linux-rng/tools/objtool, branch master

objtool: Fix segfault on unknown alternatives

2025-12-01T09:42:27Z

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: : failed to disassemble alternative Cc: Alexandre Chartre Cc: Peter Zijlstra (Intel) Cc: Josh Poimboeuf Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

objtool: Build with disassembly can fail when including bdf.h

2025-11-27T08:32:46Z

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 Suggested-by: Nathan Chancellor Signed-off-by: Alexandre Chartre Signed-off-by: Peter Zijlstra (Intel) Link: https://sourceware.org/bugzilla/show_bug.cgi?id=14243 Link: https://patch.msgid.link/20251126134519.1760889-1-alexandre.chartre@oracle.com

objtool: Trim trailing NOPs in alternative

2025-11-24T19:40:48Z

When disassembling alternatives replace trailing NOPs with a single indication of the number of bytes covered with NOPs. Signed-off-by: Alexandre Chartre Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://patch.msgid.link/20251121095340.464045-31-alexandre.chartre@oracle.com

objtool: Add wide output for disassembly

2025-11-24T19:40:48Z

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 Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://patch.msgid.link/20251121095340.464045-30-alexandre.chartre@oracle.com

objtool: Compact output for alternatives with one instruction

2025-11-24T19:40:48Z

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 Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://patch.msgid.link/20251121095340.464045-29-alexandre.chartre@oracle.com

objtool: Improve naming of group alternatives

2025-11-24T19:40:48Z

Improve the naming of group alternatives by showing the feature name and flags used by the alternative. Signed-off-by: Alexandre Chartre Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://patch.msgid.link/20251121095340.464045-28-alexandre.chartre@oracle.com

objtool: Add Function to get the name of a CPU feature

2025-11-24T19:39:47Z

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 Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://patch.msgid.link/20251121095340.464045-27-alexandre.chartre@oracle.com

objtool: Provide access to feature and flags of group alternatives

2025-11-21T14:30:14Z

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 Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://patch.msgid.link/20251121095340.464045-26-alexandre.chartre@oracle.com

objtool: Fix address references in alternatives

2025-11-21T14:30:14Z

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 Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://patch.msgid.link/20251121095340.464045-25-alexandre.chartre@oracle.com

objtool: Disassemble jump table alternatives

2025-11-21T14:30:14Z

When using the --disas option, also disassemble jump tables. Signed-off-by: Alexandre Chartre Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://patch.msgid.link/20251121095340.464045-24-alexandre.chartre@oracle.com