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* x86/bugs: Keep a per-CPU IA32_SPEC_CTRL valuePeter Zijlstra2022-07-253-6/+25
| | | | | | | | | | | | | | | | | | commit caa0ff24d5d0e02abce5e65c3d2b7f20a6617be5 upstream. Due to TIF_SSBD and TIF_SPEC_IB the actual IA32_SPEC_CTRL value can differ from x86_spec_ctrl_base. As such, keep a per-CPU value reflecting the current task's MSR content. [jpoimboe: rename] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/bugs: Enable STIBP for JMP2RETKim Phillips2022-07-252-17/+57
| | | | | | | | | | | | | | | | commit e8ec1b6e08a2102d8755ccb06fa26d540f26a2fa upstream. For untrained return thunks to be fully effective, STIBP must be enabled or SMT disabled. Co-developed-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Kim Phillips <kim.phillips@amd.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/bugs: Add AMD retbleed= boot parameterAlexandre Chartre2022-07-253-1/+125
| | | | | | | | | | | | | | | | | | | | | | | | commit 7fbf47c7ce50b38a64576b150e7011ae73d54669 upstream. Add the "retbleed=<value>" boot parameter to select a mitigation for RETBleed. Possible values are "off", "auto" and "unret" (JMP2RET mitigation). The default value is "auto". Currently, "retbleed=auto" will select the unret mitigation on AMD and Hygon and no mitigation on Intel (JMP2RET is not effective on Intel). [peterz: rebase; add hygon] [jpoimboe: cleanups] Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/bugs: Report AMD retbleed vulnerabilityAlexandre Chartre2022-07-255-0/+43
| | | | | | | | | | | | | | | | | | | | | commit 6b80b59b3555706508008f1f127b5412c89c7fd8 upstream. Report that AMD x86 CPUs are vulnerable to the RETBleed (Arbitrary Speculative Code Execution with Return Instructions) attack. [peterz: add hygon] [kim: invert parity; fam15h] Co-developed-by: Kim Phillips <kim.phillips@amd.com> Signed-off-by: Kim Phillips <kim.phillips@amd.com> Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86: Add magic AMD return-thunkPeter Zijlstra2022-07-259-8/+117
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit a149180fbcf336e97ce4eb2cdc13672727feb94d upstream. Note: needs to be in a section distinct from Retpolines such that the Retpoline RET substitution cannot possibly use immediate jumps. ORC unwinding for zen_untrain_ret() and __x86_return_thunk() is a little tricky but works due to the fact that zen_untrain_ret() doesn't have any stack ops and as such will emit a single ORC entry at the start (+0x3f). Meanwhile, unwinding an IP, including the __x86_return_thunk() one (+0x40) will search for the largest ORC entry smaller or equal to the IP, these will find the one ORC entry (+0x3f) and all works. [ Alexandre: SVM part. ] [ bp: Build fix, massages. ] Suggested-by: Andrew Cooper <Andrew.Cooper3@citrix.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> [cascardo: conflicts at arch/x86/entry/entry_64_compat.S] [cascardo: there is no ANNOTATE_NOENDBR] [cascardo: objtool commit 34c861e806478ac2ea4032721defbf1d6967df08 missing] [cascardo: conflict fixup] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> [bwh: Backported to 5.10: SEV-ES is not supported, so drop the change in arch/x86/kvm/svm/vmenter.S] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* objtool: Treat .text.__x86.* as noinstrPeter Zijlstra2022-07-251-1/+2
| | | | | | | | | | | | | | | | | commit 951ddecf435659553ed15a9214e153a3af43a9a1 upstream. Needed because zen_untrain_ret() will be called from noinstr code. Also makes sense since the thunks MUST NOT contain instrumentation nor be poked with dynamic instrumentation. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86: Use return-thunk in asm codePeter Zijlstra2022-07-253-1/+15
| | | | | | | | | | | | | | | | | | | | | | commit aa3d480315ba6c3025a60958e1981072ea37c3df upstream. Use the return thunk in asm code. If the thunk isn't needed, it will get patched into a RET instruction during boot by apply_returns(). Since alternatives can't handle relocations outside of the first instruction, putting a 'jmp __x86_return_thunk' in one is not valid, therefore carve out the memmove ERMS path into a separate label and jump to it. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> [cascardo: no RANDSTRUCT_CFLAGS] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> [bwh: Backported to 5.10: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/sev: Avoid using __x86_return_thunkKim Phillips2022-07-251-2/+6
| | | | | | | | | | | | | | | | | commit 0ee9073000e8791f8b134a8ded31bcc767f7f232 upstream. Specifically, it's because __enc_copy() encrypts the kernel after being relocated outside the kernel in sme_encrypt_execute(), and the RET macro's jmp offset isn't amended prior to execution. Signed-off-by: Kim Phillips <kim.phillips@amd.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/vsyscall_emu/64: Don't use RET in vsyscall emulationPeter Zijlstra2022-07-251-3/+6
| | | | | | | | | | | | | | commit 15583e514eb16744b80be85dea0774ece153177d upstream. This is userspace code and doesn't play by the normal kernel rules. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/kvm: Fix SETcc emulation for return thunksPeter Zijlstra2022-07-251-12/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit af2e140f34208a5dfb6b7a8ad2d56bda88f0524d upstream. Prepare the SETcc fastop stuff for when RET can be larger still. The tricky bit here is that the expressions should not only be constant C expressions, but also absolute GAS expressions. This means no ?: and 'true' is ~0. Also ensure em_setcc() has the same alignment as the actual FOP_SETCC() ops, this ensures there cannot be an alignment hole between em_setcc() and the first op. Additionally, add a .skip directive to the FOP_SETCC() macro to fill any remaining space with INT3 traps; however the primary purpose of this directive is to generate AS warnings when the remaining space goes negative. Which is a very good indication the alignment magic went side-ways. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> [cascardo: ignore ENDBR when computing SETCC_LENGTH] [cascardo: conflict fixup] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/bpf: Use alternative RET encodingPeter Zijlstra2022-07-251-2/+18
| | | | | | | | | | | | | | | commit d77cfe594ad50e0bf95d457e02ccd578791b2a15 upstream. Use the return thunk in eBPF generated code, if needed. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> [bwh: Backported to 5.10: add the necessary cnt variable to emit_return()] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/ftrace: Use alternative RET encodingPeter Zijlstra2022-07-251-2/+5
| | | | | | | | | | | | | | | | commit 1f001e9da6bbf482311e45e48f53c2bd2179e59c upstream. Use the return thunk in ftrace trampolines, if needed. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> [cascardo: still copy return from ftrace_stub] [cascardo: use memcpy(text_gen_insn) as there is no __text_gen_insn] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86,static_call: Use alternative RET encodingPeter Zijlstra2022-07-253-5/+62
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit ee88d363d15617ff50ac24fab0ffec11113b2aeb upstream. In addition to teaching static_call about the new way to spell 'RET', there is an added complication in that static_call() is allowed to rewrite text before it is known which particular spelling is required. In order to deal with this; have a static_call specific fixup in the apply_return() 'alternative' patching routine that will rewrite the static_call trampoline to match the definite sequence. This in turn creates the problem of uniquely identifying static call trampolines. Currently trampolines are 8 bytes, the first 5 being the jmp.d32/ret sequence and the final 3 a byte sequence that spells out 'SCT'. This sequence is used in __static_call_validate() to ensure it is patching a trampoline and not a random other jmp.d32. That is, false-positives shouldn't be plenty, but aren't a big concern. OTOH the new __static_call_fixup() must not have false-positives, and 'SCT' decodes to the somewhat weird but semi plausible sequence: push %rbx rex.XB push %r12 Additionally, there are SLS concerns with immediate jumps. Combined it seems like a good moment to change the signature to a single 3 byte trap instruction that is unique to this usage and will not ever get generated by accident. As such, change the signature to: '0x0f, 0xb9, 0xcc', which decodes to: ud1 %esp, %ecx Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> [cascardo: skip validation as introduced by 2105a92748e8 ("static_call,x86: Robustify trampoline patching")] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> [bwh: Backported to 5.10: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* objtool: skip non-text sections when adding return-thunk sitesThadeu Lima de Souza Cascardo2022-07-251-1/+3
| | | | | | | | | | | | | | | | The .discard.text section is added in order to reserve BRK, with a temporary function just so it can give it a size. This adds a relocation to the return thunk, which objtool will add to the .return_sites section. Linking will then fail as there are references to the .discard.text section. Do not add instructions from non-text sections to the list of return thunk calls, avoiding the reference to .discard.text. Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86,objtool: Create .return_sitesPeter Zijlstra2022-07-256-0/+84
| | | | | | | | | | | | | | | | | commit d9e9d2300681d68a775c28de6aa6e5290ae17796 upstream. Find all the return-thunk sites and record them in a .return_sites section such that the kernel can undo this. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> [cascardo: conflict fixup because of functions added to support IBT] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> [bwh: Backported to 5.10: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86: Undo return-thunk damagePeter Zijlstra2022-07-256-2/+78
| | | | | | | | | | | | | | | | | | commit 15e67227c49a57837108acfe1c80570e1bd9f962 upstream. Introduce X86_FEATURE_RETHUNK for those afflicted with needing this. [ bp: Do only INT3 padding - simpler. ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> [cascardo: CONFIG_STACK_VALIDATION vs CONFIG_OBJTOOL] [cascardo: no IBT support] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/retpoline: Use -mfunction-returnPeter Zijlstra2022-07-253-0/+16
| | | | | | | | | | | | | | | | | | | | | | | | commit 0b53c374b9eff2255a386f1f1cfb9a928e52a5ae upstream. Utilize -mfunction-return=thunk-extern when available to have the compiler replace RET instructions with direct JMPs to the symbol __x86_return_thunk. This does not affect assembler (.S) sources, only C sources. -mfunction-return=thunk-extern has been available since gcc 7.3 and clang 15. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Borislav Petkov <bp@suse.de> [cascardo: RETPOLINE_CFLAGS is at Makefile] [cascardo: remove ANNOTATE_NOENDBR from __x86_return_thunk] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Makefile: Set retpoline cflags based on CONFIG_CC_IS_{CLANG,GCC}Ben Hutchings2022-07-251-6/+8
| | | | | | | | | This was done as part of commit 7d73c3e9c51400d3e0e755488050804e4d44737a "Makefile: remove stale cc-option checks" upstream, and is needed to support backporting further retpoline changes. Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/retpoline: Swizzle retpoline thunkPeter Zijlstra2022-07-251-3/+3
| | | | | | | | | | | | | | | | | | commit 00e1533325fd1fb5459229fe37f235462649f668 upstream. Put the actual retpoline thunk as the original code so that it can become more complicated. Specifically, it allows RET to be a JMP, which can't be .altinstr_replacement since that doesn't do relocations (except for the very first instruction). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/retpoline: Cleanup some #ifdeferyPeter Zijlstra2022-07-251-1/+8
| | | | | | | | | | | | | | | | | | commit 369ae6ffc41a3c1137cab697635a84d0cc7cdcea upstream. On it's own not much of a cleanup but it prepares for more/similar code. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> [cascardo: conflict fixup because of DISABLE_ENQCMD] [cascardo: no changes at nospec-branch.h and bpf_jit_comp.c] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/cpufeatures: Move RETPOLINE flags to word 11Peter Zijlstra2022-07-251-2/+8
| | | | | | | | | | | | | | | | | | commit a883d624aed463c84c22596006e5a96f5b44db31 upstream. In order to extend the RETPOLINE features to 4, move them to word 11 where there is still room. This mostly keeps DISABLE_RETPOLINE simple. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> [bwh: Backported to 5.10: bits 8 and 9 of word 11 are also free here, so comment them accordingly] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/kvm/vmx: Make noinstr cleanPeter Zijlstra2022-07-253-6/+6
| | | | | | | | | | | | | | | | | commit 742ab6df974ae8384a2dd213db1a3a06cf6d8936 upstream. The recent mmio_stale_data fixes broke the noinstr constraints: vmlinux.o: warning: objtool: vmx_vcpu_enter_exit+0x15b: call to wrmsrl.constprop.0() leaves .noinstr.text section vmlinux.o: warning: objtool: vmx_vcpu_enter_exit+0x1bf: call to kvm_arch_has_assigned_device() leaves .noinstr.text section make it all happy again. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/realmode: build with -D__DISABLE_EXPORTSThadeu Lima de Souza Cascardo2022-07-251-1/+1
| | | | | | | | | | Commit 156ff4a544ae ("x86/ibt: Base IBT bits") added this option when building realmode in order to disable IBT there. This is also needed in order to disable return thunks. Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* objtool: Fix objtool regression on x32 systemsMikulas Patocka2022-07-253-7/+8
| | | | | | | | | | | | | | | | | | | | | | commit 22682a07acc308ef78681572e19502ce8893c4d4 upstream. Commit c087c6e7b551 ("objtool: Fix type of reloc::addend") failed to appreciate cross building from ILP32 hosts, where 'int' == 'long' and the issue persists. As such, use s64/int64_t/Elf64_Sxword for this field and suffer the pain that is ISO C99 printf formats for it. Fixes: c087c6e7b551 ("objtool: Fix type of reloc::addend") Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> [peterz: reword changelog, s/long long/s64/] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/alpine.LRH.2.02.2205161041260.11556@file01.intranet.prod.int.rdu2.redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/entry: Remove skip_r11rcxPeter Zijlstra2022-07-252-11/+2
| | | | | | | | | | | | | | | | | commit 1b331eeea7b8676fc5dbdf80d0a07e41be226177 upstream. Yes, r11 and rcx have been restored previously, but since they're being popped anyway (into rsi) might as well pop them into their own regs -- setting them to the value they already are. Less magical code. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20220506121631.365070674@infradead.org [bwh: Backported to 5.10: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* objtool: Fix symbol creationPeter Zijlstra2022-07-251-68/+128
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit ead165fa1042247b033afad7be4be9b815d04ade upstream. Nathan reported objtool failing with the following messages: warning: objtool: no non-local symbols !? warning: objtool: gelf_update_symshndx: invalid section index The problem is due to commit 4abff6d48dbc ("objtool: Fix code relocs vs weak symbols") failing to consider the case where an object would have no non-local symbols. The problem that commit tries to address is adding a STB_LOCAL symbol to the symbol table in light of the ELF spec's requirement that: In each symbol table, all symbols with STB_LOCAL binding preced the weak and global symbols. As ``Sections'' above describes, a symbol table section's sh_info section header member holds the symbol table index for the first non-local symbol. The approach taken is to find this first non-local symbol, move that to the end and then re-use the freed spot to insert a new local symbol and increment sh_info. Except it never considered the case of object files without global symbols and got a whole bunch of details wrong -- so many in fact that it is a wonder it ever worked :/ Specifically: - It failed to re-hash the symbol on the new index, so a subsequent find_symbol_by_index() would not find it at the new location and a query for the old location would now return a non-deterministic choice between the old and new symbol. - It failed to appreciate that the GElf wrappers are not a valid disk format (it works because GElf is basically Elf64 and we only support x86_64 atm.) - It failed to fully appreciate how horrible the libelf API really is and got the gelf_update_symshndx() call pretty much completely wrong; with the direct consequence that if inserting a second STB_LOCAL symbol would require moving the same STB_GLOBAL symbol again it would completely come unstuck. Write a new elf_update_symbol() function that wraps all the magic required to update or create a new symbol at a given index. Specifically, gelf_update_sym*() require an @ndx argument that is relative to the @data argument; this means you have to manually iterate the section data descriptor list and update @ndx. Fixes: 4abff6d48dbc ("objtool: Fix code relocs vs weak symbols") Reported-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/YoPCTEYjoPqE4ZxB@hirez.programming.kicks-ass.net Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [bwh: Backported to 5.10: elf_hash_add() takes a hash table pointer, not just a name] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* objtool: Fix type of reloc::addendPeter Zijlstra2022-07-253-7/+7
| | | | | | | | | | | | | | | | | | | commit c087c6e7b551b7f208c0b852304f044954cf2bb3 upstream. 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 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* objtool: Fix code relocs vs weak symbolsPeter Zijlstra2022-07-251-22/+165
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 4abff6d48dbcea8200c7ea35ba70c242d128ebf3 upstream. 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: 44f6a7c0755d ("objtool: Fix seg fault with Clang non-section symbols") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20220419203807.655552918@infradead.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* objtool: Fix SLS validation for kcov tail-call replacementPeter Zijlstra2022-07-251-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 7a53f408902d913cd541b4f8ad7dbcd4961f5b82 upstream. 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 Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* crypto: x86/poly1305 - Fixup SLSPeter Zijlstra2022-07-251-19/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 7ed7aa4de9421229be6d331ed52d5cd09c99f409 upstream. Due to being a perl generated asm file, it got missed by the mass convertion script. arch/x86/crypto/poly1305-x86_64-cryptogams.o: warning: objtool: poly1305_init_x86_64()+0x3a: missing int3 after ret arch/x86/crypto/poly1305-x86_64-cryptogams.o: warning: objtool: poly1305_blocks_x86_64()+0xf2: missing int3 after ret arch/x86/crypto/poly1305-x86_64-cryptogams.o: warning: objtool: poly1305_emit_x86_64()+0x37: missing int3 after ret arch/x86/crypto/poly1305-x86_64-cryptogams.o: warning: objtool: __poly1305_block()+0x6d: missing int3 after ret arch/x86/crypto/poly1305-x86_64-cryptogams.o: warning: objtool: __poly1305_init_avx()+0x1e8: missing int3 after ret arch/x86/crypto/poly1305-x86_64-cryptogams.o: warning: objtool: poly1305_blocks_avx()+0x18a: missing int3 after ret arch/x86/crypto/poly1305-x86_64-cryptogams.o: warning: objtool: poly1305_blocks_avx()+0xaf8: missing int3 after ret arch/x86/crypto/poly1305-x86_64-cryptogams.o: warning: objtool: poly1305_emit_avx()+0x99: missing int3 after ret arch/x86/crypto/poly1305-x86_64-cryptogams.o: warning: objtool: poly1305_blocks_avx2()+0x18a: missing int3 after ret arch/x86/crypto/poly1305-x86_64-cryptogams.o: warning: objtool: poly1305_blocks_avx2()+0x776: missing int3 after ret arch/x86/crypto/poly1305-x86_64-cryptogams.o: warning: objtool: poly1305_blocks_avx512()+0x18a: missing int3 after ret arch/x86/crypto/poly1305-x86_64-cryptogams.o: warning: objtool: poly1305_blocks_avx512()+0x796: missing int3 after ret arch/x86/crypto/poly1305-x86_64-cryptogams.o: warning: objtool: poly1305_blocks_avx512()+0x10bd: missing int3 after ret Fixes: f94909ceb1ed ("x86: Prepare asm files for straight-line-speculation") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* objtool: Default ignore INT3 for unreachablePeter Zijlstra2022-07-251-7/+5
| | | | | | | | | | | | | | commit 1ffbe4e935f9b7308615c75be990aec07464d1e7 upstream. 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 Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kvm/emulate: Fix SETcc emulation function offsets with SLSBorislav Petkov2022-07-251-2/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit fe83f5eae432ccc8e90082d6ed506d5233547473 upstream. The commit in Fixes started adding INT3 after RETs as a mitigation against straight-line speculation. The fastop SETcc implementation in kvm's insn emulator uses macro magic to generate all possible SETcc functions and to jump to them when emulating the respective instruction. However, it hardcodes the size and alignment of those functions to 4: a three-byte SETcc insn and a single-byte RET. BUT, with SLS, there's an INT3 that gets slapped after the RET, which brings the whole scheme out of alignment: 15: 0f 90 c0 seto %al 18: c3 ret 19: cc int3 1a: 0f 1f 00 nopl (%rax) 1d: 0f 91 c0 setno %al 20: c3 ret 21: cc int3 22: 0f 1f 00 nopl (%rax) 25: 0f 92 c0 setb %al 28: c3 ret 29: cc int3 and this explodes like this: int3: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 2435 Comm: qemu-system-x86 Not tainted 5.17.0-rc8-sls #1 Hardware name: Dell Inc. Precision WorkStation T3400 /0TP412, BIOS A14 04/30/2012 RIP: 0010:setc+0x5/0x8 [kvm] Code: 00 00 0f 1f 00 0f b6 05 43 24 06 00 c3 cc 0f 1f 80 00 00 00 00 0f 90 c0 c3 cc 0f \ 1f 00 0f 91 c0 c3 cc 0f 1f 00 0f 92 c0 c3 cc <0f> 1f 00 0f 93 c0 c3 cc 0f 1f 00 \ 0f 94 c0 c3 cc 0f 1f 00 0f 95 c0 Call Trace: <TASK> ? x86_emulate_insn [kvm] ? x86_emulate_instruction [kvm] ? vmx_handle_exit [kvm_intel] ? kvm_arch_vcpu_ioctl_run [kvm] ? kvm_vcpu_ioctl [kvm] ? __x64_sys_ioctl ? do_syscall_64 ? entry_SYSCALL_64_after_hwframe </TASK> Raise the alignment value when SLS is enabled and use a macro for that instead of hard-coding naked numbers. Fixes: e463a09af2f0 ("x86: Add straight-line-speculation mitigation") Reported-by: Jamie Heilman <jamie@audible.transient.net> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Jamie Heilman <jamie@audible.transient.net> Link: https://lore.kernel.org/r/YjGzJwjrvxg5YZ0Z@audible.transient.net [Add a comment and a bit of safety checking, since this is going to be changed again for IBT support. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tools arch: Update arch/x86/lib/mem{cpy,set}_64.S copies used in 'perf bench ↵Arnaldo Carvalho de Melo2022-07-252-9/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | mem memcpy' commit 35cb8c713a496e8c114eed5e2a5a30b359876df2 upstream. To bring in the change made in this cset: f94909ceb1ed4bfd ("x86: Prepare asm files for straight-line-speculation") It silences these perf tools build warnings, no change in the tools: Warning: Kernel ABI header at 'tools/arch/x86/lib/memcpy_64.S' differs from latest version at 'arch/x86/lib/memcpy_64.S' diff -u tools/arch/x86/lib/memcpy_64.S arch/x86/lib/memcpy_64.S Warning: Kernel ABI header at 'tools/arch/x86/lib/memset_64.S' differs from latest version at 'arch/x86/lib/memset_64.S' diff -u tools/arch/x86/lib/memset_64.S arch/x86/lib/memset_64.S The code generated was checked before and after using 'objdump -d /tmp/build/perf/bench/mem-memcpy-x86-64-asm.o', no changes. Cc: Borislav Petkov <bp@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86: Add straight-line-speculation mitigationPeter Zijlstra2022-07-2510-7/+40
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit e463a09af2f0677b9485a7e8e4e70b396b2ffb6f upstream. Make use of an upcoming GCC feature to mitigate straight-line-speculation for x86: https://gcc.gnu.org/g:53a643f8568067d7700a9f2facc8ba39974973d3 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102952 https://bugs.llvm.org/show_bug.cgi?id=52323 It's built tested on x86_64-allyesconfig using GCC-12 and GCC-11. Maintenance overhead of this should be fairly low due to objtool validation. Size overhead of all these additional int3 instructions comes to: text data bss dec hex filename 22267751 6933356 2011368 31212475 1dc43bb defconfig-build/vmlinux 22804126 6933356 1470696 31208178 1dc32f2 defconfig-build/vmlinux.sls Or roughly 2.4% additional text. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20211204134908.140103474@infradead.org Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [bwh: Backported to 5.10: - In scripts/Makefile.build, add the objtool option with an ifdef block, same as for other options - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* objtool: Add straight-line-speculation validationPeter Zijlstra2022-07-255-6/+29
| | | | | | | | | | | | | | | | | | | | | | commit 1cc1e4c8aab4213bd4e6353dec2620476a233d6d upstream. 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 Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [bwh: Backported to 5.10: adjust filenames, context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/alternative: Relax text_poke_bp() constraintPeter Zijlstra2022-07-251-15/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | commit 26c44b776dba4ac692a0bf5a3836feb8a63fea6b upstream. Currently, text_poke_bp() is very strict to only allow patching a single instruction; however with straight-line-speculation it will be required to patch: ret; int3, which is two instructions. As such, relax the constraints a little to allow int3 padding for all instructions that do not imply the execution of the next instruction, ie: RET, JMP.d8 and JMP.d32. While there, rename the text_poke_loc::rel32 field to ::disp. Note: this fills up the text_poke_loc structure which is now a round 16 bytes big. [ bp: Put comments ontop instead of on the side. ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20211204134908.082342723@infradead.org Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86: Prepare inline-asm for straight-line-speculationPeter Zijlstra2022-07-2511-13/+18
| | | | | | | | | | | | | | | | commit b17c2baa305cccbd16bafa289fd743cc2db77966 upstream. Replace all ret/retq instructions with ASM_RET in preparation of making it more than a single instruction. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20211204134907.964635458@infradead.org Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [bwh: Backported to 5.10: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86: Prepare asm files for straight-line-speculationPeter Zijlstra2022-07-25103-353/+353
| | | | | | | | | | | | | | | | | | | | commit f94909ceb1ed4bfdb2ada72f93236305e6d6951f upstream. Replace all ret/retq instructions with RET in preparation of making RET a macro. Since AS is case insensitive it's a big no-op without RET defined. find arch/x86/ -name \*.S | while read file do sed -i 's/\<ret[q]*\>/RET/' $file done Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20211204134907.905503893@infradead.org [bwh: Backported to 5.10: ran the above command] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/lib/atomic64_386_32: Rename thingsPeter Zijlstra2022-07-251-38/+46
| | | | | | | | | | | | | | | | | | | | | | | | commit 22da5a07c75e1104caf6a42f189c97b83d070073 upstream. Principally, in order to get rid of #define RET in this code to make place for a new RET, but also to clarify the code, rename a bunch of things: s/UNLOCK/IRQ_RESTORE/ s/LOCK/IRQ_SAVE/ s/BEGIN/BEGIN_IRQ_SAVE/ s/\<RET\>/RET_IRQ_RESTORE/ s/RET_ENDP/\tRET_IRQ_RESTORE\rENDP/ which then leaves RET unused so it can be removed. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20211204134907.841623970@infradead.org Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* bpf,x86: Respect X86_FEATURE_RETPOLINE*Peter Zijlstra2022-07-253-88/+42
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 87c87ecd00c54ecd677798cb49ef27329e0fab41 upstream. Current BPF codegen doesn't respect X86_FEATURE_RETPOLINE* flags and unconditionally emits a thunk call, this is sub-optimal and doesn't match the regular, compiler generated, code. Update the i386 JIT to emit code equal to what the compiler emits for the regular kernel text (IOW. a plain THUNK call). Update the x86_64 JIT to emit code similar to the result of compiler and kernel rewrites as according to X86_FEATURE_RETPOLINE* flags. Inlining RETPOLINE_AMD (lfence; jmp *%reg) and !RETPOLINE (jmp *%reg), while doing a THUNK call for RETPOLINE. This removes the hard-coded retpoline thunks and shrinks the generated code. Leaving a single retpoline thunk definition in the kernel. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Borislav Petkov <bp@suse.de> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Tested-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/r/20211026120310.614772675@infradead.org [cascardo: RETPOLINE_AMD was renamed to RETPOLINE_LFENCE] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> [bwh: Backported to 5.10: add the necessary cnt variable to emit_indirect_jump()] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* bpf,x86: Simplify computing label offsetsPeter Zijlstra2022-07-251-83/+42
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit dceba0817ca329868a15e2e1dd46eb6340b69206 upstream. Take an idea from the 32bit JIT, which uses the multi-pass nature of the JIT to compute the instruction offsets on a prior pass in order to compute the relative jump offsets on a later pass. Application to the x86_64 JIT is slightly more involved because the offsets depend on program variables (such as callee_regs_used and stack_depth) and hence the computed offsets need to be kept in the context of the JIT. This removes, IMO quite fragile, code that hard-codes the offsets and tries to compute the length of variable parts of it. Convert both emit_bpf_tail_call_*() functions which have an out: label at the end. Additionally emit_bpt_tail_call_direct() also has a poke table entry, for which it computes the offset from the end (and thus already relies on the previous pass to have computed addrs[i]), also convert this to be a forward based offset. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Borislav Petkov <bp@suse.de> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Tested-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/r/20211026120310.552304864@infradead.org Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> [bwh: Backported to 5.10: keep the cnt variable in emit_bpf_tail_call_{,in}direct()] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/alternative: Add debug prints to apply_retpolines()Peter Zijlstra2022-07-251-0/+6
| | | | | | | | | | | | | | | | | | | | | | | commit d4b5a5c993009ffeb5febe3b701da3faab6adb96 upstream. Make sure we can see the text changes when booting with 'debug-alternative'. Example output: [ ] SMP alternatives: retpoline at: __traceiter_initcall_level+0x1f/0x30 (ffffffff8100066f) len: 5 to: __x86_indirect_thunk_rax+0x0/0x20 [ ] SMP alternatives: ffffffff82603e58: [2:5) optimized NOPs: ff d0 0f 1f 00 [ ] SMP alternatives: ffffffff8100066f: orig: e8 cc 30 00 01 [ ] SMP alternatives: ffffffff8100066f: repl: ff d0 0f 1f 00 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/20211026120310.422273830@infradead.org Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/alternative: Try inline spectre_v2=retpoline,amdPeter Zijlstra2022-07-251-2/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit bbe2df3f6b6da7848398d55b1311d58a16ec21e4 upstream. Try and replace retpoline thunk calls with: LFENCE CALL *%\reg for spectre_v2=retpoline,amd. Specifically, the sequence above is 5 bytes for the low 8 registers, but 6 bytes for the high 8 registers. This means that unless the compilers prefix stuff the call with higher registers this replacement will fail. Luckily GCC strongly favours RAX for the indirect calls and most (95%+ for defconfig-x86_64) will be converted. OTOH clang strongly favours R11 and almost nothing gets converted. Note: it will also generate a correct replacement for the Jcc.d32 case, except unless the compilers start to prefix stuff that, it'll never fit. Specifically: Jncc.d8 1f LFENCE JMP *%\reg 1: is 7-8 bytes long, where the original instruction in unpadded form is only 6 bytes. 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/20211026120310.359986601@infradead.org [cascardo: RETPOLINE_AMD was renamed to RETPOLINE_LFENCE] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/alternative: Handle Jcc __x86_indirect_thunk_\regPeter Zijlstra2022-07-251-4/+36
| | | | | | | | | | | | | | | | | | | | | | | | | | commit 2f0cbb2a8e5bbf101e9de118fc0eb168111a5e1e upstream. Handle the rare cases where the compiler (clang) does an indirect conditional tail-call using: Jcc __x86_indirect_thunk_\reg For the !RETPOLINE case this can be rewritten to fit the original (6 byte) instruction like: Jncc.d8 1f JMP *%\reg NOP 1: 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/20211026120310.296470217@infradead.org Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/alternative: Implement .retpoline_sites supportPeter Zijlstra2022-07-254-5/+150
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 7508500900814d14e2e085cdc4e28142721abbdf upstream. Rewrite retpoline thunk call sites to be indirect calls for spectre_v2=off. This ensures spectre_v2=off is as near to a RETPOLINE=n build as possible. This is the replacement for objtool writing alternative entries to ensure the same and achieves feature-parity with the previous approach. One noteworthy feature is that it relies on the thunks to be in machine order to compute the register index. Specifically, this does not yet address the Jcc __x86_indirect_thunk_* calls generated by clang, a future patch will add this. 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/20211026120310.232495794@infradead.org [cascardo: small conflict fixup at arch/x86/kernel/module.c] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> [bwh: Backported to 5.10: - Use hex literal instead of BYTES_NOP1 - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/retpoline: Create a retpoline thunk arrayPeter Zijlstra2022-07-252-6/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 1a6f74429c42a3854980359a758e222005712aee upstream. Stick all the retpolines in a single symbol and have the individual thunks as inner labels, this should guarantee thunk order and layout. Previously there were 16 (or rather 15 without rsp) separate symbols and a toolchain might reasonably expect it could displace them however it liked, with disregard for their relative position. However, now they're part of a larger symbol. Any change to their relative position would disrupt this larger _array symbol and thus not be sound. This is the same reasoning used for data symbols. On their own there is no guarantee about their relative position wrt to one aonther, but we're still able to do arrays because an array as a whole is a single larger symbol. 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/20211026120310.169659320@infradead.org Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/retpoline: Move the retpoline thunk declarations to nospec-branch.hPeter Zijlstra2022-07-253-9/+7
| | | | | | | | | | | | | | | | commit 6fda8a38865607db739be3e567a2387376222dbd upstream. Because it makes no sense to split the retpoline gunk over multiple headers. 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/20211026120310.106290934@infradead.org Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/asm: Fixup odd GEN-for-each-reg.h usagePeter Zijlstra2022-07-252-3/+3
| | | | | | | | | | | | | | | | commit b6d3d9944bd7c9e8c06994ead3c9952f673f2a66 upstream. Currently GEN-for-each-reg.h usage leaves GEN defined, relying on any subsequent usage to start with #undef, which is rude. 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/20211026120310.041792350@infradead.org Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/asm: Fix register orderPeter Zijlstra2022-07-251-4/+10
| | | | | | | | | | | | | | | | commit a92ede2d584a2e070def59c7e47e6b6f6341c55c upstream. Ensure the register order is correct; this allows for easy translation between register number and trampoline and vice-versa. 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/20211026120309.978573921@infradead.org Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* x86/retpoline: Remove unused replacement symbolsPeter Zijlstra2022-07-252-52/+0
| | | | | | | | | | | | | | | | commit 4fe79e710d9574a14993f8b4e16b7252da72d5e8 upstream. Now that objtool no longer creates alternatives, these replacement symbols are no longer needed, remove them. 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/20211026120309.915051744@infradead.org Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-12 14:17:03 +0000