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2025-12-01objtool: 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>
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
2025-11-21objtool: 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: 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: 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: 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: 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
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