and review of the 12,461 patched files from the initial patch
      version early this week with:
       - a full scancode scan run, collecting the matched texts, detected
         license ids and scores
       - reviewing anything where there was a license detected (about 500+
         files) to ensure that the applied SPDX license was correct
       - reviewing anything where there was no detection but the patch license
         was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
         SPDX license was correct
      
      This produced a worksheet with 20 files needing minor correction.  This
      worksheet was then exported into 3 different .csv files for the
      different types of files to be modified.
      
      These .csv files were then reviewed by Greg.  Thomas wrote a script to
      parse the csv files and add the proper SPDX tag to the file, in the
      format that the file expected.  This script was further refined by Greg
      based on the output to detect more types of files automatically and to
      distinguish between header and source .c files (which need different
      comment types.)  Finally Greg ran the script using the .csv files to
      generate the patches.
      Reviewed-by: 's avatarKate Stewart <kstewart@linuxfoundation.org>
      Reviewed-by: 's avatarPhilippe Ombredanne <pombredanne@nexb.com>
      Reviewed-by: 's avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b2441318
  7. 20 Oct, 2017 1 commit
  8. 18 Oct, 2017 1 commit
  9. 28 Sep, 2017 2 commits
  10. 23 Sep, 2017 2 commits
    • Josh Poimboeuf's avatar
      x86/asm: Fix inline asm call constraints for Clang · f5caf621
      Josh Poimboeuf authored
      For inline asm statements which have a CALL instruction, we list the
      stack pointer as a constraint to convince GCC to ensure the frame
      pointer is set up first:
      
        static inline void foo()
        {
      	register void *__sp asm(_ASM_SP);
      	asm("call bar" : "+r" (__sp))
        }
      
      Unfortunately, that pattern causes Clang to corrupt the stack pointer.
      
      The fix is easy: convert the stack pointer register variable to a global
      variable.
      
      It should be noted that the end result is different based on the GCC
      version.  With GCC 6.4, this patch has exactly the same result as
      before:
      
      	defconfig	defconfig-nofp	distro		distro-nofp
       before	9820389		9491555		8816046		8516940
       after	9820389		9491555		8816046		8516940
      
      With GCC 7.2, however, GCC's behavior has changed.  It now changes its
      behavior based on the conversion of the register variable to a global.
      That somehow convinces it to *always* set up the frame pointer before
      inserting *any* inline asm.  (Therefore, listing the variable as an
      output constraint is a no-op and is no longer necessary.)  It's a bit
      overkill, but the performance impact should be negligible.  And in fact,
      there's a nice improvement with frame pointers disabled:
      
      	defconfig	defconfig-nofp	distro		distro-nofp
       before	9796316		9468236		9076191		8790305
       after	9796957		9464267		9076381		8785949
      
      So in summary, while listing the stack pointer as an output constraint
      is no longer necessary for newer versions of GCC, it's still needed for
      older versions.
      Suggested-by: 's avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
      Reported-by: 's avatarMatthias Kaehlcke <mka@chromium.org>
      Signed-off-by: 's avatarJosh Poimboeuf <jpoimboe@redhat.com>
      Cc: Alexander Potapenko <glider@google.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Dmitriy Vyukov <dvyukov@google.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Miguel Bernal Marin <miguel.bernal.marin@linux.intel.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/3db862e970c432ae823cf515c52b54fec8270e0e.1505942196.git.jpoimboe@redhat.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      f5caf621
    • Josh Poimboeuf's avatar
      objtool: Handle another GCC stack pointer adjustment bug · 0d0970ee
      Josh Poimboeuf authored
      The kbuild bot reported the following warning with GCC 4.4 and a
      randconfig:
      
        net/socket.o: warning: objtool: compat_sock_ioctl()+0x1083: stack state mismatch: cfa1=7+160 cfa2=-1+0
      
      This is caused by another GCC non-optimization, where it backs up and
      restores the stack pointer for no apparent reason:
      
          2f91:       48 89 e0                mov    %rsp,%rax
          2f94:       4c 89 e7                mov    %r12,%rdi
          2f97:       4c 89 f6                mov    %r14,%rsi
          2f9a:       ba 20 00 00 00          mov    $0x20,%edx
          2f9f:       48 89 c4                mov    %rax,%rsp
      
      This issue would have been happily ignored before the following commit:
      
        dd88a0a0 ("objtool: Handle GCC stack pointer adjustment bug")
      
      But now that objtool is paying attention to such stack pointer writes
      to/from a register, it needs to understand them properly.  In this case
      that means recognizing that the "mov %rsp, %rax" instruction is
      potentially a backup of the stack pointer.
      Reported-by: 's avatarkbuild test robot <fengguang.wu@intel.com>
      Signed-off-by: 's avatarJosh Poimboeuf <jpoimboe@redhat.com>
      Cc: Alexander Potapenko <glider@google.com>
      Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Dmitriy Vyukov <dvyukov@google.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Matthias Kaehlcke <mka@chromium.org>
      Cc: Miguel Bernal Marin <miguel.bernal.marin@linux.intel.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Fixes: dd88a0a0 ("objtool: Handle GCC stack pointer adjustment bug")
      Link: http://lkml.kernel.org/r/8c7aa8e9a36fbbb6655d9d8e7cea58958c912da8.1505942196.git.jpoimboe@redhat.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      0d0970ee
  11. 15 Sep, 2017 3 commits
  12. 30 Aug, 2017 1 commit
    • Josh Poimboeuf's avatar
      objtool: Handle GCC stack pointer adjustment bug · dd88a0a0
      Josh Poimboeuf authored
      Arnd Bergmann reported the following warning with GCC 7.1.1:
      
        fs/fs_pin.o: warning: objtool: pin_kill()+0x139: stack state mismatch: cfa1=7+88 cfa2=7+96
      
      And the kbuild robot reported the following warnings with GCC 5.4.1:
      
        fs/fs_pin.o: warning: objtool: pin_kill()+0x182: return with modified stack frame
        fs/quota/dquot.o: warning: objtool: dquot_alloc_inode()+0x140: stack state mismatch: cfa1=7+120 cfa2=7+128
        fs/quota/dquot.o: warning: objtool: dquot_free_inode()+0x11a: stack state mismatch: cfa1=7+112 cfa2=7+120
      
      Those warnings are caused by an unusual GCC non-optimization where it
      uses an intermediate register to adjust the stack pointer.  It does:
      
        lea    0x8(%rsp), %rcx
        ...
        mov    %rcx, %rsp
      
      Instead of the obvious:
      
        add    $0x8, %rsp
      
      It makes no sense to use an intermediate register, so I opened a GCC bug
      to track it:
      
        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81813
      
      But it's not exactly a high-priority bug and it looks like we'll be
      stuck with this issue for a while.  So for now we have to track register
      values when they're loaded with stack pointer offsets.
      
      This is kind of a big workaround for a tiny problem, but c'est la vie.
      I hope to eventually create a GCC plugin to implement a big chunk of
      objtool's functionality.  Hopefully at that point we'll be able to
      remove of a lot of these GCC-isms from the objtool code.
      Reported-by: 's avatarArnd Bergmann <arnd@arndb.de>
      Reported-by: 's avatarkbuild test robot <fengguang.wu@intel.com>
      Signed-off-by: 's avatarJosh 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/6a41a96884c725e7f05413bb7df40cfe824b2444.1504028945.git.jpoimboe@redhat.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      dd88a0a0
  13. 21 Aug, 2017 2 commits
  14. 11 Aug, 2017 2 commits
  15. 28 Jul, 2017 4 commits
    • Josh Poimboeuf's avatar
      objtool: Disable GCC '-Wpacked' warnings · 21ec3bf6
      Josh Poimboeuf authored
      Objtool is failing to build with GCC 4.4.7 due to the following
      warnings:
      
        cc1: warnings being treated as errors
        In file included from orc.h:21,
                         from orc_gen.c:21:
        orc_types.h:86: error: packed attribute is unnecessary for ‘sp_offset’
        orc_types.h:87: error: packed attribute is unnecessary for ‘bp_offset’
        orc_types.h:88: error: packed attribute is unnecessary for ‘sp_reg’
      
      I suspect those warnings are a GCC bug.  But -Wpacked isn't very useful
      anyway, so just disable it.
      Signed-off-by: 's avatarJosh Poimboeuf <jpoimboe@redhat.com>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Fixes: 627fce14 ("objtool: Add ORC unwind table generation")
      Link: http://lkml.kernel.org/r/76d85d7b5a87566465095c500bce222ff5d7b146.1501188854.git.jpoimboe@redhat.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      21ec3bf6
    • Josh Poimboeuf's avatar
      objtool: Fix '-mtune=atom' decoding support in objtool 2.0 · 5b8de48e
      Josh Poimboeuf authored
      With '-mtune=atom', which is enabled with CONFIG_MATOM=y, GCC uses some
      unusual instructions for setting up the stack.
      
      Instead of:
      
        mov %rsp, %rbp
      
      it does:
      
        lea (%rsp), %rbp
      
      And instead of:
      
        add imm, %rsp
      
      it does:
      
        lea disp(%rsp), %rsp
      
      Add support for these instructions to the objtool decoder.
      Reported-by: 's avatarArnd Bergmann <arnd@arndb.de>
      Signed-off-by: 's avatarJosh Poimboeuf <jpoimboe@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Fixes: baa41469 ("objtool: Implement stack validation 2.0")
      Link: http://lkml.kernel.org/r/4ea1db896e821226efe1f8e09f270771bde47e65.1501188854.git.jpoimboe@redhat.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      5b8de48e
    • Josh Poimboeuf's avatar
      objtool: Skip unreachable warnings for 'alt' instructions · 0e2bb2bc
      Josh Poimboeuf authored
      When a whitelisted function uses one of the ALTERNATIVE macros, it
      produces false positive warnings like:
      
        arch/x86/kvm/vmx.o: warning: objtool: .altinstr_replacement+0x0: unreachable instruction
        arch/x86/kvm/svm.o: warning: objtool: .altinstr_replacement+0x6e: unreachable instruction
      
      There's no easy way to whitelist alternative instructions, so instead
      just skip any 'unreachable' warnings associated with them.
      Reported-by: 's avatarArnd Bergmann <arnd@arndb.de>
      Signed-off-by: 's avatarJosh 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/a5d0a8c60155f03b36a31fac871e12cf75f35fd0.1501188854.git.jpoimboe@redhat.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      0e2bb2bc
    • Josh Poimboeuf's avatar
      objtool: Assume unannotated UD2 instructions are dead ends · 649ea4d5
      Josh Poimboeuf authored
      Arnd reported some false positive warnings with GCC 7:
      
        drivers/hid/wacom_wac.o: warning: objtool: wacom_bpt3_touch()+0x2a5: stack state mismatch: cfa1=7+8 cfa2=6+16
        drivers/iio/adc/vf610_adc.o: warning: objtool: vf610_adc_calculate_rates() falls through to next function vf610_adc_sample_set()
        drivers/pwm/pwm-hibvt.o: warning: objtool: hibvt_pwm_get_state() falls through to next function hibvt_pwm_remove()
        drivers/pwm/pwm-mediatek.o: warning: objtool: mtk_pwm_config() falls through to next function mtk_pwm_enable()
        drivers/spi/spi-bcm2835.o: warning: objtool: .text: unexpected end of section
        drivers/spi/spi-bcm2835aux.o: warning: objtool: .text: unexpected end of section
        drivers/watchdog/digicolor_wdt.o: warning: objtool: dc_wdt_get_timeleft() falls through to next function dc_wdt_restart()
      
      When GCC 7 detects a potential divide-by-zero condition, it sometimes
      inserts a UD2 instruction for the case where the divisor is zero,
      instead of letting the hardware trap on the divide instruction.
      
      Objtool doesn't consider UD2 to be fatal unless it's annotated with
      unreachable().  So it considers the GCC-generated UD2 to be non-fatal,
      and it tries to follow the control flow past the UD2 and gets
      confused.
      
      Previously, objtool *did* assume UD2 was always a dead end.  That
      changed with the following commit:
      
        d1091c7f ("objtool: Improve detection of BUG() and other dead ends")
      
      The motivation behind that change was that Peter was planning on using
      UD2 for __WARN(), which is *not* a dead end.  However, it turns out
      that some emulators rely on UD2 being fatal, so he ended up using
      'ud0' instead:
      
        9a93848f ("x86/debug: Implement __WARN() using UD0")
      
      For GCC 4.5+, it should be safe to go back to the previous assumption
      that UD2 is fatal, even when it's not annotated with unreachable().
      
      But for pre-4.5 versions of GCC, the unreachable() macro isn't
      supported, so such cases of UD2 need to be explicitly annotated as
      reachable.
      Reported-by: 's avatarArnd Bergmann <arnd@arndb.de>
      Signed-off-by: 's avatarJosh Poimboeuf <jpoimboe@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Fixes: d1091c7f ("objtool: Improve detection of BUG() and other dead ends")
      Link: http://lkml.kernel.org/r/e57fa9dfede25f79487da8126ee9cdf7b856db65.1501188854.git.jpoimboe@redhat.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      649ea4d5
  16. 25 Jul, 2017 1 commit
  17. 18 Jul, 2017 2 commits
    • Josh Poimboeuf's avatar
      objtool, x86: Add facility for asm code to provide unwind hints · 39358a03
      Josh Poimboeuf authored
      Some asm (and inline asm) code does special things to the stack which
      objtool can't understand.  (Nor can GCC or GNU assembler, for that
      matter.)  In such cases we need a facility for the code to provide
      annotations, so the unwinder can unwind through it.
      
      This provides such a facility, in the form of unwind hints.  They're
      similar to the GNU assembler .cfi* directives, but they give more
      information, and are needed in far fewer places, because objtool can
      fill in the blanks by following branches and adjusting the stack pointer
      for pushes and pops.
      Signed-off-by: 's avatarJosh 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/0f5f3c9104fca559ff4088bece1d14ae3bca52d5.1499786555.git.jpoimboe@redhat.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      39358a03
    • Josh Poimboeuf's avatar
      objtool: Add ORC unwind table generation · 627fce14
      Josh Poimboeuf authored
      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: 's avatarJosh 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.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      627fce14
  18. 08 Jul, 2017 1 commit
    • Josh Poimboeuf's avatar
      objtool: Fix sibling call detection logic · 4855022a
      Josh Poimboeuf authored
      With some configs, objtool reports the following warning:
      
        arch/x86/kernel/ftrace.o: warning: objtool: ftrace_modify_code_direct()+0x2d: sibling call from callable instruction with modified stack frame
      
      The instruction it's complaining about isn't actually a sibling call.
      It's just a normal jump to an address inside the function.  Objtool
      thought it was a sibling call because the instruction's jump_dest wasn't
      initialized because the function was supposed to be ignored due to its
      use of sync_core().
      
      Objtool ended up validating the function instead of ignoring it because
      it didn't properly recognize a sibling call to the function.  So fix the
      sibling call logic.  Also add a warning to catch ignored functions being
      validated so we'll get a more useful error message next time.
      Reported-by: 's avatarMike Galbraith <efault@gmx.de>
      Signed-off-by: 's avatarJosh 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/96cc8ecbcdd8cb29ddd783817b4af918a6a171b0.1499437107.git.jpoimboe@redhat.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      4855022a
  19. 30 Jun, 2017 3 commits
  20. 27 Jun, 2017 1 commit
  21. 16 Jun, 2017 1 commit
  22. 19 Apr, 2017 1 commit
  23. 07 Mar, 2017 1 commit
    • Josh Poimboeuf's avatar
      objtool: Fix another GCC jump table detection issue · 5c51f4ae
      Josh Poimboeuf authored
      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: 's avatarArnd Bergmann <arnd@arndb.de>
      Tested-by: 's avatarArnd Bergmann <arnd@arndb.de>
      Signed-off-by: 's avatarJosh 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: 3732710f ("objtool: Improve rare switch jump table pattern detection")
      Link: http://lkml.kernel.org/r/20170302225723.3ndbsnl4hkqbne7a@trebleSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      5c51f4ae
  24. 01 Mar, 2017 1 commit
  25. 24 Feb, 2017 1 commit
    • Josh Poimboeuf's avatar
      objtool: Improve detection of BUG() and other dead ends · d1091c7f
      Josh Poimboeuf authored
      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: 's avatarPeter Zijlstra (Intel) <peterz@infradead.org>
      Signed-off-by: 's avatarJosh 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.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      d1091c7f
  26. 19 Jan, 2017 1 commit
  27. 11 Dec, 2016 1 commit