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8 daysobjtool: Fix segfault on unknown alternativesIngo Molnar
So 'objtool --link -d vmlinux.o' gets surprised by this endbr64+endbr64 pattern in ___bpf_prog_run(): ___bpf_prog_run: 1e7680: ___bpf_prog_run+0x0 push %r12 1e7682: ___bpf_prog_run+0x2 mov %rdi,%r12 1e7685: ___bpf_prog_run+0x5 push %rbp 1e7686: ___bpf_prog_run+0x6 xor %ebp,%ebp 1e7688: ___bpf_prog_run+0x8 push %rbx 1e7689: ___bpf_prog_run+0x9 mov %rsi,%rbx 1e768c: ___bpf_prog_run+0xc movzbl (%rbx),%esi 1e768f: ___bpf_prog_run+0xf movzbl %sil,%edx 1e7693: ___bpf_prog_run+0x13 mov %esi,%eax 1e7695: ___bpf_prog_run+0x15 mov 0x0(,%rdx,8),%rdx 1e769d: ___bpf_prog_run+0x1d jmp 0x1e76a2 <__x86_indirect_thunk_rdx> 1e76a2: ___bpf_prog_run+0x22 endbr64 1e76a6: ___bpf_prog_run+0x26 endbr64 1e76aa: ___bpf_prog_run+0x2a mov 0x4(%rbx),%edx And crashes due to blindly dereferencing alt->insn->alt_group. Bail out on NULL ->alt_group, which produces this warning and continues with the disassembly, instead of a segfault: .git/O/vmlinux.o: warning: objtool: <alternative.1e769d>: failed to disassemble alternative Cc: Alexandre Chartre <alexandre.chartre@oracle.com> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Josh Poimboeuf <jpoimboe@kernel.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
12 daysobjtool: Build with disassembly can fail when including bdf.hAlexandre Chartre
Building objtool with disassembly support can fail when including the bdf.h file: In file included from tools/objtool/include/objtool/arch.h:108, from check.c:14: /usr/include/bfd.h:35:2: error: #error config.h must be included before this header 35 | #error config.h must be included before this header | ^~~~~ This check is present in the bfd.h file generated from the binutils source code, but it is not necessarily present in the bfd.h file provided in a binutil package (for example, it is not present in the binutil RPM). The solution to this issue is to define the PACKAGE macro before including bfd.h. This is the solution suggested by the binutil developer in bug 14243, and it is used by other kernel tools which also use bfd.h (perf and bpf). Fixes: 59953303827ec ("objtool: Disassemble code with libopcodes instead of running objdump") Closes: https://lore.kernel.org/all/3fa261fd-3b46-4cbe-b48d-7503aabc96cb@oracle.com/ Reported-by: Nathan Chancellor <nathan@kernel.org> Suggested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://sourceware.org/bugzilla/show_bug.cgi?id=14243 Link: https://patch.msgid.link/20251126134519.1760889-1-alexandre.chartre@oracle.com
2025-11-24objtool: Trim trailing NOPs in alternativeAlexandre Chartre
When disassembling alternatives replace trailing NOPs with a single indication of the number of bytes covered with NOPs. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-31-alexandre.chartre@oracle.com
2025-11-24objtool: Add wide output for disassemblyAlexandre Chartre
Add the --wide option to provide a wide output when disassembling. With this option, the disassembly of alternatives is displayed side-by-side instead of one above the other. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-30-alexandre.chartre@oracle.com
2025-11-24objtool: Compact output for alternatives with one instructionAlexandre Chartre
When disassembling, if an instruction has alternatives which are all made of a single instruction then print each alternative on a single line (instruction + description) so that the output is more compact. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-29-alexandre.chartre@oracle.com
2025-11-24objtool: Improve naming of group alternativesAlexandre Chartre
Improve the naming of group alternatives by showing the feature name and flags used by the alternative. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-28-alexandre.chartre@oracle.com
2025-11-24objtool: Add Function to get the name of a CPU featureAlexandre Chartre
Add a function to get the name of a CPU feature. The function is architecture dependent and currently only implemented for x86. The feature names are automatically generated from the cpufeatures.h include file. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-27-alexandre.chartre@oracle.com
2025-11-21objtool: Provide access to feature and flags of group alternativesAlexandre Chartre
Each alternative of a group alternative depends on a specific feature and flags. Provide access to the feature/flags for each alternative as an attribute (feature) in struct alt_group. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-26-alexandre.chartre@oracle.com
2025-11-21objtool: Fix address references in alternativesAlexandre Chartre
When using the --disas option, alternatives are disassembled but address references in non-default alternatives can be incorrect. The problem is that alternatives are shown as if they were replacing the original code of the alternative. So if an alternative is referencing an address inside the alternative then the reference has to be adjusted to the location of the original code. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-25-alexandre.chartre@oracle.com
2025-11-21objtool: Disassemble jump table alternativesAlexandre Chartre
When using the --disas option, also disassemble jump tables. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-24-alexandre.chartre@oracle.com
2025-11-21objtool: Disassemble exception table alternativesAlexandre Chartre
When using the --disas option, also disassemble exception tables (EX_TABLE). Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-23-alexandre.chartre@oracle.com
2025-11-21objtool: Print addresses with alternative instructionsAlexandre Chartre
All alternatives are disassemble side-by-side when using the --disas option. However the address of each instruction is not printed because instructions from different alternatives are not necessarily aligned. Change this behavior to print the address of each instruction. Spaces will appear between instructions from the same alternative when instructions from different alternatives do not have the same alignment. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-22-alexandre.chartre@oracle.com
2025-11-21objtool: Disassemble group alternativesAlexandre Chartre
When using the --disas option, disassemble all group alternatives. Jump tables and exception tables (which are handled as alternatives) are not disassembled at the moment. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-21-alexandre.chartre@oracle.com
2025-11-21objtool: Print headers for alternativesAlexandre Chartre
When using the --disas option, objtool doesn't currently disassemble any alternative. Print an header for each alternative. This identifies places where alternatives are present but alternative code is still not disassembled at the moment. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-20-alexandre.chartre@oracle.com
2025-11-21objtool: Preserve alternatives orderAlexandre Chartre
Preserve the order in which alternatives are defined. Currently objtool stores alternatives in a list in reverse order. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-19-alexandre.chartre@oracle.com
2025-11-21objtool: Add the --disas=<function-pattern> actionAlexandre Chartre
Add the --disas=<function-pattern> actions to disassemble the specified functions. The function pattern can be a single function name (e.g. --disas foo to disassemble the function with the name "foo"), or a shell wildcard pattern (e.g. --disas foo* to disassemble all functions with a name starting with "foo"). Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-18-alexandre.chartre@oracle.com
2025-11-21objtool: Do not validate IBT for .return_sites and .call_sitesAlexandre Chartre
The .return_sites and .call_sites sections reference text addresses, but not with the intent to indirect branch to them, so they don't need to be validated for IBT. This is useful when running objtool on object files which already have .return_sites or .call_sites sections, for example to re-run objtool after it has reported an error or a warning. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-17-alexandre.chartre@oracle.com
2025-11-21objtool: Improve tracing of alternative instructionsAlexandre Chartre
When tracing function validation, improve the reporting of alternative instruction by more clearly showing the different alternatives beginning and end. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-16-alexandre.chartre@oracle.com
2025-11-21objtool: Add functions to better name alternativesAlexandre Chartre
Add the disas_alt_name() and disas_alt_type_name() to provide a name and a type name for an alternative. This will be used to better name alternatives when tracing their execution. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-15-alexandre.chartre@oracle.com
2025-11-21objtool: Identify the different types of alternativesAlexandre Chartre
Alternative code, including jump table and exception table, is represented with the same struct alternative structure. But there is no obvious way to identify whether the struct represents alternative instructions, a jump table or an exception table. So add a type to struct alternative to clearly identify the type of alternative. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-14-alexandre.chartre@oracle.com
2025-11-21objtool: Improve register reporting during function validationAlexandre Chartre
When tracing function validation, instruction state changes can report changes involving registers. These registers are reported with the name "r<num>" (e.g. "r3"). Print the CPU specific register name instead of a generic name (e.g. print "rbx" instead of "r3" on x86). Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-13-alexandre.chartre@oracle.com
2025-11-21objtool: Trace instruction state changes during function validationAlexandre Chartre
During function validation, objtool maintains a per-instruction state, in particular to track call frame information. When tracing validation, print any instruction state changes. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-12-alexandre.chartre@oracle.com
2025-11-21objtool: Add option to trace function validationAlexandre Chartre
Add an option to trace and have information during the validation of specified functions. Functions are specified with the --trace option which can be a single function name (e.g. --trace foo to trace the function with the name "foo"), or a shell wildcard pattern (e.g. --trace foo* to trace all functions with a name starting with "foo"). Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-11-alexandre.chartre@oracle.com
2025-11-21objtool: Record symbol name max lengthAlexandre Chartre
Keep track of the maximum length of symbol names. This will help formatting the code flow between different functions. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-10-alexandre.chartre@oracle.com
2025-11-21objtool: Extract code to validate instruction from the validate branch loopAlexandre Chartre
The code to validate a branch loops through all instructions of the branch and validate each instruction. Move the code to validate an instruction to a separated function. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-9-alexandre.chartre@oracle.com
2025-11-21objtool: Disassemble instruction on warning or backtraceAlexandre Chartre
When an instruction warning (WARN_INSN) or backtrace (BT_INSN) is issued, disassemble the instruction to provide more context. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-8-alexandre.chartre@oracle.com
2025-11-21objtool: Store instruction disassembly resultAlexandre Chartre
When disassembling an instruction store the result instead of directly printing it. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-7-alexandre.chartre@oracle.com
2025-11-21objtool: Print symbol during disassemblyAlexandre Chartre
Print symbols referenced during disassembly instead of just printing raw addresses. Also handle address relocation. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-6-alexandre.chartre@oracle.com
2025-11-21objtool: Disassemble code with libopcodes instead of running objdumpAlexandre Chartre
objtool executes the objdump command to disassemble code. Use libopcodes instead to have more control about the disassembly scope and output. If libopcodes is not present then objtool is built without disassembly support. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-4-alexandre.chartre@oracle.com
2025-11-21objtool: Create disassembly contextAlexandre Chartre
Create a structure to store information for disassembling functions. For now, it is just a wrapper around an objtool file. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-3-alexandre.chartre@oracle.com
2025-11-21objtool: Move disassembly functions to a separated fileAlexandre Chartre
objtool disassembles functions which have warnings. Move the code to do that to a dedicated file. The code is just moved, it is not changed. Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://patch.msgid.link/20251121095340.464045-2-alexandre.chartre@oracle.com
2025-11-21Revert "objtool: Warn on functions with ambiguous -ffunction-sections ↵Josh Poimboeuf
section names" This reverts commit 9c7dc1dd897a1cdcade9566ea4664b03fbabf4a4. The check-function-names.sh script now provides the function name checking functionality for all architectures, making the objtool check redundant. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://patch.msgid.link/c7d549d4de8bd1490d106b99630eea5efc69a4dd.1763669451.git.jpoimboe@kernel.org
2025-11-21objtool: Remove second pass of .cold function correlationJosh Poimboeuf
The .cold function parent/child correlation logic has two passes: one in read_symbols() and one in add_jump_destinations(). The second pass was added with commit cd77849a69cf ("objtool: Fix GCC 8 cold subfunction detection for aliased functions") to ensure that if the parent symbol had aliases then the canonical symbol was chosen as the parent. That solution was rather clunky, not to mention incomplete due to the existence of alternatives and switch tables. Now that we have sym->alias, the canonical alias fix can be done much simpler in the first pass, making the second pass obsolete. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/bdab245a38000a5407f663a031f39e14c67a43d4.1763671318.git.jpoimboe@kernel.org
2025-11-21objtool: Skip non-canonical aliased symbols in add_jump_table_alts()Josh Poimboeuf
If a symbol has aliases, make add_jump_table_alts() skip the non-canonical ones to avoid any surprises. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/169aa17564b9aadb74897945ea74ac2eb70c5b13.1763671318.git.jpoimboe@kernel.org
2025-11-21objtool: Return canonical symbol when aliases exist in symbol finding helpersJosh Poimboeuf
When symbol alias ambiguity exists in the symbol finding helper functions, return the canonical sym->alias, as that's the one which gets used by validate_branch() and elsewhere. This doesn't fix any known issues, just makes the symbol alias behavior more robust. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/450470a4897706af77453ad333e18af5ebab653c.1763671318.git.jpoimboe@kernel.org
2025-11-21objtool: Don't alias undefined symbolsJosh Poimboeuf
Objtool is mistakenly aliasing all undefined symbols. That's obviously wrong, though it has no consequence since objtool happens to only use sym->alias for defined symbols. Fix it regardless. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/bc401173a7717757eee672fc1ca5a20451d77b86.1763671318.git.jpoimboe@kernel.org
2025-11-21objtool: Fix .cold function detection for duplicate symbolsJosh Poimboeuf
The objtool .cold child/parent correlation is done in two phases: first in elf_add_symbol() and later in add_jump_destinations(). The first phase is rather crude and can pick the wrong parent if there are duplicates with the same name. The second phase usually fixes that, but only if the parent has a direct jump to the child. It does *not* work if the only branch from the parent to the child is an alternative or jump table entry. Make the first phase more robust by looking for the parent in the same STT_FILE as the child. Fixes the following objtool warnings in an AutoFDO build with a large CLANG_AUTOFDO_PROFILE profile: vmlinux.o: warning: objtool: rdev_add_key() falls through to next function rdev_add_key.cold() vmlinux.o: warning: objtool: rdev_set_default_key() falls through to next function rdev_set_default_key.cold() Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/82c7b52e40efa75dd10e1c550cc75c1ce10ac2c9.1763671318.git.jpoimboe@kernel.org
2025-11-21objtool: Support Clang AUTOFDO .cold functionsJosh Poimboeuf
AutoFDO enables -fsplit-machine-functions which can move the cold parts of a function to a <func>.cold symbol in a .text.split.<func> section. Unlike GCC, the Clang <func>.cold symbols are not marked STT_FUNC. This confuses objtool in several ways, resulting in warnings like the following: vmlinux.o: warning: objtool: apply_retpolines.cold+0xfc: unsupported instruction in callable function vmlinux.o: warning: objtool: machine_check_poll.cold+0x2e: unsupported instruction in callable function vmlinux.o: warning: objtool: free_deferred_objects.cold+0x1f: relocation to !ENDBR: free_deferred_objects.cold+0x26 vmlinux.o: warning: objtool: rpm_idle.cold+0xe0: relocation to !ENDBR: rpm_idle.cold+0xe7 vmlinux.o: warning: objtool: tcp_rcv_state_process.cold+0x1c: relocation to !ENDBR: tcp_rcv_state_process.cold+0x23 Fix it by marking the .cold symbols as STT_FUNC. Fixes: 2fd65f7afd5a ("AutoFDO: Enable machine function split optimization for AutoFDO") Closes: https://lore.kernel.org/20251103215244.2080638-2-xur@google.com Reported-by: Rong Xu <xur@google.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: xur@google.com Tested-by: xur@google.com Link: https://patch.msgid.link/20a67326f04b2a361c031b56d58e8a803b3c5893.1763671318.git.jpoimboe@kernel.org
2025-11-18objtool: Set minimum xxhash version to 0.8Josh Poimboeuf
XXH3 is only supported starting with xxhash 0.8. Enforce that. Fixes: 0d83da43b1e1 ("objtool/klp: Add --checksum option to generate per-function checksums") Closes: https://lore.kernel.org/SN6PR02MB41579B83CD295C9FEE40EED6D4FCA@SN6PR02MB4157.namprd02.prod.outlook.com Reported-by: Michael Kelley <mhklinux@outlook.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Michael Kelley <mhklinux@outlook.com> Link: https://patch.msgid.link/7227c94692a3a51840278744c7af31b4797c6b96.1762990139.git.jpoimboe@kernel.org
2025-11-13objtool: Warn on functions with ambiguous -ffunction-sections section namesJosh Poimboeuf
When compiled with -ffunction-sections, a function named startup() will be placed in .text.startup. However, .text.startup is also used by the compiler for functions with __attribute__((constructor)). That creates an ambiguity for the vmlinux linker script, which needs to differentiate those two cases. Similar naming conflicts exist for functions named exit(), split(), unlikely(), hot() and unknown(). One potential solution would be to use '#ifdef CC_USING_FUNCTION_SECTIONS' to create two distinct implementations of the TEXT_MAIN macro. However, -ffunction-sections can be (and is) enabled or disabled on a per-object basis (for example via ccflags-y or AUTOFDO_PROFILE). So the recently unified TEXT_MAIN macro (commit 1ba9f8979426 ("vmlinux.lds: Unify TEXT_MAIN, DATA_MAIN, and related macros")) is necessary. This means there's no way for the linker script to disambiguate things. Instead, use objtool to warn on any function names whose resulting section names might create ambiguity when the kernel is compiled (in whole or in part) with -ffunction-sections. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: live-patching@vger.kernel.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://patch.msgid.link/65fedea974fe14be487c8867a0b8d0e4a294ce1e.1762991150.git.jpoimboe@kernel.org
2025-11-13Merge tag 'v6.18-rc5' into objtool/core, to pick up fixesIngo Molnar
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2025-11-10tools/objtool: Copy the __cleanup unused variable fix for older clangBorislav Petkov (AMD)
Copy from 54da6a092431 ("locking: Introduce __cleanup() based infrastructure") the bits which mark the variable with a cleanup attribute unused so that my clang 15 can dispose of it properly instead of warning that it is unused which then fails the build due to -Werror. Suggested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/r/20251031114919.GBaQSiPxZrziOs3RCW@fat_crate.local
2025-11-01objtool: Fix skip_alt_group() for non-alternative STAC/CLACJosh Poimboeuf
If an insn->alt points to a STAC/CLAC instruction, skip_alt_group() assumes it's part of an alternative ("alt group") as opposed to some other kind of "alt" such as an exception fixup. While that assumption may hold true in the current code base, Linus has an out-of-tree patch which breaks that assumption by replacing the STAC/CLAC alternatives with raw STAC/CLAC instructions. Make skip_alt_group() more robust by making sure it's actually an alt group before continuing. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Fixes: 2d12c6fb7875 ("objtool: Remove ANNOTATE_IGNORE_ALTERNATIVE from CLAC/STAC") Closes: https://lore.kernel.org/CAHk-=wi6goUT36sR8GE47_P-aVrd5g38=VTRHpktWARbyE-0ow@mail.gmail.com Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Linus Torvalds <torvalds@linux-foundation.org> Link: https://patch.msgid.link/3d22415f7b8e06a64e0873b21f48389290eeaa49.1761767616.git.jpoimboe@kernel.org
2025-10-30objtool: Remove unneeded semicolonChen Ni
Remove unnecessary semicolons reported by Coccinelle/coccicheck and the semantic patch at scripts/coccinelle/misc/semicolon.cocci. Signed-off-by: Chen Ni <nichen@iscas.ac.cn> Link: https://patch.msgid.link/20251020020916.1070369-1-nichen@iscas.ac.cn Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-10-30x86/smpboot: Mark native_play_dead() as __noreturnThorsten Blum
native_play_dead() ends by calling the non-returning function hlt_play_dead() and therefore also never returns. The !CONFIG_HOTPLUG_CPU stub version of native_play_dead() unconditionally calls BUG() and does not return either. Add the __noreturn attribute to both function definitions and their declaration to document this behavior and to potentially improve compiler optimizations. Remove the obsolete comment, and add native_play_dead() to the objtool's list of __noreturn functions. Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev> Link: https://patch.msgid.link/20251027155107.183136-1-thorsten.blum@linux.dev Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-10-22objtool: Fix failure when being compiled on x32 systemMikulas Patocka
Fix compilation failure when compiling the kernel with the x32 toolchain. In file included from check.c:16: check.c: In function ¡check_abs_references¢: /usr/src/git/linux-2.6/tools/objtool/include/objtool/warn.h:47:17: error: format ¡%lx¢ expects argument of type ¡long unsigned int¢, but argument 7 has type ¡u64¢ {aka ¡long long unsigned int¢} [-Werror=format=] 47 | "%s%s%s: objtool" extra ": " format "\n", \ | ^~~~~~~~~~~~~~~~~ /usr/src/git/linux-2.6/tools/objtool/include/objtool/warn.h:54:9: note: in expansion of macro ¡___WARN¢ 54 | ___WARN(severity, "", format, ##__VA_ARGS__) | ^~~~~~~ /usr/src/git/linux-2.6/tools/objtool/include/objtool/warn.h:74:27: note: in expansion of macro ¡__WARN¢ 74 | #define WARN(format, ...) __WARN(WARN_STR, format, ##__VA_ARGS__) | ^~~~~~ check.c:4713:33: note: in expansion of macro ¡WARN¢ 4713 | WARN("section %s has absolute relocation at offset 0x%lx", | ^~~~ Fixes: 0d6e4563fc03 ("objtool: Add action to check for absence of absolute relocations") Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Ard Biesheuvel <ardb@kernel.org> Link: https://patch.msgid.link/1ac32fff-2e67-5155-f570-69aad5bf5412@redhat.com
2025-10-22objtool/rust: add one more `noreturn` Rust functionMiguel Ojeda
Between Rust 1.79 and 1.86, under `CONFIG_RUST_KERNEL_DOCTESTS=y`, `objtool` may report: rust/doctests_kernel_generated.o: warning: objtool: rust_doctest_kernel_alloc_kbox_rs_13() falls through to next function rust_doctest_kernel_alloc_kvec_rs_0() (as well as in rust_doctest_kernel_alloc_kvec_rs_0) due to calls to the `noreturn` symbol: core::option::expect_failed from code added in commits 779db37373a3 ("rust: alloc: kvec: implement AsPageIter for VVec") and 671618432f46 ("rust: alloc: kbox: implement AsPageIter for VBox"). Thus add the mangled one to the list so that `objtool` knows it is actually `noreturn`. This can be reproduced as well in other versions by tweaking the code, such as the latest stable Rust (1.90.0). Stable does not have code that triggers this, but it could have it in the future. Downstream forks could too. Thus tag it for backport. See commit 56d680dd23c3 ("objtool/rust: list `noreturn` Rust functions") for more details. Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Cc: stable@vger.kernel.org # Needed in 6.12.y and later. Link: https://patch.msgid.link/20251020020714.2511718-1-ojeda@kernel.org
2025-10-22objtool/klp: Add the debian-based package name of xxhash to the hintBorislav Petkov (AMD)
Add the debian package name for the devel version of the xxHash package "libxxhash-dev". Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://patch.msgid.link/20251017194732.7713-1-bp@kernel.org
2025-10-16Merge branch 'objtool/core' of ↵Peter Zijlstra
https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux This series introduces new objtool features and a klp-build script to generate livepatch modules using a source .patch as input. This builds on concepts from the longstanding out-of-tree kpatch [1] project which began in 2012 and has been used for many years to generate livepatch modules for production kernels. However, this is a complete rewrite which incorporates hard-earned lessons from 12+ years of maintaining kpatch. Key improvements compared to kpatch-build: - Integrated with objtool: Leverages objtool's existing control-flow graph analysis to help detect changed functions. - Works on vmlinux.o: Supports late-linked objects, making it compatible with LTO, IBT, and similar. - Simplified code base: ~3k fewer lines of code. - Upstream: No more out-of-tree #ifdef hacks, far less cruft. - Cleaner internals: Vastly simplified logic for symbol/section/reloc inclusion and special section extraction. - Robust __LINE__ macro handling: Avoids false positive binary diffs caused by the __LINE__ macro by introducing a fix-patch-lines script which injects #line directives into the source .patch to preserve the original line numbers at compile time. The primary user interface is the klp-build script which does the following: - Builds an original kernel with -function-sections and -fdata-sections, plus objtool function checksumming. - Applies the .patch file and rebuilds the kernel using the same options. - Runs 'objtool klp diff' to detect changed functions and generate intermediate binary diff objects. - Builds a kernel module which links the diff objects with some livepatch module init code (scripts/livepatch/init.c). - Finalizes the livepatch module (aka work around linker wreckage) using 'objtool klp post-link'. I've tested with a variety of patches on defconfig and Fedora-config kernels with both GCC and Clang.
2025-10-14livepatch/klp-build: Introduce klp-build script for generating livepatch modulesJosh Poimboeuf
Add a klp-build script which automates the generation of a livepatch module from a source .patch file by performing the following steps: - Builds an original kernel with -function-sections and -fdata-sections, plus objtool function checksumming. - Applies the .patch file and rebuilds the kernel using the same options. - Runs 'objtool klp diff' to detect changed functions and generate intermediate binary diff objects. - Builds a kernel module which links the diff objects with some livepatch module init code (scripts/livepatch/init.c). - Finalizes the livepatch module (aka work around linker wreckage) using 'objtool klp post-link'. Acked-by: Petr Mladek <pmladek@suse.com> Tested-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
generated by cgit v1.2.3 (git 2.46.0) at 2025-12-09 01:32:11 +0000