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2020-04-30objtool: Remove check preventing branches within alternativeJulien Thierry1-6/+0
While jumping from outside an alternative region to the middle of an alternative region is very likely wrong, jumping from an alternative region into the same region is valid. It is a common pattern on arm64. The first pattern is unlikely to happen in practice and checking only for this adds a lot of complexity. Just remove the current check. Suggested-by: Josh Poimboeuf <[email protected]> Signed-off-by: Julien Thierry <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2020-04-25objtool: Fix stack offset tracking for indirect CFAsJosh Poimboeuf1-1/+1
When the current frame address (CFA) is stored on the stack (i.e., cfa->base == CFI_SP_INDIRECT), objtool neglects to adjust the stack offset when there are subsequent pushes or pops. This results in bad ORC data at the end of the ENTER_IRQ_STACK macro, when it puts the previous stack pointer on the stack and does a subsequent push. This fixes the following unwinder warning: WARNING: can't dereference registers at 00000000f0a6bdba for ip interrupt_entry+0x9f/0xa0 Fixes: 627fce14809b ("objtool: Add ORC unwind table generation") Reported-by: Vince Weaver <[email protected]> Reported-by: Dave Jones <[email protected]> Reported-by: Steven Rostedt <[email protected]> Reported-by: Vegard Nossum <[email protected]> Reported-by: Joe Mario <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Jann Horn <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: https://lore.kernel.org/r/853d5d691b29e250333332f09b8e27410b2d9924.1587808742.git.jpoimboe@redhat.com
2020-04-23objtool: Rename elf_read() to elf_open_read()Ingo Molnar1-1/+1
'struct elf *' handling is an open/close paradigm, make sure the naming matches that: elf_open_read() elf_write() elf_close() Acked-by: Josh Poimboeuf <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Sami Tolvanen <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2020-04-22objtool: Also consider .entry.text as noinstrThomas Gleixner1-6/+12
Consider all of .entry.text as noinstr. This gets us coverage across the PTI boundary. While we could add everything .noinstr.text into .entry.text that would bloat the amount of code in the user mapping. Signed-off-by: Thomas Gleixner <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Add STT_NOTYPE noinstr validationPeter Zijlstra1-16/+30
Make sure to also check STT_NOTYPE symbols for noinstr violations. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Rearrange validate_section()Peter Zijlstra1-22/+29
In preparation of further changes, once again break out the loop body. No functional changes intended. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Avoid iterating !text section symbolsPeter Zijlstra1-1/+5
validate_functions() iterates all sections their symbols; this is pointless to do for !text sections as they won't have instructions anyway. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Use sec_offset_hash() for insn_hashPeter Zijlstra1-2/+3
In preparation for find_insn_containing(), change insn_hash to use sec_offset_hash(). This actually reduces runtime; probably because mixing in the section index reduces the collisions due to text sections all starting their instructions at offset 0. Runtime on vmlinux.o from 3.1 to 2.5 seconds. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Implement noinstr validationPeter Zijlstra1-0/+98
Validate that any call out of .noinstr.text is in between instr_begin() and instr_end() annotations. This annotation is useful to ensure correct behaviour wrt tracing sensitive code like entry/exit and idle code. When we run code in a sensitive context we want a guarantee no unknown code is ran. Since this validation relies on knowing the section of call destination symbols, we must run it on vmlinux.o instead of on individual object files. Add two options: -d/--duplicate "duplicate validation for vmlinux" -l/--vmlinux "vmlinux.o validation" Where the latter auto-detects when objname ends with "vmlinux.o" and the former will force all validations, also those already done on !vmlinux object files. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Fix !CFI insn_state propagationPeter Zijlstra1-127/+137
Objtool keeps per instruction CFI state in struct insn_state and will save/restore this where required. However, insn_state has grown some !CFI state, and this must not be saved/restored (that would loose/destroy state). Fix this by moving the CFI specific parts of insn_state into struct cfi_state. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Rename struct cfi_statePeter Zijlstra1-1/+1
There's going to be a new struct cfi_state, rename this one to make place. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Remove SAVE/RESTORE hintsPeter Zijlstra1-39/+3
The SAVE/RESTORE hints are now unused; remove them. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Introduce HINT_RET_OFFSETPeter Zijlstra1-8/+16
Normally objtool ensures a function keeps the stack layout invariant. But there is a useful exception, it is possible to stuff the return stack in order to 'inject' a 'call': push $fun ret In this case the invariant mentioned above is violated. Add an objtool HINT to annotate this and allow a function exit with a modified stack frame. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Better handle IRETPeter Zijlstra1-13/+16
Teach objtool a little more about IRET so that we can avoid using the SAVE/RESTORE annotation. In particular, make the weird corner case in insn->restore go away. The purpose of that corner case is to deal with the fact that UNWIND_HINT_RESTORE lands on the instruction after IRET, but that instruction can end up being outside the basic block, consider: if (cond) sync_core() foo(); Then the hint will land on foo(), and we'll encounter the restore hint without ever having seen the save hint. By teaching objtool about the arch specific exception frame size, and assuming that any IRET in an STT_FUNC symbol is an exception frame sized POP, we can remove the use of save/restore hints for this code. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Support multiple stack_op per instructionJulien Thierry1-28/+46
Instruction sets can include more or less complex operations which might not fit the currently defined set of stack_ops. Combining more than one stack_op provides more flexibility to describe the behaviour of an instruction. This also reduces the need to define new stack_ops specific to a single instruction set. Allow instruction decoders to generate multiple stack_op per instruction. Signed-off-by: Julien Thierry <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Remove redundant .rodata section name comparisonMuchun Song1-2/+2
If the prefix of section name is not '.rodata', the following function call can never return 0. strcmp(sec->name, C_JUMP_TABLE_SECTION) So the name comparison is pointless, just remove it. Signed-off-by: Muchun Song <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Add abstraction for destination offsetsRaphael Gault1-8/+10
The jump and call destination relocation offsets are x86-specific. Abstract them by calling arch-specific implementations. [ jthierry: Remove superfluous comment; replace other addend offsets with arch_dest_rela_offset() ] Signed-off-by: Raphael Gault <[email protected]> Signed-off-by: Julien Thierry <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Use arch specific values in restore_reg()Julien Thierry1-2/+2
The initial register state is set up by arch specific code. Use the value the arch code has set when restoring registers from the stack. Suggested-by: Raphael Gault <[email protected]> Signed-off-by: Julien Thierry <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Ignore empty alternativesJulien Thierry1-0/+6
The .alternatives section can contain entries with no original instructions. Objtool will currently crash when handling such an entry. Just skip that entry, but still give a warning to discourage useless entries. Signed-off-by: Julien Thierry <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Clean instruction state before each function validationJulien Thierry1-7/+6
When a function fails its validation, it might leave a stale state that will be used for the validation of other functions. That would cause false warnings on potentially valid functions. Reset the instruction state before the validation of each individual function. Signed-off-by: Julien Thierry <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2020-04-22objtool: Remove redundant checks on operand typeJulien Thierry1-3/+1
POP operations are already in the code path where the destination operand is OP_DEST_REG. There is no need to check the operand type again. Signed-off-by: Julien Thierry <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
2020-04-14objtool: Make BP scratch register warning more robustJosh Poimboeuf1-2/+2
If func is NULL, a seg fault can result. This is a theoretical issue which was found by Coverity, ID: 1492002 ("Dereference after null check"). Fixes: c705cecc8431 ("objtool: Track original function across branches") Reported-by: Gustavo A. R. Silva <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lkml.kernel.org/r/afc628693a37acd287e843bcc5c0430263d93c74.1585761021.git.jpoimboe@redhat.com
2020-04-14objtool: Fix switch table detection in .text.unlikelyJosh Poimboeuf1-4/+1
If a switch jump table's indirect branch is in a ".cold" subfunction in .text.unlikely, objtool doesn't detect it, and instead prints a false warning: drivers/media/v4l2-core/v4l2-ioctl.o: warning: objtool: v4l_print_format.cold()+0xd6: sibling call from callable instruction with modified stack frame drivers/hwmon/max6650.o: warning: objtool: max6650_probe.cold()+0xa5: sibling call from callable instruction with modified stack frame drivers/media/dvb-frontends/drxk_hard.o: warning: objtool: init_drxk.cold()+0x16f: sibling call from callable instruction with modified stack frame Fix it by comparing the function, instead of the section and offset. Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions") Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/157c35d42ca9b6354bbb1604fe9ad7d1153ccb21.1585761021.git.jpoimboe@redhat.com
2020-04-14objtool: Fix CONFIG_UBSAN_TRAP unreachable warningsJosh Poimboeuf1-2/+15
CONFIG_UBSAN_TRAP causes GCC to emit a UD2 whenever it encounters an unreachable code path. This includes __builtin_unreachable(). Because the BUG() macro uses __builtin_unreachable() after it emits its own UD2, this results in a double UD2. In this case objtool rightfully detects that the second UD2 is unreachable: init/main.o: warning: objtool: repair_env_string()+0x1c8: unreachable instruction We weren't able to figure out a way to get rid of the double UD2s, so just silence the warning. Reported-by: Randy Dunlap <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Reviewed-by: Kees Cook <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/6653ad73c6b59c049211bd7c11ed3809c20ee9f5.1585761021.git.jpoimboe@redhat.com
2020-04-13objtool, kcsan: Add explicit check functions to uaccess whitelistMarco Elver1-0/+2
Add explicitly invoked KCSAN check functions to objtool's uaccess whitelist. This is needed in order to permit calling into kcsan_check_scoped_accesses() from the fast-path, which in turn calls __kcsan_check_access(). __kcsan_check_access() is the generic variant of the already whitelisted specializations __tsan_{read,write}N. Signed-off-by: Marco Elver <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]>
2020-04-13Merge tag 'v5.7-rc1' into locking/kcsan, to resolve conflicts and refreshIngo Molnar1-110/+159
Resolve these conflicts: arch/x86/Kconfig arch/x86/kernel/Makefile Do a minor "evil merge" to move the KCSAN entry up a bit by a few lines in the Kconfig to reduce the probability of future conflicts. Signed-off-by: Ingo Molnar <[email protected]>
2020-03-30Merge branch 'locking-core-for-linus' of ↵Linus Torvalds1-0/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: "The main changes in this cycle were: - Continued user-access cleanups in the futex code. - percpu-rwsem rewrite that uses its own waitqueue and atomic_t instead of an embedded rwsem. This addresses a couple of weaknesses, but the primary motivation was complications on the -rt kernel. - Introduce raw lock nesting detection on lockdep (CONFIG_PROVE_RAW_LOCK_NESTING=y), document the raw_lock vs. normal lock differences. This too originates from -rt. - Reuse lockdep zapped chain_hlocks entries, to conserve RAM footprint on distro-ish kernels running into the "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" depletion of the lockdep chain-entries pool. - Misc cleanups, smaller fixes and enhancements - see the changelog for details" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (55 commits) fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t thermal/x86_pkg_temp: Make pkg_temp_lock a raw_spinlock_t Documentation/locking/locktypes: Minor copy editor fixes Documentation/locking/locktypes: Further clarifications and wordsmithing m68knommu: Remove mm.h include from uaccess_no.h x86: get rid of user_atomic_cmpxchg_inatomic() generic arch_futex_atomic_op_inuser() doesn't need access_ok() x86: don't reload after cmpxchg in unsafe_atomic_op2() loop x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access_end() objtool: whitelist __sanitizer_cov_trace_switch() [parisc, s390, sparc64] no need for access_ok() in futex handling sh: no need of access_ok() in arch_futex_atomic_op_inuser() futex: arch_futex_atomic_op_inuser() calling conventions change completion: Use lockdep_assert_RT_in_threaded_ctx() in complete_all() lockdep: Add posixtimer context tracing bits lockdep: Annotate irq_work lockdep: Add hrtimer context tracing bits lockdep: Introduce wait-type checks completion: Use simple wait queues sched/swait: Prepare usage in completions ...
2020-03-27objtool: whitelist __sanitizer_cov_trace_switch()Al Viro1-0/+1
it's not really different from e.g. __sanitizer_cov_trace_cmp4(); as it is, the switches that generate an array of labels get rejected by objtool, while slightly different set of cases that gets compiled into a series of comparisons is accepted. Signed-off-by: Al Viro <[email protected]>
2020-03-25objtool: Re-arrange validate_functions()Peter Zijlstra1-22/+30
In preparation to adding a vmlinux.o specific pass, rearrange some code. No functional changes intended. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2020-03-25objtool: Delete cleanup()Peter Zijlstra1-19/+0
Perf shows we spend a measurable amount of time spend cleaning up right before we exit anyway. Avoid the needsless work and just terminate. This reduces objtool on vmlinux.o runtime from 5.4s to 4.8s Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2020-03-25objtool: Optimize read_sections()Peter Zijlstra1-9/+9
Perf showed that __hash_init() is a significant portion of read_sections(), so instead of doing a per section rela_hash, use an elf-wide rela_hash. Statistics show us there are about 1.1 million relas, so size it accordingly. This reduces the objtool on vmlinux.o runtime to a third, from 15 to 5 seconds. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2020-03-25objtool: Add a statistics modePeter Zijlstra1-0/+5
Have it print a few numbers which can be used to size the hashtables. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2020-03-25objtool: Rename func_for_each_insn_all()Peter Zijlstra1-6/+6
Now that func_for_each_insn() is available, rename func_for_each_insn_all(). This gets us: sym_for_each_insn() - iterate on symbol offset/len func_for_each_insn() - iterate on insn->func Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2020-03-25objtool: Rename func_for_each_insn()Peter Zijlstra1-8/+8
There is func_for_each_insn() and func_for_each_insn_all(), the both iterate the instructions, but the first uses symbol offset/length while the second uses insn->func. Rename func_for_each_insn() to sym_for_eac_insn() because it iterates on symbol information. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2020-03-25objtool: Introduce validate_return()Peter Zijlstra1-28/+36
Trivial 'cleanup' to save one indentation level and match validate_call(). Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Miroslav Benes <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2020-02-21objtool: Improve call destination function detectionJosh Poimboeuf1-9/+18
A recent clang change, combined with a binutils bug, can trigger a situation where a ".Lprintk$local" STT_NOTYPE symbol gets created at the same offset as the "printk" STT_FUNC symbol. This confuses objtool: kernel/printk/printk.o: warning: objtool: ignore_loglevel_setup()+0x10: can't find call dest symbol at .text+0xc67 Improve the call destination detection by looking specifically for an STT_FUNC symbol. Reported-by: Nick Desaulniers <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Tested-by: Nathan Chancellor <[email protected]> Link: https://github.com/ClangBuiltLinux/linux/issues/872 Link: https://sourceware.org/bugzilla/show_bug.cgi?id=25551 Link: https://lkml.kernel.org/r/0a7ee320bc0ea4469bd3dc450a7b4725669e0ea9.1581997059.git.jpoimboe@redhat.com
2020-02-21objtool: Fix clang switch table edge caseJosh Poimboeuf1-2/+9
Clang has the ability to create a switch table which is not a jump table, but is rather a table of string pointers. This confuses objtool, because it sees the relocations for the string pointers and assumes they're part of a jump table: drivers/ata/sata_dwc_460ex.o: warning: objtool: sata_dwc_bmdma_start_by_tag()+0x3a2: can't find switch jump table net/ceph/messenger.o: warning: objtool: ceph_con_workfn()+0x47c: can't find switch jump table Make objtool's find_jump_table() smart enough to distinguish between a switch jump table (which has relocations to text addresses in the same function as the original instruction) and other anonymous rodata (which may have relocations to elsewhere). Reported-by: Nick Desaulniers <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Tested-by: Nathan Chancellor <[email protected]> Link: https://github.com/ClangBuiltLinux/linux/issues/485 Link: https://lkml.kernel.org/r/263f6aae46d33da0b86d7030ced878cb5cab1788.1581997059.git.jpoimboe@redhat.com
2020-02-11objtool: Add relocation check for alternative sectionsJosh Poimboeuf1-0/+21
Relocations in alternative code can be dangerous, because the code is copy/pasted to the text section after relocations have been resolved, which can corrupt PC-relative addresses. However, relocations might be acceptable in some cases, depending on the architecture. For example, the x86 alternatives code manually fixes up the target addresses for PC-relative jumps and calls. So disallow relocations in alternative code, except where the x86 arch code allows it. This code may need to be tweaked for other arches when objtool gets support for them. Suggested-by: Linus Torvalds <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Reviewed-by: Julien Thierry <[email protected]> Link: https://lkml.kernel.org/r/7b90b68d093311e4e8f6b504a9e1c758fd7e0002.1581359535.git.jpoimboe@redhat.com
2020-02-11objtool: Add is_static_jump() helperJosh Poimboeuf1-6/+9
There are several places where objtool tests for a non-dynamic (aka direct) jump. Move the check to a helper function. Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Reviewed-by: Julien Thierry <[email protected]> Link: https://lkml.kernel.org/r/9b8b438df918276315e4765c60d2587f3c7ad698.1581359535.git.jpoimboe@redhat.com
2020-02-11objtool: Fail the kernel build on fatal errorsJosh Poimboeuf1-3/+9
When objtool encounters a fatal error, it usually means the binary is corrupt or otherwise broken in some way. Up until now, such errors were just treated as warnings which didn't fail the kernel build. However, objtool is now stable enough that if a fatal error is discovered, it most likely means something is seriously wrong and it should fail the kernel build. Note that this doesn't apply to "normal" objtool warnings; only fatal ones. Suggested-by: Borislav Petkov <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Reviewed-by: Julien Thierry <[email protected]> Link: https://lkml.kernel.org/r/f18c3743de0fef673d49dd35760f26bdef7f6fc3.1581359535.git.jpoimboe@redhat.com
2019-12-30Merge tag 'v5.5-rc4' into locking/kcsan, to resolve conflictsIngo Molnar1-0/+2
Conflicts: init/main.c lib/Kconfig.debug Signed-off-by: Ingo Molnar <[email protected]>
2019-11-26Merge branch 'x86-asm-for-linus' of ↵Linus Torvalds1-0/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 asm updates from Ingo Molnar: "The main changes in this cycle were: - Cross-arch changes to move the linker sections for NOTES and EXCEPTION_TABLE into the RO_DATA area, where they belong on most architectures. (Kees Cook) - Switch the x86 linker fill byte from x90 (NOP) to 0xcc (INT3), to trap jumps into the middle of those padding areas instead of sliding execution. (Kees Cook) - A thorough cleanup of symbol definitions within x86 assembler code. The rather randomly named macros got streamlined around a (hopefully) straightforward naming scheme: SYM_START(name, linkage, align...) SYM_END(name, sym_type) SYM_FUNC_START(name) SYM_FUNC_END(name) SYM_CODE_START(name) SYM_CODE_END(name) SYM_DATA_START(name) SYM_DATA_END(name) etc - with about three times of these basic primitives with some label, local symbol or attribute variant, expressed via postfixes. No change in functionality intended. (Jiri Slaby) - Misc other changes, cleanups and smaller fixes" * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (67 commits) x86/entry/64: Remove pointless jump in paranoid_exit x86/entry/32: Remove unused resume_userspace label x86/build/vdso: Remove meaningless CFLAGS_REMOVE_*.o m68k: Convert missed RODATA to RO_DATA x86/vmlinux: Use INT3 instead of NOP for linker fill bytes x86/mm: Report actual image regions in /proc/iomem x86/mm: Report which part of kernel image is freed x86/mm: Remove redundant address-of operators on addresses xtensa: Move EXCEPTION_TABLE to RO_DATA segment powerpc: Move EXCEPTION_TABLE to RO_DATA segment parisc: Move EXCEPTION_TABLE to RO_DATA segment microblaze: Move EXCEPTION_TABLE to RO_DATA segment ia64: Move EXCEPTION_TABLE to RO_DATA segment h8300: Move EXCEPTION_TABLE to RO_DATA segment c6x: Move EXCEPTION_TABLE to RO_DATA segment arm64: Move EXCEPTION_TABLE to RO_DATA segment alpha: Move EXCEPTION_TABLE to RO_DATA segment x86/vmlinux: Move EXCEPTION_TABLE to RO_DATA segment x86/vmlinux: Actually use _etext for the end of the text segment vmlinux.lds.h: Allow EXCEPTION_TABLE to live in RO_DATA ...
2019-11-16objtool, kcsan: Add KCSAN runtime functions to whitelistMarco Elver1-0/+18
This patch adds KCSAN runtime functions to the objtool whitelist. Signed-off-by: Marco Elver <[email protected]> Acked-by: Paul E. McKenney <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]>
2019-10-28ubsan, x86: Annotate and allow __ubsan_handle_shift_out_of_bounds() in ↵Peter Zijlstra1-0/+1
uaccess regions The new check_zeroed_user() function uses variable shifts inside of a user_access_begin()/user_access_end() section and that results in GCC emitting __ubsan_handle_shift_out_of_bounds() calls, even though through value range analysis it would be able to see that the UB in question is impossible. Annotate and whitelist this UBSAN function; continued use of user_access_begin()/user_access_end() will undoubtedly result in further uses of function. Reported-by: Randy Dunlap <[email protected]> Tested-by: Randy Dunlap <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Acked-by: Randy Dunlap <[email protected]> Acked-by: Christian Brauner <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephen Rothwell <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Fixes: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper") Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
2019-09-30objtool: add kunit_try_catch_throw to the noreturn listBrendan Higgins1-0/+1
Fix the following warning seen on GCC 7.3: kunit/test-test.o: warning: objtool: kunit_test_unsuccessful_try() falls through to next function kunit_test_catch() kunit_try_catch_throw is a function added in the following patch in this series; it allows KUnit, a unit testing framework for the kernel, to bail out of a broken test. As a consequence, it is a new __noreturn function that objtool thinks is broken (as seen above). So fix this warning by adding kunit_try_catch_throw to objtool's noreturn list. Reported-by: kbuild test robot <[email protected]> Signed-off-by: Brendan Higgins <[email protected]> Acked-by: Josh Poimboeuf <[email protected]> Link: https://www.spinics.net/lists/linux-kbuild/msg21708.html Cc: Peter Zijlstra <[email protected]> Signed-off-by: Shuah Khan <[email protected]>
2019-09-25KVM: x86: Check kvm_rebooting in kvm_spurious_fault()Sean Christopherson1-1/+0
Explicitly check kvm_rebooting in kvm_spurious_fault() prior to invoking BUG(), as opposed to assuming the caller has already done so. Letting kvm_spurious_fault() be called "directly" will allow VMX to better optimize its low level assembly flows. As a happy side effect, kvm_spurious_fault() no longer needs to be marked as a dead end since it doesn't unconditionally BUG(). Acked-by: Paolo Bonzini <[email protected]> Cc: Josh Poimboeuf <[email protected]> Signed-off-by: Sean Christopherson <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]>
2019-07-25objtool: Improve UACCESS coveragePeter Zijlstra1-3/+4
A clang build reported an (obvious) double CLAC while a GCC build did not; it turns out that objtool only re-visits instructions if the first visit was with AC=0. If OTOH the first visit was with AC=1, it completely ignores any subsequent visit, even when it has AC=0. Fix this by using a visited mask instead of a boolean, and (explicitly) mark the AC state. $ ./objtool check -b --no-fp --retpoline --uaccess drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x22: redundant UACCESS disable drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xea: (alt) drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0xffffffffffffffff: (branch) drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xd9: (alt) drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xb2: (branch) drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0x39: (branch) drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0x0: <=== (func) Reported-by: Josh Poimboeuf <[email protected]> Reported-by: Thomas Gleixner <[email protected]> Reported-by: Sedat Dilek <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Nathan Chancellor <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Tested-by: Sedat Dilek <[email protected]> Link: https://github.com/ClangBuiltLinux/linux/issues/617 Link: https://lkml.kernel.org/r/5359166aad2d53f3145cd442d83d0e5115e0cd17.1564007838.git.jpoimboe@redhat.com
2019-07-18objtool: Support conditional retpolinesJosh Poimboeuf1-2/+10
A Clang-built kernel is showing the following warning: arch/x86/kernel/platform-quirks.o: warning: objtool: x86_early_init_platform_quirks()+0x84: unreachable instruction That corresponds to this code: 7e: 0f 85 00 00 00 00 jne 84 <x86_early_init_platform_quirks+0x84> 80: R_X86_64_PC32 __x86_indirect_thunk_r11-0x4 84: c3 retq This is a conditional retpoline sibling call, which is now possible thanks to retpolines. Objtool hasn't seen that before. It's incorrectly interpreting the conditional jump as an unconditional dynamic jump. Reported-by: Nick Desaulniers <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/30d4c758b267ef487fb97e6ecb2f148ad007b554.1563413318.git.jpoimboe@redhat.com
2019-07-18objtool: Convert insn type to enumJosh Poimboeuf1-7/+0
This makes it easier to add new instruction types. Also it's hopefully more robust since the compiler should warn about out-of-range enums. Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/0740e96af0d40e54cfd6a07bf09db0fbd10793cd.1563413318.git.jpoimboe@redhat.com
2019-07-18objtool: Fix seg fault on bad switch table entryJosh Poimboeuf1-1/+1
In one rare case, Clang generated the following code: 5ca: 83 e0 21 and $0x21,%eax 5cd: b9 04 00 00 00 mov $0x4,%ecx 5d2: ff 24 c5 00 00 00 00 jmpq *0x0(,%rax,8) 5d5: R_X86_64_32S .rodata+0x38 which uses the corresponding jump table relocations: 000000000038 000200000001 R_X86_64_64 0000000000000000 .text + 834 000000000040 000200000001 R_X86_64_64 0000000000000000 .text + 5d9 000000000048 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000050 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000058 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000060 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000068 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000070 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000078 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000080 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000088 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000090 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000098 000200000001 R_X86_64_64 0000000000000000 .text + b96 0000000000a0 000200000001 R_X86_64_64 0000000000000000 .text + b96 0000000000a8 000200000001 R_X86_64_64 0000000000000000 .text + b96 0000000000b0 000200000001 R_X86_64_64 0000000000000000 .text + b96 0000000000b8 000200000001 R_X86_64_64 0000000000000000 .text + b96 0000000000c0 000200000001 R_X86_64_64 0000000000000000 .text + b96 0000000000c8 000200000001 R_X86_64_64 0000000000000000 .text + b96 0000000000d0 000200000001 R_X86_64_64 0000000000000000 .text + b96 0000000000d8 000200000001 R_X86_64_64 0000000000000000 .text + b96 0000000000e0 000200000001 R_X86_64_64 0000000000000000 .text + b96 0000000000e8 000200000001 R_X86_64_64 0000000000000000 .text + b96 0000000000f0 000200000001 R_X86_64_64 0000000000000000 .text + b96 0000000000f8 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000100 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000108 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000110 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000118 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000120 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000128 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000130 000200000001 R_X86_64_64 0000000000000000 .text + b96 000000000138 000200000001 R_X86_64_64 0000000000000000 .text + 82f 000000000140 000200000001 R_X86_64_64 0000000000000000 .text + 828 Since %eax was masked with 0x21, only the first two and the last two entries are possible. Objtool doesn't actually emulate all the code, so it isn't smart enough to know that all the middle entries aren't reachable. They point to the NOP padding area after the end of the function, so objtool seg faulted when it tried to dereference a NULL insn->func. After this fix, objtool still gives an "unreachable" error because it stops reading the jump table when it encounters the bad addresses: /home/jpoimboe/objtool-tests/adm1275.o: warning: objtool: adm1275_probe()+0x828: unreachable instruction While the above code is technically correct, it's very wasteful of memory -- it uses 34 jump table entries when only 4 are needed. It's also not possible for objtool to validate this type of switch table because the unused entries point outside the function and objtool has no way of determining if that's intentional. Hopefully the Clang folks can fix it. Reported-by: Arnd Bergmann <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Nick Desaulniers <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Link: https://lkml.kernel.org/r/a9db88eec4f1ca089e040989846961748238b6d8.1563413318.git.jpoimboe@redhat.com
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