kernel/linux.git/tools/objtool/builtin-check.c, branch v4.9.166

objtool: sync up with the 4.14.47 version of objtool

2018-06-05T08:28:57+00:00

There are pros and cons of dealing with tools in the kernel directory. The pros are the fact that development happens fast, and new features can be added to the kernel and the tools at the same times. The cons are when dealing with backported kernel patches, it can be necessary to backport parts of the tool changes as well. For 4.9.y so far, we have backported individual patches. That quickly breaks down when there are minor differences between how backports were handled, so grabbing 40+ patch long series can be difficult, not impossible, but really frustrating to attempt. To help mitigate this mess, here's a single big patch to sync up the objtool logic to the 4.14.47 version of the tool. From this point forward (after some other minor header file patches are applied), the tool should be in sync and much easier to maintain over time. This has survivied my limited testing, and as the codebase is identical to 4.14.47, I'm pretty comfortable dropping this big change in here in 4.9.y. Hopefully all goes well... Cc: Josh Poimboeuf Signed-off-by: Greg Kroah-Hartman

objtool: Move checking code to check.c

2018-06-05T08:28:55+00:00

commit dcc914f44f065ef73685b37e59877a5bb3cb7358 upstream. 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 Reviewed-by: Jiri Slaby Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/294c5c695fd73c1a5000bbe5960a7c9bec4ee6b4.1498659915.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar [backported by hand to 4.9, this was a pain... - gregkh] Signed-off-by: Greg Kroah-Hartman

objtool: Improve detection of BUG() and other dead ends

2018-06-05T08:28:55+00:00

commit d1091c7fa3d52ebce4dd3f15d04155b3469b2f90 upstream. 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) Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/41a6d33971462ebd944a1c60ad4bf5be86c17b77.1487712920.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

objtool: Fix retpoline support for pre-ORC objtool

2018-01-17T08:39:00+00:00

Objtool 1.0 (pre-ORC) produces the following warning when it encounters a retpoline: arch/x86/crypto/camellia-aesni-avx2-asm_64.o: warning: objtool: .altinstr_replacement+0xf: return instruction outside of a callable function That warning is meant to catch GCC bugs and missing ENTRY/ENDPROC annotations, neither of which are applicable to alternatives. Silence the warning for alternative instructions, just like objtool 2.0 already does. Reported-by: David Woodhouse Signed-off-by: Josh Poimboeuf Signed-off-by: Greg Kroah-Hartman

objtool: Allow alternatives to be ignored

2018-01-17T08:38:58+00:00

commit 258c76059cece01bebae098e81bacb1af2edad17 upstream. Getting objtool to understand retpolines is going to be a bit of a challenge. For now, take advantage of the fact that retpolines are patched in with alternatives. Just read the original (sane) non-alternative instruction, and ignore the patched-in retpoline. This allows objtool to understand the control flow *around* the retpoline, even if it can't yet follow what's inside. This means the ORC unwinder will fail to unwind from inside a retpoline, but will work fine otherwise. Signed-off-by: Josh Poimboeuf Signed-off-by: David Woodhouse Signed-off-by: Thomas Gleixner Cc: gnomes@lxorguk.ukuu.org.uk Cc: Rik van Riel Cc: Andi Kleen Cc: thomas.lendacky@amd.com Cc: Peter Zijlstra Cc: Linus Torvalds Cc: Jiri Kosina Cc: Andy Lutomirski Cc: Dave Hansen Cc: Kees Cook Cc: Tim Chen Cc: Greg Kroah-Hartman Cc: Paul Turner Link: https://lkml.kernel.org/r/1515707194-20531-3-git-send-email-dwmw@amazon.co.uk [dwmw2: Applies to tools/objtool/builtin-check.c not check.[ch]] Signed-off-by: David Woodhouse Signed-off-by: Greg Kroah-Hartman

objtool: Detect jumps to retpoline thunks

2018-01-17T08:38:58+00:00

commit 39b735332cb8b33a27c28592d969e4016c86c3ea upstream. A direct jump to a retpoline thunk is really an indirect jump in disguise. Change the objtool instruction type accordingly. Objtool needs to know where indirect branches are so it can detect switch statement jump tables. This fixes a bunch of warnings with CONFIG_RETPOLINE like: arch/x86/events/intel/uncore_nhmex.o: warning: objtool: nhmex_rbox_msr_enable_event()+0x44: sibling call from callable instruction with modified stack frame kernel/signal.o: warning: objtool: copy_siginfo_to_user()+0x91: sibling call from callable instruction with modified stack frame ... Signed-off-by: Josh Poimboeuf Signed-off-by: David Woodhouse Signed-off-by: Thomas Gleixner Cc: gnomes@lxorguk.ukuu.org.uk Cc: Rik van Riel Cc: Andi Kleen Cc: thomas.lendacky@amd.com Cc: Peter Zijlstra Cc: Linus Torvalds Cc: Jiri Kosina Cc: Andy Lutomirski Cc: Dave Hansen Cc: Kees Cook Cc: Tim Chen Cc: Greg Kroah-Hartman Cc: Paul Turner Link: https://lkml.kernel.org/r/1515707194-20531-2-git-send-email-dwmw@amazon.co.uk [dwmw2: Applies to tools/objtool/builtin-check.c not check.c] Signed-off-by: David Woodhouse Signed-off-by: Greg Kroah-Hartman

objtool, modules: Discard objtool annotation sections for modules

2018-01-17T08:38:58+00:00

commit e390f9a9689a42f477a6073e2e7df530a4c1b740 upstream. 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 Signed-off-by: Josh Poimboeuf Cc: Jessica Yu Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends") Link: http://lkml.kernel.org/r/20170301180444.lhd53c5tibc4ns77@treble Signed-off-by: Ingo Molnar [dwmw2: Remove the unreachable part in backporting since it's not here yet] Signed-off-by: David Woodhouse Signed-off-by: Greg Kroah-Hartman

objtool: Fix another GCC jump table detection issue

2017-07-05T12:40:30+00:00

commit 5c51f4ae84df0f9df33ac08aa5be50061a8b4242 upstream. 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 Tested-by: Arnd Bergmann Signed-off-by: Josh Poimboeuf Cc: Denys Vlasenko Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 3732710ff6f2 ("objtool: Improve rare switch jump table pattern detection") Link: http://lkml.kernel.org/r/20170302225723.3ndbsnl4hkqbne7a@treble Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

objtool: Fix rare switch jump table pattern detection

2016-10-27T06:20:27+00:00

The following commit: 3732710ff6f2 ("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 Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 3732710ff6f2 ("objtool: Improve rare switch jump table pattern detection") Link: http://lkml.kernel.org/r/20161026153408.2rifnw7bvoc5sex7@treble Signed-off-by: Ingo Molnar

objtool: Skip all "unreachable instruction" warnings for gcov kernels

2016-10-16T07:12:36+00:00

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 Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/38d5c87d61d9cd46486dd2c86f46603dff0df86f.1476393584.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar