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2017-03-07objtool: Fix another GCC jump table detection issueJosh Poimboeuf
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: 3732710ff6f2 ("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>
2017-03-01objtool, modules: Discard objtool annotation sections for modulesJosh Poimboeuf
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: d1091c7fa3d5 ("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>
2017-02-24objtool: Improve detection of BUG() and other dead endsJosh Poimboeuf
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>
2017-01-19objtool: Fix IRET's opcodeJiri Slaby
The IRET opcode is 0xcf according to the Intel manual and also to objdump of my vmlinux: 1ea8: 48 cf iretq Fix the opcode in arch_decode_instruction(). The previous value (0xc5) seems to correspond to LDS. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-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/20170118132921.19319-1-jslaby@suse.cz Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-12-17Merge branch 'kbuild' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild Pull kbuild updates from Michal Marek: - prototypes for x86 asm-exported symbols (Adam Borowski) and a warning about missing CRCs (Nick Piggin) - asm-exports fix for LTO (Nicolas Pitre) - thin archives improvements (Nick Piggin) - linker script fix for CONFIG_LD_DEAD_CODE_DATA_ELIMINATION (Nick Piggin) - genksyms support for __builtin_va_list keyword - misc minor fixes * 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild: x86/kbuild: enable modversions for symbols exported from asm kbuild: fix scripts/adjust_autoksyms.sh* for the no modules case scripts/kallsyms: remove last remnants of --page-offset option make use of make variable CURDIR instead of calling pwd kbuild: cmd_export_list: tighten the sed script kbuild: minor improvement for thin archives build kbuild: modpost warn if export version crc is missing kbuild: keep data tables through dead code elimination kbuild: improve linker compatibility with lib-ksyms.o build genksyms: Regenerate parser kbuild/genksyms: handle va_list type kbuild: thin archives for multi-y targets kbuild: kallsyms allow 3-pass generation if symbols size has changed
2016-12-11make use of make variable CURDIR instead of calling pwdUwe Kleine-König
make already provides the current working directory in a variable, so make use of it instead of forking a shell. Also replace usage of PWD by CURDIR. PWD is provided by most shells, but not all, so this makes the build system more robust. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Michal Marek <mmarek@suse.com>
2016-12-06objtool: Fix bytes check of lea's rex_prefixJiri Slaby
For the "lea %(rsp), %rbp" case, we check if there is a rex_prefix. But we check 'bytes' which is insn_byte_t[4] in rex_prefix (insn_field structure). Therefore, the check is always true. Instead, check 'nbytes' which is the right one. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-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/20161205105551.25917-1-jslaby@suse.cz Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-10-27objtool: Fix rare switch jump table pattern detectionJosh Poimboeuf
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 <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: 3732710ff6f2 ("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>
2016-10-16objtool: Skip all "unreachable instruction" warnings for gcov kernelsJosh Poimboeuf
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>
2016-10-16objtool: Improve rare switch jump table pattern detectionJosh Poimboeuf
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>
2016-10-11objtool: Support '-mtune=atom' stack frame setup instructionJosh Poimboeuf
Arnd reported that enabling CONFIG_MATOM results in a bunch of objtool false positive frame pointer warnings: arch/x86/events/intel/ds.o: warning: objtool: intel_pmu_pebs_del()+0x43: call without frame pointer save/setup security/keys/keyring.o: warning: objtool: keyring_read()+0x59: call without frame pointer save/setup kernel/signal.o: warning: objtool: __dequeue_signal()+0xd8: call without frame pointer save/setup ... objtool gets confused by the fact that the '-mtune=atom' GCC option sometimes uses 'lea (%rsp),%rbp' instead of 'mov %rsp,%rbp'. The instructions are effectively the same, but objtool doesn't know about the 'lea' variant. Fix the false warnings by adding support for 'lea (%rsp),%rbp' in the objtool decoder. 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> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-09-23objtool: Add do_task_dead() to global noreturn listJosh Poimboeuf
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: 9af6528ee9b6 ("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>
2016-07-30Merge branch 'core-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull misc fixes from Thomas Gleixner: "This update contains: - a fix for stomp-machine so the nmi_watchdog wont trigger on the cpu waiting for the others to execute the callback - various fixes and updates to objtool including an resync of the instruction decoder to match the kernel's decoder" * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Un-capitalize "Warning" for out-of-sync instruction decoder objtool: Resync x86 instruction decoder with the kernel's objtool: Support new GCC 6 switch jump table pattern stop_machine: Touch_nmi_watchdog() after MULTI_STOP_PREPARE objtool: Add 'fixdep' to objtool/.gitignore
2016-07-29objtool: Un-capitalize "Warning" for out-of-sync instruction decoderJosh Poimboeuf
Change "Warning" to "warning" to make it look more like a GCC warning. Hopefully that will be enough to help the 0-day bot or other automated tools catch this warning earlier before it ends up in Linus's tree. 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/b1669f391a5db91040427fd9f8e1e79db18f9709.1469751119.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-29objtool: Resync x86 instruction decoder with the kernel'sJosh Poimboeuf
This fixes the following warning: Warning: objtool: x86 instruction decoder differs from kernel Unfortunately we have three identical copies of the x86 instruction decoder in the kernel tree that have to be manually kept in sync. It's on my TODO list to at least library-ize the ones in the tools subdir so we'd only have two of them instead of three. In the meantime, here's another manual sync. 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> Fixes: c61f4d5ebaf0 ("perf tools: Add AVX-512 support to the instruction decoder used by Intel PT") Link: http://lkml.kernel.org/r/d7f74b4d91fed25b0be33cd5c86f5131fa1a7529.1469751119.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-29objtool: Support new GCC 6 switch jump table patternJosh Poimboeuf
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>
2016-07-28Merge tag 'libnvdimm-for-4.8' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm Pull libnvdimm updates from Dan Williams: - Replace pcommit with ADR / directed-flushing. The pcommit instruction, which has not shipped on any product, is deprecated. Instead, the requirement is that platforms implement either ADR, or provide one or more flush addresses per nvdimm. ADR (Asynchronous DRAM Refresh) flushes data in posted write buffers to the memory controller on a power-fail event. Flush addresses are defined in ACPI 6.x as an NVDIMM Firmware Interface Table (NFIT) sub-structure: "Flush Hint Address Structure". A flush hint is an mmio address that when written and fenced assures that all previous posted writes targeting a given dimm have been flushed to media. - On-demand ARS (address range scrub). Linux uses the results of the ACPI ARS commands to track bad blocks in pmem devices. When latent errors are detected we re-scrub the media to refresh the bad block list, userspace can also request a re-scrub at any time. - Support for the Microsoft DSM (device specific method) command format. - Support for EDK2/OVMF virtual disk device memory ranges. - Various fixes and cleanups across the subsystem. * tag 'libnvdimm-for-4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (41 commits) libnvdimm-btt: Delete an unnecessary check before the function call "__nd_device_register" nfit: do an ARS scrub on hitting a latent media error nfit: move to nfit/ sub-directory nfit, libnvdimm: allow an ARS scrub to be triggered on demand libnvdimm: register nvdimm_bus devices with an nd_bus driver pmem: clarify a debug print in pmem_clear_poison x86/insn: remove pcommit Revert "KVM: x86: add pcommit support" nfit, tools/testing/nvdimm/: unify shutdown paths libnvdimm: move ->module to struct nvdimm_bus_descriptor nfit: cleanup acpi_nfit_init calling convention nfit: fix _FIT evaluation memory leak + use after free tools/testing/nvdimm: add manufacturing_{date|location} dimm properties tools/testing/nvdimm: add virtual ramdisk range acpi, nfit: treat virtual ramdisk SPA as pmem region pmem: kill __pmem address space pmem: kill wmb_pmem() libnvdimm, pmem: use nvdimm_flush() for namespace I/O writes fs/dax: remove wmb_pmem() libnvdimm, pmem: flush posted-write queues on shutdown ...
2016-07-27objtool: Add 'fixdep' to objtool/.gitignorePaul Gortmaker
To fix: Untracked files: (use "git add <file>..." to include in what will be committed) tools/objtool/fixdep Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.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> Link: http://lkml.kernel.org/r/a4571f6893caf737d05524cfa3829c2abc1fb240.1469452729.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-26Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fixes from Ingo Molnar: "This tree contains tooling fixes plus some additions: - fixes to the vdso2c build environment that Stephen Rothwell is using for the linux-next build (Arnaldo Carvalho de Melo) - AVX-512 instruction mappings (Adrian Hunter) - misc fixes" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: Revert "perf tools: event.h needs asm/perf_regs.h" x86: Make the vdso2c compiler use the host architecture headers tools build: Fix objtool build with ARCH=x86_64 objtool: Always use host headers objtool: Use tools/scripts/Makefile.arch to get ARCH and HOSTARCH tools build: Add HOSTARCH Makefile variable perf tests kmod-path: Fix build on ubuntu:16.04-x-armhf perf tools: Add AVX-512 instructions to the new instructions test perf tools: Add AVX-512 support to the instruction decoder used by Intel PT x86/insn: Add AVX-512 support to the instruction decoder x86/insn: perf tools: Fix vcvtph2ps instruction decoding
2016-07-25Merge branch 'perf-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf updates from Ingo Molnar: "With over 300 commits it's been a busy cycle - with most of the work concentrated on the tooling side (as it should). The main kernel side enhancements were: - Add per event callchain limit: Recently we introduced a sysctl to tune the max-stack for all events for which callchains were requested: $ sysctl kernel.perf_event_max_stack kernel.perf_event_max_stack = 127 Now this patch introduces a way to configure this per event, i.e. this becomes possible: $ perf record -e sched:*/max-stack=2/ -e block:*/max-stack=10/ -a allowing finer tuning of how much buffer space callchains use. This uses an u16 from the reserved space at the end, leaving another u16 for future use. There has been interest in even finer tuning, namely to control the max stack for kernel and userspace callchains separately. Further discussion is needed, we may for instance use the remaining u16 for that and when it is present, assume that the sample_max_stack introduced in this patch applies for the kernel, and the u16 left is used for limiting the userspace callchain (Arnaldo Carvalho de Melo) - Optimize AUX event (hardware assisted side-band event) delivery (Kan Liang) - Rework Intel family name macro usage (this is partially x86 arch work) (Dave Hansen) - Refine and fix Intel LBR support (David Carrillo-Cisneros) - Add support for Intel 'TopDown' events (Andi Kleen) - Intel uncore PMU driver fixes and enhancements (Kan Liang) - ... other misc changes. Here's an incomplete list of the tooling enhancements (but there's much more, see the shortlog and the git log for details): - Support cross unwinding, i.e. collecting '--call-graph dwarf' perf.data files in one machine and then doing analysis in another machine of a different hardware architecture. This enables, for instance, to do: $ perf record -a --call-graph dwarf on a x86-32 or aarch64 system and then do 'perf report' on it on a x86_64 workstation (He Kuang) - Allow reading from a backward ring buffer (one setup via sys_perf_event_open() with perf_event_attr.write_backward = 1) (Wang Nan) - Finish merging initial SDT (Statically Defined Traces) support, see cset comments for details about how it all works (Masami Hiramatsu) - Support attaching eBPF programs to tracepoints (Wang Nan) - Add demangling of symbols in programs written in the Rust language (David Tolnay) - Add support for tracepoints in the python binding, including an example, that sets up and parses sched:sched_switch events, tools/perf/python/tracepoint.py (Jiri Olsa) - Introduce --stdio-color to set up the color output mode selection in 'annotate' and 'report', allowing emit color escape sequences when redirecting the output of these tools (Arnaldo Carvalho de Melo) - Add 'callindent' option to 'perf script -F', to indent the Intel PT call stack, making this output more ftrace-like (Adrian Hunter, Andi Kleen) - Allow dumping the object files generated by llvm when processing eBPF scriptlet events (Wang Nan) - Add stackcollapse.py script to help generating flame graphs (Paolo Bonzini) - Add --ldlat option to 'perf mem' to specify load latency for loads event (e.g. cpu/mem-loads/ ) (Jiri Olsa) - Tooling support for Intel TopDown counters, recently added to the kernel (Andi Kleen)" * 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (303 commits) perf tests: Add is_printable_array test perf tools: Make is_printable_array global perf script python: Fix string vs byte array resolving perf probe: Warn unmatched function filter correctly perf cpu_map: Add more helpers perf stat: Balance opening and reading events tools: Copy linux/{hash,poison}.h and check for drift perf tools: Remove include/linux/list.h from perf's MANIFEST tools: Copy the bitops files accessed from the kernel and check for drift Remove: kernel unistd*h files from perf's MANIFEST, not used perf tools: Remove tools/perf/util/include/linux/const.h perf tools: Remove tools/perf/util/include/asm/byteorder.h perf tools: Add missing linux/compiler.h include to perf-sys.h perf jit: Remove some no-op error handling perf jit: Add missing curly braces objtool: Initialize variable to silence old compiler objtool: Add -I$(srctree)/tools/arch/$(ARCH)/include/uapi perf record: Add --tail-synthesize option perf session: Don't warn about out of order event if write_backward is used perf tools: Enable overwrite settings ...
2016-07-23x86/insn: remove pcommitDan Williams
The pcommit instruction is being deprecated in favor of either ADR (asynchronous DRAM refresh: flush-on-power-fail) at the platform level, or posted-write-queue flush addresses as defined by the ACPI 6.x NFIT (NVDIMM Firmware Interface Table). Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Acked-by: Ingo Molnar <mingo@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-07-22tools build: Fix objtool build with ARCH=x86_64Josh Poimboeuf
The objtool build fails in a cross-compiled environment on a non-x86 host with "ARCH=x86_64": tools/objtool/objtool-in.o: In function `decode_instructions': tools/objtool/builtin-check.c:276: undefined reference to `arch_decode_instruction' We could override the ARCH environment variable and change it back to x86, similar to what the objtool Makefile was doing before; but it's tricky to override environment variables consistently. Instead, take a similar approach used by the Linux top-level Makefile and introduce a SRCARCH Makefile variable which evaluates to "x86" when ARCH is either "x86_64" or "x86". Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> 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/20160722191920.ej62fnspnqurbaa7@treble Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-22objtool: Always use host headersArnaldo Carvalho de Melo
From a conversation with Josh: From http://lkml.kernel.org/r/20160722034118.guckaniobf3f7czc@treble : It needs to be compiled with the host (powerpc) compiler, but then it needs to disassemble target (x86) files. ---- So use HOSTARCH instead of ARCH. 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: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Wang Nan <wangnan0@huawei.com> Link: http://lkml.kernel.org/r/20160722034118.guckaniobf3f7czc@treble Link: http://lkml.kernel.org/n/tip-le1m1yzxnfpt3msbblu40nm8@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-22objtool: Use tools/scripts/Makefile.arch to get ARCH and HOSTARCHArnaldo Carvalho de Melo
objtool's Makefile was setting up ARCH but fixing up just the x86_64 -> x86, using Makefile.arch will do the necessary fixups for all arches. 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: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Wang Nan <wangnan0@huawei.com> Link: http://lkml.kernel.org/n/tip-hbq0bbh03u2b722vozcyql31@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-15objtool: Initialize variable to silence old compilerArnaldo Carvalho de Melo
gcc version 4.1.2 20080704 (Red Hat 4.1.2-55) barfs with: CC /tmp/build/objtool/builtin-check.o cc1: warnings being treated as errors builtin-check.c: In function 'cmd_check': builtin-check.c:667: warning: 'prev_rela' may be used uninitialized in this function mv: cannot stat `/tmp/build/objtool/.builtin-check.o.tmp': No such file or directory make[1]: *** [/tmp/build/objtool/builtin-check.o] Error 1 Init it to NULL to silence it. 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-qolo31rl2ojlwj1lj9dhemyz@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-15objtool: Add -I$(srctree)/tools/arch/$(ARCH)/include/uapiArnaldo Carvalho de Melo
So that it can find asm/bitsperlong.h to get the __BITS_PER_LONG definition. 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: Peter Zijlstra <peterz@infradead.org> Cc: Wang Nan <wangnan0@huawei.com> Link: http://lkml.kernel.org/n/tip-pr3pvskh65pey4po7t122z4j@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-13objtool: Avoid checking code drift on busybox's diffArnaldo Carvalho de Melo
That doesn't have -I to match lines. 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-1zqv1h6okt70e2huokkdtf1u@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-13objtool: Add fallback from ELF_C_READ_MMAP to ELF_C_READArnaldo Carvalho de Melo
Not all libelf implementations have this "Please, ELF_C_READ, but use mmap if possible" elf_begin() cmd, so provide a fallback to plain old ELF_C_READ. Case in point: Alpine Linux 3.4. 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-1fctuknrawgoi5xqon4mu9dv@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-12tools lib subcmd: Use str_error_r()Arnaldo Carvalho de Melo
To make it portable to non-glibc systems, that follow the XSI variant instead of the GNU specific one that gets in place when _GNU_SOURCE is defined. 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: Steven Rostedt <rostedt@goodmis.org> Cc: Wang Nan <wangnan0@huawei.com> Link: http://lkml.kernel.org/n/tip-bozcszy93tpgw9ad6qm3dhpx@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-12perf tools: Uninline scnprintf() and vscnprint()Arnaldo Carvalho de Melo
They were in tools/include/linux/kernel.h, requiring that it in turn included stdio.h, which is way too heavy. 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-855h8olnkot9v0dajuee1lo3@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2016-07-10objtool: Fix STACK_FRAME_NON_STANDARD macro checking for function symbolsJosh Poimboeuf
Mathieu Desnoyers reported that the STACK_FRAME_NON_STANDARD macro wasn't working with the lttng_filter_interpret_bytecode() function in the lttng-modules code. Usually the relocation created by STACK_FRAME_NON_STANDARD creates a reference to a section symbol like this: Offset Type Value Addend Name 000000000000000000 X86_64_64 000000000000000000 +3136 .text But in this case it created a reference to a function symbol: Offset Type Value Addend Name 000000000000000000 X86_64_64 0x00000000000003a0 +0 lttng_filter_interpret_bytecode To be honest I have no idea what causes gcc to decide to do one over the other. But both are valid ELF, so add support for the function symbol. Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.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: lttng-dev@lists.lttng.org Link: http://lkml.kernel.org/r/9cee42843bc6d94e990a152e4e0319cfdf6756ef.1466023450.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-17objtool: Allow building with older libelfJan Beulich
The switch to elf_getshdr{num,strndx} post-dates the oldest tool chain the kernel is supposed to be able to build with, so try to cope with such an environment. Signed-off-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: <stable@vger.kernel.org> # for v4.6 Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jan Beulich <JBeulich@suse.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Link: http://lkml.kernel.org/r/732dae6872b7ff187d94f22bb699a12849d3fe04.1463430618.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-16objtool: Detect falling through to the next functionJosh Poimboeuf
There are several cases in compiled C code where a function may not return at the end, and may instead fall through to the next function. That may indicate a bug in the code, or a gcc bug, or even an objtool bug. But in each case, objtool reports an unhelpful warning, something like: drivers/scsi/qla2xxx/qla_attr.o: warning: objtool: qla2x00_get_fc_host_stats()+0x0: duplicate frame pointer save drivers/scsi/qla2xxx/qla_attr.o: warning: objtool: qla2x00_get_fc_host_stats()+0x0: frame pointer state mismatch Detect this situation and print a more useful error message: drivers/scsi/qla2xxx/qla_attr.o: warning: objtool: qla2x00_get_host_fabric_name() falls through to next function qla2x00_get_starget_node_name() Also add some information about this warning and its potential causes to the documentation. Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> 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 Olsa <jolsa@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/caa4ec6c687931db805e692d4e4bf06cd87d33e6.1460729697.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-15objtool: Add workaround for GCC switch jump table bugJosh Poimboeuf
GCC has a rare quirk, currently only seen in three driver functions in the kernel, and only with certain obscure non-distro configs, which can cause objtool to produce "unreachable instruction" false positive warnings. As part of an optimization, GCC makes a copy of an existing switch jump table, modifies it, and then hard-codes the jump (albeit with an indirect jump) to use a single entry in the table. The rest of the jump table and some of its jump targets remain as dead code. In such a case we can just crudely ignore all unreachable instruction warnings for the entire object file. Ideally we would just ignore them for the function, but that would require redesigning the code quite a bit. And honestly that's just not worth doing: unreachable instruction warnings are of questionable value anyway, and this is a very rare issue. kbuild reports: https://lkml.kernel.org/r/201603231906.LWcVUpxm%25fengguang.wu@intel.com https://lkml.kernel.org/r/201603271114.K9i45biy%25fengguang.wu@intel.com https://lkml.kernel.org/r/201603291058.zuJ6ben1%25fengguang.wu@intel.com GCC bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70604 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> Link: http://lkml.kernel.org/r/700fa029bbb0feff34f03ffc69d666a3c3b57a61.1460663532.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-09objtool: Only print one warning per functionJosh Poimboeuf
When objtool discovers an issue, it's very common for it to flood the terminal with a lot of duplicate warnings. For example: warning: objtool: rtlwifi_rate_mapping()+0x2e7: frame pointer state mismatch warning: objtool: rtlwifi_rate_mapping()+0x2f3: frame pointer state mismatch warning: objtool: rtlwifi_rate_mapping()+0x2ff: frame pointer state mismatch warning: objtool: rtlwifi_rate_mapping()+0x30b: frame pointer state mismatch ... The first warning is usually all you need. Change it to only warn once per function. Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/c47f3ca38aa01e2a9b6601f9e38efd414c3f3c18.1457502970.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-09objtool: Add several performance improvementsJosh Poimboeuf
Use hash tables for instruction and rela lookups (and keep the linked lists around for sequential access). Also cache the section struct for the "__func_stack_frame_non_standard" section. With this change, "objtool check net/wireless/nl80211.o" goes from: real 0m1.168s user 0m1.163s sys 0m0.005s to: real 0m0.059s user 0m0.042s sys 0m0.017s for a 20x speedup. With the same object, it should be noted that the memory heap usage grew from 8MB to 62MB. Reducing the memory usage is on the TODO list. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/dd0d8e1449506cfa7701b4e7ba73577077c44253.1457502970.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-09objtool: Fix false positive warnings for functions with multiple switch ↵Josh Poimboeuf
statements Ingo reported [1] some false positive objtool warnings: drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2e7: frame pointer state mismatch drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2f3: frame pointer state mismatch ... And so did the 0-day bot [2]: drivers/gpu/drm/radeon/cik.o: warning: objtool: cik_tiling_mode_table_init()+0x6ce: call without frame pointer save/setup drivers/gpu/drm/radeon/cik.o: warning: objtool: cik_tiling_mode_table_init()+0x72b: call without frame pointer save/setup ... Both sets of warnings involve functions which have multiple switch statements. When there's more than one switch statement in a function, objtool interprets all the switch jump tables as a single table. If the targets of one jump table assume a stack frame and the targets of another one don't, it prints false positive warnings. Fix the bug by detecting the size of each switch jump table. For multiple tables, each one ends where the next one begins. [1] https://lkml.kernel.org/r/20160308103716.GA9618@gmail.com [2] https://lists.01.org/pipermail/kbuild-all/2016-March/018124.html Reported-by: Ingo Molnar <mingo@kernel.org> Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/2d7eecc6bc52d301f494b80f5fd62c2b6c895658.1457502970.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-09objtool: Rename some variables and functionsJosh Poimboeuf
Rename some list heads to distinguish them from hash node heads, which are added later in the patch series. Also rename the get_*() functions to add_*(), which is more descriptive: they "add" data to the objtool_file struct. Also rename rodata_rela and text_rela to be clearer: - text_rela refers to a rela entry in .rela.text. - rodata_rela refers to a rela entry in .rela.rodata. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/ee0eca2bba8482aa45758958c5586c00a7b71e62.1457502970.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-09objtool: Remove superflous INIT_LIST_HEADJosh Poimboeuf
The insns list is initialized twice, in cmd_check() and in decode_instructions(). Remove the latter. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/be6e21d7eec1f072095d22a1cbe144057135e097.1457502970.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-09objtool: Add helper macros for traversing instructionsJosh Poimboeuf
Add some helper macros to make it easier to traverse instructions, and to abstract the details of the instruction list implementation in preparation for creating a hash structure. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/8e1715d5035bc02b4db28d0fccef6bb1170d1f12.1457502970.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-09objtool: Fix false positive warnings related to sibling callsJosh Poimboeuf
With some configs [1], objtool prints a bunch of false positive warnings like: arch/x86/events/core.o: warning: objtool: x86_del_exclusive()+0x0: frame pointer state mismatch For some reason this config has a bunch of sibling calls. When objtool follows a sibling call jump, it attempts to compare the frame pointer state. But it also accidentally compares the FENTRY state, resulting in a false positive warning. [1] https://lkml.kernel.org/r/20160308154909.GA20956@gmail.com Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/382de77ccaaa8cd79b27a155c3d109ebd4ce0219.1457502970.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-09objtool: Compile with debugging symbolsJosh Poimboeuf
Compile objtool with debugging symbols ('-g') to help tools like perf and gdb understand what it's doing. Combined with '-O2', it's not always helpful, but it's better than nothing. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/c295e9ee9ed360dc8b2e1d180c859f11cfc151ef.1457502970.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-09objtool: Detect infinite recursionJosh Poimboeuf
I don't _think_ dead_end_function() can get into a recursive loop, but just in case, stop the loop and print a warning. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/ff489a63e6feb88abb192cfb361d81626dcf3e89.1457502970.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-09objtool: Prevent infinite recursion in noreturn detectionJosh Poimboeuf
Ingo reported an infinite loop in objtool with a certain randconfig [1]. With the given config, two functions in crypto/ablkcipher.o contained sibling calls to each other, which threw the recursive call in dead_end_function() for a loop (literally!). Split the noreturn detection into two passes. In the first pass, check for return instructions. In the second pass, do the potentially recursive sibling call check. In most cases, the first pass will be good enough. In the rare case where a second pass is needed, recursion should hopefully no longer be possible. [1] https://lkml.kernel.org/r/20160308154909.GA20956@gmail.com Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/16afb602640ef43b7782087d6cca17bf6fc13603.1457502970.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-03objtool: Support CROSS_COMPILEJosh Poimboeuf
When building with CONFIG_STACK_VALIDATION on a ppc64le host with an x86 cross-compiler, Stephen Rothwell saw the following objtool build errors: DESCEND objtool CC /home/sfr/next/x86_64_allmodconfig/tools/objtool/builtin-check.o CC /home/sfr/next/x86_64_allmodconfig/tools/objtool/special.o CC /home/sfr/next/x86_64_allmodconfig/tools/objtool/elf.o CC /home/sfr/next/x86_64_allmodconfig/tools/objtool/objtool.o MKDIR /home/sfr/next/x86_64_allmodconfig/tools/objtool/arch/x86/insn/ CC /home/sfr/next/x86_64_allmodconfig/tools/objtool/libstring.o elf.c:22:23: fatal error: sys/types.h: No such file or directory compilation terminated. CC /home/sfr/next/x86_64_allmodconfig/tools/objtool/exec-cmd.o CC /home/sfr/next/x86_64_allmodconfig/tools/objtool/help.o builtin-check.c:28:20: fatal error: string.h: No such file or directory compilation terminated. objtool.c:28:19: fatal error: stdio.h: No such file or directory compilation terminated. It fails to build because it tries to compile objtool with the cross-compiler instead of the host compiler. Ensure that it always uses the host compiler by ignoring CROSS_COMPILE. In order to do that properly, the libsubcmd.a library needs to be built in tools/objtool/ rather than tools/lib/subcmd/. The latter directory contains the cross-compiled version which is needed for perf and possibly other tools. Note that cross-compiling for x86 on a _big_ endian system would result in a bunch of false positive objtool warnings during the kernel build because it isn't endian-aware. But that's generally a rare edge case and there haven't been any reports of anybody needing that. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/55b63eefc347f1bb28573f972d8d1adbf1f1c31d.1456962210.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-03x86/asm/decoder: Use explicitly signed charsJosh Poimboeuf
When running objtool on a ppc64le host to analyze x86 binaries, it reports a lot of false warnings like: ipc/compat_mq.o: warning: objtool: compat_SyS_mq_open()+0x91: can't find jump dest instruction at .text+0x3a5 The warnings are caused by the x86 instruction decoder setting the wrong value for the jump instruction's immediate field because it assumes that "char == signed char", which isn't true for all architectures. When converting char to int, gcc sign-extends on x86 but doesn't sign-extend on ppc64le. According to the gcc man page, that's a feature, not a bug: > Each kind of machine has a default for what "char" should be. It is > either like "unsigned char" by default or like "signed char" by > default. > > Ideally, a portable program should always use "signed char" or > "unsigned char" when it depends on the signedness of an object. Conform to the "standards" by changing the "char" casts to "signed char". This results in no actual changes to the object code on x86. Note: the x86 decoder now lives in three different locations in the kernel tree, which are all kept in sync via makefile checks and warnings: in-kernel, perf, and objtool. This fixes all three locations. Eventually we should probably try to at least converge the two separate "tools" locations into a single shared location. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/9dd4161719b20e6def9564646d68bfbe498c549f.1456962210.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-29objtool: Add tool to perform compile-time stack metadata validationJosh Poimboeuf
This adds a host tool named objtool which has a "check" subcommand which analyzes .o files to ensure the validity of stack metadata. It enforces a set of rules on asm code and C inline assembly code so that stack traces can be reliable. For each function, it recursively follows all possible code paths and validates the correct frame pointer state at each instruction. It also follows code paths involving kernel special sections, like .altinstructions, __jump_table, and __ex_table, which can add alternative execution paths to a given instruction (or set of instructions). Similarly, it knows how to follow switch statements, for which gcc sometimes uses jump tables. Here are some of the benefits of validating stack metadata: a) More reliable stack traces for frame pointer enabled kernels Frame pointers are used for debugging purposes. They allow runtime code and debug tools to be able to walk the stack to determine the chain of function call sites that led to the currently executing code. For some architectures, frame pointers are enabled by CONFIG_FRAME_POINTER. For some other architectures they may be required by the ABI (sometimes referred to as "backchain pointers"). For C code, gcc automatically generates instructions for setting up frame pointers when the -fno-omit-frame-pointer option is used. But for asm code, the frame setup instructions have to be written by hand, which most people don't do. So the end result is that CONFIG_FRAME_POINTER is honored for C code but not for most asm code. For stack traces based on frame pointers to be reliable, all functions which call other functions must first create a stack frame and update the frame pointer. If a first function doesn't properly create a stack frame before calling a second function, the *caller* of the first function will be skipped on the stack trace. For example, consider the following example backtrace with frame pointers enabled: [<ffffffff81812584>] dump_stack+0x4b/0x63 [<ffffffff812d6dc2>] cmdline_proc_show+0x12/0x30 [<ffffffff8127f568>] seq_read+0x108/0x3e0 [<ffffffff812cce62>] proc_reg_read+0x42/0x70 [<ffffffff81256197>] __vfs_read+0x37/0x100 [<ffffffff81256b16>] vfs_read+0x86/0x130 [<ffffffff81257898>] SyS_read+0x58/0xd0 [<ffffffff8181c1f2>] entry_SYSCALL_64_fastpath+0x12/0x76 It correctly shows that the caller of cmdline_proc_show() is seq_read(). If we remove the frame pointer logic from cmdline_proc_show() by replacing the frame pointer related instructions with nops, here's what it looks like instead: [<ffffffff81812584>] dump_stack+0x4b/0x63 [<ffffffff812d6dc2>] cmdline_proc_show+0x12/0x30 [<ffffffff812cce62>] proc_reg_read+0x42/0x70 [<ffffffff81256197>] __vfs_read+0x37/0x100 [<ffffffff81256b16>] vfs_read+0x86/0x130 [<ffffffff81257898>] SyS_read+0x58/0xd0 [<ffffffff8181c1f2>] entry_SYSCALL_64_fastpath+0x12/0x76 Notice that cmdline_proc_show()'s caller, seq_read(), has been skipped. Instead the stack trace seems to show that cmdline_proc_show() was called by proc_reg_read(). The benefit of "objtool check" here is that because it ensures that *all* functions honor CONFIG_FRAME_POINTER, no functions will ever[*] be skipped on a stack trace. [*] unless an interrupt or exception has occurred at the very beginning of a function before the stack frame has been created, or at the very end of the function after the stack frame has been destroyed. This is an inherent limitation of frame pointers. b) 100% reliable stack traces for DWARF enabled kernels This is not yet implemented. For more details about what is planned, see tools/objtool/Documentation/stack-validation.txt. c) Higher live patching compatibility rate This is not yet implemented. For more details about what is planned, see tools/objtool/Documentation/stack-validation.txt. To achieve the validation, "objtool check" enforces the following rules: 1. Each callable function must be annotated as such with the ELF function type. In asm code, this is typically done using the ENTRY/ENDPROC macros. If objtool finds a return instruction outside of a function, it flags an error since that usually indicates callable code which should be annotated accordingly. This rule is needed so that objtool can properly identify each callable function in order to analyze its stack metadata. 2. Conversely, each section of code which is *not* callable should *not* be annotated as an ELF function. The ENDPROC macro shouldn't be used in this case. This rule is needed so that objtool can ignore non-callable code. Such code doesn't have to follow any of the other rules. 3. Each callable function which calls another function must have the correct frame pointer logic, if required by CONFIG_FRAME_POINTER or the architecture's back chain rules. This can by done in asm code with the FRAME_BEGIN/FRAME_END macros. This rule ensures that frame pointer based stack traces will work as designed. If function A doesn't create a stack frame before calling function B, the _caller_ of function A will be skipped on the stack trace. 4. Dynamic jumps and jumps to undefined symbols are only allowed if: a) the jump is part of a switch statement; or b) the jump matches sibling call semantics and the frame pointer has the same value it had on function entry. This rule is needed so that objtool can reliably analyze all of a function's code paths. If a function jumps to code in another file, and it's not a sibling call, objtool has no way to follow the jump because it only analyzes a single file at a time. 5. A callable function may not execute kernel entry/exit instructions. The only code which needs such instructions is kernel entry code, which shouldn't be be in callable functions anyway. This rule is just a sanity check to ensure that callable functions return normally. It currently only supports x86_64. I tried to make the code generic so that support for other architectures can hopefully be plugged in relatively easily. On my Lenovo laptop with a i7-4810MQ 4-core/8-thread CPU, building the kernel with objtool checking every .o file adds about three seconds of total build time. It hasn't been optimized for performance yet, so there are probably some opportunities for better build performance. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/f3efb173de43bd067b060de73f856567c0fa1174.1456719558.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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