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2020-08-24objtool, kcsan: Add __tsan_read_write to uaccess whitelistMarco Elver
Adds the new __tsan_read_write compound instrumentation to objtool's uaccess whitelist. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24objtool: Add atomic builtin TSAN instrumentation to uaccess whitelistMarco Elver
Adds the new TSAN functions that may be emitted for atomic builtins to objtool's uaccess whitelist. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org>
2020-08-03Merge tag 'objtool-core-2020-08-03' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull objtool updates from Ingo Molnar: - Add support for non-rela relocations, in preparation to merge 'recordmcount' functionality into objtool - Fix assumption that broke under --ffunction-sections (LTO) builds - Misc cleanups * tag 'objtool-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Add support for relocations without addends objtool: Rename rela to reloc objtool: Use sh_info to find the base for .rela sections objtool: Do not assume order of parent/child functions
2020-06-28Merge tag 'objtool_urgent_for_5.8_rc3' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull objtool fixes from Borislav Petkov: "Three fixes from Peter Zijlstra suppressing KCOV instrumentation in noinstr sections. Peter Zijlstra says: "Address KCOV vs noinstr. There is no function attribute to selectively suppress KCOV instrumentation, instead teach objtool to NOP out the calls in noinstr functions" This cures a bunch of KCOV crashes (as used by syzcaller)" * tag 'objtool_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Fix noinstr vs KCOV objtool: Provide elf_write_{insn,reloc}() objtool: Clean up elf_write() condition
2020-06-25objtool: Don't consider vmlinux a C-filePeter Zijlstra
Avoids issuing C-file warnings for vmlinux. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200618144801.701257527@infradead.org
2020-06-18Merge branch 'objtool/urgent' into objtool/corePeter Zijlstra
Conflicts: tools/objtool/elf.c tools/objtool/elf.h tools/objtool/orc_gen.c tools/objtool/check.c Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-06-18objtool: Fix noinstr vs KCOVPeter Zijlstra
Since many compilers cannot disable KCOV with a function attribute, help it to NOP out any __sanitizer_cov_*() calls injected in noinstr code. This turns: 12: e8 00 00 00 00 callq 17 <lockdep_hardirqs_on+0x17> 13: R_X86_64_PLT32 __sanitizer_cov_trace_pc-0x4 into: 12: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 13: R_X86_64_NONE __sanitizer_cov_trace_pc-0x4 Just like recordmcount does. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Dmitry Vyukov <dvyukov@google.com>
2020-06-18objtool: Provide elf_write_{insn,reloc}()Peter Zijlstra
This provides infrastructure to rewrite instructions; this is immediately useful for helping out with KCOV-vs-noinstr, but will also come in handy for a bunch of variable sized jump-label patches that are still on ice. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-06-18objtool: Clean up elf_write() conditionPeter Zijlstra
With there being multiple ways to change the ELF data, let's more concisely track modification. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-06-17Merge branch 'objtool/core' of ↵Peter Zijlstra
git://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux into objtool/core
2020-06-15x86/entry, ubsan, objtool: Whitelist __ubsan_handle_*()Peter Zijlstra
The UBSAN instrumentation only inserts external CALLs when things go 'BAD', much like WARN(). So treat them similar to WARN()s for noinstr, that is: allow them, at the risk of taking the machine down, to get their message out. Suggested-by: Marco Elver <elver@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Marco Elver <elver@google.com>
2020-06-11Rebase locking/kcsan to locking/urgentThomas Gleixner
Merge the state of the locking kcsan branch before the read/write_once() and the atomics modifications got merged. Squash the fallout of the rebase on top of the read/write once and atomic fallback work into the merge. The history of the original branch is preserved in tag locking-kcsan-2020-06-02. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2020-06-02objtool: Add support for relocations without addendsMatt Helsley
Currently objtool only collects information about relocations with addends. In recordmcount, which we are about to merge into objtool, some supported architectures do not use rela relocations. Signed-off-by: Matt Helsley <mhelsley@vmware.com> Reviewed-by: Julien Thierry <jthierry@redhat.com> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-06-01objtool: Rename rela to relocMatt Helsley
Before supporting additional relocation types rename the relevant types and functions from "rela" to "reloc". This work be done with the following regex: sed -e 's/struct rela/struct reloc/g' \ -e 's/\([_\*]\)rela\(s\{0,1\}\)/\1reloc\2/g' \ -e 's/tmprela\(s\{0,1\}\)/tmpreloc\1/g' \ -e 's/relasec/relocsec/g' \ -e 's/rela_list/reloc_list/g' \ -e 's/rela_hash/reloc_hash/g' \ -e 's/add_rela/add_reloc/g' \ -e 's/rela->/reloc->/g' \ -e '/rela[,\.]/{ s/\([^\.>]\)rela\([\.,]\)/\1reloc\2/g ; }' \ -e 's/rela =/reloc =/g' \ -e 's/relas =/relocs =/g' \ -e 's/relas\[/relocs[/g' \ -e 's/relaname =/relocname =/g' \ -e 's/= rela\;/= reloc\;/g' \ -e 's/= relas\;/= relocs\;/g' \ -e 's/= relaname\;/= relocname\;/g' \ -e 's/, rela)/, reloc)/g' \ -e 's/\([ @]\)rela\([ "]\)/\1reloc\2/g' \ -e 's/ rela$/ reloc/g' \ -e 's/, relaname/, relocname/g' \ -e 's/sec->rela/sec->reloc/g' \ -e 's/(\(!\{0,1\}\)rela/(\1reloc/g' \ -i \ arch.h \ arch/x86/decode.c \ check.c \ check.h \ elf.c \ elf.h \ orc_gen.c \ special.c Notable exceptions which complicate the regex include gelf_* library calls and standard/expected section names which still use "rela" because they encode the type of relocation expected. Also, keep "rela" in the struct because it encodes a specific type of relocation we currently expect. It will eventually turn into a member of an anonymous union when a susequent patch adds implicit addend, or "rel", relocation support. Signed-off-by: Matt Helsley <mhelsley@vmware.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-05-28objtool: Use sh_info to find the base for .rela sectionsSami Tolvanen
ELF doesn't require .rela section names to match the base section. Use the section index in sh_info to find the section instead of looking it up by name. LLD, for example, generates a .rela section that doesn't match the base section name when we merge sections in a linker script for a binary compiled with -ffunction-sections. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2020-05-28objtool: Do not assume order of parent/child functionsKristen Carlson Accardi
If a .cold function is examined prior to it's parent, the link to the parent/child function can be overwritten when the parent is examined. Only update pfunc and cfunc if they were previously nil to prevent this from happening. This fixes an issue seen when compiling with -ffunction-sections. Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-05-20objtool: Enable compilation of objtool for all architecturesMatt Helsley
Objtool currently only compiles for x86 architectures. This is fine as it presently does not support tooling for other architectures. However, we would like to be able to convert other kernel tools to run as objtool sub commands because they too process ELF object files. This will allow us to convert tools such as recordmcount to use objtool's ELF code. Since much of recordmcount's ELF code is copy-paste code to/from a variety of other kernel tools (look at modpost for example) this means that if we can convert recordmcount we can convert more. We define weak definitions for subcommand entry functions and other weak definitions for shared functions critical to building existing subcommands. These return 127 when the command is missing which signify tools that do not exist on all architectures. In this case the "check" and "orc" tools do not exist on all architectures so we only add them for x86. Future changes adding support for "check", to arm64 for example, can then modify the SUBCMD_CHECK variable when building for arm64. Objtool is not currently wired in to KConfig to be built for other architectures because it's not needed for those architectures and there are no commands it supports other than those for x86. As more command support is enabled on various architectures the necessary KConfig changes can be made (e.g. adding "STACK_VALIDATION") to trigger building objtool. [ jpoimboe: remove aliases, add __weak macro, add error messages ] Cc: Julien Thierry <jthierry@redhat.com> Signed-off-by: Matt Helsley <mhelsley@vmware.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-05-20objtool: Move struct objtool_file into arch-independent headerMatt Helsley
The objtool_file structure describes the files objtool works on, is used by the check subcommand, and the check.h header is included by the orc subcommands so it's presently used by all subcommands. Since the structure will be useful in all subcommands besides check, and some subcommands may not want to include check.h to get the definition, split the structure out into a new header meant for use by all objtool subcommands. Signed-off-by: Matt Helsley <mhelsley@vmware.com> Reviewed-by: Julien Thierry <jthierry@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-05-20objtool: Exit successfully when requesting helpMatt Helsley
When the user requests help it's not an error so do not exit with a non-zero exit code. This is not especially useful for a user but any script that might wish to check that objtool --help is at least available can't rely on the exit code to crudely check that, for example, building an objtool executable succeeds. Signed-off-by: Matt Helsley <mhelsley@vmware.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-05-20objtool: Add check_kcov_mode() to the uaccess safelistJosh Poimboeuf
check_kcov_mode() is called by write_comp_data() and __sanitizer_cov_trace_pc(), which are already on the uaccess safe list. It's notrace and doesn't call out to anything else, so add it to the list too. This fixes the following warnings: kernel/kcov.o: warning: objtool: __sanitizer_cov_trace_pc()+0x15: call to check_kcov_mode() with UACCESS enabled kernel/kcov.o: warning: objtool: write_comp_data()+0x1b: call to check_kcov_mode() with UACCESS enabled Reported-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-05-18Merge tag 'v5.7-rc6' into objtool/core, to pick up fixes and resolve ↵Ingo Molnar
semantic conflict Resolve structural conflict between: 59566b0b622e: ("x86/ftrace: Have ftrace trampolines turn read-only at the end of system boot up") which introduced a new reference to 'ftrace_epilogue', and: 0298739b7983: ("x86,ftrace: Fix ftrace_regs_caller() unwind") Which renamed it to 'ftrace_caller_end'. Rename the new usage site in the merge commit. Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-05-15objtool: optimize add_dead_ends for split sectionsSami Tolvanen
Instead of iterating through all instructions to find the last instruction each time .rela.discard.(un)reachable points beyond the section, use find_insn to locate the last instruction by looking at the last bytes of the section instead. Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200421220843.188260-3-samitolvanen@google.com
2020-05-15objtool: use gelf_getsymshndx to handle >64k sectionsSami Tolvanen
Currently, objtool fails to load the correct section for symbols when the index is greater than SHN_LORESERVE. Use gelf_getsymshndx instead of gelf_getsym to handle >64k sections. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/20200421220843.188260-2-samitolvanen@google.com
2020-05-15objtool: Allow no-op CFI ops in alternativesPeter Zijlstra
Randy reported a false-positive: arch/x86/hyperv/hv_apic.o: warning: objtool: hv_apic_write()+0x25: alternative modifies stack What happens is that: alternative_io("movl %0, %P1", "xchgl %0, %P1", X86_BUG_11AP, 13d: 89 9d 00 d0 7f ff mov %ebx,-0x803000(%rbp) decodes to an instruction with CFI-ops because it modifies RBP. However, due to this being a !frame-pointer build, that should not in fact change the CFI state. So instead of dis-allowing any CFI-op, verify the op would've actually changed the CFI state. Fixes: 7117f16bf460 ("objtool: Fix ORC vs alternatives") Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> Tested-by: Randy Dunlap <rdunlap@infradead.org>
2020-05-10Merge tag 'x86-urgent-2020-05-10' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fixes from Thomas Gleixner: "A set of fixes for x86: - Ensure that direct mapping alias is always flushed when changing page attributes. The optimization for small ranges failed to do so when the virtual address was in the vmalloc or module space. - Unbreak the trace event registration for syscalls without arguments caused by the refactoring of the SYSCALL_DEFINE0() macro. - Move the printk in the TSC deadline timer code to a place where it is guaranteed to only be called once during boot and cannot be rearmed by clearing warn_once after boot. If it's invoked post boot then lockdep rightfully complains about a potential deadlock as the calling context is different. - A series of fixes for objtool and the ORC unwinder addressing variety of small issues: - Stack offset tracking for indirect CFAs in objtool ignored subsequent pushs and pops - Repair the unwind hints in the register clearing entry ASM code - Make the unwinding in the low level exit to usermode code stop after switching to the trampoline stack. The unwind hint is no longer valid and the ORC unwinder emits a warning as it can't find the registers anymore. - Fix unwind hints in switch_to_asm() and rewind_stack_do_exit() which caused objtool to generate bogus ORC data. - Prevent unwinder warnings when dumping the stack of a non-current task as there is no way to be sure about the validity because the dumped stack can be a moving target. - Make the ORC unwinder behave the same way as the frame pointer unwinder when dumping an inactive tasks stack and do not skip the first frame. - Prevent ORC unwinding before ORC data has been initialized - Immediately terminate unwinding when a unknown ORC entry type is found. - Prevent premature stop of the unwinder caused by IRET frames. - Fix another infinite loop in objtool caused by a negative offset which was not catched. - Address a few build warnings in the ORC unwinder and add missing static/ro_after_init annotations" * tag 'x86-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/unwind/orc: Move ORC sorting variables under !CONFIG_MODULES x86/apic: Move TSC deadline timer debug printk ftrace/x86: Fix trace event registration for syscalls without arguments x86/mm/cpa: Flush direct map alias during cpa objtool: Fix infinite loop in for_offset_range() x86/unwind/orc: Fix premature unwind stoppage due to IRET frames x86/unwind/orc: Fix error path for bad ORC entry type x86/unwind/orc: Prevent unwinding before ORC initialization x86/unwind/orc: Don't skip the first frame for inactive tasks x86/unwind: Prevent false warnings for non-current tasks x86/unwind/orc: Convert global variables to static x86/entry/64: Fix unwind hints in rewind_stack_do_exit() x86/entry/64: Fix unwind hints in __switch_to_asm() x86/entry/64: Fix unwind hints in kernel exit path x86/entry/64: Fix unwind hints in register clearing code objtool: Fix stack offset tracking for indirect CFAs
2020-05-08Merge branch 'kcsan-for-tip' of ↵Thomas Gleixner
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into locking/kcsan Pull KCSAN updates from Paul McKenney.
2020-05-07objtool: Fix infinite loop in find_jump_table()Josh Poimboeuf
Kristen found a hang in objtool when building with -ffunction-sections. It was caused by evergreen_pcie_gen2_enable.cold() being laid out immediately before evergreen_pcie_gen2_enable(). Since their "pfunc" is always the same, find_jump_table() got into an infinite loop because it didn't recognize the boundary between the two functions. Fix that with a new prev_insn_same_sym() helper, which doesn't cross subfunction boundaries. Reported-by: Kristen Carlson Accardi <kristen@linux.intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/378b51c9d9c894dc3294bc460b4b0869e950b7c5.1588110291.git.jpoimboe@redhat.com
2020-05-06objtool, kcsan: Add kcsan_disable_current() and kcsan_enable_current_nowarn()Marco Elver
Both are safe to be called from uaccess contexts. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-04-30objtool: Add support for intra-function callsAlexandre Chartre
Change objtool to support intra-function calls. On x86, an intra-function call is represented in objtool as a push onto the stack (of the return address), and a jump to the destination address. That way the stack information is correctly updated and the call flow is still accurate. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200414103618.12657-4-alexandre.chartre@oracle.com
2020-04-30objtool: Move the IRET hack into the arch decoderMiroslav Benes
Quoting Julien: "And the other suggestion is my other email was that you don't even need to add INSN_EXCEPTION_RETURN. You can keep IRET as INSN_CONTEXT_SWITCH by default and x86 decoder lookups the symbol conaining an iret. If it's a function symbol, it can just set the type to INSN_OTHER so that it caries on to the next instruction after having handled the stack_op." Suggested-by: Julien Thierry <jthierry@redhat.com> Signed-off-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200428191659.913283807@infradead.org
2020-04-30objtool: Remove INSN_STACKPeter Zijlstra
With the unconditional use of handle_insn_ops(), INSN_STACK has lost its purpose. Remove it. Suggested-by: Julien Thierry <jthierry@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200428191659.854203028@infradead.org
2020-04-30objtool: Make handle_insn_ops() unconditionalPeter Zijlstra
Now that every instruction has a list of stack_ops; we can trivially distinquish those instructions that do not have stack_ops, their list is empty. This means we can now call handle_insn_ops() unconditionally. Suggested-by: Julien Thierry <jthierry@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200428191659.795115188@infradead.org
2020-04-30objtool: Rework allocating stack_ops on decodePeter Zijlstra
Wrap each stack_op in a macro that allocates and adds it to the list. This simplifies trying to figure out what to do with the pre-allocated stack_op at the end. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200428191659.736151601@infradead.org
2020-04-30objtool: UNWIND_HINT_RET_OFFSET should not check registersAlexandre Chartre
UNWIND_HINT_RET_OFFSET will adjust a modified stack. However if a callee-saved register was pushed on the stack then the stack frame will still appear modified. So stop checking registers when UNWIND_HINT_RET_OFFSET is used. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200407073142.20659-3-alexandre.chartre@oracle.com
2020-04-30objtool: is_fentry_call() crashes if call has no destinationAlexandre Chartre
Fix is_fentry_call() so that it works if a call has no destination set (call_dest). This needs to be done in order to support intra- function calls. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200414103618.12657-2-alexandre.chartre@oracle.com
2020-04-30objtool: Fix ORC vs alternativesPeter Zijlstra
Jann reported that (for instance) entry_64.o:general_protection has very odd ORC data: 0000000000000f40 <general_protection>: #######sp:sp+8 bp:(und) type:iret end:0 f40: 90 nop #######sp:(und) bp:(und) type:call end:0 f41: 90 nop f42: 90 nop #######sp:sp+8 bp:(und) type:iret end:0 f43: e8 a8 01 00 00 callq 10f0 <error_entry> #######sp:sp+0 bp:(und) type:regs end:0 f48: f6 84 24 88 00 00 00 testb $0x3,0x88(%rsp) f4f: 03 f50: 74 00 je f52 <general_protection+0x12> f52: 48 89 e7 mov %rsp,%rdi f55: 48 8b 74 24 78 mov 0x78(%rsp),%rsi f5a: 48 c7 44 24 78 ff ff movq $0xffffffffffffffff,0x78(%rsp) f61: ff ff f63: e8 00 00 00 00 callq f68 <general_protection+0x28> f68: e9 73 02 00 00 jmpq 11e0 <error_exit> #######sp:(und) bp:(und) type:call end:0 f6d: 0f 1f 00 nopl (%rax) Note the entry at 0xf41. Josh found this was the result of commit: 764eef4b109a ("objtool: Rewrite alt->skip_orig") Due to the early return in validate_branch() we no longer set insn->cfi of the original instruction stream (the NOPs at 0xf41 and 0xf42) and we'll end up with the above weirdness. In other discussions we realized alternatives should be ORC invariant; that is, due to there being only a single ORC table, it must be valid for all alternatives. The easiest way to ensure this is to not allow any stack modifications in alternatives. When we enforce this latter observation, we get the property that the whole alternative must have the same CFI, which we can employ to fix the former report. Fixes: 764eef4b109a ("objtool: Rewrite alt->skip_orig") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200428191659.499074346@infradead.org
2020-04-30objtool: Uniquely identify alternative instruction groupsAlexandre Chartre
Assign a unique identifier to every alternative instruction group in order to be able to tell which instructions belong to what alternative. [peterz: extracted from a larger patch] Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz>
2020-04-30objtool: Remove check preventing branches within alternativeJulien Thierry
While jumping from outside an alternative region to the middle of an alternative region is very likely wrong, jumping from an alternative region into the same region is valid. It is a common pattern on arm64. The first pattern is unlikely to happen in practice and checking only for this adds a lot of complexity. Just remove the current check. Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Julien Thierry <jthierry@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lkml.kernel.org/r/20200327152847.15294-6-jthierry@redhat.com
2020-04-26objtool: Fix infinite loop in for_offset_range()Josh Poimboeuf
Randy reported that objtool got stuck in an infinite loop when processing drivers/i2c/busses/i2c-parport.o. It was caused by the following code: 00000000000001fd <line_set>: 1fd: 48 b8 00 00 00 00 00 movabs $0x0,%rax 204: 00 00 00 1ff: R_X86_64_64 .rodata-0x8 207: 41 55 push %r13 209: 41 89 f5 mov %esi,%r13d 20c: 41 54 push %r12 20e: 49 89 fc mov %rdi,%r12 211: 55 push %rbp 212: 48 89 d5 mov %rdx,%rbp 215: 53 push %rbx 216: 0f b6 5a 01 movzbl 0x1(%rdx),%ebx 21a: 48 8d 34 dd 00 00 00 lea 0x0(,%rbx,8),%rsi 221: 00 21e: R_X86_64_32S .rodata 222: 48 89 f1 mov %rsi,%rcx 225: 48 29 c1 sub %rax,%rcx find_jump_table() saw the .rodata reference and tried to find a jump table associated with it (though there wasn't one). The -0x8 rela addend is unusual. It caused find_jump_table() to send a negative table_offset (unsigned 0xfffffffffffffff8) to find_rela_by_dest(). The negative offset should have been harmless, but it actually threw for_offset_range() for a loop... literally. When the mask value got incremented past the end value, it also wrapped to zero, causing the loop exit condition to remain true forever. Prevent this scenario from happening by ensuring the incremented value is always >= the starting value. Fixes: 74b873e49d92 ("objtool: Optimize find_rela_by_dest_range()") Reported-by: Randy Dunlap <rdunlap@infradead.org> Tested-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Julien Thierry <jthierry@redhat.com> Cc: Miroslav Benes <mbenes@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/02b719674b031800b61e33c30b2e823183627c19.1587842122.git.jpoimboe@redhat.com
2020-04-25objtool: Fix stack offset tracking for indirect CFAsJosh Poimboeuf
When the current frame address (CFA) is stored on the stack (i.e., cfa->base == CFI_SP_INDIRECT), objtool neglects to adjust the stack offset when there are subsequent pushes or pops. This results in bad ORC data at the end of the ENTER_IRQ_STACK macro, when it puts the previous stack pointer on the stack and does a subsequent push. This fixes the following unwinder warning: WARNING: can't dereference registers at 00000000f0a6bdba for ip interrupt_entry+0x9f/0xa0 Fixes: 627fce14809b ("objtool: Add ORC unwind table generation") Reported-by: Vince Weaver <vincent.weaver@maine.edu> Reported-by: Dave Jones <dsj@fb.com> Reported-by: Steven Rostedt <rostedt@goodmis.org> Reported-by: Vegard Nossum <vegard.nossum@oracle.com> Reported-by: Joe Mario <jmario@redhat.com> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Jann Horn <jannh@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/853d5d691b29e250333332f09b8e27410b2d9924.1587808742.git.jpoimboe@redhat.com
2020-04-23objtool: Constify arch_decode_instruction()Ingo Molnar
Mostly straightforward constification, except that WARN_FUNC() needs a writable pointer while we have read-only pointers, so deflect this to WARN(). Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20200422103205.61900-4-mingo@kernel.org
2020-04-23objtool: Rename elf_read() to elf_open_read()Ingo Molnar
'struct elf *' handling is an open/close paradigm, make sure the naming matches that: elf_open_read() elf_write() elf_close() Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20200422103205.61900-3-mingo@kernel.org
2020-04-23objtool: Constify 'struct elf *' parametersIngo Molnar
In preparation to parallelize certain parts of objtool, map out which uses of various data structures are read-only vs. read-write. As a first step constify 'struct elf' pointer passing, most of the secondary uses of it in find_symbol_*() methods are read-only. Also, while at it, better group the 'struct elf' handling methods in elf.h. Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20200422103205.61900-2-mingo@kernel.org
2020-04-22objtool: Fix off-by-one in symbol_by_offset()Julien Thierry
Sometimes, WARN_FUNC() and other users of symbol_by_offset() will associate the first instruction of a symbol with the symbol preceding it. This is because symbol->offset + symbol->len is already outside of the symbol's range. Fixes: 2a362ecc3ec9 ("objtool: Optimize find_symbol_*() and read_symbols()") Signed-off-by: Julien Thierry <jthierry@redhat.com> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-04-22objtool: Fix 32bit cross buildsPeter Zijlstra
Apparently there's people doing 64bit builds on 32bit machines. Fixes: 74b873e49d92 ("objtool: Optimize find_rela_by_dest_range()") Reported-by: youling257@gmail.com Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-04-22objtool: Also consider .entry.text as noinstrThomas Gleixner
Consider all of .entry.text as noinstr. This gets us coverage across the PTI boundary. While we could add everything .noinstr.text into .entry.text that would bloat the amount of code in the user mapping. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200416115119.525037514@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22objtool: Add STT_NOTYPE noinstr validationPeter Zijlstra
Make sure to also check STT_NOTYPE symbols for noinstr violations. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200416115119.465335884@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22objtool: Rearrange validate_section()Peter Zijlstra
In preparation of further changes, once again break out the loop body. No functional changes intended. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200416115119.405863817@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22objtool: Avoid iterating !text section symbolsPeter Zijlstra
validate_functions() iterates all sections their symbols; this is pointless to do for !text sections as they won't have instructions anyway. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200416115119.346582716@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22objtool: Use sec_offset_hash() for insn_hashPeter Zijlstra
In preparation for find_insn_containing(), change insn_hash to use sec_offset_hash(). This actually reduces runtime; probably because mixing in the section index reduces the collisions due to text sections all starting their instructions at offset 0. Runtime on vmlinux.o from 3.1 to 2.5 seconds. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200416115119.227240432@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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