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2023-08-17objtool/x86: Fixup frame-pointer vs rethunkPeter Zijlstra
For stack-validation of a frame-pointer build, objtool validates that every CALL instruction is preceded by a frame-setup. The new SRSO return thunks violate this with their RSB stuffing trickery. Extend the __fentry__ exception to also cover the embedded_insn case used for this. This cures: vmlinux.o: warning: objtool: srso_untrain_ret+0xd: call without frame pointer save/setup Fixes: 4ae68b26c3ab ("objtool/x86: Fix SRSO mess") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20230816115921.GH980931@hirez.programming.kicks-ass.net
2023-08-16x86/cpu: Rename original retbleed methodsPeter Zijlstra
Rename the original retbleed return thunk and untrain_ret to retbleed_return_thunk() and retbleed_untrain_ret(). No functional changes. Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230814121148.909378169@infradead.org
2023-08-16objtool/x86: Fix SRSO messPeter Zijlstra
Objtool --rethunk does two things: - it collects all (tail) call's of __x86_return_thunk and places them into .return_sites. These are typically compiler generated, but RET also emits this same. - it fudges the validation of the __x86_return_thunk symbol; because this symbol is inside another instruction, it can't actually find the instruction pointed to by the symbol offset and gets upset. Because these two things pertained to the same symbol, there was no pressing need to separate these two separate things. However, alas, along comes SRSO and more crazy things to deal with appeared. The SRSO patch itself added the following symbol names to identify as rethunk: 'srso_untrain_ret', 'srso_safe_ret' and '__ret' Where '__ret' is the old retbleed return thunk, 'srso_safe_ret' is a new similarly embedded return thunk, and 'srso_untrain_ret' is completely unrelated to anything the above does (and was only included because of that INT3 vs UD2 issue fixed previous). Clear things up by adding a second category for the embedded instruction thing. Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230814121148.704502245@infradead.org
2023-08-14x86/retpoline,kprobes: Fix position of thunk sections with CONFIG_LTO_CLANGPetr Pavlu
The linker script arch/x86/kernel/vmlinux.lds.S matches the thunk sections ".text.__x86.*" from arch/x86/lib/retpoline.S as follows: .text { [...] TEXT_TEXT [...] __indirect_thunk_start = .; *(.text.__x86.*) __indirect_thunk_end = .; [...] } Macro TEXT_TEXT references TEXT_MAIN which normally expands to only ".text". However, with CONFIG_LTO_CLANG, TEXT_MAIN becomes ".text .text.[0-9a-zA-Z_]*" which wrongly matches also the thunk sections. The output layout is then different than expected. For instance, the currently defined range [__indirect_thunk_start, __indirect_thunk_end] becomes empty. Prevent the problem by using ".." as the first separator, for example, ".text..__x86.indirect_thunk". This pattern is utilized by other explicit section names which start with one of the standard prefixes, such as ".text" or ".data", and that need to be individually selected in the linker script. [ nathan: Fix conflicts with SRSO and fold in fix issue brought up by Andrew Cooper in post-review: https://lore.kernel.org/20230803230323.1478869-1-andrew.cooper3@citrix.com ] Fixes: dc5723b02e52 ("kbuild: add support for Clang LTO") Signed-off-by: Petr Pavlu <petr.pavlu@suse.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230711091952.27944-2-petr.pavlu@suse.com
2023-06-07objtool: Free insns when doneJosh Poimboeuf
Free the decoded instructions as they're no longer needed after this point. This frees up a big chunk of heap, which will come handy when skipping the reading of DWARF section data. Link: https://lore.kernel.org/r/4d4bca1a0f869de020dac80d91f9acbf6df77eab.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Get rid of reloc->rel[a]Josh Poimboeuf
Get the relocation entry info from the underlying rsec->data. With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 35.12G - After: peak heap memory consumption: 29.93G Link: https://lore.kernel.org/r/2be32323de6d8cc73179ee0ff14b71f4e7cefaa0.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Get rid of reloc->jump_table_startJosh Poimboeuf
Rework the jump table logic slightly so 'jump_table_start' is no longer needed. With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 40.37G - After: peak heap memory consumption: 38.64G Link: https://lore.kernel.org/r/e1602ed8a6171ada3cfac0bd8449892ec82bd188.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Get rid of reloc->addendJosh Poimboeuf
Get the addend from the embedded GElf_Rel[a] struct. With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 42.10G - After: peak heap memory consumption: 40.37G Link: https://lore.kernel.org/r/ad2354f95d9ddd86094e3f7687acfa0750657784.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Get rid of reloc->typeJosh Poimboeuf
Get the type from the embedded GElf_Rel[a] struct. Link: https://lore.kernel.org/r/d1c1f8da31e4f052a2478aea585fcf355cacc53a.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Get rid of reloc->offsetJosh Poimboeuf
Get the offset from the embedded GElf_Rel[a] struct. With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 43.83G - After: peak heap memory consumption: 42.10G Link: https://lore.kernel.org/r/2b9ec01178baa346a99522710bf2e82159412e3a.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Add for_each_reloc()Josh Poimboeuf
Link: https://lore.kernel.org/r/dbfcb1037d8b958e52d097b67829c4c6811c24bb.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Add elf_create_section_pair()Josh Poimboeuf
When creating an annotation section, allocate the reloc section data at the beginning. This simplifies the data model a bit and also saves memory due to the removal of malloc() in elf_rebuild_reloc_section(). With allyesconfig + CONFIG_DEBUG_INFO: - Before: peak heap memory consumption: 53.49G - After: peak heap memory consumption: 49.02G Link: https://lore.kernel.org/r/048e908f3ede9b66c15e44672b6dda992b1dae3e.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Consolidate rel/rela handlingJosh Poimboeuf
The GElf_Rel[a] structs have more similarities than differences. It's safe to hard-code the assumptions about their shared fields as they will never change. Consolidate their handling where possible, getting rid of duplicated code. Also, at least for now we only ever create rela sections, so simplify the relocation creation code to be rela-only. Link: https://lore.kernel.org/r/dcabf6df400ca500ea929f1e4284f5e5ec0b27c8.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Improve reloc namingJosh Poimboeuf
- The term "reloc" is overloaded to mean both "an instance of struct reloc" and "a reloc section". Change the latter to "rsec". - For variable names, use "sec" for regular sections and "rsec" for rela sections to prevent them getting mixed up. - For struct reloc variables, use "reloc" instead of "rel" everywhere for consistency. Link: https://lore.kernel.org/r/8b790e403df46f445c21003e7893b8f53b99a6f3.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Remove flags argument from elf_create_section()Josh Poimboeuf
Simplify the elf_create_section() interface a bit by removing the flags argument. Most callers don't care about changing the section header flags. If needed, they can be modified afterwards, just like any other section header field. Link: https://lore.kernel.org/r/515235d9cf62637a14bee37bfa9169ef20065471.1685464332.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07objtool: Allow stack operations in UNWIND_HINT_UNDEFINED regionsJosh Poimboeuf
If the code specified UNWIND_HINT_UNDEFINED, skip the "undefined stack state" warning due to a stack operation. Just ignore the stack op and continue to propagate the undefined state. Link: https://lore.kernel.org/r/820c5b433f17c84e8761fb7465a8d319d706b1cf.1685981486.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-06-07tools: Remove unnecessary variablesLu Hongfei
There are several places where warnings variables are not needed, remove them and directly return 0. Signed-off-by: Lu Hongfei <luhongfei@vivo.com> Link: https://lore.kernel.org/r/20230530075649.21661-1-luhongfei@vivo.com Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-05-16objtool: Move noreturn function list to separate fileJosh Poimboeuf
This makes it a little cleaner and easier to maintain. Suggested-by: Peter Zijlstra <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/cecacf07a69a244c74474c18b7652627de67a528.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-05-16objtool: Remove superfluous global_noreturns entriesJosh Poimboeuf
lbug_with_loc() no longer exists, and resume_play_dead() is static (objtool only checks globals and weaks). Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/2725d7f2ccc2361c6903de9ebaa2b5bb304f7ac2.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-05-16objtool: Ignore exc_double_fault() __noreturn warningsJosh Poimboeuf
This is a hack, but it works for now. Problem is, exc_double_fault() may or may not return, depending on whether CONFIG_X86_ESPFIX64 is set. But objtool has no visibility to the kernel config. "Fix" it by silencing the exc_double_fault() __noreturn warning. This removes the following warning: vmlinux.o: warning: objtool: xenpv_exc_double_fault+0xd: exc_double_fault() is missing a __noreturn annotation Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/a45b085071d3a7d049a20f9e78754452336ecbe8.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-05-16objtool: Detect missing __noreturn annotationsJosh Poimboeuf
Most "unreachable instruction" warnings these days seem to actually be the result of a missing __noreturn annotation. Add an explicit check for that. Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/6e2b93d8c65eaed6c4166a358269dc0ef01f890c.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-05-16objtool: Include backtrace in verbose modeJosh Poimboeuf
Include backtrace in verbose mode. This makes it easy to gather all the information needed for diagnosing objtool warnings. Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/c255224fabcf7e64bac232fec1c77c9fc2d7d7ab.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-05-16objtool: Add verbose option for disassembling affected functionsJosh Poimboeuf
When a warning is associated with a function, add an option to disassemble that function. This makes it easier for reporters to submit the information needed to diagnose objtool warnings. Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/dd0fe13428ede186f09c74059a8001f4adcea5fc.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-05-16objtool: Limit unreachable warnings to once per functionJosh Poimboeuf
Unreachable instruction warnings are limited to once per object file. That no longer makes sense for vmlinux validation, which might have more unreachable instructions lurking in other places. Change it to once per function. Note this affects some other (much rarer) non-fatal warnings as well. In general I think one-warning-per-function makes sense, as related warnings can accumulate quickly and we want to eventually get back to failing the build with -Werror anyway. Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/9d38f881bfc34e031c74e4e90064ccb3e49f599a.1681853186.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
2023-04-28Merge tag 'objtool-core-2023-04-27' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull objtool updates from Ingo Molnar: - Mark arch_cpu_idle_dead() __noreturn, make all architectures & drivers that did this inconsistently follow this new, common convention, and fix all the fallout that objtool can now detect statically - Fix/improve the ORC unwinder becoming unreliable due to UNWIND_HINT_EMPTY ambiguity, split it into UNWIND_HINT_END_OF_STACK and UNWIND_HINT_UNDEFINED to resolve it - Fix noinstr violations in the KCSAN code and the lkdtm/stackleak code - Generate ORC data for __pfx code - Add more __noreturn annotations to various kernel startup/shutdown and panic functions - Misc improvements & fixes * tag 'objtool-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits) x86/hyperv: Mark hv_ghcb_terminate() as noreturn scsi: message: fusion: Mark mpt_halt_firmware() __noreturn x86/cpu: Mark {hlt,resume}_play_dead() __noreturn btrfs: Mark btrfs_assertfail() __noreturn objtool: Include weak functions in global_noreturns check cpu: Mark nmi_panic_self_stop() __noreturn cpu: Mark panic_smp_self_stop() __noreturn arm64/cpu: Mark cpu_park_loop() and friends __noreturn x86/head: Mark *_start_kernel() __noreturn init: Mark start_kernel() __noreturn init: Mark [arch_call_]rest_init() __noreturn objtool: Generate ORC data for __pfx code x86/linkage: Fix padding for typed functions objtool: Separate prefix code from stack validation code objtool: Remove superfluous dead_end_function() check objtool: Add symbol iteration helpers objtool: Add WARN_INSN() scripts/objdump-func: Support multiple functions context_tracking: Fix KCSAN noinstr violation objtool: Add stackleak instrumentation to uaccess safe list ...
2023-04-26Merge tag 'for-6.4-tag' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux Pull btrfs updates from David Sterba: "Mostly core changes and cleanups, some notable fixes and two performance improvements in directory logging. The IO path cleanups are removing or refactoring old code, scrub main loop has been completely rewritten also refactoring old code. There are some changes to non-btrfs code, mostly trivial, the cgroup punt bio logic is only moved from generic code. Performance improvements: - improve logging changes in a directory during one transaction, avoid iterating over items and reduce lock contention (fsync time 4x lower) - when logging directory entries during one transaction, reduce locking of subvolume trees by checking tree-log instead (improvement in throughput and latency for concurrent access to a subvolume) Notable fixes: - dev-replace: - properly honor read mode when requested to avoid reading from source device - target device won't be used for eventual read repair, this is unreliable for NODATASUM files - when there are unpaired (and unrepairable) metadata during replace, exit early with error and don't try to finish whole operation - scrub ioctl properly rejects unknown flags - fix global block reserve calculations - fix partial direct io write when there's a page fault in the middle, iomap will try to continue with partial request but the btrfs part did not match that, this can lead to zeros written instead of data Core changes: - io path: - continued cleanups and refactoring around bio handling - extent io submit path simplifications and cleanups - flush write path simplifications and cleanups - rework logic of passing sync mode of bio, with further cleanups - rewrite scrub code flow, restructure how the stripes are enumerated and verified in a more unified way - allow to set lower threshold for block group reclaim in debug mode to aid zoned mode testing - remove obsolete time-based delayed ref throttling logic when truncating items - DREW locks are not using percpu variables anymore - more warning fixes (-Wmaybe-uninitialized) - u64 division simplifications - error handling improvements Non-btrfs code changes: - push cgroup punt bio logic to btrfs code (there was no other user of that), the functionality can be now selected separately by BLK_CGROUP_PUNT_BIO - crc32c_impl removed after removing last uses in btrfs code - add btrfs_assertfail() to objtool table" * tag 'for-6.4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (147 commits) btrfs: mark btrfs_assertfail() __noreturn btrfs: fix uninitialized variable warnings btrfs: use log root when iterating over index keys when logging directory btrfs: avoid iterating over all indexes when logging directory btrfs: dev-replace: error out if we have unrepaired metadata error during btrfs: remove pointless loop at btrfs_get_next_valid_item() btrfs: scrub: reject unsupported scrub flags btrfs: reinterpret async discard iops_limit=0 as no delay btrfs: set default discard iops_limit to 1000 btrfs: remove unused raid56 functions which were dedicated for scrub btrfs: scrub: remove scrub_bio structure btrfs: scrub: remove scrub_block and scrub_sector structures btrfs: scrub: remove the old scrub recheck code btrfs: scrub: remove the old writeback infrastructure btrfs: scrub: remove scrub_parity structure btrfs: scrub: use scrub_stripe to implement RAID56 P/Q scrub btrfs: scrub: switch scrub_simple_mirror() to scrub_stripe infrastructure btrfs: scrub: introduce helper to queue a stripe for scrub btrfs: scrub: introduce error reporting functionality for scrub_stripe btrfs: scrub: introduce a writeback helper for scrub_stripe ...
2023-04-18x86: improve on the non-rep 'copy_user' functionLinus Torvalds
The old 'copy_user_generic_unrolled' function was oddly implemented for largely historical reasons: it had been largely based on the uncached copy case, which has some other concerns. For example, the __copy_user_nocache() function uses 'movnti' for the destination stores, and those want the destination to be aligned. In contrast, the regular copy function doesn't really care, and trying to align things only complicates matters. Also, like the clear_user function, the copy function had some odd handling of the repeat counts, complicating the exception handling for no really good reason. So as with clear_user, just write it to keep all the byte counts in the %rcx register, exactly like the 'rep movs' functionality that this replaces. Unlike a real 'rep movs', we do allow for this to trash a few temporary registers to not have to unnecessarily save/restore registers on the stack. And like the clearing case, rename this to what it now clearly is: 'rep_movs_alternative', and make it one coherent function, so that it shows up as such in profiles (instead of the odd split between "copy_user_generic_unrolled" and "copy_user_short_string", the latter of which was not about strings at all, and which was shared with the uncached case). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-04-18x86: improve on the non-rep 'clear_user' functionLinus Torvalds
The old version was oddly written to have the repeat count in multiple registers. So instead of taking advantage of %rax being zero, it had some sub-counts in it. All just for a "single word clearing" loop, which isn't even efficient to begin with. So get rid of those games, and just keep all the state in the same registers we got it in (and that we should return things in). That not only makes this act much more like 'rep stos' (which this function is replacing), but makes it much easier to actually do the obvious loop unrolling. Also rename the function from the now nonsensical 'clear_user_original' to what it now clearly is: 'rep_stos_alternative'. End result: if we don't have a fast 'rep stosb', at least we can have a fast fallback for it. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-04-18x86: inline the 'rep movs' in user copies for the FSRM caseLinus Torvalds
This does the same thing for the user copies as commit 0db7058e8e23 ("x86/clear_user: Make it faster") did for clear_user(). In other words, it inlines the "rep movs" case when X86_FEATURE_FSRM is set, avoiding the function call entirely. In order to do that, it makes the calling convention for the out-of-line case ("copy_user_generic_unrolled") match the 'rep movs' calling convention, although it does also end up clobbering a number of additional registers. Also, to simplify code sharing in the low-level assembly with the __copy_user_nocache() function (that uses the normal C calling convention), we end up with a kind of mixed return value for the low-level asm code: it will return the result in both %rcx (to work as an alternative for the 'rep movs' case), _and_ in %rax (for the nocache case). We could avoid this by wrapping __copy_user_nocache() callers in an inline asm, but since the cost is just an extra register copy, it's probably not worth it. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-04-18x86: move stac/clac from user copy routines into callersLinus Torvalds
This is preparatory work for inlining the 'rep movs' case, but also a cleanup. The __copy_user_nocache() function was mis-used by the rdma code to do uncached kernel copies that don't actually want user copies at all, and as a result doesn't want the stac/clac either. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-04-18x86: don't use REP_GOOD or ERMS for user memory clearingLinus Torvalds
The modern target to use is FSRS (Fast Short REP STOS), and the other cases should only be used for bigger areas (ie mainly things like page clearing). Note! This changes the conditional for the inlining from FSRM ("fast short rep movs") to FSRS ("fast short rep stos"). We'll have a separate fixup for AMD microarchitectures that have a good 'rep stosb' yet do not set the new Intel-specific FSRS bit (because FSRM was there first). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-04-17btrfs: mark btrfs_assertfail() __noreturnJosh Poimboeuf
Fixes a bunch of warnings including: vmlinux.o: warning: objtool: select_reloc_root+0x314: unreachable instruction vmlinux.o: warning: objtool: finish_inode_if_needed+0x15b1: unreachable instruction vmlinux.o: warning: objtool: get_bio_sector_nr+0x259: unreachable instruction vmlinux.o: warning: objtool: raid_wait_read_end_io+0xc26: unreachable instruction vmlinux.o: warning: objtool: raid56_parity_alloc_scrub_rbio+0x37b: unreachable instruction ... Reported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/oe-kbuild-all/202302210709.IlXfgMpX-lkp@intel.com/ Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-04-14x86/hyperv: Mark hv_ghcb_terminate() as noreturnGuilherme G. Piccoli
Annotate the function prototype and definition as noreturn to prevent objtool warnings like: vmlinux.o: warning: objtool: hyperv_init+0x55c: unreachable instruction Also, as per Josh's suggestion, add it to the global_noreturns list. As a comparison, an objdump output without the annotation: [...] 1b63: mov $0x1,%esi 1b68: xor %edi,%edi 1b6a: callq ffffffff8102f680 <hv_ghcb_terminate> 1b6f: jmpq ffffffff82f217ec <hyperv_init+0x9c> # unreachable 1b74: cmpq $0xffffffffffffffff,-0x702a24(%rip) [...] Now, after adding the __noreturn to the function prototype: [...] 17df: callq ffffffff8102f6d0 <hv_ghcb_negotiate_protocol> 17e4: test %al,%al 17e6: je ffffffff82f21bb9 <hyperv_init+0x469> [...] <many insns> 1bb9: mov $0x1,%esi 1bbe: xor %edi,%edi 1bc0: callq ffffffff8102f680 <hv_ghcb_terminate> 1bc5: nopw %cs:0x0(%rax,%rax,1) # end of function Reported-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/32453a703dfcf0d007b473c9acbf70718222b74b.1681342859.git.jpoimboe@kernel.org
2023-04-14scsi: message: fusion: Mark mpt_halt_firmware() __noreturnJosh Poimboeuf
mpt_halt_firmware() doesn't return. Mark it as such. Fixes the following warnings: vmlinux.o: warning: objtool: mptscsih_abort+0x7f4: unreachable instruction vmlinux.o: warning: objtool: mptctl_timeout_expired+0x310: unreachable instruction Reported-by: kernel test robot <lkp@intel.com> Reported-by: Mark Rutland <mark.rutland@arm.com> Debugged-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/d8129817423422355bf30e90dadc6764261b53e0.1681342859.git.jpoimboe@kernel.org
2023-04-14x86/cpu: Mark {hlt,resume}_play_dead() __noreturnJosh Poimboeuf
Fixes the following warning: vmlinux.o: warning: objtool: resume_play_dead+0x21: unreachable instruction Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/ce1407c4bf88b1334fe40413126343792a77ca50.1681342859.git.jpoimboe@kernel.org
2023-04-14btrfs: Mark btrfs_assertfail() __noreturnJosh Poimboeuf
Fixes a bunch of warnings including: vmlinux.o: warning: objtool: select_reloc_root+0x314: unreachable instruction vmlinux.o: warning: objtool: finish_inode_if_needed+0x15b1: unreachable instruction vmlinux.o: warning: objtool: get_bio_sector_nr+0x259: unreachable instruction vmlinux.o: warning: objtool: raid_wait_read_end_io+0xc26: unreachable instruction vmlinux.o: warning: objtool: raid56_parity_alloc_scrub_rbio+0x37b: unreachable instruction ... Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/960bd9c0c9e3cfc409ba9c35a17644b11b832956.1681342859.git.jpoimboe@kernel.org
2023-04-14objtool: Include weak functions in global_noreturns checkJosh Poimboeuf
If a global function doesn't return, and its prototype has the __noreturn attribute, its weak counterpart must also not return so that it matches the prototype and meets call site expectations. To properly follow the compiled control flow at the call sites, change the global_noreturns check to include both global and weak functions. On the other hand, if a weak function isn't in global_noreturns, assume the prototype doesn't have __noreturn. Even if the weak function doesn't return, call sites treat it like a returnable function. Fixes the following warning: kernel/sched/build_policy.o: warning: objtool: do_idle() falls through to next function play_idle_precise() Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/ede3460d63f4a65d282c86f1175bd2662c2286ba.1681342859.git.jpoimboe@kernel.org
2023-04-14cpu: Mark nmi_panic_self_stop() __noreturnJosh Poimboeuf
In preparation for improving objtool's handling of weak noreturn functions, mark nmi_panic_self_stop() __noreturn. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/316fc6dfab5a8c4e024c7185484a1ee5fb0afb79.1681342859.git.jpoimboe@kernel.org
2023-04-14cpu: Mark panic_smp_self_stop() __noreturnJosh Poimboeuf
In preparation for improving objtool's handling of weak noreturn functions, mark panic_smp_self_stop() __noreturn. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/92d76ab5c8bf660f04fdcd3da1084519212de248.1681342859.git.jpoimboe@kernel.org
2023-04-14x86/head: Mark *_start_kernel() __noreturnJosh Poimboeuf
Now that start_kernel() is __noreturn, mark its chain of callers __noreturn. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/c2525f96b88be98ee027ee0291d58003036d4120.1681342859.git.jpoimboe@kernel.org
2023-04-14init: Mark start_kernel() __noreturnJosh Poimboeuf
Now that arch_call_rest_init() is __noreturn, mark its caller start_kernel() __noreturn. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/7069acf026a195f26a88061227fba5a3b0337b9a.1681342859.git.jpoimboe@kernel.org
2023-04-14init: Mark [arch_call_]rest_init() __noreturnJosh Poimboeuf
In preparation for improving objtool's handling of weak noreturn functions, mark start_kernel(), arch_call_rest_init(), and rest_init() __noreturn. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Link: https://lore.kernel.org/r/7194ed8a989a85b98d92e62df660f4a90435a723.1681342859.git.jpoimboe@kernel.org
2023-04-14objtool: Generate ORC data for __pfx codeJosh Poimboeuf
Allow unwinding from prefix code by copying the CFI from the starting instruction of the corresponding function. Even when the NOPs are replaced, they're still stack-invariant instructions so the same ORC entry can be reused everywhere. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/bc3344e51f3e87102f1301a0be0f72a7689ea4a4.1681331135.git.jpoimboe@kernel.org
2023-04-14objtool: Separate prefix code from stack validation codeJosh Poimboeuf
Simplify the prefix code by moving it after validate_reachable_instructions(). Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/d7f31ac2de462d0cd7b1db01b7ecb525c057c8f6.1681331135.git.jpoimboe@kernel.org
2023-04-14objtool: Remove superfluous dead_end_function() checkJosh Poimboeuf
annotate_call_site() already sets 'insn->dead_end' for calls to dead end functions. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/5d603a301e9a8b1036b61503385907e154867ace.1681325924.git.jpoimboe@kernel.org
2023-04-14objtool: Add symbol iteration helpersJosh Poimboeuf
Add [sec_]for_each_sym() and use them. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/59023e5886ab125aa30702e633be7732b1acaa7e.1681325924.git.jpoimboe@kernel.org
2023-04-14objtool: Add WARN_INSN()Josh Poimboeuf
It's easier to use and also gives easy access to the instruction's containing function, which is useful for printing that function's symbol. It will also be useful in the future for rate-limiting and disassembly of warned functions. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/2eaa3155c90fba683d8723599f279c46025b75f3.1681325924.git.jpoimboe@kernel.org
2023-04-14objtool: Add stackleak instrumentation to uaccess safe listJosh Poimboeuf
If a function has a large stack frame, the stackleak plugin adds a call to stackleak_track_stack() after the prologue. This function may be called in uaccess-enabled code. Add it to the uaccess safe list. Fixes the following warning: vmlinux.o: warning: objtool: kasan_report+0x12: call to stackleak_track_stack() with UACCESS enabled Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/42e9b487ef89e9b237fd5220ad1c7cf1a2ad7eb8.1681320562.git.jpoimboe@kernel.org
2023-04-14Revert "objtool: Support addition to set CFA base"Josh Poimboeuf
Commit 468af56a7bba ("objtool: Support addition to set CFA base") was added as a preparatory patch for arm64 support, but that support never came. It triggers a false positive warning on x86, so just revert it for now. Fixes the following warning: vmlinux.o: warning: objtool: cdce925_regmap_i2c_write+0xdb: stack state mismatch: cfa1=4+120 cfa2=5+40 Fixes: 468af56a7bba ("objtool: Support addition to set CFA base") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/oe-kbuild-all/202304080538.j5G6h1AB-lkp@intel.com/
2023-03-23x86,objtool: Split UNWIND_HINT_EMPTY in twoJosh Poimboeuf
Mark reported that the ORC unwinder incorrectly marks an unwind as reliable when the unwind terminates prematurely in the dark corners of return_to_handler() due to lack of information about the next frame. The problem is UNWIND_HINT_EMPTY is used in two different situations: 1) The end of the kernel stack unwind before hitting user entry, boot code, or fork entry 2) A blind spot in ORC coverage where the unwinder has to bail due to lack of information about the next frame The ORC unwinder has no way to tell the difference between the two. When it encounters an undefined stack state with 'end=1', it blindly marks the stack reliable, which can break the livepatch consistency model. Fix it by splitting UNWIND_HINT_EMPTY into UNWIND_HINT_UNDEFINED and UNWIND_HINT_END_OF_STACK. Reported-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/fd6212c8b450d3564b855e1cb48404d6277b4d9f.1677683419.git.jpoimboe@kernel.org
generated by cgit (git 2.34.1) at 2025-04-09 22:52:54 +0000