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Merge tag 'objtool-core-2025-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molnar: - klp-build livepatch module generation (Josh Poimboeuf) Introduce 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 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. - Disassemble code with libopcodes instead of running objdump (Alexandre Chartre) - Disassemble support (-d option to objtool) by Alexandre Chartre, which supports the decoding of various Linux kernel code generation specials such as alternatives: 17ef: sched_balance_find_dst_group+0x62f mov 0x34(%r9),%edx 17f3: sched_balance_find_dst_group+0x633 | <alternative.17f3> | X86_FEATURE_POPCNT 17f3: sched_balance_find_dst_group+0x633 | call 0x17f8 <__sw_hweight64> | popcnt %rdi,%rax 17f8: sched_balance_find_dst_group+0x638 cmp %eax,%edx ... jump table alternatives: 1895: sched_use_asym_prio+0x5 test $0x8,%ch 1898: sched_use_asym_prio+0x8 je 0x18a9 <sched_use_asym_prio+0x19> 189a: sched_use_asym_prio+0xa | <jump_table.189a> | JUMP 189a: sched_use_asym_prio+0xa | jmp 0x18ae <sched_use_asym_prio+0x1e> | nop2 189c: sched_use_asym_prio+0xc mov $0x1,%eax 18a1: sched_use_asym_prio+0x11 and $0x80,%ecx ... exception table alternatives: native_read_msr: 5b80: native_read_msr+0x0 mov %edi,%ecx 5b82: native_read_msr+0x2 | <ex_table.5b82> | EXCEPTION 5b82: native_read_msr+0x2 | rdmsr | resume at 0x5b84 <native_read_msr+0x4> 5b84: native_read_msr+0x4 shl $0x20,%rdx .... x86 feature flag decoding (also see the X86_FEATURE_POPCNT example in sched_balance_find_dst_group() above): 2faaf: start_thread_common.constprop.0+0x1f jne 0x2fba4 <start_thread_common.constprop.0+0x114> 2fab5: start_thread_common.constprop.0+0x25 | <alternative.2fab5> | X86_FEATURE_ALWAYS | X86_BUG_NULL_SEG 2fab5: start_thread_common.constprop.0+0x25 | jmp 0x2faba <.altinstr_aux+0x2f4> | jmp 0x4b0 <start_thread_common.constprop.0+0x3f> | nop5 2faba: start_thread_common.constprop.0+0x2a mov $0x2b,%eax ... NOP sequence shortening: 1048e2: snapshot_write_finalize+0xc2 je 0x104917 <snapshot_write_finalize+0xf7> 1048e4: snapshot_write_finalize+0xc4 nop6 1048ea: snapshot_write_finalize+0xca nop11 1048f5: snapshot_write_finalize+0xd5 nop11 104900: snapshot_write_finalize+0xe0 mov %rax,%rcx 104903: snapshot_write_finalize+0xe3 mov 0x10(%rdx),%rax ... and much more. - Function validation tracing support (Alexandre Chartre) - Various -ffunction-sections fixes (Josh Poimboeuf) - Clang AutoFDO (Automated Feedback-Directed Optimizations) support (Josh Poimboeuf) - Misc fixes and cleanups (Borislav Petkov, Chen Ni, Dylan Hatch, Ingo Molnar, John Wang, Josh Poimboeuf, Pankaj Raghav, Peter Zijlstra, Thorsten Blum) * tag 'objtool-core-2025-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (129 commits) objtool: Fix segfault on unknown alternatives objtool: Build with disassembly can fail when including bdf.h objtool: Trim trailing NOPs in alternative objtool: Add wide output for disassembly objtool: Compact output for alternatives with one instruction objtool: Improve naming of group alternatives objtool: Add Function to get the name of a CPU feature objtool: Provide access to feature and flags of group alternatives objtool: Fix address references in alternatives objtool: Disassemble jump table alternatives objtool: Disassemble exception table alternatives objtool: Print addresses with alternative instructions objtool: Disassemble group alternatives objtool: Print headers for alternatives objtool: Preserve alternatives order objtool: Add the --disas=<function-pattern> action objtool: Do not validate IBT for .return_sites and .call_sites objtool: Improve tracing of alternative instructions objtool: Add functions to better name alternatives objtool: Identify the different types of alternatives ...
2 parents b53440f + 6ec33db commit 63e6995

99 files changed

Lines changed: 7592 additions & 1246 deletions

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‎MAINTAINERS‎

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@@ -14459,10 +14459,11 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching.g
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F: Documentation/ABI/testing/sysfs-kernel-livepatch
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F: Documentation/livepatch/
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F: arch/powerpc/include/asm/livepatch.h
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F: include/linux/livepatch.h
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F: include/linux/livepatch*.h
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F: kernel/livepatch/
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F: kernel/module/livepatch.c
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F: samples/livepatch/
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F: scripts/livepatch/
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F: tools/testing/selftests/livepatch/
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LLC (802.2)

‎arch/s390/include/asm/nospec-insn.h‎

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#ifdef CONFIG_EXPOLINE_EXTERN
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SYM_CODE_START(\name)
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#else
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.pushsection .text.\name,"axG",@progbits,\name,comdat
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.pushsection .text..\name,"axG",@progbits,\name,comdat
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.globl \name
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.hidden \name
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.type \name,@function

‎arch/s390/kernel/vmlinux.lds.S‎

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@@ -51,7 +51,7 @@ SECTIONS
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IRQENTRY_TEXT
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SOFTIRQENTRY_TEXT
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FTRACE_HOTPATCH_TRAMPOLINES_TEXT
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*(.text.*_indirect_*)
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*(.text..*_indirect_*)
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*(.gnu.warning)
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. = ALIGN(PAGE_SIZE);
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_etext = .; /* End of text section */

‎arch/x86/Kconfig‎

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@@ -261,6 +261,7 @@ config X86
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select HAVE_FUNCTION_ERROR_INJECTION
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select HAVE_KRETPROBES
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select HAVE_RETHOOK
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select HAVE_KLP_BUILD if X86_64
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select HAVE_LIVEPATCH if X86_64
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select HAVE_MIXED_BREAKPOINTS_REGS
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select HAVE_MOD_ARCH_SPECIFIC

‎arch/x86/boot/startup/Makefile‎

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@@ -36,7 +36,7 @@ $(patsubst %.o,$(obj)/%.o,$(lib-y)): OBJECT_FILES_NON_STANDARD := y
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# relocations, even if other objtool actions are being deferred.
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#
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$(pi-objs): objtool-enabled = 1
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$(pi-objs): objtool-args = $(if $(delay-objtool),,$(objtool-args-y)) --noabs
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$(pi-objs): objtool-args = $(if $(delay-objtool),--dry-run,$(objtool-args-y)) --noabs
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#
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# Confine the startup code by prefixing all symbols with __pi_ (for position

‎arch/x86/include/asm/alternative.h‎

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@@ -198,6 +198,7 @@ static inline int alternatives_text_reserved(void *start, void *end)
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#define ALTINSTR_ENTRY(ft_flags) \
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".pushsection .altinstructions,\"a\"\n" \
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ANNOTATE_DATA_SPECIAL \
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" .long 771b - .\n" /* label */ \
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" .long 774f - .\n" /* new instruction */ \
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" .4byte " __stringify(ft_flags) "\n" /* feature + flags */ \
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#define ALTINSTR_REPLACEMENT(newinstr) /* replacement */ \
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".pushsection .altinstr_replacement, \"ax\"\n" \
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ANNOTATE_DATA_SPECIAL \
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"# ALT: replacement\n" \
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"774:\n\t" newinstr "\n775:\n" \
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".popsection\n"
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* instruction. See apply_alternatives().
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*/
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.macro altinstr_entry orig alt ft_flags orig_len alt_len
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ANNOTATE_DATA_SPECIAL
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.long \orig - .
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.long \alt - .
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.4byte \ft_flags
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.popsection ; \
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.pushsection .altinstr_replacement,"ax" ; \
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ANNOTATE_DATA_SPECIAL ; \
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newinst ; \
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.popsection ;

‎arch/x86/include/asm/asm.h‎

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#ifndef _ASM_X86_ASM_H
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#define _ASM_X86_ASM_H
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#include <linux/annotate.h>
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#ifdef __ASSEMBLER__
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# define __ASM_FORM(x, ...) x,## __VA_ARGS__
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# define __ASM_FORM_RAW(x, ...) x,## __VA_ARGS__
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# define _ASM_EXTABLE_TYPE(from, to, type) \
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.pushsection "__ex_table","a" ; \
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.balign 4 ; \
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ANNOTATE_DATA_SPECIAL ; \
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.long (from) - . ; \
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.long (to) - . ; \
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.long type ; \
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# define _ASM_EXTABLE_TYPE(from, to, type) \
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" .pushsection \"__ex_table\",\"a\"\n" \
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" .balign 4\n" \
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ANNOTATE_DATA_SPECIAL \
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# define _ASM_EXTABLE_TYPE_REG(from, to, type, reg) \
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ANNOTATE_DATA_SPECIAL \
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‎arch/x86/include/asm/bug.h‎

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#define _BUG_FLAGS_ASM(ins, file, line, flags, size, extra) \
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".pushsection __bug_table,\"aw\"\n" \
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ANNOTATE_DATA_SPECIAL \
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__BUG_ENTRY(file, line, flags) \
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"\t.org 2b + " size "\n" \
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‎arch/x86/include/asm/cpufeature.h‎

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asm goto(ALTERNATIVE_TERNARY("jmp 6f", %c[feature], "", "jmp %l[t_no]")
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".pushsection .altinstr_aux,\"ax\"\n"
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"6:\n"
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ANNOTATE_DATA_SPECIAL
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" testb %[bitnum], %a[cap_byte]\n"
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" jnz %l[t_yes]\n"
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" jmp %l[t_no]\n"

‎arch/x86/include/asm/jump_label.h‎

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#define JUMP_TABLE_ENTRY(key, label) \
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".pushsection __jump_table, \"aw\" \n\t" \
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_ASM_ALIGN "\n\t" \
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ANNOTATE_DATA_SPECIAL \
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".long 1b - . \n\t" \
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".long " label " - . \n\t" \
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_ASM_PTR " " key " - . \n\t" \

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