linux/tools/objtool/include, branch v6.18

Merge tag 'x86_core_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2025-10-11T18:19:16Z

Pull more x86 updates from Borislav Petkov: - Remove a bunch of asm implementing condition flags testing in KVM's emulator in favor of int3_emulate_jcc() which is written in C - Replace KVM fastops with C-based stubs which avoids problems with the fastop infra related to latter not adhering to the C ABI due to their special calling convention and, more importantly, bypassing compiler control-flow integrity checking because they're written in asm - Remove wrongly used static branches and other ugliness accumulated over time in hyperv's hypercall implementation with a proper static function call to the correct hypervisor call variant - Add some fixes and modifications to allow running FRED-enabled kernels in KVM even on non-FRED hardware - Add kCFI improvements like validating indirect calls and prepare for enabling kCFI with GCC. Add cmdline params documentation and other code cleanups - Use the single-byte 0xd6 insn as the official #UD single-byte undefined opcode instruction as agreed upon by both x86 vendors - Other smaller cleanups and touchups all over the place * tag 'x86_core_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) x86,retpoline: Optimize patch_retpoline() x86,ibt: Use UDB instead of 0xEA x86/cfi: Remove __noinitretpoline and __noretpoline x86/cfi: Add "debug" option to "cfi=" bootparam x86/cfi: Standardize on common "CFI:" prefix for CFI reports x86/cfi: Document the "cfi=" bootparam options x86/traps: Clarify KCFI instruction layout compiler_types.h: Move __nocfi out of compiler-specific header objtool: Validate kCFI calls x86/fred: KVM: VMX: Always use FRED for IRQs when CONFIG_X86_FRED=y x86/fred: Play nice with invoking asm_fred_entry_from_kvm() on non-FRED hardware x86/fred: Install system vector handlers even if FRED isn't fully enabled x86/hyperv: Use direct call to hypercall-page x86/hyperv: Clean up hv_do_hypercall() KVM: x86: Remove fastops KVM: x86: Convert em_salc() to C KVM: x86: Introduce EM_ASM_3WCL KVM: x86: Introduce EM_ASM_1SRC2 KVM: x86: Introduce EM_ASM_2CL KVM: x86: Introduce EM_ASM_2W ...

objtool: Add action to check for absence of absolute relocations

2025-09-03T15:59:51Z

The x86 startup code must not use absolute references to code or data, as it executes before the kernel virtual mapping is up. Add an action to objtool to check all allocatable sections (with the exception of __patchable_function_entries, which uses absolute references for nebulous reasons) and raise an error if any absolute references are found. Note that debug sections typically contain lots of absolute references too, but those are not allocatable so they will be ignored. Signed-off-by: Ard Biesheuvel Signed-off-by: Borislav Petkov (AMD) Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/20250828102202.1849035-39-ardb+git@google.com

objtool: Validate kCFI calls

2025-08-18T12:23:09Z

Validate that all indirect calls adhere to kCFI rules. Notably doing nocfi indirect call to a cfi function is broken. Apparently some Rust 'core' code violates this and explodes when ran with FineIBT. All the ANNOTATE_NOCFI_SYM sites are prime targets for attackers. - runtime EFI is especially henous because it also needs to disable IBT. Basically calling unknown code without CFI protection at runtime is a massice security issue. - Kexec image handover; if you can exploit this, you get to keep it :-) Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Acked-by: Sean Christopherson Link: https://lkml.kernel.org/r/20250714103441.496787279@infradead.org

objtool: Speed up SHT_GROUP reindexing

2025-05-14T11:09:02Z

After elf_update_group_sh_info() was introduced, a prototype version of "objtool klp diff" went from taking ~1s to several minutes, due to looping almost endlessly in elf_update_group_sh_info() while creating thousands of local symbols in a file with thousands of sections. Dramatically improve the performance by marking all symbols' correlated SHT_GROUP sections while reading the object. That way there's no need to search for it every time a symbol gets reindexed. Fixes: 2cb291596e2c ("objtool: Fix up st_info in COMDAT group section") Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Tested-by: Rong Xu Link: https://lkml.kernel.org/r/2a33e583c87e3283706f346f9d59aac20653b7fd.1746662991.git.jpoimboe@kernel.org

objtool: Split INSN_CONTEXT_SWITCH into INSN_SYSCALL and INSN_SYSRET

2025-04-08T07:14:11Z

INSN_CONTEXT_SWITCH is ambiguous. It can represent both call semantics (SYSCALL, SYSENTER) and return semantics (SYSRET, IRET, RETS, RETU). Those differ significantly: calls preserve control flow whereas returns terminate it. Objtool uses an arbitrary rule for INSN_CONTEXT_SWITCH that almost works by accident: if in a function, keep going; otherwise stop. It should instead be based on the semantics of the underlying instruction. In preparation for improving that, split INSN_CONTEXT_SWITCH into INSN_SYCALL and INSN_SYSRET. No functional change. Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Cc: Linus Torvalds Link: https://lore.kernel.org/r/19a76c74d2c051d3bc9a775823cafc65ad267a7a.1744095216.git.jpoimboe@kernel.org

objtool: Change "warning:" to "error: " for fatal errors

2025-04-01T07:07:13Z

This is similar to GCC's behavior and makes it more obvious why the build failed. Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Cc: Linus Torvalds Link: https://lore.kernel.org/r/0ea76f4b0e7a370711ed9f75fd0792bb5979c2bf.1743481539.git.jpoimboe@kernel.org

Revert "objtool: Increase per-function WARN_FUNC() rate limit"

2025-04-01T07:07:13Z

This reverts commit 0a7fb6f07e3ad497d31ae9a2082d2cacab43d54a. The "skipping duplicate warnings" warning is technically not an actual warning, which can cause confusion. This feature isn't all that useful anyway. It's exceedingly rare for a function to have more than one unrelated warning. Suggested-by: Ingo Molnar Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Cc: Linus Torvalds Link: https://lore.kernel.org/r/e5abe5e858acf1a9207a5dfa0f37d17ac9dca872.1743481539.git.jpoimboe@kernel.org

objtool: Reduce CONFIG_OBJTOOL_WERROR verbosity

2025-03-25T08:20:27Z

Remove the following from CONFIG_OBJTOOL_WERROR: * backtrace * "upgraded warnings to errors" message * cmdline args This makes the default output less cluttered and makes it easier to spot the actual warnings. Note the above options are still are available with --verbose or OBJTOOL_VERBOSE=1. Also, do the cmdline arg printing on all warnings, regardless of werror. Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Cc: Linus Torvalds Link: https://lore.kernel.org/r/d61df69f64b396fa6b2a1335588aad7a34ea9e71.1742852846.git.jpoimboe@kernel.org

objtool: Improve error handling

2025-03-25T08:20:27Z

Fix some error handling issues, improve error messages, properly distinguish betwee errors and warnings, and generally try to make all the error handling more consistent. Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Cc: Linus Torvalds Link: https://lore.kernel.org/r/3094bb4463dad29b6bd1bea03848d1571ace771c.1742852846.git.jpoimboe@kernel.org

objtool: Fix X86_FEATURE_SMAP alternative handling

2025-03-25T08:20:26Z

For X86_FEATURE_SMAP alternatives which replace NOP with STAC or CLAC, uaccess validation skips the NOP branch to avoid following impossible code paths, e.g. where a STAC would be patched but a CLAC wouldn't. However, it's not safe to assume an X86_FEATURE_SMAP alternative is patching STAC/CLAC. There can be other alternatives, like static_cpu_has(), where both branches need to be validated. Fix that by repurposing ANNOTATE_IGNORE_ALTERNATIVE for skipping either original instructions or new ones. This is a more generic approach which enables the removal of the feature checking hacks and the insn->ignore bit. Fixes the following warnings: arch/x86/mm/fault.o: warning: objtool: do_user_addr_fault+0x8ec: __stack_chk_fail() missing __noreturn in .c/.h or NORETURN() in noreturns.h arch/x86/mm/fault.o: warning: objtool: do_user_addr_fault+0x8f1: unreachable instruction [ mingo: Fix up conflicts with recent x86 changes. ] Fixes: ea24213d8088 ("objtool: Add UACCESS validation") Reported-by: kernel test robot Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Cc: Linus Torvalds Link: https://lore.kernel.org/r/de0621ca242130156a55d5d74fed86994dfa4c9c.1742852846.git.jpoimboe@kernel.org Closes: https://lore.kernel.org/oe-kbuild-all/202503181736.zkZUBv4N-lkp@intel.com/