- 22 Apr, 2022 16 commits
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Josh Poimboeuf authored
Objtool has some hacks in place to workaround toolchain limitations which otherwise would break no-instrumentation rules. Make the hacks explicit (and optional for other arches) by turning it into a cmdline option and kernel config option. Signed-off-by:
Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by:
Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by:
Miroslav Benes <mbenes@suse.cz> Link: https://lkml.kernel.org/r/b326eeb9c33231b9dfbb925f194ed7ee40edcd7c.1650300597.git.jpoimboe@redhat.com
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Josh Poimboeuf authored
Objtool secretly does a jump label hack to overcome the limitations of the toolchain. Make the hack explicit (and optional for other arches) by turning it into a cmdline option and kernel config option. Signed-off-by:
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Josh Poimboeuf authored
As part of making objtool more modular, put the existing static call code behind a new '--static-call' option. Signed-off-by:
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Josh Poimboeuf authored
Now that CONFIG_STACK_VALIDATION is frame-pointer specific, do the same for the '--stackval' option. Now the '--no-fp' option is redundant and can be removed. Signed-off-by:
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Josh Poimboeuf authored
Now that stack validation is an optional feature of objtool, add CONFIG_OBJTOOL and replace most usages of CONFIG_STACK_VALIDATION with it. CONFIG_STACK_VALIDATION can now be considered to be frame-pointer specific. CONFIG_UNWINDER_ORC is already inherently valid for live patching, so no need to "validate" it. Signed-off-by:
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Josh Poimboeuf authored
Extricate sls functionality from validate_branch() so they can be executed (or ported) independently from each other. Signed-off-by:
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Josh Poimboeuf authored
Extricate ibt from validate_branch() so they can be executed (or ported) independently from each other. While shuffling code around, simplify and improve the ibt logic: - Ignore an explicit list of known sections which reference functions for reasons other than indirect branching to them. This helps prevent unnnecesary sealing. - Warn on missing !ENDBR for all other sections, not just .data and .rodata. This finds additional warnings, because there are sections other than .[ro]data which reference function pointers. For example, the ksymtab sections which are used for exporting symbols. Signed-off-by:
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Josh Poimboeuf authored
Make stack validation an explicit cmdline option so that individual objtool features can be enabled individually by other arches. Signed-off-by:
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Josh Poimboeuf authored
To help prevent objtool users from having to do math to convert function addresses to section addresses, and to help out with finding data addresses reported by IBT validation, add an option to print the section address in addition to the function address. Normal: vmlinux.o: warning: objtool: fixup_exception()+0x2d1: unreachable instruction With '--sec-address': vmlinux.o: warning: objtool: fixup_exception()+0x2d1 (.text+0x76c51): unreachable instruction Suggested-by:
Nick Desaulniers <ndesaulniers@google.com> Signed-off-by:
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Josh Poimboeuf authored
The parentheses in the "func()+off" address output are inconsistent with how the kernel prints function addresses, breaking Peter's scripts. Remove them. Suggested-by:
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Josh Poimboeuf authored
Objtool has a fairly singular focus. It runs on object files and does validations and transformations which can be combined in various ways. The subcommand model has never been a good fit, making it awkward to combine and remove options. Remove the "check" and "orc" subcommands in favor of a more traditional cmdline option model. This makes it much more flexible to use, and easier to port individual features to other arches. Signed-off-by:
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Josh Poimboeuf authored
Split the existing options into two groups: actions, which actually do something; and options, which modify the actions in some way. Also there's no need to have short flags for all the non-action options. Reserve short flags for the more important actions. While at it: - change a few of the short flags to be more intuitive - make option descriptions more consistently descriptive - sort options in the source like they are when printed - move options to a global struct Signed-off-by:
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Josh Poimboeuf authored
The OPTION_GROUP option type is a way of grouping certain options together in the printed usage text. It happens to be completely broken, thanks to the fact that the subcmd option sorting just sorts everything, without regard for grouping. Luckily, nobody uses this option anyway, though that will change shortly. Fix it by sorting each group individually. Signed-off-by:
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Peter Zijlstra authored
Merge the x86/urgent objtool/IBT changes as a base Signed-off-by: -
Peter Zijlstra authored
Occasionally objtool driven code patching (think .static_call_sites .retpoline_sites etc..) goes sideways and it tries to patch an instruction that doesn't match. Much head-scatching and cursing later the problem is as outlined below and affects every section that objtool generates for us, very much including the ORC data. The below uses .static_call_sites because it's convenient for demonstration purposes, but as mentioned the ORC sections, .retpoline_sites and __mount_loc are all similarly affected. Consider: foo-weak.c: extern void __SCT__foo(void); __attribute__((weak)) void foo(void) { return __SCT__foo(); } foo.c: extern void __SCT__foo(void); extern void my_foo(void); void foo(void) { my_foo(); return __SCT__foo(); } These generate the obvious code (gcc -O2 -fcf-protection=none -fno-asynchronous-unwind-tables -c foo*.c): foo-weak.o: 0000000000000000 <foo>: 0: e9 00 00 00 00 jmpq 5 <foo+0x5> 1: R_X86_64_PLT32 __SCT__foo-0x4 foo.o: 0000000000000000 <foo>: 0: 48 83 ec 08 sub $0x8,%rsp 4: e8 00 00 00 00 callq 9 <foo+0x9> 5: R_X86_64_PLT32 my_foo-0x4 9: 48 83 c4 08 add $0x8,%rsp d: e9 00 00 00 00 jmpq 12 <foo+0x12> e: R_X86_64_PLT32 __SCT__foo-0x4 Now, when we link these two files together, you get something like (ld -r -o foos.o foo-weak.o foo.o): foos.o: 0000000000000000 <foo-0x10>: 0: e9 00 00 00 00 jmpq 5 <foo-0xb> 1: R_X86_64_PLT32 __SCT__foo-0x4 5: 66 2e 0f 1f 84 00 00 00 00 00 nopw %cs:0x0(%rax,%rax,1) f: 90 nop 0000000000000010 <foo>: 10: 48 83 ec 08 sub $0x8,%rsp 14: e8 00 00 00 00 callq 19 <foo+0x9> 15: R_X86_64_PLT32 my_foo-0x4 19: 48 83 c4 08 add $0x8,%rsp 1d: e9 00 00 00 00 jmpq 22 <foo+0x12> 1e: R_X86_64_PLT32 __SCT__foo-0x4 Noting that ld preserves the weak function text, but strips the symbol off of it (hence objdump doing that funny negative offset thing). This does lead to 'interesting' unused code issues with objtool when ran on linked objects, but that seems to be working (fingers crossed). So far so good.. Now lets consider the objtool static_call output section (readelf output, old binutils): foo-weak.o: Relocation section '.rela.static_call_sites' at offset 0x2c8 contains 1 entry: Offset Info Type Symbol's Value Symbol's Name + Addend 0000000000000000 0000000200000002 R_X86_64_PC32 0000000000000000 .text + 0 0000000000000004 0000000d00000002 R_X86_64_PC32 0000000000000000 __SCT__foo + 1 foo.o: Relocation section '.rela.static_call_sites' at offset 0x310 contains 2 entries: Offset Info Type Symbol's Value Symbol's Name + Addend 0000000000000000 0000000200000002 R_X86_64_PC32 0000000000000000 .text + d 0000000000000004 0000000d00000002 R_X86_64_PC32 0000000000000000 __SCT__foo + 1 foos.o: Relocation section '.rela.static_call_sites' at offset 0x430 contains 4 entries: Offset Info Type Symbol's Value Symbol's Name + Addend 0000000000000000 0000000100000002 R_X86_64_PC32 0000000000000000 .text + 0 0000000000000004 0000000d00000002 R_X86_64_PC32 0000000000000000 __SCT__foo + 1 0000000000000008 0000000100000002 R_X86_64_PC32 0000000000000000 .text + 1d 000000000000000c 0000000d00000002 R_X86_64_PC32 0000000000000000 __SCT__foo + 1 So we have two patch sites, one in the dead code of the weak foo and one in the real foo. All is well. *HOWEVER*, when the toolchain strips unused section symbols it generates things like this (using new enough binutils): foo-weak.o: Relocation section '.rela.static_call_sites' at offset 0x2c8 contains 1 entry: Offset Info Type Symbol's Value Symbol's Name + Addend 0000000000000000 0000000200000002 R_X86_64_PC32 0000000000000000 foo + 0 0000000000000004 0000000d00000002 R_X86_64_PC32 0000000000000000 __SCT__foo + 1 foo.o: Relocation section '.rela.static_call_sites' at offset 0x310 contains 2 entries: Offset Info Type Symbol's Value Symbol's Name + Addend 0000000000000000 0000000200000002 R_X86_64_PC32 0000000000000000 foo + d 0000000000000004 0000000d00000002 R_X86_64_PC32 0000000000000000 __SCT__foo + 1 foos.o: Relocation section '.rela.static_call_sites' at offset 0x430 contains 4 entries: Offset Info Type Symbol's Value Symbol's Name + Addend 0000000000000000 0000000100000002 R_X86_64_PC32 0000000000000000 foo + 0 0000000000000004 0000000d00000002 R_X86_64_PC32 0000000000000000 __SCT__foo + 1 0000000000000008 0000000100000002 R_X86_64_PC32 0000000000000000 foo + d 000000000000000c 0000000d00000002 R_X86_64_PC32 0000000000000000 __SCT__foo + 1 And now we can see how that foos.o .static_call_sites goes side-ways, we now have _two_ patch sites in foo. One for the weak symbol at foo+0 (which is no longer a static_call site!) and one at foo+d which is in fact the right location. This seems to happen when objtool cannot find a section symbol, in which case it falls back to any other symbol to key off of, however in this case that goes terribly wrong! As such, teach objtool to create a section symbol when there isn't one. Fixes: 44f6a7c0 ("objtool: Fix seg fault with Clang non-section symbols") Signed-off-by: -
Peter Zijlstra authored
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: 627fce14 ("objtool: Add ORC unwind table generation") Signed-off-by:
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- 19 Apr, 2022 20 commits
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Josh Poimboeuf authored
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: ed53a0d9 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls") Signed-off-by:
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Josh Poimboeuf authored
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:
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Josh Poimboeuf authored
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:
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Josh Poimboeuf authored
For unwinding sanity, a function shouldn't jump to the middle of another function. Move the short string user copy code out to a separate non-function code snippet. Signed-off-by:
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Nur Hussein authored
There is only one m in becoming. Signed-off-by:
Nur Hussein <hussein@unixcat.org> Signed-off-by:
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Josh Poimboeuf authored
Fixes: 89bc853e ("objtool: Find unused ENDBR instructions") Signed-off-by:
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Josh Poimboeuf authored
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: 89bc853e ("objtool: Find unused ENDBR instructions") Signed-off-by:
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Josh Poimboeuf authored
The startup_xen() kernel entry point is referenced by the ".note.Xen" section, and is the real entry point of the VM. Control transfer is through IRET, which *could* set NEED_ENDBR, however Xen currently does no such thing. Add ANNOTATE_NOENDBR to silence future objtool warnings. Fixes: ed53a0d9 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls") Signed-off-by:
Andrew Cooper <andrew.cooper3@citrix.com> Link: https://lkml.kernel.org/r/a87bd48b06d11ec4b98122a429e71e489b4e48c3.1650300597.git.jpoimboe@redhat.com
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Josh Poimboeuf authored
The __put_user_nocheck*() inner labels are exported, so in keeping with the "allow exported functions to be indirectly called" policy, add ENDBR. Fixes: ed53a0d9 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls") Signed-off-by:
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Josh Poimboeuf authored
The retpolines are exported, so they're referenced by ksymtab sections. But they're never indirect-branched to, so add ANNOTATE_NOENDBR. Fixes: ed53a0d9 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls") Signed-off-by:
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Josh Poimboeuf authored
The static call trampoline is never indirect-branched to, but is referenced by the static call key. Add ANNOTATE_NOENDBR. Fixes: ed53a0d9 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls") Signed-off-by:
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Josh Poimboeuf authored
With IBT support in, objtool is now fully capable of following vmlinux code flow in LTO mode. Start reporting unreachable warnings for Clang LTO as well. Fixes: ed53a0d9 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls") Signed-off-by:
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Peter Zijlstra authored
Objtool can figure out that some \cfunc()s are noreturn and then complains about certain instances having unreachable tails: vmlinux.o: warning: objtool: asm_exc_xen_unknown_trap()+0x16: unreachable instruction Signed-off-by:
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Peter Zijlstra authored
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:
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Peter Zijlstra authored
SYM_CODE_START*() doesn't get auto-validated and needs an UNWIND hint to get checked, add one. vmlinux.o: warning: objtool: pvh_start_xen()+0x0: unreachable Reported-by:
Thomas Gleixner <tglx@linutronix.de> Reported-by:
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Peter Zijlstra authored
Apparently GCC can fail to inline a 'static inline' single caller function: lib/strnlen_user.o: warning: objtool: strnlen_user()+0x33: call to do_strnlen_user() with UACCESS enabled lib/strncpy_from_user.o: warning: objtool: strncpy_from_user()+0x33: call to do_strncpy_from_user() with UACCESS enabled Reported-by:
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Josh Poimboeuf authored
Create a new section for x86 unwinder maintenance. Signed-off-by:
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Dmitry Monakhov authored
A crash was observed in the ORC unwinder: BUG: stack guard page was hit at 000000000dd984a2 (stack is 00000000d1caafca..00000000613712f0) kernel stack overflow (page fault): 0000 [#1] SMP NOPTI CPU: 93 PID: 23787 Comm: context_switch1 Not tainted 5.4.145 #1 RIP: 0010:unwind_next_frame Call Trace: <NMI> perf_callchain_kernel get_perf_callchain perf_callchain perf_prepare_sample perf_event_output_forward __perf_event_overflow perf_ibs_handle_irq perf_ibs_nmi_handler nmi_handle default_do_nmi do_nmi end_repeat_nmi This was really two bugs: 1) The perf IBS code passed inconsistent regs to the unwinder. 2) The unwinder didn't handle the bad input gracefully. Fix the latter bug. The ORC unwinder needs to be immune against bad inputs. The problem is that stack_access_ok() doesn't recheck the validity of the full range of registers after switching to the next valid stack with get_stack_info(). Fix that. [ jpoimboe: rewrote commit log ] Signed-off-by:
Dmitry Monakhov <dmtrmonakhov@yandex-team.ru> Signed-off-by:
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Borislav Petkov authored
When resuming from system sleep state, restore_processor_state() restores the boot CPU MSRs. These MSRs could be emulated by microcode. If microcode is not loaded yet, writing to emulated MSRs leads to unchecked MSR access error: ... PM: Calling lapic_suspend+0x0/0x210 unchecked MSR access error: WRMSR to 0x10f (tried to write 0x0...0) at rIP: ... (native_write_msr) Call Trace: <TASK> ? restore_processor_state x86_acpi_suspend_lowlevel acpi_suspend_enter suspend_devices_and_enter pm_suspend.cold state_store kobj_attr_store sysfs_kf_write kernfs_fop_write_iter new_sync_write vfs_write ksys_write __x64_sys_write do_syscall_64 entry_SYSCALL_64_after_hwframe RIP: 0033:0x7fda13c260a7 To ensure microcode emulated MSRs are available for restoration, load the microcode on the boot CPU before restoring these MSRs. [ Pawan: write commit message and productize it. ] Fixes: e2a1256b ("x86/speculation: Restore speculation related MSRs during S3 resume") Reported-by:Kyle D. Pelton <kyle.d.pelton@intel.com> Signed-off-by:
Borislav Petkov <bp@suse.de> Signed-off-by:
Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Tested-by:
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Tony Luck authored
Intel is subdividing the mobile segment with additional models with the same codename. Using the Intel "N" and "P" suffices for these will be less confusing than trying to map to some different naming convention. Signed-off-by:
Tony Luck <tony.luck@intel.com> Signed-off-by:
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- 17 Apr, 2022 4 commits
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Linus Torvalds authored
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git://git.kernel.org/pub/scm/linux/kernel/git/xen/tipLinus Torvalds authored
Pull xen fixlet from Juergen Gross: "A single cleanup patch for the Xen balloon driver" * tag 'for-linus-5.18-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: xen/balloon: don't use PV mode extra memory for zone device allocations
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull x86 fixes from Thomas Gleixner: "Two x86 fixes related to TSX: - Use either MSR_TSX_FORCE_ABORT or MSR_IA32_TSX_CTRL to disable TSX to cover all CPUs which allow to disable it. - Disable TSX development mode at boot so that a microcode update which provides TSX development mode does not suddenly make the system vulnerable to TSX Asynchronous Abort" * tag 'x86-urgent-2022-04-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/tsx: Disable TSX development mode at boot x86/tsx: Use MSR_TSX_CTRL to clear CPUID bits -
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull timer fixes from Thomas Gleixner: "A small set of fixes for the timers core: - Fix the warning condition in __run_timers() which does not take into account that a CPU base (especially the deferrable base) never has a timer armed on it and therefore the next_expiry value can become stale. - Replace a WARN_ON() in the NOHZ code with a WARN_ON_ONCE() to prevent endless spam in dmesg. - Remove the double star from a comment which is not meant to be in kernel-doc format" * tag 'timers-urgent-2022-04-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: tick/sched: Fix non-kernel-doc comment tick/nohz: Use WARN_ON_ONCE() to prevent console saturation timers: Fix warning condition in __run_timers()
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