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2022-04-22Merge branch 'tip/x86/urgent'Peter Zijlstra
Merge the x86/urgent objtool/IBT changes as a base Signed-off-by: Peter Zijlstra <peterz@infradead.org>
2022-04-22objtool: Fix type of reloc::addendPeter Zijlstra
Elf{32,64}_Rela::r_addend is of type: Elf{32,64}_Sword, that means that our reloc::addend needs to be long or face tuncation issues when we do elf_rebuild_reloc_section(): - 107: 48 b8 00 00 00 00 00 00 00 00 movabs $0x0,%rax 109: R_X86_64_64 level4_kernel_pgt+0x80000067 + 107: 48 b8 00 00 00 00 00 00 00 00 movabs $0x0,%rax 109: R_X86_64_64 level4_kernel_pgt-0x7fffff99 Fixes: 627fce14809b ("objtool: Add ORC unwind table generation") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20220419203807.596871927@infradead.org
2022-04-19objtool: Fix function fallthrough detection for vmlinuxJosh Poimboeuf
Objtool's function fallthrough detection only works on C objects. The distinction between C and assembly objects no longer makes sense with objtool running on vmlinux.o. Now that copy_user_64.S has been fixed up, and an objtool sibling call detection bug has been fixed, the asm code is in "compliance" and this hack is no longer needed. Remove it. Fixes: ed53a0d97192 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls") Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/b434cff98eca3a60dcc64c620d7d5d405a0f441c.1649718562.git.jpoimboe@redhat.com
2022-04-19objtool: Fix sibling call detection in alternativesJosh Poimboeuf
In add_jump_destinations(), sibling call detection requires 'insn->func' to be valid. But alternative instructions get their 'func' set in handle_group_alt(), which runs *after* add_jump_destinations(). So sibling calls in alternatives code don't get properly detected. Fix that by changing the initialization order: call add_special_section_alts() *before* add_jump_destinations(). This also means the special case for a missing 'jump_dest' in add_jump_destinations() can be removed, as it has already been dealt with. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/c02e0a0a2a4286b5f848d17c77fdcb7e0caf709c.1649718562.git.jpoimboe@redhat.com
2022-04-19objtool: Don't set 'jump_dest' for sibling callsJosh Poimboeuf
For most sibling calls, 'jump_dest' is NULL because objtool treats the jump like a call and sets 'call_dest'. But there are a few edge cases where that's not true. Make it consistent to avoid unexpected behavior. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/8737d6b9d1691831aed73375f444f0f42da3e2c9.1649718562.git.jpoimboe@redhat.com
2022-04-19objtool: Use offstr() to print address of missing ENDBRJosh Poimboeuf
Fixes: 89bc853eae4a ("objtool: Find unused ENDBR instructions") Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/95d12e800c736a3f7d08d61dabb760b2d5251a8e.1650300597.git.jpoimboe@redhat.com
2022-04-19objtool: Print data address for "!ENDBR" data warningsJosh Poimboeuf
When a "!ENDBR" warning is reported for a data section, objtool just prints the text address of the relocation target twice, without giving any clues about the location of the original data reference: vmlinux.o: warning: objtool: dcbnl_netdevice_event()+0x0: .text+0xb64680: data relocation to !ENDBR: dcbnl_netdevice_event+0x0 Instead, print the address of the data reference, in addition to the address of the relocation target. vmlinux.o: warning: objtool: dcbnl_nb+0x0: .data..read_mostly+0xe260: data relocation to !ENDBR: dcbnl_netdevice_event+0x0 Fixes: 89bc853eae4a ("objtool: Find unused ENDBR instructions") Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/762e88d51300e8eaf0f933a5b0feae20ac033bea.1650300597.git.jpoimboe@redhat.com
2022-04-19x86,objtool: Mark cpu_startup_entry() __noreturnPeter Zijlstra
GCC-8 isn't clever enough to figure out that cpu_start_entry() is a noreturn while objtool is. This results in code after the call in start_secondary(). Give GCC a hand so that they all agree on things. vmlinux.o: warning: objtool: start_secondary()+0x10e: unreachable Reported-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220408094718.383658532@infradead.org
2022-04-05objtool: Fix SLS validation for kcov tail-call replacementPeter Zijlstra
Since not all compilers have a function attribute to disable KCOV instrumentation, objtool can rewrite KCOV instrumentation in noinstr functions as per commit: f56dae88a81f ("objtool: Handle __sanitize_cov*() tail calls") However, this has subtle interaction with the SLS validation from commit: 1cc1e4c8aab4 ("objtool: Add straight-line-speculation validation") In that when a tail-call instrucion is replaced with a RET an additional INT3 instruction is also written, but is not represented in the decoded instruction stream. This then leads to false positive missing INT3 objtool warnings in noinstr code. Instead of adding additional struct instruction objects, mark the RET instruction with retpoline_safe to suppress the warning (since we know there really is an INT3). Fixes: 1cc1e4c8aab4 ("objtool: Add straight-line-speculation validation") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220323230712.GA8939@worktop.programming.kicks-ass.net
2022-04-05objtool: Fix IBT tail-call detectionPeter Zijlstra
Objtool reports: arch/x86/crypto/poly1305-x86_64.o: warning: objtool: poly1305_blocks_avx() falls through to next function poly1305_blocks_x86_64() arch/x86/crypto/poly1305-x86_64.o: warning: objtool: poly1305_emit_avx() falls through to next function poly1305_emit_x86_64() arch/x86/crypto/poly1305-x86_64.o: warning: objtool: poly1305_blocks_avx2() falls through to next function poly1305_blocks_x86_64() Which reads like: 0000000000000040 <poly1305_blocks_x86_64>: 40: f3 0f 1e fa endbr64 ... 0000000000000400 <poly1305_blocks_avx>: 400: f3 0f 1e fa endbr64 404: 44 8b 47 14 mov 0x14(%rdi),%r8d 408: 48 81 fa 80 00 00 00 cmp $0x80,%rdx 40f: 73 09 jae 41a <poly1305_blocks_avx+0x1a> 411: 45 85 c0 test %r8d,%r8d 414: 0f 84 2a fc ff ff je 44 <poly1305_blocks_x86_64+0x4> ... These are simple conditional tail-calls and *should* be recognised as such by objtool, however due to a mistake in commit 08f87a93c8ec ("objtool: Validate IBT assumptions") this is failing. Specifically, the jump_dest is +4, this means the instruction pointed at will not be ENDBR and as such it will fail the second clause of is_first_func_insn() that was supposed to capture this exact case. Instead, have is_first_func_insn() look at the previous instruction. Fixes: 08f87a93c8ec ("objtool: Validate IBT assumptions") Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220322115125.811582125@infradead.org
2022-03-15objtool: Find unused ENDBR instructionsPeter Zijlstra
Find all ENDBR instructions which are never referenced and stick them in a section such that the kernel can poison them, sealing the functions from ever being an indirect call target. This removes about 1-in-4 ENDBR instructions. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154319.763643193@infradead.org
2022-03-15objtool: Validate IBT assumptionsPeter Zijlstra
Intel IBT requires that every indirect JMP/CALL targets an ENDBR instructions, failing this #CP happens and we die. Similarly, all exception entries should be ENDBR. Find all code relocations and ensure they're either an ENDBR instruction or ANNOTATE_NOENDBR. For the exceptions look for UNWIND_HINT_IRET_REGS at sym+0 not being ENDBR. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154319.705110141@infradead.org
2022-03-15objtool: Read the NOENDBR annotationPeter Zijlstra
Read the new NOENDBR annotation. While there, attempt to not bloat struct instruction. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154319.586815435@infradead.org
2022-03-15objtool: Rework ASM_REACHABLEPeter Zijlstra
Currently ASM_REACHABLE only works for UD2 instructions; reorder things to also allow over-riding dead_end_function(). To that end: - Mark INSN_BUG instructions in decode_instructions(), this saves having to iterate all instructions yet again. - Have add_call_destinations() set insn->dead_end for dead_end_function() calls. - Move add_dead_ends() *after* add_call_destinations() such that ASM_REACHABLE can clear the ->dead_end mark. - have validate_branch() only check ->dead_end. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154319.410010807@infradead.org
2022-03-15x86: Mark __invalid_creds() __noreturnPeter Zijlstra
vmlinux.o: warning: objtool: ksys_unshare()+0x36c: unreachable instruction 0000 0000000000067040 <ksys_unshare>: ... 0364 673a4: 4c 89 ef mov %r13,%rdi 0367 673a7: e8 00 00 00 00 call 673ac <ksys_unshare+0x36c> 673a8: R_X86_64_PLT32 __invalid_creds-0x4 036c 673ac: e9 28 ff ff ff jmp 672d9 <ksys_unshare+0x299> 0371 673b1: 41 bc f4 ff ff ff mov $0xfffffff4,%r12d 0377 673b7: e9 80 fd ff ff jmp 6713c <ksys_unshare+0xfc> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/Yi9gOW9f1GGwwUD6@hirez.programming.kicks-ass.net
2022-03-15exit: Mark do_group_exit() __noreturnPeter Zijlstra
vmlinux.o: warning: objtool: get_signal()+0x108: unreachable instruction 0000 000000000007f930 <get_signal>: ... 0103 7fa33: e8 00 00 00 00 call 7fa38 <get_signal+0x108> 7fa34: R_X86_64_PLT32 do_group_exit-0x4 0108 7fa38: 41 8b 45 74 mov 0x74(%r13),%eax Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154319.351270711@infradead.org
2022-03-15x86: Mark stop_this_cpu() __noreturnPeter Zijlstra
vmlinux.o: warning: objtool: smp_stop_nmi_callback()+0x2b: unreachable instruction 0000 0000000000047cf0 <smp_stop_nmi_callback>: ... 0026 47d16: e8 00 00 00 00 call 47d1b <smp_stop_nmi_callback+0x2b> 47d17: R_X86_64_PLT32 stop_this_cpu-0x4 002b 47d1b: b8 01 00 00 00 mov $0x1,%eax Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154319.290905453@infradead.org
2022-03-15objtool: Ignore extra-symbol codePeter Zijlstra
There's a fun implementation detail on linking STB_WEAK symbols. When the linker combines two translation units, where one contains a weak function and the other an override for it. It simply strips the STB_WEAK symbol from the symbol table, but doesn't actually remove the code. The result is that when objtool is ran in a whole-archive kind of way, it will encounter *heaps* of unused (and unreferenced) code. All rudiments of weak functions. Additionally, when a weak implementation is split into a .cold subfunction that .cold symbol is left in place, even though completely unused. Teach objtool to ignore such rudiments by searching for symbol holes; that is, code ranges that fall outside the given symbol bounds. Specifically, ignore a sequence of unreachable instruction iff they occupy a single hole, additionally ignore any .cold subfunctions referenced. Both ld.bfd and ld.lld behave like this. LTO builds otoh can (and do) properly DCE weak functions. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154319.232019347@infradead.org
2022-03-15objtool: Rename --duplicate to --ltoPeter Zijlstra
In order to prepare for LTO like objtool runs for modules, rename the duplicate argument to lto. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154319.172584233@infradead.org
2022-03-15objtool: Default ignore INT3 for unreachablePeter Zijlstra
Ignore all INT3 instructions for unreachable code warnings, similar to NOP. This allows using INT3 for various paddings instead of NOPs. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154317.343312938@infradead.org
2022-01-24objtool: Fix truncated string warningSergei Trofimovich
On GCC 12, the build fails due to a possible truncated string: check.c: In function 'validate_call': check.c:2865:58: error: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size 9 [-Werror=format-truncation=] 2865 | snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx); | ^~ In theory it's a valid bug: static char pvname[16]; int idx; ... idx = (rel->addend / sizeof(void *)); snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx); There are only 7 chars for %d while it could take up to 9, so the printed "pv_ops[%d]" string could get truncated. In reality the bug should never happen, because pv_ops only has ~80 entries, so 7 chars for the integer is more than enough. Still, it's worth fixing. Bump the buffer size by 2 bytes to silence the warning. [ jpoimboe: changed size to 19; massaged changelog ] Fixes: db2b0c5d7b6f ("objtool: Support pv_opsindirect calls for noinstr") Reported-by: Adam Borowski <kilobyte@angband.pl> Reported-by: Martin Liška <mliska@suse.cz> Signed-off-by: Sergei Trofimovich <slyich@gmail.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220120233748.2062559-1-slyich@gmail.com
2022-01-17Merge branch 'signal-for-v5.17' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull signal/exit/ptrace updates from Eric Biederman: "This set of changes deletes some dead code, makes a lot of cleanups which hopefully make the code easier to follow, and fixes bugs found along the way. The end-game which I have not yet reached yet is for fatal signals that generate coredumps to be short-circuit deliverable from complete_signal, for force_siginfo_to_task not to require changing userspace configured signal delivery state, and for the ptrace stops to always happen in locations where we can guarantee on all architectures that the all of the registers are saved and available on the stack. Removal of profile_task_ext, profile_munmap, and profile_handoff_task are the big successes for dead code removal this round. A bunch of small bug fixes are included, as most of the issues reported were small enough that they would not affect bisection so I simply added the fixes and did not fold the fixes into the changes they were fixing. There was a bug that broke coredumps piped to systemd-coredump. I dropped the change that caused that bug and replaced it entirely with something much more restrained. Unfortunately that required some rebasing. Some successes after this set of changes: There are few enough calls to do_exit to audit in a reasonable amount of time. The lifetime of struct kthread now matches the lifetime of struct task, and the pointer to struct kthread is no longer stored in set_child_tid. The flag SIGNAL_GROUP_COREDUMP is removed. The field group_exit_task is removed. Issues where task->exit_code was examined with signal->group_exit_code should been examined were fixed. There are several loosely related changes included because I am cleaning up and if I don't include them they will probably get lost. The original postings of these changes can be found at: https://lkml.kernel.org/r/87a6ha4zsd.fsf@email.froward.int.ebiederm.org https://lkml.kernel.org/r/87bl1kunjj.fsf@email.froward.int.ebiederm.org https://lkml.kernel.org/r/87r19opkx1.fsf_-_@email.froward.int.ebiederm.org I trimmed back the last set of changes to only the obviously correct once. Simply because there was less time for review than I had hoped" * 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (44 commits) ptrace/m68k: Stop open coding ptrace_report_syscall ptrace: Remove unused regs argument from ptrace_report_syscall ptrace: Remove second setting of PT_SEIZED in ptrace_attach taskstats: Cleanup the use of task->exit_code exit: Use the correct exit_code in /proc/<pid>/stat exit: Fix the exit_code for wait_task_zombie exit: Coredumps reach do_group_exit exit: Remove profile_handoff_task exit: Remove profile_task_exit & profile_munmap signal: clean up kernel-doc comments signal: Remove the helper signal_group_exit signal: Rename group_exit_task group_exec_task coredump: Stop setting signal->group_exit_task signal: Remove SIGNAL_GROUP_COREDUMP signal: During coredumps set SIGNAL_GROUP_EXIT in zap_process signal: Make coredump handling explicit in complete_signal signal: Have prepare_signal detect coredumps using signal->core_state signal: Have the oom killer detect coredumps using signal->core_state exit: Move force_uaccess back into do_exit exit: Guarantee make_task_dead leaks the tsk when calling do_task_exit ...
2022-01-12Merge tag 'x86_core_for_v5.17_rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 core updates from Borislav Petkov: - Get rid of all the .fixup sections because this generates misleading/wrong stacktraces and confuse RELIABLE_STACKTRACE and LIVEPATCH as the backtrace misses the function which is being fixed up. - Add Straight Line Speculation mitigation support which uses a new compiler switch -mharden-sls= which sticks an INT3 after a RET or an indirect branch in order to block speculation after them. Reportedly, CPUs do speculate behind such insns. - The usual set of cleanups and improvements * tag 'x86_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits) x86/entry_32: Fix segment exceptions objtool: Remove .fixup handling x86: Remove .fixup section x86/word-at-a-time: Remove .fixup usage x86/usercopy: Remove .fixup usage x86/usercopy_32: Simplify __copy_user_intel_nocache() x86/sgx: Remove .fixup usage x86/checksum_32: Remove .fixup usage x86/vmx: Remove .fixup usage x86/kvm: Remove .fixup usage x86/segment: Remove .fixup usage x86/fpu: Remove .fixup usage x86/xen: Remove .fixup usage x86/uaccess: Remove .fixup usage x86/futex: Remove .fixup usage x86/msr: Remove .fixup usage x86/extable: Extend extable functionality x86/entry_32: Remove .fixup usage x86/entry_64: Remove .fixup usage x86/copy_mc_64: Remove .fixup usage ...
2021-12-15objtool: Add a missing comma to avoid string concatenationEric W. Biederman
Recently the kbuild robot reported two new errors: >> lib/kunit/kunit-example-test.o: warning: objtool: .text.unlikely: unexpected end of section >> arch/x86/kernel/dumpstack.o: warning: objtool: oops_end() falls through to next function show_opcodes() I don't know why they did not occur in my test setup but after digging it I realized I had accidentally dropped a comma in tools/objtool/check.c when I renamed rewind_stack_do_exit to rewind_stack_and_make_dead. Add that comma back to fix objtool errors. Link: https://lkml.kernel.org/r/202112140949.Uq5sFKR1-lkp@intel.com Fixes: 0e25498f8cd4 ("exit: Add and use make_task_dead.") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13exit: Rename complete_and_exit to kthread_complete_and_exitEric W. Biederman
Update complete_and_exit to call kthread_exit instead of do_exit. Change the name to reflect this change in functionality. All of the users of complete_and_exit are causing the current kthread to exit so this change makes it clear what is happening. Move the implementation of kthread_complete_and_exit from kernel/exit.c to to kernel/kthread.c. As this function is kthread specific it makes most sense to live with the kthread functions. There are no functional change. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13exit: Rename module_put_and_exit to module_put_and_kthread_exitEric W. Biederman
Update module_put_and_exit to call kthread_exit instead of do_exit. Change the name to reflect this change in functionality. All of the users of module_put_and_exit are causing the current kthread to exit so this change makes it clear what is happening. There is no functional change. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13exit: Implement kthread_exitEric W. Biederman
The way the per task_struct exit_code is used by kernel threads is not quite compatible how it is used by userspace applications. The low byte of the userspace exit_code value encodes the exit signal. While kthreads just use the value as an int holding ordinary kernel function exit status like -EPERM. Add kthread_exit to clearly separate the two kinds of uses. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13exit: Add and use make_task_dead.Eric W. Biederman
There are two big uses of do_exit. The first is it's design use to be the guts of the exit(2) system call. The second use is to terminate a task after something catastrophic has happened like a NULL pointer in kernel code. Add a function make_task_dead that is initialy exactly the same as do_exit to cover the cases where do_exit is called to handle catastrophic failure. In time this can probably be reduced to just a light wrapper around do_task_dead. For now keep it exactly the same so that there will be no behavioral differences introducing this new concept. Replace all of the uses of do_exit that use it for catastraphic task cleanup with make_task_dead to make it clear what the code is doing. As part of this rename rewind_stack_do_exit rewind_stack_and_make_dead. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-11objtool: Remove .fixup handlingPeter Zijlstra
The .fixup has gone the way of the Dodo, that test will always be false. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20211110101326.261496792@infradead.org
2021-12-09objtool, kcsan: Remove memory barrier instrumentation from noinstrMarco Elver
Teach objtool to turn instrumentation required for memory barrier modeling into nops in noinstr text. The __tsan_func_entry/exit calls are still emitted by compilers even with the __no_sanitize_thread attribute. The memory barrier instrumentation will be inserted explicitly (without compiler help), and thus needs to also explicitly be removed. Signed-off-by: Marco Elver <elver@google.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09objtool, kcsan: Add memory barrier instrumentation to whitelistMarco Elver
Adds KCSAN's memory barrier instrumentation to objtool's uaccess whitelist. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-08objtool: Add straight-line-speculation validationPeter Zijlstra
Teach objtool to validate the straight-line-speculation constraints: - speculation trap after indirect calls - speculation trap after RET Notable: when an instruction is annotated RETPOLINE_SAFE, indicating speculation isn't a problem, also don't care about sls for that instruction. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20211204134908.023037659@infradead.org
2021-11-11static_call,x86: Robustify trampoline patchingPeter Zijlstra
Add a few signature bytes after the static call trampoline and verify those bytes match before patching the trampoline. This avoids patching random other JMPs (such as CFI jump-table entries) instead. These bytes decode as: d: 53 push %rbx e: 43 54 rex.XB push %r12 And happen to spell "SCT". Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20211030074758.GT174703@worktop.programming.kicks-ass.net
2021-11-01Merge tag 'trace-v5.16' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: - kprobes: Restructured stack unwinder to show properly on x86 when a stack dump happens from a kretprobe callback. - Fix to bootconfig parsing - Have tracefs allow owner and group permissions by default (only denying others). There's been pressure to allow non root to tracefs in a controlled fashion, and using groups is probably the safest. - Bootconfig memory managament updates. - Bootconfig clean up to have the tools directory be less dependent on changes in the kernel tree. - Allow perf to be traced by function tracer. - Rewrite of function graph tracer to be a callback from the function tracer instead of having its own trampoline (this change will happen on an arch by arch basis, and currently only x86_64 implements it). - Allow multiple direct trampolines (bpf hooks to functions) be batched together in one synchronization. - Allow histogram triggers to add variables that can perform calculations against the event's fields. - Use the linker to determine architecture callbacks from the ftrace trampoline to allow for proper parameter prototypes and prevent warnings from the compiler. - Extend histogram triggers to key off of variables. - Have trace recursion use bit magic to determine preempt context over if branches. - Have trace recursion disable preemption as all use cases do anyway. - Added testing for verification of tracing utilities. - Various small clean ups and fixes. * tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (101 commits) tracing/histogram: Fix semicolon.cocci warnings tracing/histogram: Fix documentation inline emphasis warning tracing: Increase PERF_MAX_TRACE_SIZE to handle Sentinel1 and docker together tracing: Show size of requested perf buffer bootconfig: Initialize ret in xbc_parse_tree() ftrace: do CPU checking after preemption disabled ftrace: disable preemption when recursion locked tracing/histogram: Document expression arithmetic and constants tracing/histogram: Optimize division by a power of 2 tracing/histogram: Covert expr to const if both operands are constants tracing/histogram: Simplify handling of .sym-offset in expressions tracing: Fix operator precedence for hist triggers expression tracing: Add division and multiplication support for hist triggers tracing: Add support for creating hist trigger variables from literal selftests/ftrace: Stop tracing while reading the trace file by default MAINTAINERS: Update KPROBES and TRACING entries test_kprobes: Move it from kernel/ to lib/ docs, kprobes: Remove invalid URL and add new reference samples/kretprobes: Fix return value if register_kretprobe() failed lib/bootconfig: Fix the xbc_get_info kerneldoc ...
2021-10-28objtool,x86: Replace alternatives with .retpoline_sitesPeter Zijlstra
Instead of writing complete alternatives, simply provide a list of all the retpoline thunk calls. Then the kernel is free to do with them as it pleases. Simpler code all-round. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Borislav Petkov <bp@suse.de> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Tested-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/r/20211026120309.850007165@infradead.org
2021-10-28objtool: Shrink struct instructionPeter Zijlstra
Any one instruction can only ever call a single function, therefore insn->mcount_loc_node is superfluous and can use insn->call_node. This shrinks struct instruction, which is by far the most numerous structure objtool creates. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Borislav Petkov <bp@suse.de> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Tested-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/r/20211026120309.785456706@infradead.org
2021-10-28objtool: Explicitly avoid self modifying code in .altinstr_replacementPeter Zijlstra
Assume ALTERNATIVE()s know what they're doing and do not change, or cause to change, instructions in .altinstr_replacement sections. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Borislav Petkov <bp@suse.de> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Tested-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/r/20211026120309.722511775@infradead.org
2021-10-28objtool: Classify symbolsPeter Zijlstra
In order to avoid calling str*cmp() on symbol names, over and over, do them all once upfront and store the result. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Borislav Petkov <bp@suse.de> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Tested-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/r/20211026120309.658539311@infradead.org
2021-10-07Merge branch 'objtool/urgent'Peter Zijlstra
Fixup conflicts. # Conflicts: # tools/objtool/check.c
2021-10-05objtool: Remove redundant 'len' field from struct sectionJoe Lawrence
The section structure already contains sh_size, so just remove the extra 'len' member that requires extra mirroring and potential confusion. Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20210822225037.54620-3-joe.lawrence@redhat.com Cc: Andy Lavr <andy.lavr@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org
2021-09-30objtool: Ignore unwind hints for ignored functionsJosh Poimboeuf
If a function is ignored, also ignore its hints. This is useful for the case where the function ignore is conditional on frame pointers, e.g. STACK_FRAME_NON_STANDARD_FP(). Link: https://lkml.kernel.org/r/163163048317.489837.10988954983369863209.stgit@devnote2 Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Tested-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-09-17objtool: Support pv_opsindirect calls for noinstrPeter Zijlstra
Normally objtool will now follow indirect calls; there is no need. However, this becomes a problem with noinstr validation; if there's an indirect call from noinstr code, we very much need to know it is to another noinstr function. Luckily there aren't many indirect calls in entry code with the obvious exception of paravirt. As such, noinstr validation didn't work with paravirt kernels. In order to track pv_ops[] call targets, objtool reads the static pv_ops[] tables as well as direct assignments to the pv_ops[] array, provided the compiler makes them a single instruction like: bf87: 48 c7 05 00 00 00 00 00 00 00 00 movq $0x0,0x0(%rip) bf92 <xen_init_spinlocks+0x5f> bf8a: R_X86_64_PC32 pv_ops+0x268 There are, as of yet, no warnings for when this goes wrong :/ Using the functions found with the above means, all pv_ops[] calls are now subject to noinstr validation. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210624095149.118815755@infradead.org
2021-09-15objtool: Handle __sanitize_cov*() tail callsPeter Zijlstra
Turns out the compilers also generate tail calls to __sanitize_cov*(), make sure to also patch those out in noinstr code. Fixes: 0f1441b44e82 ("objtool: Fix noinstr vs KCOV") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Marco Elver <elver@google.com> Link: https://lore.kernel.org/r/20210624095147.818783799@infradead.org
2021-09-15objtool: Introduce CFI hashPeter Zijlstra
Andi reported that objtool on vmlinux.o consumes more memory than his system has, leading to horrific performance. This is in part because we keep a struct instruction for every instruction in the file in-memory. Shrink struct instruction by removing the CFI state (which includes full register state) from it and demand allocating it. Given most instructions don't actually change CFI state, there's lots of repetition there, so add a hash table to find previous CFI instances. Reduces memory consumption (and runtime) for processing an x86_64-allyesconfig: pre: 4:40.84 real, 143.99 user, 44.18 sys, 30624988 mem post: 2:14.61 real, 108.58 user, 25.04 sys, 16396184 mem Suggested-by: Andi Kleen <andi@firstfloor.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210624095147.756759107@infradead.org
2021-09-15x86/xen: Mark cpu_bringup_and_idle() as dead_end_functionPeter Zijlstra
The asm_cpu_bringup_and_idle() function is required to push the return value on the stack in order to make ORC happy, but the only reason objtool doesn't complain is because of a happy accident. The thing is that asm_cpu_bringup_and_idle() doesn't return, so validate_branch() never terminates and falls through to the next function, which in the normal case is the hypercall_page. And that, as it happens, is 4095 NOPs and a RET. Make asm_cpu_bringup_and_idle() terminate on it's own, by making the function it calls as a dead-end. This way we no longer rely on what code happens to come after. Fixes: c3881eb58d56 ("x86/xen: Make the secondary CPU idle tasks reliable") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Juergen Gross <jgross@suse.com> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/20210624095147.693801717@infradead.org
2021-05-14objtool: Reflow handle_jump_alt()Peter Zijlstra
Miroslav figured the code flow in handle_jump_alt() was sub-optimal with that goto. Reflow the code to make it clearer. Reported-by: Miroslav Benes <mbenes@suse.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/YJ00lgslY+IpA/rL@hirez.programming.kicks-ass.net
2021-05-12objtool: Provide stats for jump_labelsPeter Zijlstra
Add objtool --stats to count the jump_label sites it encounters. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210506194158.153101906@infradead.org
2021-05-12objtool: Rewrite jump_label instructionsPeter Zijlstra
When a jump_entry::key has bit1 set, rewrite the instruction to be a NOP. This allows the compiler/assembler to emit JMP (and thus decide on which encoding to use). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210506194158.091028792@infradead.org
2021-04-28Merge tag 'objtool-core-2021-04-28' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull objtool updates from Ingo Molnar: - Standardize the crypto asm code so that it looks like compiler- generated code to objtool - so that it can understand it. This enables unwinding from crypto asm code - and also fixes the last known remaining objtool warnings for LTO and more. - x86 decoder fixes: clean up and fix the decoder, and also extend it a bit - Misc fixes and cleanups * tag 'objtool-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) x86/crypto: Enable objtool in crypto code x86/crypto/sha512-ssse3: Standardize stack alignment prologue x86/crypto/sha512-avx2: Standardize stack alignment prologue x86/crypto/sha512-avx: Standardize stack alignment prologue x86/crypto/sha256-avx2: Standardize stack alignment prologue x86/crypto/sha1_avx2: Standardize stack alignment prologue x86/crypto/sha_ni: Standardize stack alignment prologue x86/crypto/crc32c-pcl-intel: Standardize jump table x86/crypto/camellia-aesni-avx2: Unconditionally allocate stack buffer x86/crypto/aesni-intel_avx: Standardize stack alignment prologue x86/crypto/aesni-intel_avx: Fix register usage comments x86/crypto/aesni-intel_avx: Remove unused macros objtool: Support asm jump tables objtool: Parse options from OBJTOOL_ARGS objtool: Collate parse_options() users objtool: Add --backup objtool,x86: More ModRM sugar objtool,x86: Rewrite ADD/SUB/AND objtool,x86: Support %riz encodings objtool,x86: Simplify register decode ...
2021-04-19objtool: Support asm jump tablesJosh Poimboeuf
Objtool detection of asm jump tables would normally just work, except for the fact that asm retpolines use alternatives. Objtool thinks the alternative code path (a jump to the retpoline) is a sibling call. Don't treat alternative indirect branches as sibling calls when the original instruction has a jump table. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Tested-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Sami Tolvanen <samitolvanen@google.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Link: https://lore.kernel.org/r/460cf4dc675d64e1124146562cabd2c05aa322e8.1614182415.git.jpoimboe@redhat.com
generated by cgit (git 2.34.1) at 2025-05-04 04:00:46 +0000