lwn.git/tools/objtool, branch master

Merge tag 'objtool-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-04-14T20:00:04+00:00

Pull objtool updates from Ingo Molnar: - KLP support updates and fixes (Song Liu) - KLP-build script updates and fixes (Joe Lawrence) - Support Clang RAX DRAP sequence, to address clang false positive (Josh Poimboeuf) - Reorder ORC register numbering to match regular x86 register numbering (Josh Poimboeuf) - Misc cleanups (Wentong Tian, Song Liu) * tag 'objtool-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool/x86: Reorder ORC register numbering objtool: Support Clang RAX DRAP sequence livepatch/klp-build: report patch validation fuzz livepatch/klp-build: add terminal color output livepatch/klp-build: provide friendlier error messages livepatch/klp-build: improve short-circuit validation livepatch/klp-build: fix shellcheck complaints livepatch/klp-build: add Makefile with check target livepatch/klp-build: add grep-override function livepatch/klp-build: switch to GNU patch and recountdiff livepatch/klp-build: support patches that add/remove files objtool/klp: Correlate locals to globals objtool/klp: Match symbols based on demangled_name for global variables objtool/klp: Remove .llvm suffix in demangle_name() objtool/klp: Also demangle global objects objtool/klp: Use sym->demangled_name for symbol_name hash objtool/klp: Remove trailing '_' in demangle_name() objtool/klp: Remove redundant strcmp() in correlate_symbols() objtool: Use section/symbol type helpers

Merge branch 'nocache-cleanup'

2026-04-13T15:39:51+00:00

This series cleans up some of the special user copy functions naming and semantics. In particular, get rid of the (very traditional) double underscore names and behavior: the whole "optimize away the range check" model has been largely excised from the other user accessors because it's so subtle and can be unsafe, but also because it's just not a relevant optimization any more. To do that, a couple of drivers that misused the "user" copies as kernel copies in order to get non-temporal stores had to be fixed up, but that kind of code should never have been allowed anyway. The x86-only "nocache" version was also renamed to more accurately reflect what it actually does. This was all done because I looked at this code due to a report by Jann Horn, and I just couldn't stand the inconsistent naming, the horrible semantics, and the random misuse of these functions. This code should probably be cleaned up further, but it's at least slightly closer to normal semantics. I had a more intrusive series that went even further in trying to normalize the semantics, but that ended up hitting so many other inconsistencies between different architectures in this area (eg 'size_t' vs 'unsigned long' vs 'int' as size arguments, and various iovec check differences that Vasily Gorbik pointed out) that I ended up with this more limited version that fixed the worst of the issues. Reported-by: Jann Horn Tested-by: Will Deacon Link: https://lore.kernel.org/all/CAHk-=wgg1QVWNWG-UCFo1hx0zqrPnB3qhPzUTrWNft+MtXQXig@mail.gmail.com/ * nocache-cleanup: x86-64/arm64/powerpc: clean up and rename __copy_from_user_flushcache x86: rename and clean up __copy_from_user_inatomic_nocache() x86-64: rename misleadingly named '__copy_user_nocache()' function

x86-64: rename misleadingly named '__copy_user_nocache()' function

2026-03-30T22:05:56+00:00

This function was a masterclass in bad naming, for various historical reasons. It claimed to be a non-cached user copy. It is literally _neither_ of those things. It's a specialty memory copy routine that uses non-temporal stores for the destination (but not the source), and that does exception handling for both source and destination accesses. Also note that while it works for unaligned targets, any unaligned parts (whether at beginning or end) will not use non-temporal stores, since only words and quadwords can be non-temporal on x86. The exception handling means that it _can_ be used for user space accesses, but not on its own - it needs all the normal "start user space access" logic around it. But typically the user space access would be the source, not the non-temporal destination. That was the original intention of this, where the destination was some fragile persistent memory target that needed non-temporal stores in order to catch machine check exceptions synchronously and deal with them gracefully. Thus that non-descriptive name: one use case was to copy from user space into a non-cached kernel buffer. However, the existing users are a mix of that intended use-case, and a couple of random drivers that just did this as a performance tweak. Some of those random drivers then actively misused the user copying version (with STAC/CLAC and all) to do kernel copies without ever even caring about the exception handling, _just_ for the non-temporal destination. Rename it as a first small step to actually make it halfway sane, and change the prototype to be more normal: it doesn't take a user pointer unless the caller has done the proper conversion, and the argument size is the full size_t (it still won't actually copy more than 4GB in one go, but there's also no reason to silently truncate the size argument in the caller). Finally, use this now sanely named function in the NTB code, which mis-used a user copy version (with STAC/CLAC and all) of this interface despite it not actually being a user copy at all. Signed-off-by: Linus Torvalds

objtool/x86: Reorder ORC register numbering

2026-03-18T08:38:52+00:00

Reorder the ORC register values so their ordering matches the x86 instruction set register encodings. No functional change intended. Suggested-by: Peter Zijlstra Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel)

objtool: Support Clang RAX DRAP sequence

2026-03-18T08:38:52+00:00

Recent Clang can use RAX as a temporary register for the DRAP stack alignment sequence. Add support for that. Fixes the following warning: vmlinux.o: error: objtool: vmw_host_printf+0xd: unknown CFA base reg 0 Closes: https://lore.kernel.org/cefefdd1-7b82-406d-8ff4-e4b167e45ee6@app.fastmail.com Reported-by: Arnd Bergmann Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/3f33dc720b83dc6d3a2b7094f75a5c90a0b1cbc5.1773708458.git.jpoimboe@kernel.org

objtool: Fix Clang jump table detection

2026-03-16T22:31:25+00:00

With Clang, there can be a conditional forward jump between the load of the jump table address and the indirect branch. Fixes the following warning: vmlinux.o: warning: objtool: ___bpf_prog_run+0x1c5: sibling call from callable instruction with modified stack frame Reported-by: Arnd Bergmann Closes: https://lore.kernel.org/a426d669-58bb-4be1-9eaa-6f3d83109e2d@app.fastmail.com Link: https://patch.msgid.link/7d8600caed08901b6679767488acd639f6df9688.1773071992.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf

objtool/klp: fix mkstemp() failure with long paths

2026-03-16T19:40:31+00:00

The elf_create_file() function fails with EINVAL when the build directory path is long enough to truncate the "XXXXXX" suffix in the 256-byte tmp_name buffer. Simplify the code to remove the unnecessary dirname()/basename() split and concatenation. Instead, allocate the exact number of bytes needed for the path. Acked-by: Song Liu Signed-off-by: Joe Lawrence Link: https://patch.msgid.link/20260310203751.1479229-3-joe.lawrence@redhat.com Signed-off-by: Josh Poimboeuf

objtool/klp: fix data alignment in __clone_symbol()

2026-03-16T19:39:45+00:00

Commit 356e4b2f5b80 ("objtool: Fix data alignment in elf_add_data()") corrected the alignment of data within a section (honoring the section's sh_addralign). Apply the same alignment when klp-diff mode clones a symbol, adjusting the new symbol's offset for the output section's sh_addralign. Fixes: dd590d4d57eb ("objtool/klp: Introduce klp diff subcommand for diffing object files") Signed-off-by: Joe Lawrence Link: https://patch.msgid.link/20260310203751.1479229-2-joe.lawrence@redhat.com Signed-off-by: Josh Poimboeuf

Merge tag 'objtool-urgent-2026-03-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-03-15T17:36:01+00:00

Pull objtool fixes from Ingo Molnar: - Fix cross-build bug by using HOSTCFLAGS for HAVE_XXHASH test - Fix klp bug by fixing detection of corrupt static branch/call entries - Handle unsupported pr_debug() usage more gracefully - Fix hypothetical klp bug by avoiding NULL pointer dereference when printing code symbol name - Fix data alignment bug in elf_add_data() causing mangled strings - Fix confusing ERROR_INSN() error message - Handle unexpected Clang RSP musical chairs causing false positive warnings - Fix another objtool stack overflow in validate_branch() * tag 'objtool-urgent-2026-03-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Fix another stack overflow in validate_branch() objtool: Handle Clang RSP musical chairs objtool: Fix ERROR_INSN() error message objtool: Fix data alignment in elf_add_data() objtool: Use HOSTCFLAGS for HAVE_XXHASH test objtool/klp: Avoid NULL pointer dereference when printing code symbol name objtool/klp: Disable unsupported pr_debug() usage objtool/klp: Fix detection of corrupt static branch/call entries

objtool: Fix another stack overflow in validate_branch()

2026-03-09T15:45:13+00:00

The insn state is getting saved on the stack twice for each recursive iteration. No need for that, once is enough. Fixes the following reported stack overflow: drivers/scsi/qla2xxx/qla_dbg.o: error: SIGSEGV: objtool stack overflow! Segmentation fault Fixes: 70589843b36f ("objtool: Add option to trace function validation") Reported-by: Arnd Bergmann Closes: https://lore.kernel.org/90956545-2066-46e3-b547-10c884582eb0@app.fastmail.com Link: https://patch.msgid.link/8b97f62d083457f3b0a29a424275f7957dd3372f.1772821683.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf