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63e6995005
- 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)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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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
...
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| .. | ||
| 842 | ||
| crc | ||
| crypto | ||
| dim | ||
| fonts | ||
| kunit | ||
| lz4 | ||
| lzo | ||
| math | ||
| pldmfw | ||
| raid6 | ||
| reed_solomon | ||
| test_fortify | ||
| tests | ||
| vdso | ||
| xz | ||
| zlib_deflate | ||
| zlib_dfltcc | ||
| zlib_inflate | ||
| zstd | ||
| .gitignore | ||
| alloc_tag.c | ||
| argv_split.c | ||
| ashldi3.c | ||
| ashrdi3.c | ||
| asn1_decoder.c | ||
| asn1_encoder.c | ||
| assoc_array.c | ||
| atomic64_test.c | ||
| atomic64.c | ||
| audit.c | ||
| base64.c | ||
| bcd.c | ||
| bch.c | ||
| bitmap-str.c | ||
| bitmap.c | ||
| bitrev.c | ||
| bootconfig-data.S | ||
| bootconfig.c | ||
| bsearch.c | ||
| btree.c | ||
| bucket_locks.c | ||
| bug.c | ||
| build_OID_registry | ||
| buildid.c | ||
| bust_spinlocks.c | ||
| check_signature.c | ||
| checksum.c | ||
| closure.c | ||
| clz_ctz.c | ||
| clz_tab.c | ||
| cmdline.c | ||
| cmpdi2.c | ||
| cmpxchg-emu.c | ||
| codetag.c | ||
| compat_audit.c | ||
| cpu_rmap.c | ||
| cpumask.c | ||
| ctype.c | ||
| debug_info.c | ||
| debug_locks.c | ||
| debugobjects.c | ||
| dec_and_lock.c | ||
| decompress_bunzip2.c | ||
| decompress_inflate.c | ||
| decompress_unlz4.c | ||
| decompress_unlzma.c | ||
| decompress_unlzo.c | ||
| decompress_unxz.c | ||
| decompress_unzstd.c | ||
| decompress.c | ||
| devmem_is_allowed.c | ||
| devres.c | ||
| dhry_1.c | ||
| dhry_2.c | ||
| dhry_run.c | ||
| dhry.h | ||
| digsig.c | ||
| dump_stack.c | ||
| dynamic_debug.c | ||
| dynamic_queue_limits.c | ||
| earlycpio.c | ||
| errname.c | ||
| error-inject.c | ||
| errseq.c | ||
| extable.c | ||
| fault-inject-usercopy.c | ||
| fault-inject.c | ||
| fdt_addresses.c | ||
| fdt_empty_tree.c | ||
| fdt_ro.c | ||
| fdt_rw.c | ||
| fdt_strerror.c | ||
| fdt_sw.c | ||
| fdt_wip.c | ||
| fdt.c | ||
| find_bit_benchmark_rust.rs | ||
| find_bit_benchmark.c | ||
| find_bit.c | ||
| flex_proportions.c | ||
| fw_table.c | ||
| genalloc.c | ||
| generic-radix-tree.c | ||
| glob.c | ||
| globtest.c | ||
| group_cpus.c | ||
| hexdump.c | ||
| hweight.c | ||
| idr.c | ||
| inflate.c | ||
| interval_tree_test.c | ||
| interval_tree.c | ||
| iomap_copy.c | ||
| iomap.c | ||
| iomem_copy.c | ||
| iommu-helper.c | ||
| iov_iter.c | ||
| irq_poll.c | ||
| irq_regs.c | ||
| is_single_threaded.c | ||
| kasprintf.c | ||
| Kconfig | ||
| Kconfig.debug | ||
| Kconfig.kasan | ||
| Kconfig.kcsan | ||
| Kconfig.kfence | ||
| Kconfig.kgdb | ||
| Kconfig.kmsan | ||
| Kconfig.ubsan | ||
| kfifo.c | ||
| klist.c | ||
| kobject_uevent.c | ||
| kobject.c | ||
| kstrtox.c | ||
| kstrtox.h | ||
| linear_ranges.c | ||
| list_debug.c | ||
| list_sort.c | ||
| llist.c | ||
| locking-selftest-hardirq.h | ||
| locking-selftest-mutex.h | ||
| locking-selftest-rlock-hardirq.h | ||
| locking-selftest-rlock-softirq.h | ||
| locking-selftest-rlock.h | ||
| locking-selftest-rsem.h | ||
| locking-selftest-rtmutex.h | ||
| locking-selftest-softirq.h | ||
| locking-selftest-spin-hardirq.h | ||
| locking-selftest-spin-softirq.h | ||
| locking-selftest-spin.h | ||
| locking-selftest-wlock-hardirq.h | ||
| locking-selftest-wlock-softirq.h | ||
| locking-selftest-wlock.h | ||
| locking-selftest-wsem.h | ||
| locking-selftest.c | ||
| lockref.c | ||
| logic_iomem.c | ||
| logic_pio.c | ||
| lru_cache.c | ||
| lshrdi3.c | ||
| lwq.c | ||
| Makefile | ||
| maple_tree.c | ||
| memcat_p.c | ||
| memory-notifier-error-inject.c | ||
| memregion.c | ||
| memweight.c | ||
| min_heap.c | ||
| muldi3.c | ||
| net_utils.c | ||
| netdev-notifier-error-inject.c | ||
| nlattr.c | ||
| nmi_backtrace.c | ||
| notifier-error-inject.c | ||
| notifier-error-inject.h | ||
| objagg.c | ||
| objpool.c | ||
| of-reconfig-notifier-error-inject.c | ||
| oid_registry.c | ||
| once.c | ||
| packing_test.c | ||
| packing.c | ||
| parman.c | ||
| parser.c | ||
| percpu_counter.c | ||
| percpu_test.c | ||
| percpu-refcount.c | ||
| plist.c | ||
| pm-notifier-error-inject.c | ||
| polynomial.c | ||
| radix-tree.c | ||
| radix-tree.h | ||
| random32.c | ||
| ratelimit.c | ||
| rbtree_test.c | ||
| rbtree.c | ||
| rcuref.c | ||
| ref_tracker.c | ||
| refcount.c | ||
| rhashtable.c | ||
| sbitmap.c | ||
| scatterlist.c | ||
| seq_buf.c | ||
| sg_pool.c | ||
| sg_split.c | ||
| siphash.c | ||
| smp_processor_id.c | ||
| sort.c | ||
| stackdepot.c | ||
| stmp_device.c | ||
| string_helpers.c | ||
| string.c | ||
| strncpy_from_user.c | ||
| strnlen_user.c | ||
| sys_info.c | ||
| syscall.c | ||
| test_bitmap.c | ||
| test_bitops.c | ||
| test_bpf.c | ||
| test_debug_virtual.c | ||
| test_dynamic_debug.c | ||
| test_firmware.c | ||
| test_fpu_glue.c | ||
| test_fpu_impl.c | ||
| test_fpu.h | ||
| test_free_pages.c | ||
| test_hexdump.c | ||
| test_hmm_uapi.h | ||
| test_hmm.c | ||
| test_ida.c | ||
| test_kho.c | ||
| test_kmod.c | ||
| test_lockup.c | ||
| test_maple_tree.c | ||
| test_memcat_p.c | ||
| test_meminit.c | ||
| test_min_heap.c | ||
| test_module.c | ||
| test_objagg.c | ||
| test_objpool.c | ||
| test_parman.c | ||
| test_ref_tracker.c | ||
| test_rhashtable.c | ||
| test_static_key_base.c | ||
| test_static_keys.c | ||
| test_sysctl.c | ||
| test_ubsan.c | ||
| test_uuid.c | ||
| test_vmalloc.c | ||
| test_xarray.c | ||
| test-kstrtox.c | ||
| textsearch.c | ||
| timerqueue.c | ||
| trace_readwrite.c | ||
| ts_bm.c | ||
| ts_fsm.c | ||
| ts_kmp.c | ||
| ubsan.c | ||
| ubsan.h | ||
| ucmpdi2.c | ||
| ucs2_string.c | ||
| union_find.c | ||
| usercopy.c | ||
| uuid.c | ||
| vsprintf.c | ||
| win_minmax.c | ||
| xarray.c | ||
| xxhash.c | ||