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2025-05-18objtool/rust: add one more `noreturn` Rust function for Rust 1.87.0Miguel Ojeda1-0/+1
commit 19f5ca461d5fc09bdf93a9f8e4bd78ed3a49dc71 upstream. Starting with Rust 1.87.0 (expected 2025-05-15), `objtool` may report: rust/core.o: warning: objtool: _R..._4core9panicking9panic_fmt() falls through to next function _R..._4core9panicking18panic_nounwind_fmt() rust/core.o: warning: objtool: _R..._4core9panicking18panic_nounwind_fmt() falls through to next function _R..._4core9panicking5panic() The reason is that `rust_begin_unwind` is now mangled: _R..._7___rustc17rust_begin_unwind Thus add the mangled one to the list so that `objtool` knows it is actually `noreturn`. See commit 56d680dd23c3 ("objtool/rust: list `noreturn` Rust functions") for more details. Alternatively, we could remove the fixed one in `noreturn.h` and relax this test to cover both, but it seems best to be strict as long as we can. Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Cc: Josh Poimboeuf <jpoimboe@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Link: https://lore.kernel.org/r/20250502140237.1659624-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-05-02objtool: Ignore end-of-section jumps for KCOV/GCOVJosh Poimboeuf1-6/+16
commit 0d7597749f5a3ac67851d3836635d084df15fb66 upstream. When KCOV or GCOV is enabled, dead code can be left behind, in which case objtool silences unreachable and undefined behavior (fallthrough) warnings. Fallthrough warnings, and their variant "end of section" warnings, were silenced with the following commit: 6b023c784204 ("objtool: Silence more KCOV warnings") Another variant of a fallthrough warning is a jump to the end of a function. If that function happens to be at the end of a section, the jump destination doesn't actually exist. Normally that would be a fatal objtool error, but for KCOV/GCOV it's just another undefined behavior fallthrough. Silence it like the others. Fixes the following warning: drivers/iommu/dma-iommu.o: warning: objtool: iommu_dma_sw_msi+0x92: can't find jump dest instruction at .text+0x54d5 Fixes: 6b023c784204 ("objtool: Silence more KCOV warnings") Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/08fbe7d7e1e20612206f1df253077b94f178d93e.1743481539.git.jpoimboe@kernel.org Closes: https://lore.kernel.org/314f8809-cd59-479b-97d7-49356bf1c8d1@infradead.org/ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-05-02objtool: Stop UNRET validation on UD2Josh Poimboeuf1-0/+3
[ Upstream commit 9f9cc012c2cbac4833746a0182e06a8eec940d19 ] In preparation for simplifying INSN_SYSCALL, make validate_unret() terminate control flow on UD2 just like validate_branch() already does. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/ce841269e7e28c8b7f32064464a9821034d724ff.1744095216.git.jpoimboe@kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-05-02objtool, panic: Disable SMAP in __stack_chk_fail()Josh Poimboeuf1-1/+4
[ Upstream commit 72c774aa9d1e16bfd247096935e7dae194d84929 ] __stack_chk_fail() can be called from uaccess-enabled code. Make sure uaccess gets disabled before calling panic(). Fixes the following warning: kernel/trace/trace_branch.o: error: objtool: ftrace_likely_update+0x1ea: call to __stack_chk_fail() with UACCESS enabled Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/a3e97e0119e1b04c725a8aa05f7bc83d98e657eb.1742852847.git.jpoimboe@kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-05-02objtool: Silence more KCOV warningsJosh Poimboeuf1-0/+6
[ Upstream commit 6b023c7842048c4bbeede802f3cf36b96c7a8b25 ] In the past there were issues with KCOV triggering unreachable instruction warnings, which is why unreachable warnings are now disabled with CONFIG_KCOV. Now some new KCOV warnings are showing up with GCC 14: vmlinux.o: warning: objtool: cpuset_write_resmask() falls through to next function cpuset_update_active_cpus.cold() drivers/usb/core/driver.o: error: objtool: usb_deregister() falls through to next function usb_match_device() sound/soc/codecs/snd-soc-wcd934x.o: warning: objtool: .text.wcd934x_slim_irq_handler: unexpected end of section All are caused by GCC KCOV not finishing an optimization, leaving behind a never-taken conditional branch to a basic block which falls through to the next function (or end of section). At a high level this is similar to the unreachable warnings mentioned above, in that KCOV isn't fully removing dead code. Treat it the same way by adding these to the list of warnings to ignore with CONFIG_KCOV. Reported-by: Ingo Molnar <mingo@kernel.org> Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/66a61a0b65d74e072d3dc02384e395edb2adc3c5.1742852846.git.jpoimboe@kernel.org Closes: https://lore.kernel.org/Z9iTsI09AEBlxlHC@gmail.com Closes: https://lore.kernel.org/oe-kbuild-all/202503180044.oH9gyPeg-lkp@intel.com/ Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-04-25objtool/rust: add one more `noreturn` Rust function for Rust 1.86.0Miguel Ojeda1-0/+1
commit a3cd5f507b72c0532c3345b6913557efab34f405 upstream. Starting with Rust 1.86.0 (see upstream commit b151b513ba2b ("Insert null checks for pointer dereferences when debug assertions are enabled") [1]), under some kernel configurations with `CONFIG_RUST_DEBUG_ASSERTIONS=y`, one may trigger a new `objtool` warning: rust/kernel.o: warning: objtool: _R..._6kernel9workqueue6system() falls through to next function _R...9workqueue14system_highpri() due to a call to the `noreturn` symbol: core::panicking::panic_null_pointer_dereference Thus add it to the list so that `objtool` knows it is actually `noreturn`. See commit 56d680dd23c3 ("objtool/rust: list `noreturn` Rust functions") for more details. Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Fixes: 56d680dd23c3 ("objtool/rust: list `noreturn` Rust functions") Link: https://github.com/rust-lang/rust/commit/b151b513ba2b65c7506ec1a80f2712bbd09154d1 [1] Reviewed-by: Alice Ryhl <aliceryhl@google.com> Link: https://lore.kernel.org/r/20250413002338.1741593-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-04-20objtool: Fix INSN_CONTEXT_SWITCH handling in validate_unret()Josh Poimboeuf1-0/+5
[ Upstream commit a8df7d0ef92eca28c610206c6748daf537ac0586 ] The !CONFIG_IA32_EMULATION version of xen_entry_SYSCALL_compat() ends with a SYSCALL instruction which is classified by objtool as INSN_CONTEXT_SWITCH. Unlike validate_branch(), validate_unret() doesn't consider INSN_CONTEXT_SWITCH in a non-function to be a dead end, so it keeps going past the end of xen_entry_SYSCALL_compat(), resulting in the following warning: vmlinux.o: warning: objtool: xen_reschedule_interrupt+0x2a: RET before UNTRAIN Fix that by adding INSN_CONTEXT_SWITCH handling to validate_unret() to match what validate_branch() is already doing. Fixes: a09a6e2399ba ("objtool: Add entry UNRET validation") Reported-by: Andrew Cooper <andrew.cooper3@citrix.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/f5eda46fd09f15b1f5cde3d9ae3b92b958342add.1744095216.git.jpoimboe@kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-04-10objtool: Fix verbose disassembly if CROSS_COMPILE isn't setDavid Laight1-0/+2
[ Upstream commit e77956e4e5c11218e60a1fe8cdbccd02476f2e56 ] In verbose mode, when printing the disassembly of affected functions, if CROSS_COMPILE isn't set, the objdump command string gets prefixed with "(null)". Somehow this worked before. Maybe some versions of glibc return an empty string instead of NULL. Fix it regardless. [ jpoimboe: Rewrite commit log. ] Fixes: ca653464dd097 ("objtool: Add verbose option for disassembling affected functions") Signed-off-by: David Laight <david.laight.linux@gmail.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/20250215142321.14081-1-david.laight.linux@gmail.com Link: https://lore.kernel.org/r/b931a4786bc0127aa4c94e8b35ed617dcbd3d3da.1743481539.git.jpoimboe@kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-04-10objtool: Fix segfault in ignore_unreachable_insn()Josh Poimboeuf1-1/+1
[ Upstream commit 69d41d6dafff0967565b971d950bd10443e4076c ] Check 'prev_insn' before dereferencing it. Fixes: bd841d6154f5 ("objtool: Fix CONFIG_UBSAN_TRAP unreachable warnings") Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/5df4ff89c9e4b9e788b77b0531234ffa7ba03e9e.1743136205.git.jpoimboe@kernel.org Closes: https://lore.kernel.org/d86b4cc6-0b97-4095-8793-a7384410b8ab@app.fastmail.com Closes: https://lore.kernel.org/Z-V_rruKY0-36pqA@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-04-10objtool: Fix detection of consecutive jump tables on Clang 20Josh Poimboeuf1-18/+8
[ Upstream commit ef753d66051ca03bee1982ce047f9eaf90f81ab4 ] The jump table detection code assumes jump tables are in the same order as their corresponding indirect branches. That's apparently not always true with Clang 20. Fix that by changing how multiple jump tables are detected. In the first detection pass, mark the beginning of each jump table so the second pass can tell where one ends and the next one begins. Fixes the following warnings: vmlinux.o: warning: objtool: SiS_GetCRT2Ptr+0x1ad: stack state mismatch: cfa1=4+8 cfa2=5+16 sound/core/seq/snd-seq.o: warning: objtool: cc_ev_to_ump_midi2+0x589: return with modified stack frame Fixes: be2f0b1e1264 ("objtool: Get rid of reloc->jump_table_start") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/141752fff614eab962dba6bdfaa54aa67ff03bba.1742852846.git.jpoimboe@kernel.org Closes: https://lore.kernel.org/oe-kbuild-all/202503171547.LlCTJLQL-lkp@intel.com/ Closes: https://lore.kernel.org/oe-kbuild-all/202503200535.J3hAvcjw-lkp@intel.com/ Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-04-10objtool: Handle PC relative relocation typeTiezhu Yang1-1/+6
[ Upstream commit c4b93b06230ae49870187189d9f7342f6ad4f14e ] For the most part, an absolute relocation type is used for rodata. In the case of STT_SECTION, reloc->sym->offset is always zero, for the other symbol types, reloc_addend(reloc) is always zero, thus it can use a simple statement "reloc->sym->offset + reloc_addend(reloc)" to obtain the symbol offset for various symbol types. When compiling on LoongArch, there exist PC relative relocation types for rodata, it needs to calculate the symbol offset with "S + A - PC" according to the spec of "ELF for the LoongArch Architecture". If there is only one jump table in the rodata, the "PC" is the entry address which is equal with the value of reloc_offset(reloc), at this time, reloc_offset(table) is 0. If there are many jump tables in the rodata, the "PC" is the offset of the jump table's base address which is equal with the value of reloc_offset(reloc) - reloc_offset(table). So for LoongArch, if the relocation type is PC relative, it can use a statement "reloc_offset(reloc) - reloc_offset(table)" to get the "PC" value when calculating the symbol offset with "S + A - PC" for one or many jump tables in the rodata. Add an arch-specific function arch_jump_table_sym_offset() to assign the symbol offset, for the most part that is an absolute relocation, the default value is "reloc->sym->offset + reloc_addend(reloc)" in the weak definition, it can be overridden by each architecture that has different requirements. Link: https://github.com/loongson/la-abi-specs/blob/release/laelf.adoc Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Link: https://lore.kernel.org/r/20250211115016.26913-4-yangtiezhu@loongson.cn Acked-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Stable-dep-of: ef753d66051c ("objtool: Fix detection of consecutive jump tables on Clang 20") Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-04-10objtool: Handle different entry size of rodataTiezhu Yang1-1/+1
[ Upstream commit 091bf313f8a852a7f30c3a8dcef569edfd06f5dc ] In the most cases, the entry size of rodata is 8 bytes because the relocation type is 64 bit. There are also 32 bit relocation types, the entry size of rodata should be 4 bytes in this case. Add an arch-specific function arch_reloc_size() to assign the entry size of rodata for x86, powerpc and LoongArch. Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Link: https://lore.kernel.org/r/20250211115016.26913-3-yangtiezhu@loongson.cn Acked-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Stable-dep-of: ef753d66051c ("objtool: Fix detection of consecutive jump tables on Clang 20") Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-04-10objtool: Handle various symbol types of rodataTiezhu Yang1-5/+11
[ Upstream commit ab6ce22b789622ca732e91cbb3a5cb5ba370cbd0 ] In the relocation section ".rela.rodata" of each .o file compiled with LoongArch toolchain, there are various symbol types such as STT_NOTYPE, STT_OBJECT, STT_FUNC in addition to the usual STT_SECTION, it needs to use reloc symbol offset instead of reloc addend to find the destination instruction in find_jump_table() and add_jump_table(). For the most part, an absolute relocation type is used for rodata. In the case of STT_SECTION, reloc->sym->offset is always zero, and for the other symbol types, reloc_addend(reloc) is always zero, thus it can use a simple statement "reloc->sym->offset + reloc_addend(reloc)" to obtain the symbol offset for various symbol types. Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Link: https://lore.kernel.org/r/20250211115016.26913-2-yangtiezhu@loongson.cn Acked-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Stable-dep-of: ef753d66051c ("objtool: Fix detection of consecutive jump tables on Clang 20") Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-04-10x86/traps: Make exc_double_fault() consistently noreturnJosh Poimboeuf1-30/+1
[ Upstream commit 8085fcd78c1a3dbdf2278732579009d41ce0bc4e ] The CONFIG_X86_ESPFIX64 version of exc_double_fault() can return to its caller, but the !CONFIG_X86_ESPFIX64 version never does. In the latter case the compiler and/or objtool may consider it to be implicitly noreturn. However, due to the currently inflexible way objtool detects noreturns, a function's noreturn status needs to be consistent across configs. The current workaround for this issue is to suppress unreachable warnings for exc_double_fault()'s callers. Unfortunately that can result in ORC coverage gaps and potentially worse issues like inert static calls and silently disabled CPU mitigations. Instead, prevent exc_double_fault() from ever being implicitly marked noreturn by forcing a return behind a never-taken conditional. Until a more integrated noreturn detection method exists, this is likely the least objectionable workaround. Fixes: 55eeab2a8a11 ("objtool: Ignore exc_double_fault() __noreturn warnings") Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Brendan Jackman <jackmanb@google.com> Link: https://lore.kernel.org/r/d1f4026f8dc35d0de6cc61f2684e0cb6484009d1.1741975349.git.jpoimboe@kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-03-01Merge tag 'objtool-urgent-2025-02-28' of ↵Linus Torvalds1-3/+4
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull objtool fixes from Ingo Molnar: "Fix an objtool false positive, and objtool related build warnings that happens on PIE-enabled architectures such as LoongArch" * tag 'objtool-urgent-2025-02-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Add bch2_trans_unlocked_or_in_restart_error() to bcachefs noreturns objtool: Fix C jump table annotations for Clang vmlinux.lds: Ensure that const vars with relocations are mapped R/O
2025-02-25objtool: Fix C jump table annotations for ClangArd Biesheuvel1-3/+4
A C jump table (such as the one used by the BPF interpreter) is a const global array of absolute code addresses, and this means that the actual values in the table may not be known until the kernel is booted (e.g., when using KASLR or when the kernel VA space is sized dynamically). When using PIE codegen, the compiler will default to placing such const global objects in .data.rel.ro (which is annotated as writable), rather than .rodata (which is annotated as read-only). As C jump tables are explicitly emitted into .rodata, this used to result in warnings for LoongArch builds (which uses PIE codegen for the entire kernel) like Warning: setting incorrect section attributes for .rodata..c_jump_table due to the fact that the explicitly specified .rodata section inherited the read-write annotation that the compiler uses for such objects when using PIE codegen. This warning was suppressed by explicitly adding the read-only annotation to the __attribute__((section(""))) string, by commit c5b1184decc8 ("compiler.h: specify correct attribute for .rodata..c_jump_table") Unfortunately, this hack does not work on Clang's integrated assembler, which happily interprets the appended section type and permission specifiers as part of the section name, which therefore no longer matches the hard-coded pattern '.rodata..c_jump_table' that objtool expects, causing it to emit a warning kernel/bpf/core.o: warning: objtool: ___bpf_prog_run+0x20: sibling call from callable instruction with modified stack frame Work around this, by emitting C jump tables into .data.rel.ro instead, which is treated as .rodata by the linker script for all builds, not just PIE based ones. Fixes: c5b1184decc8 ("compiler.h: specify correct attribute for .rodata..c_jump_table") Tested-by: Tiezhu Yang <yangtiezhu@loongson.cn> # on LoongArch Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20250221135704.431269-6-ardb+git@google.com Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2025-02-16Merge tag 'objtool_urgent_for_v6.14_rc3' of ↵Linus Torvalds1-1/+10
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull objtool fixes from Borislav Petkov: - Move a warning about a lld.ld breakage into the verbose setting as said breakage has been fixed in the meantime - Teach objtool to ignore dangling jump table entries added by Clang * tag 'objtool_urgent_for_v6.14_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Move dodgy linker warn to verbose objtool: Ignore dangling jump table entries
2025-02-13objtool/rust: add one more `noreturn` Rust functionMiguel Ojeda1-0/+1
Starting with Rust 1.85.0 (currently in beta, to be released 2025-02-20), under some kernel configurations with `CONFIG_RUST_DEBUG_ASSERTIONS=y`, one may trigger a new `objtool` warning: rust/kernel.o: warning: objtool: _R...securityNtB2_11SecurityCtx8as_bytes() falls through to next function _R...core3ops4drop4Drop4drop() due to a call to the `noreturn` symbol: core::panicking::assert_failed::<usize, usize> Thus add it to the list so that `objtool` knows it is actually `noreturn`. Do so matching with `strstr` since it is a generic. See commit 56d680dd23c3 ("objtool/rust: list `noreturn` Rust functions") for more details. Cc: stable@vger.kernel.org # Needed in 6.12.y and 6.13.y only (Rust is pinned in older LTSs). Fixes: 56d680dd23c3 ("objtool/rust: list `noreturn` Rust functions") Reviewed-by: Gary Guo <gary@garyguo.net> Link: https://lore.kernel.org/r/20250112143951.751139-1-ojeda@kernel.org [ Updated Cc: stable@ to include 6.13.y. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-02-08objtool: Move dodgy linker warn to verbosePeter Zijlstra1-1/+1
The lld.ld borkage is fixed in the latest llvm release (?) but will not be backported, meaning we're stuck with broken linker for a fair while. Lets not spam all clang build logs and move warning to verbose. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2025-02-08objtool: Ignore dangling jump table entriesJosh Poimboeuf1-0/+9
Clang sometimes leaves dangling unused jump table entries which point to the end of the function. Ignore them. Closes: https://lore.kernel.org/20250113235835.vqgvb7cdspksy5dn@jpoimboe Reported-by: Klaus Kusche <klaus.kusche@computerix.info> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/ee25c0b7e80113e950bd1d4c208b671d35774ff4.1736891751.git.jpoimboe@kernel.org
2025-01-21Merge tag 'objtool-core-2025-01-20' of ↵Linus Torvalds1-305/+121
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull objtool updates from Ingo Molnar: - Introduce the generic section-based annotation infrastructure a.k.a. ASM_ANNOTATE/ANNOTATE (Peter Zijlstra) - Convert various facilities to ASM_ANNOTATE/ANNOTATE: (Peter Zijlstra) - ANNOTATE_NOENDBR - ANNOTATE_RETPOLINE_SAFE - instrumentation_{begin,end}() - VALIDATE_UNRET_BEGIN - ANNOTATE_IGNORE_ALTERNATIVE - ANNOTATE_INTRA_FUNCTION_CALL - {.UN}REACHABLE - Optimize the annotation-sections parsing code (Peter Zijlstra) - Centralize annotation definitions in <linux/objtool.h> - Unify & simplify the barrier_before_unreachable()/unreachable() definitions (Peter Zijlstra) - Convert unreachable() calls to BUG() in x86 code, as unreachable() has unreliable code generation (Peter Zijlstra) - Remove annotate_reachable() and annotate_unreachable(), as it's unreliable against compiler optimizations (Peter Zijlstra) - Fix non-standard ANNOTATE_REACHABLE annotation order (Peter Zijlstra) - Robustify the annotation code by warning about unknown annotation types (Peter Zijlstra) - Allow arch code to discover jump table size, in preparation of annotated jump table support (Ard Biesheuvel) * tag 'objtool-core-2025-01-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mm: Convert unreachable() to BUG() objtool: Allow arch code to discover jump table size objtool: Warn about unknown annotation types objtool: Fix ANNOTATE_REACHABLE to be a normal annotation objtool: Convert {.UN}REACHABLE to ANNOTATE objtool: Remove annotate_{,un}reachable() loongarch: Use ASM_REACHABLE x86: Convert unreachable() to BUG() unreachable: Unify objtool: Collect more annotations in objtool.h objtool: Collapse annotate sequences objtool: Convert ANNOTATE_INTRA_FUNCTION_CALL to ANNOTATE objtool: Convert ANNOTATE_IGNORE_ALTERNATIVE to ANNOTATE objtool: Convert VALIDATE_UNRET_BEGIN to ANNOTATE objtool: Convert instrumentation_{begin,end}() to ANNOTATE objtool: Convert ANNOTATE_RETPOLINE_SAFE to ANNOTATE objtool: Convert ANNOTATE_NOENDBR to ANNOTATE objtool: Generic annotation infrastructure
2024-12-13objtool/x86: allow syscall instructionJuergen Gross1-3/+6
The syscall instruction is used in Xen PV mode for doing hypercalls. Allow syscall to be used in the kernel in case it is tagged with an unwind hint for objtool. This is part of XSA-466 / CVE-2024-53241. Reported-by: Andrew Cooper <andrew.cooper3@citrix.com> Signed-off-by: Juergen Gross <jgross@suse.com> Co-developed-by: Peter Zijlstra <peterz@infradead.org>
2024-12-02objtool: Allow arch code to discover jump table sizeArd Biesheuvel1-11/+20
In preparation for adding support for annotated jump tables, where ELF relocations and symbols are used to describe the locations of jump tables in the executable, refactor the jump table discovery logic so the table size can be returned from arch_find_switch_table(). Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20241011170847.334429-12-ardb+git@google.com
2024-12-02objtool: Warn about unknown annotation typesPeter Zijlstra1-0/+13
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20241128094312.611961175@infradead.org
2024-12-02objtool: Fix ANNOTATE_REACHABLE to be a normal annotationPeter Zijlstra1-23/+0
Currently REACHABLE is weird for being on the instruction after the instruction it modifies. Since all REACHABLE annotations have an explicit instruction, flip them around. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20241128094312.494176035@infradead.org
2024-12-02objtool: Convert {.UN}REACHABLE to ANNOTATEPeter Zijlstra1-60/+22
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20241128094312.353431347@infradead.org
2024-12-02objtool: Remove annotate_{,un}reachable()Peter Zijlstra1-41/+2
There are no users of annotate_reachable() left. And the annotate_unreachable() usage in unreachable() is plain wrong; it will hide dangerous fall-through code-gen. Remove both. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20241128094312.235637588@infradead.org
2024-12-02objtool: Collapse annotate sequencesPeter Zijlstra1-55/+32
Reduce read_annotate() runs by collapsing subsequent runs into a single call. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20241128094311.688871544@infradead.org
2024-12-02objtool: Convert ANNOTATE_INTRA_FUNCTION_CALL to ANNOTATEPeter Zijlstra1-57/+39
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20241128094311.584892071@infradead.org
2024-12-02objtool: Convert ANNOTATE_IGNORE_ALTERNATIVE to ANNOTATEPeter Zijlstra1-35/+10
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20241128094311.465691316@infradead.org
2024-12-02objtool: Convert VALIDATE_UNRET_BEGIN to ANNOTATEPeter Zijlstra1-23/+5
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20241128094311.358508242@infradead.org
2024-12-02objtool: Convert instrumentation_{begin,end}() to ANNOTATEPeter Zijlstra1-39/+10
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20241128094311.245980207@infradead.org
2024-12-02objtool: Convert ANNOTATE_RETPOLINE_SAFE to ANNOTATEPeter Zijlstra1-34/+18
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20241128094311.145275669@infradead.org
2024-12-02objtool: Convert ANNOTATE_NOENDBR to ANNOTATEPeter Zijlstra1-27/+5
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20241128094311.042140333@infradead.org
2024-12-02objtool: Generic annotation infrastructurePeter Zijlstra1-0/+45
Avoid endless .discard.foo sections for each annotation, create a single .discard.annotate_insn section that takes an annotation type along with the instruction. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20241128094310.932794537@infradead.org
2024-12-01Merge tag 'kbuild-v6.13' of ↵Linus Torvalds1-0/+2
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: - Add generic support for built-in boot DTB files - Enable TAB cycling for dialog buttons in nconfig - Fix issues in streamline_config.pl - Refactor Kconfig - Add support for Clang's AutoFDO (Automatic Feedback-Directed Optimization) - Add support for Clang's Propeller, a profile-guided optimization. - Change the working directory to the external module directory for M= builds - Support building external modules in a separate output directory - Enable objtool for *.mod.o and additional kernel objects - Use lz4 instead of deprecated lz4c - Work around a performance issue with "git describe" - Refactor modpost * tag 'kbuild-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (85 commits) kbuild: rename .tmp_vmlinux.kallsyms0.syms to .tmp_vmlinux0.syms gitignore: Don't ignore 'tags' directory kbuild: add dependency from vmlinux to resolve_btfids modpost: replace tdb_hash() with hash_str() kbuild: deb-pkg: add python3:native to build dependency genksyms: reduce indentation in export_symbol() modpost: improve error messages in device_id_check() modpost: rename alias symbol for MODULE_DEVICE_TABLE() modpost: rename variables in handle_moddevtable() modpost: move strstarts() to modpost.h modpost: convert do_usb_table() to a generic handler modpost: convert do_of_table() to a generic handler modpost: convert do_pnp_device_entry() to a generic handler modpost: convert do_pnp_card_entries() to a generic handler modpost: call module_alias_printf() from all do_*_entry() functions modpost: pass (struct module *) to do_*_entry() functions modpost: remove DEF_FIELD_ADDR_VAR() macro modpost: deduplicate MODULE_ALIAS() for all drivers modpost: introduce module_alias_printf() helper modpost: remove unnecessary check in do_acpi_entry() ...
2024-11-27kbuild: Add Propeller configuration for kernel buildRong Xu1-0/+1
Add the build support for using Clang's Propeller optimizer. Like AutoFDO, Propeller uses hardware sampling to gather information about the frequency of execution of different code paths within a binary. This information is then used to guide the compiler's optimization decisions, resulting in a more efficient binary. The support requires a Clang compiler LLVM 19 or later, and the create_llvm_prof tool (https://github.com/google/autofdo/releases/tag/v0.30.1). This commit is limited to x86 platforms that support PMU features like LBR on Intel machines and AMD Zen3 BRS. Here is an example workflow for building an AutoFDO+Propeller optimized kernel: 1) Build the kernel on the host machine, with AutoFDO and Propeller build config CONFIG_AUTOFDO_CLANG=y CONFIG_PROPELLER_CLANG=y then $ make LLVM=1 CLANG_AUTOFDO_PROFILE=<autofdo_profile> “<autofdo_profile>” is the profile collected when doing a non-Propeller AutoFDO build. This step builds a kernel that has the same optimization level as AutoFDO, plus a metadata section that records basic block information. This kernel image runs as fast as an AutoFDO optimized kernel. 2) Install the kernel on test/production machines. 3) Run the load tests. The '-c' option in perf specifies the sample event period. We suggest using a suitable prime number, like 500009, for this purpose. For Intel platforms: $ perf record -e BR_INST_RETIRED.NEAR_TAKEN:k -a -N -b -c <count> \ -o <perf_file> -- <loadtest> For AMD platforms: The supported system are: Zen3 with BRS, or Zen4 with amd_lbr_v2 # To see if Zen3 support LBR: $ cat proc/cpuinfo | grep " brs" # To see if Zen4 support LBR: $ cat proc/cpuinfo | grep amd_lbr_v2 # If the result is yes, then collect the profile using: $ perf record --pfm-events RETIRED_TAKEN_BRANCH_INSTRUCTIONS:k -a \ -N -b -c <count> -o <perf_file> -- <loadtest> 4) (Optional) Download the raw perf file to the host machine. 5) Generate Propeller profile: $ create_llvm_prof --binary=<vmlinux> --profile=<perf_file> \ --format=propeller --propeller_output_module_name \ --out=<propeller_profile_prefix>_cc_profile.txt \ --propeller_symorder=<propeller_profile_prefix>_ld_profile.txt “create_llvm_prof” is the profile conversion tool, and a prebuilt binary for linux can be found on https://github.com/google/autofdo/releases/tag/v0.30.1 (can also build from source). "<propeller_profile_prefix>" can be something like "/home/user/dir/any_string". This command generates a pair of Propeller profiles: "<propeller_profile_prefix>_cc_profile.txt" and "<propeller_profile_prefix>_ld_profile.txt". 6) Rebuild the kernel using the AutoFDO and Propeller profile files. CONFIG_AUTOFDO_CLANG=y CONFIG_PROPELLER_CLANG=y and $ make LLVM=1 CLANG_AUTOFDO_PROFILE=<autofdo_profile> \ CLANG_PROPELLER_PROFILE_PREFIX=<propeller_profile_prefix> Co-developed-by: Han Shen <shenhan@google.com> Signed-off-by: Han Shen <shenhan@google.com> Signed-off-by: Rong Xu <xur@google.com> Suggested-by: Sriraman Tallam <tmsriram@google.com> Suggested-by: Krzysztof Pszeniczny <kpszeniczny@google.com> Suggested-by: Nick Desaulniers <ndesaulniers@google.com> Suggested-by: Stephane Eranian <eranian@google.com> Tested-by: Yonghong Song <yonghong.song@linux.dev> Tested-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Kees Cook <kees@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-11-11objtool: Exclude __tracepoints data from ENDBR checksPeter Zijlstra1-0/+1
For some, as of yet unexplained reason, Clang-19, but not GCC, generates and endless stream of: drivers/iio/imu/bno055/bno055_ser.o: warning: objtool: __tracepoint_send_chunk+0x20: data relocation to !ENDBR: __SCT__tp_func_send_chunk+0x0 drivers/iio/imu/bno055/bno055_ser.o: warning: objtool: __tracepoint_cmd_retry+0x20: data relocation to !ENDBR: __SCT__tp_func_cmd_retry+0x0 drivers/iio/imu/bno055/bno055_ser.o: warning: objtool: __tracepoint_write_reg+0x20: data relocation to !ENDBR: __SCT__tp_func_write_reg+0x0 drivers/iio/imu/bno055/bno055_ser.o: warning: objtool: __tracepoint_read_reg+0x20: data relocation to !ENDBR: __SCT__tp_func_read_reg+0x0 drivers/iio/imu/bno055/bno055_ser.o: warning: objtool: __tracepoint_recv+0x20: data relocation to !ENDBR: __SCT__tp_func_recv+0x0 Which is entirely correct, but harmless. Add the __tracepoints section to the exclusion list. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20241108184618.GG38786@noisy.programming.kicks-ass.net
2024-11-06kbuild: Add AutoFDO support for Clang buildRong Xu1-0/+1
Add the build support for using Clang's AutoFDO. Building the kernel with AutoFDO does not reduce the optimization level from the compiler. AutoFDO uses hardware sampling to gather information about the frequency of execution of different code paths within a binary. This information is then used to guide the compiler's optimization decisions, resulting in a more efficient binary. Experiments showed that the kernel can improve up to 10% in latency. The support requires a Clang compiler after LLVM 17. This submission is limited to x86 platforms that support PMU features like LBR on Intel machines and AMD Zen3 BRS. Support for SPE on ARM 1, and BRBE on ARM 1 is part of planned future work. Here is an example workflow for AutoFDO kernel: 1) Build the kernel on the host machine with LLVM enabled, for example, $ make menuconfig LLVM=1 Turn on AutoFDO build config: CONFIG_AUTOFDO_CLANG=y With a configuration that has LLVM enabled, use the following command: scripts/config -e AUTOFDO_CLANG After getting the config, build with $ make LLVM=1 2) Install the kernel on the test machine. 3) Run the load tests. The '-c' option in perf specifies the sample event period. We suggest using a suitable prime number, like 500009, for this purpose. For Intel platforms: $ perf record -e BR_INST_RETIRED.NEAR_TAKEN:k -a -N -b -c <count> \ -o <perf_file> -- <loadtest> For AMD platforms: The supported system are: Zen3 with BRS, or Zen4 with amd_lbr_v2 For Zen3: $ cat proc/cpuinfo | grep " brs" For Zen4: $ cat proc/cpuinfo | grep amd_lbr_v2 $ perf record --pfm-events RETIRED_TAKEN_BRANCH_INSTRUCTIONS:k -a \ -N -b -c <count> -o <perf_file> -- <loadtest> 4) (Optional) Download the raw perf file to the host machine. 5) To generate an AutoFDO profile, two offline tools are available: create_llvm_prof and llvm_profgen. The create_llvm_prof tool is part of the AutoFDO project and can be found on GitHub (https://github.com/google/autofdo), version v0.30.1 or later. The llvm_profgen tool is included in the LLVM compiler itself. It's important to note that the version of llvm_profgen doesn't need to match the version of Clang. It needs to be the LLVM 19 release or later, or from the LLVM trunk. $ llvm-profgen --kernel --binary=<vmlinux> --perfdata=<perf_file> \ -o <profile_file> or $ create_llvm_prof --binary=<vmlinux> --profile=<perf_file> \ --format=extbinary --out=<profile_file> Note that multiple AutoFDO profile files can be merged into one via: $ llvm-profdata merge -o <profile_file> <profile_1> ... <profile_n> 6) Rebuild the kernel using the AutoFDO profile file with the same config as step 1, (Note CONFIG_AUTOFDO_CLANG needs to be enabled): $ make LLVM=1 CLANG_AUTOFDO_PROFILE=<profile_file> Co-developed-by: Han Shen <shenhan@google.com> Signed-off-by: Han Shen <shenhan@google.com> Signed-off-by: Rong Xu <xur@google.com> Suggested-by: Sriraman Tallam <tmsriram@google.com> Suggested-by: Krzysztof Pszeniczny <kpszeniczny@google.com> Suggested-by: Nick Desaulniers <ndesaulniers@google.com> Suggested-by: Stephane Eranian <eranian@google.com> Tested-by: Yonghong Song <yonghong.song@linux.dev> Tested-by: Yabin Cui <yabinc@google.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Kees Cook <kees@kernel.org> Tested-by: Peter Jung <ptr1337@cachyos.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-10-18objtool: Detect non-relocated text referencesJosh Poimboeuf1-48/+64
When kernel IBT is enabled, objtool detects all text references in order to determine which functions can be indirectly branched to. In text, such references look like one of the following: mov $0x0,%rax R_X86_64_32S .init.text+0x7e0a0 lea 0x0(%rip),%rax R_X86_64_PC32 autoremove_wake_function-0x4 Either way the function pointer is denoted by a relocation, so objtool just reads that. However there are some "lea xxx(%rip)" cases which don't use relocations because they're referencing code in the same translation unit. Objtool doesn't have visibility to those. The only currently known instances of that are a few hand-coded asm text references which don't actually need ENDBR. So it's not actually a problem at the moment. However if we enable -fpie, the compiler would start generating them and there would definitely be bugs in the IBT sealing. Detect non-relocated text references and handle them appropriately. [ Note: I removed the manual static_call_tramp check -- that should already be handled by the noendbr check. ] Reported-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2024-09-27Merge tag 'loongarch-6.12' of ↵Linus Torvalds1-3/+20
git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson Pull LoongArch updates from Huacai Chen: - Fix objtool about do_syscall() and Clang - Enable generic CPU vulnerabilites support - Enable ACPI BGRT handling - Rework CPU feature probe from CPUCFG/IOCSR - Add ARCH_HAS_SET_MEMORY support - Add ARCH_HAS_SET_DIRECT_MAP support - Improve hardware page table walker - Simplify _percpu_read() and _percpu_write() - Add advanced extended IRQ model documentions - Some bug fixes and other small changes * tag 'loongarch-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson: Docs/LoongArch: Add advanced extended IRQ model description LoongArch: Remove posix_types.h include from sigcontext.h LoongArch: Fix memleak in pci_acpi_scan_root() LoongArch: Simplify _percpu_read() and _percpu_write() LoongArch: Improve hardware page table walker LoongArch: Add ARCH_HAS_SET_DIRECT_MAP support LoongArch: Add ARCH_HAS_SET_MEMORY support LoongArch: Rework CPU feature probe from CPUCFG/IOCSR LoongArch: Enable ACPI BGRT handling LoongArch: Enable generic CPU vulnerabilites support LoongArch: Remove STACK_FRAME_NON_STANDARD(do_syscall) LoongArch: Set AS_HAS_THIN_ADD_SUB as y if AS_IS_LLVM LoongArch: Enable objtool for Clang objtool: Handle frame pointer related instructions
2024-09-17objtool: Handle frame pointer related instructionsTiezhu Yang1-3/+20
After commit a0f7085f6a63 ("LoongArch: Add RANDOMIZE_KSTACK_OFFSET support"), there are three new instructions "addi.d $fp, $sp, 32", "sub.d $sp, $sp, $t0" and "addi.d $sp, $fp, -32" for the secondary stack in do_syscall(), then there is a objtool warning "return with modified stack frame" and no handle_syscall() which is the previous frame of do_syscall() in the call trace when executing the command "echo l > /proc/sysrq-trigger". objdump shows something like this: 0000000000000000 <do_syscall>: 0: 02ff8063 addi.d $sp, $sp, -32 4: 29c04076 st.d $fp, $sp, 16 8: 29c02077 st.d $s0, $sp, 8 c: 29c06061 st.d $ra, $sp, 24 10: 02c08076 addi.d $fp, $sp, 32 ... 74: 0011b063 sub.d $sp, $sp, $t0 ... a8: 4c000181 jirl $ra, $t0, 0 ... dc: 02ff82c3 addi.d $sp, $fp, -32 e0: 28c06061 ld.d $ra, $sp, 24 e4: 28c04076 ld.d $fp, $sp, 16 e8: 28c02077 ld.d $s0, $sp, 8 ec: 02c08063 addi.d $sp, $sp, 32 f0: 4c000020 jirl $zero, $ra, 0 The instruction "sub.d $sp, $sp, $t0" changes the stack bottom and the new stack size is a random value, in order to find the return address of do_syscall() which is stored in the original stack frame after executing "jirl $ra, $t0, 0", it should use fp which points to the original stack top. At the beginning, the thought is tended to decode the secondary stack instruction "sub.d $sp, $sp, $t0" and set it as a label, then check this label for the two frame pointer instructions to change the cfa base and cfa offset during the period of secondary stack in update_cfi_state(). This is valid for GCC but invalid for Clang due to there are different secondary stack instructions for ClangBuiltLinux on LoongArch, something like this: 0000000000000000 <do_syscall>: ... 88: 00119064 sub.d $a0, $sp, $a0 8c: 00150083 or $sp, $a0, $zero ... Actually, it equals to a single instruction "sub.d $sp, $sp, $a0", but there is no proper condition to check it as a label like GCC, and so the beginning thought is not a good way. Essentially, there are two special frame pointer instructions which are "addi.d $fp, $sp, imm" and "addi.d $sp, $fp, imm", the first one points fp to the original stack top and the second one restores the original stack bottom from fp. Based on the above analysis, in order to avoid adding an arch-specific update_cfi_state(), we just add a member "frame_pointer" in the "struct symbol" as a label to avoid affecting the current normal case, then set it as true only if there is "addi.d $sp, $fp, imm". The last is to check this label for the two frame pointer instructions to change the cfa base and cfa offset in update_cfi_state(). Tested with the following two configs: (1) CONFIG_RANDOMIZE_KSTACK_OFFSET=y && CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=n (2) CONFIG_RANDOMIZE_KSTACK_OFFSET=y && CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y By the way, there is no effect for x86 with this patch, tested on the x86 machine with Fedora 40 system. Cc: stable@vger.kernel.org # 6.9+ Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2024-08-19objtool/rust: list `noreturn` Rust functionsMiguel Ojeda1-1/+51
Rust functions may be `noreturn` (i.e. diverging) by returning the "never" type, `!`, e.g. fn f() -> ! { loop {} } Thus list the known `noreturn` functions to avoid such warnings. Without this, `objtool` would complain if enabled for Rust, e.g.: rust/core.o: warning: objtool: _R...9panic_fmt() falls through to next function _R...18panic_nounwind_fmt() rust/alloc.o: warning: objtool: .text: unexpected end of section In order to do so, we cannot match symbols' names exactly, for two reasons: - Rust mangling scheme [1] contains disambiguators [2] which we cannot predict (e.g. they may vary depending on the compiler version). One possibility to solve this would be to parse v0 and ignore/zero those before comparison. - Some of the diverging functions come from `core`, i.e. the Rust standard library, which may change with each compiler version since they are implementation details (e.g. `panic_internals`). Thus, to workaround both issues, only part of the symbols are matched, instead of using the `NORETURN` macro in `noreturns.h`. Ideally, just like for the C side, we should have a better solution. For instance, the compiler could give us the list via something like: $ rustc --emit=noreturns ... [ Kees agrees this should be automated and Peter says: So it would be fairly simple to make objtool consume a magic section emitted by the compiler.. I think we've asked the compiler folks for that at some point even, but I don't have clear recollections. We will ask upstream Rust about it. And if they agree, then perhaps we can get Clang/GCC to implement something similar too -- for this sort of thing we can take advantage of the shorter cycles of `rustc` as well as their unstable features concept to experiment. Gary proposed using DWARF (though it would need to be available), and wrote a proof of concept script using the `object` and `gimli` crates: https://gist.github.com/nbdd0121/449692570622c2f46a29ad9f47c3379a - Miguel ] Link: https://rust-lang.github.io/rfcs/2603-rust-symbol-name-mangling-v0.html [1] Link: https://doc.rust-lang.org/rustc/symbol-mangling/v0.html#disambiguator [2] Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Kees Cook <kees@kernel.org> Tested-by: Benno Lossin <benno.lossin@proton.me> Link: https://lore.kernel.org/r/20240725183325.122827-6-ojeda@kernel.org [ Added `len_mismatch_fail` symbol for new `kernel` crate code merged since then as well as 3 more `core::panicking` symbols that appear in `RUST_DEBUG_ASSERTIONS=y` builds. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-07-04kmsan: allow disabling KMSAN checks for the current taskIlya Leoshkevich1-0/+2
Like for KASAN, it's useful to temporarily disable KMSAN checks around, e.g., redzone accesses. Introduce kmsan_disable_current() and kmsan_enable_current(), which are similar to their KASAN counterparts. Make them reentrant in order to handle memory allocations in interrupt context. Repurpose the allow_reporting field for this. Link: https://lkml.kernel.org/r/20240621113706.315500-12-iii@linux.ibm.com Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> Reviewed-by: Alexander Potapenko <glider@google.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: <kasan-dev@googlegroups.com> Cc: Marco Elver <elver@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Steven Rostedt (Google) <rostedt@goodmis.org> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-03-31objtool: Fix compile failure when using the x32 compilerMikulas Patocka1-1/+1
When compiling the v6.9-rc1 kernel with the x32 compiler, the following errors are reported. The reason is that we take an "unsigned long" variable and print it using "PRIx64" format string. In file included from check.c:16: check.c: In function ‘add_dead_ends’: /usr/src/git/linux-2.6/tools/objtool/include/objtool/warn.h:46:17: error: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 5 has type ‘long unsigned int’ [-Werror=format=] 46 | "%s: warning: objtool: " format "\n", \ | ^~~~~~~~~~~~~~~~~~~~~~~~ check.c:613:33: note: in expansion of macro ‘WARN’ 613 | WARN("can't find unreachable insn at %s+0x%" PRIx64, | ^~~~ ... Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: linux-kernel@vger.kernel.org
2024-03-22Merge tag 'loongarch-6.9' of ↵Linus Torvalds1-18/+34
git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson Pull LoongArch updates from Huacai Chen: - Add objtool support for LoongArch - Add ORC stack unwinder support for LoongArch - Add kernel livepatching support for LoongArch - Select ARCH_HAS_CURRENT_STACK_POINTER in Kconfig - Select HAVE_ARCH_USERFAULTFD_MINOR in Kconfig - Some bug fixes and other small changes * tag 'loongarch-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson: LoongArch/crypto: Clean up useless assignment operations LoongArch: Define the __io_aw() hook as mmiowb() LoongArch: Remove superfluous flush_dcache_page() definition LoongArch: Move {dmw,tlb}_virt_to_page() definition to page.h LoongArch: Change __my_cpu_offset definition to avoid mis-optimization LoongArch: Select HAVE_ARCH_USERFAULTFD_MINOR in Kconfig LoongArch: Select ARCH_HAS_CURRENT_STACK_POINTER in Kconfig LoongArch: Add kernel livepatching support LoongArch: Add ORC stack unwinder support objtool: Check local label in read_unwind_hints() objtool: Check local label in add_dead_ends() objtool/LoongArch: Enable orc to be built objtool/x86: Separate arch-specific and generic parts objtool/LoongArch: Implement instruction decoder objtool/LoongArch: Enable objtool to be built
2024-03-13Merge tag 'hardening-v6.9-rc1' of ↵Linus Torvalds1-0/+12
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull hardening updates from Kees Cook: "As is pretty normal for this tree, there are changes all over the place, especially for small fixes, selftest improvements, and improved macro usability. Some header changes ended up landing via this tree as they depended on the string header cleanups. Also, a notable set of changes is the work for the reintroduction of the UBSAN signed integer overflow sanitizer so that we can continue to make improvements on the compiler side to make this sanitizer a more viable future security hardening option. Summary: - string.h and related header cleanups (Tanzir Hasan, Andy Shevchenko) - VMCI memcpy() usage and struct_size() cleanups (Vasiliy Kovalev, Harshit Mogalapalli) - selftests/powerpc: Fix load_unaligned_zeropad build failure (Michael Ellerman) - hardened Kconfig fragment updates (Marco Elver, Lukas Bulwahn) - Handle tail call optimization better in LKDTM (Douglas Anderson) - Use long form types in overflow.h (Andy Shevchenko) - Add flags param to string_get_size() (Andy Shevchenko) - Add Coccinelle script for potential struct_size() use (Jacob Keller) - Fix objtool corner case under KCFI (Josh Poimboeuf) - Drop 13 year old backward compat CAP_SYS_ADMIN check (Jingzi Meng) - Add str_plural() helper (Michal Wajdeczko, Kees Cook) - Ignore relocations in .notes section - Add comments to explain how __is_constexpr() works - Fix m68k stack alignment expectations in stackinit Kunit test - Convert string selftests to KUnit - Add KUnit tests for fortified string functions - Improve reporting during fortified string warnings - Allow non-type arg to type_max() and type_min() - Allow strscpy() to be called with only 2 arguments - Add binary mode to leaking_addresses scanner - Various small cleanups to leaking_addresses scanner - Adding wrapping_*() arithmetic helper - Annotate initial signed integer wrap-around in refcount_t - Add explicit UBSAN section to MAINTAINERS - Fix UBSAN self-test warnings - Simplify UBSAN build via removal of CONFIG_UBSAN_SANITIZE_ALL - Reintroduce UBSAN's signed overflow sanitizer" * tag 'hardening-v6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (51 commits) selftests/powerpc: Fix load_unaligned_zeropad build failure string: Convert helpers selftest to KUnit string: Convert selftest to KUnit sh: Fix build with CONFIG_UBSAN=y compiler.h: Explain how __is_constexpr() works overflow: Allow non-type arg to type_max() and type_min() VMCI: Fix possible memcpy() run-time warning in vmci_datagram_invoke_guest_handler() lib/string_helpers: Add flags param to string_get_size() x86, relocs: Ignore relocations in .notes section objtool: Fix UNWIND_HINT_{SAVE,RESTORE} across basic blocks overflow: Use POD in check_shl_overflow() lib: stackinit: Adjust target string to 8 bytes for m68k sparc: vdso: Disable UBSAN instrumentation kernel.h: Move lib/cmdline.c prototypes to string.h leaking_addresses: Provide mechanism to scan binary files leaking_addresses: Ignore input device status lines leaking_addresses: Use File::Temp for /tmp files MAINTAINERS: Update LEAKING_ADDRESSES details fortify: Improve buffer overflow reporting fortify: Add KUnit tests for runtime overflows ...
2024-03-11objtool: Check local label in read_unwind_hints()Tiezhu Yang1-1/+11
When update the latest upstream gcc and binutils, it generates some objtool warnings on LoongArch, like this: arch/loongarch/kernel/entry.o: warning: objtool: ret_from_fork+0x0: unreachable instruction We can see that the reloc sym name is local label instead of section in relocation section '.rela.discard.unwind_hints', in this case, the reloc sym type is STT_NOTYPE instead of STT_SECTION. Let us check it to not return -1, then use reloc->sym->offset instead of reloc addend which is 0 to find the corresponding instruction. Here are some detailed info: [fedora@linux 6.8.test]$ gcc --version gcc (GCC) 14.0.1 20240129 (experimental) [fedora@linux 6.8.test]$ as --version GNU assembler (GNU Binutils) 2.42.50.20240129 [fedora@linux 6.8.test]$ readelf -r arch/loongarch/kernel/entry.o | grep -A 3 "rela.discard.unwind_hints" Relocation section '.rela.discard.unwind_hints' at offset 0x3a8 contains 7 entries: Offset Info Type Sym. Value Sym. Name + Addend 000000000000 000a00000063 R_LARCH_32_PCREL 0000000000000000 .Lhere_1 + 0 00000000000c 000b00000063 R_LARCH_32_PCREL 00000000000000a8 .Lhere_50 + 0 Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2024-03-11objtool: Check local label in add_dead_ends()Tiezhu Yang1-17/+23
When update the latest upstream gcc and binutils, it generates more objtool warnings on LoongArch, like this: init/main.o: warning: objtool: unexpected relocation symbol type in .rela.discard.unreachable We can see that the reloc sym name is local label instead of section in relocation section '.rela.discard.unreachable', in this case, the reloc sym type is STT_NOTYPE instead of STT_SECTION. As suggested by Peter Zijlstra, we add a "local_label" member in struct symbol, then set it as true if symbol type is STT_NOTYPE and symbol name starts with ".L" string in classify_symbols(). Let's check reloc->sym->local_label to not return -1 in add_dead_ends(), and also use reloc->sym->offset instead of reloc addend which is 0 to find the corresponding instruction. At the same time, let's replace the variable "addend" with "offset" to reflect the reality. Here are some detailed info: [fedora@linux 6.8.test]$ gcc --version gcc (GCC) 14.0.1 20240129 (experimental) [fedora@linux 6.8.test]$ as --version GNU assembler (GNU Binutils) 2.42.50.20240129 [fedora@linux 6.8.test]$ readelf -r init/main.o | grep -A 2 "rela.discard.unreachable" Relocation section '.rela.discard.unreachable' at offset 0x6028 contains 1 entry: Offset Info Type Sym. Value Sym. Name + Addend 000000000000 00d900000063 R_LARCH_32_PCREL 00000000000002c4 .L500^B1 + 0 Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2024-03-01objtool: Fix UNWIND_HINT_{SAVE,RESTORE} across basic blocksJosh Poimboeuf1-0/+12
If SAVE and RESTORE unwind hints are in different basic blocks, and objtool sees the RESTORE before the SAVE, it errors out with: vmlinux.o: warning: objtool: vmw_port_hb_in+0x242: objtool isn't smart enough to handle this CFI save/restore combo In such a case, defer following the RESTORE block until the straight-line path gets followed later. Fixes: 8faea26e6111 ("objtool: Re-add UNWIND_HINT_{SAVE_RESTORE}") Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202402240702.zJFNmahW-lkp@intel.com/ Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20240227073527.avcm5naavbv3cj5s@treble Signed-off-by: Kees Cook <keescook@chromium.org>
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