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2022-10-26objtool: Preserve special st_shndx indexes in elf_update_symbolSami Tolvanen1-1/+6
[ Upstream commit 5141d3a06b2da1731ac82091298b766a1f95d3d8 ] elf_update_symbol fails to preserve the special st_shndx values between [SHN_LORESERVE, SHN_HIRESERVE], which results in it converting SHN_ABS entries into SHN_UNDEF, for example. Explicitly check for the special indexes and ensure these symbols are not marked undefined. Fixes: ead165fa1042 ("objtool: Fix symbol creation") Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20220908215504.3686827-17-samitolvanen@google.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-07-23x86/retbleed: Add fine grained Kconfig knobsPeter Zijlstra3-4/+10
commit f43b9876e857c739d407bc56df288b0ebe1a9164 upstream. Do fine-grained Kconfig for all the various retbleed parts. NOTE: if your compiler doesn't support return thunks this will silently 'upgrade' your mitigation to IBPB, you might not like this. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> [cascardo: there is no CONFIG_OBJTOOL] [cascardo: objtool calling and option parsing has changed] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-23objtool: Re-add UNWIND_HINT_{SAVE_RESTORE}Josh Poimboeuf2-0/+41
commit 8faea26e611189e933ea2281975ff4dc7c1106b6 upstream. Commit c536ed2fffd5 ("objtool: Remove SAVE/RESTORE hints") removed the save/restore unwind hints because they were no longer needed. Now they're going to be needed again so re-add them. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-23objtool: Add entry UNRET validationPeter Zijlstra4-6/+177
commit a09a6e2399ba0595c3042b3164f3ca68a3cff33e upstream. Since entry asm is tricky, add a validation pass that ensures the retbleed mitigation has been done before the first actual RET instruction. Entry points are those that either have UNWIND_HINT_ENTRY, which acts as UNWIND_HINT_EMPTY but marks the instruction as an entry point, or those that have UWIND_HINT_IRET_REGS at +0. This is basically a variant of validate_branch() that is intra-function and it will simply follow all branches from marked entry points and ensures that all paths lead to ANNOTATE_UNRET_END. If a path hits RET or an indirection the path is a fail and will be reported. There are 3 ANNOTATE_UNRET_END instances: - UNTRAIN_RET itself - exception from-kernel; this path doesn't need UNTRAIN_RET - all early exceptions; these also don't need UNTRAIN_RET 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: tools/objtool/builtin-check.c no link option validation] [cascardo: tools/objtool/check.c opts.ibt is ibt] [cascardo: tools/objtool/include/objtool/builtin.h leave unret option as bool, no struct opts] [cascardo: objtool is still called from scripts/link-vmlinux.sh] [cascardo: no IBT support] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-23objtool: Update Retpoline validationPeter Zijlstra1-6/+13
commit 9bb2ec608a209018080ca262f771e6a9ff203b6f upstream. Update retpoline validation with the new CONFIG_RETPOLINE requirement of not having bare naked RET instructions. 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 at arch/x86/xen/xen-head.S] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-23x86: Add magic AMD return-thunkPeter Zijlstra1-3/+17
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-23objtool: Treat .text.__x86.* as noinstrPeter Zijlstra1-1/+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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-23objtool: skip non-text sections when adding return-thunk sitesThadeu Lima de Souza Cascardo1-1/+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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-23x86,objtool: Create .return_sitesPeter Zijlstra6-0/+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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-23objtool: Default ignore INT3 for unreachablePeter Zijlstra1-7/+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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-23objtool: Introduce CFI hashPeter Zijlstra6-35/+160
commit 8b946cc38e063f0f7bb67789478c38f6d7d457c9 upstream. 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 Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-23objtool,x86: Replace alternatives with .retpoline_sitesPeter Zijlstra5-252/+93
commit 134ab5bd1883312d7a4b3033b05c6b5a1bb8889b upstream. 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 [cascardo: fixed conflict because of missing 8b946cc38e063f0f7bb67789478c38f6d7d457c9] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-23objtool: Shrink struct instructionPeter Zijlstra2-4/+3
commit c509331b41b7365e17396c246e8c5797bccc8074 upstream. 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 Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-23objtool: Explicitly avoid self modifying code in .altinstr_replacementPeter Zijlstra1-11/+32
commit dd003edeffa3cb87bc9862582004f405d77d7670 upstream. 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 [cascardo: context adjustment] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-23objtool: Classify symbolsPeter Zijlstra2-14/+27
commit 1739c66eb7bd5f27f1b69a5a26e10e8327d1e136 upstream. 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 [cascardo: no pv_target on struct symbol, because of missing db2b0c5d7b6f19b3c2cab08c531b65342eb5252b] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-06-09objtool: Fix symbol creationPeter Zijlstra1-68/+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>
2022-06-09objtool: Fix objtool regression on x32 systemsMikulas Patocka3-7/+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>
2022-05-15objtool: Fix SLS validation for kcov tail-call replacementPeter Zijlstra1-0/+10
[ Upstream commit 7a53f408902d913cd541b4f8ad7dbcd4961f5b82 ] 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>
2022-05-15objtool: Add straight-line-speculation validationPeter Zijlstra5-6/+27
[ Upstream commit 1cc1e4c8aab4213bd4e6353dec2620476a233d6d ] 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>
2022-05-09objtool: Fix type of reloc::addendPeter Zijlstra3-7/+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>
2022-05-09objtool: Fix code relocs vs weak symbolsPeter Zijlstra1-22/+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>
2021-11-18objtool: Handle __sanitize_cov*() tail callsPeter Zijlstra3-74/+105
[ Upstream commit f56dae88a81fded66adf2bea9922d1d98d1da14f ] 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 Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-11-18x86/xen: Mark cpu_bringup_and_idle() as dead_end_functionPeter Zijlstra1-0/+1
[ Upstream commit 9af9dcf11bda3e2c0e24c1acaacb8685ad974e93 ] 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 Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-10-07objtool: Update section header before relocationsMichael Forney1-29/+17
The libelf implementation from elftoolchain has a safety check in gelf_update_rel[a] to check that the data corresponds to a section that has type SHT_REL[A] [0]. If the relocation is updated before the section header is updated with the proper type, this check fails. To fix this, update the section header first, before the relocations. Previously, the section size was calculated in elf_rebuild_reloc_section by counting the number of entries in the reloc_list. However, we now need the size during elf_write so instead keep a running total and add to it for every new relocation. [0] https://sourceforge.net/p/elftoolchain/mailman/elftoolchain-developers/thread/CAGw6cBtkZro-8wZMD2ULkwJ39J+tHtTtAWXufMjnd3cQ7XG54g@mail.gmail.com/ Signed-off-by: Michael Forney <mforney@mforney.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20210509000103.11008-2-mforney@mforney.org
2021-10-07objtool: Check for gelf_update_rel[a] failuresMichael Forney1-2/+8
Otherwise, if these fail we end up with garbage data in the .rela.orc_unwind_ip section, leading to errors like ld: fs/squashfs/namei.o: bad reloc symbol index (0x7f16 >= 0x12) for offset 0x7f16d5c82cc8 in section `.orc_unwind_ip' Signed-off-by: Michael Forney <mforney@mforney.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20210509000103.11008-1-mforney@mforney.org
2021-10-05objtool: Remove redundant 'len' field from struct sectionJoe Lawrence5-20/+17
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
2021-10-05objtool: Make .altinstructions section entry size consistentJoe Lawrence1-1/+1
Commit e31694e0a7a7 ("objtool: Don't make .altinstructions writable") aligned objtool-created and kernel-created .altinstructions section flags, but there remains a minor discrepency in their use of a section entry size: objtool sets one while the kernel build does not. While sh_entsize of sizeof(struct alt_instr) seems intuitive, this small deviation can cause failures with external tooling (kpatch-build). Fix this by creating new .altinstructions sections with sh_entsize of 0 and then later updating sec->sh_size as alternatives are added to the section. An added benefit is avoiding the data descriptor and buffer created by elf_create_section(), but previously unused by elf_add_alternative(). Fixes: 9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls") 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/20210822225037.54620-2-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
2021-10-05objtool: Remove reloc symbol type checks in get_alt_entry()Josh Poimboeuf1-29/+7
Converting a special section's relocation reference to a symbol is straightforward. No need for objtool to complain that it doesn't know how to handle it. Just handle it. This fixes the following warning: arch/x86/kvm/emulate.o: warning: objtool: __ex_table+0x4: don't know how to handle reloc symbol type: kvm_fastop_exception Fixes: 24ff65257375 ("objtool: Teach get_alt_entry() about more relocation types") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/feadbc3dfb3440d973580fad8d3db873cbfe1694.1633367242.git.jpoimboe@redhat.com Cc: Peter Zijlstra <peterz@infradead.org> Cc: x86@kernel.org Cc: Miroslav Benes <mbenes@suse.cz> Cc: linux-kernel@vger.kernel.org
2021-10-03objtool: print out the symbol type when complaining about itLinus Torvalds1-4/+8
The objtool warning that the kvm instruction emulation code triggered wasn't very useful: arch/x86/kvm/emulate.o: warning: objtool: __ex_table+0x4: don't know how to handle reloc symbol type: kvm_fastop_exception in that it helpfully tells you which symbol name it had trouble figuring out the relocation for, but it doesn't actually say what the unknown symbol type was that triggered it all. In this case it was because of missing type information (type 0, aka STT_NOTYPE), but on the whole it really should just have printed that out as part of the message. Because if this warning triggers, that's very much the first thing you want to know - why did reloc2sec_off() return failure for that symbol? So rather than just saying you can't handle some type of symbol without saying what the type _was_, just print out the type number too. Fixes: 24ff65257375 ("objtool: Teach get_alt_entry() about more relocation types") Link: https://lore.kernel.org/lkml/CAHk-=wiZwq-0LknKhXN4M+T8jbxn_2i9mcKpO+OaBSSq_Eh7tg@mail.gmail.com/ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-10-01objtool: Teach get_alt_entry() about more relocation typesPeter Zijlstra1-7/+25
Occasionally objtool encounters symbol (as opposed to section) relocations in .altinstructions. Typically they are the alternatives written by elf_add_alternative() as encountered on a noinstr validation run on vmlinux after having already ran objtool on the individual .o files. Basically this is the counterpart of commit 44f6a7c0755d ("objtool: Fix seg fault with Clang non-section symbols"), because when these new assemblers (binutils now also does this) strip the section symbols, elf_add_reloc_to_insn() is forced to emit symbol based relocations. As such, teach get_alt_entry() about different relocation types. Fixes: 9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls") Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/r/YVWUvknIEVNkPvnP@hirez.programming.kicks-ass.net
2021-06-28Merge tags 'objtool-urgent-2021-06-28' and 'objtool-core-2021-06-28' of ↵Linus Torvalds8-51/+136
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull objtool fix and updates from Ingo Molnar: "An ELF format fix for a section flags mismatch bug that breaks kernel tooling such as kpatch-build. The biggest change in this cycle is the new code to handle and rewrite variable sized jump labels - which results in slightly tighter code generation in hot paths, through the use of short(er) NOPs. Also a number of cleanups and fixes, and a change to the generic include/linux/compiler.h to handle a s390 GCC quirk" * tag 'objtool-urgent-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Don't make .altinstructions writable * tag 'objtool-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Improve reloc hash size guestimate instrumentation.h: Avoid using inline asm operand modifiers compiler.h: Avoid using inline asm operand modifiers kbuild: Fix objtool dependency for 'OBJECT_FILES_NON_STANDARD_<obj> := n' objtool: Reflow handle_jump_alt() jump_label/x86: Remove unused JUMP_LABEL_NOP_SIZE jump_label, x86: Allow short NOPs objtool: Provide stats for jump_labels objtool: Rewrite jump_label instructions objtool: Decode jump_entry::key addend jump_label, x86: Emit short JMP jump_label: Free jump_entry::key bit1 for build use jump_label, x86: Add variable length patching support jump_label, x86: Introduce jump_entry_size() jump_label, x86: Improve error when we fail expected text jump_label, x86: Factor out the __jump_table generation jump_label, x86: Strip ASM jump_label support x86, objtool: Dont exclude arch/x86/realmode/ objtool: Rewrite hashtable sizing
2021-06-24objtool: Don't make .altinstructions writableJosh Poimboeuf1-1/+1
When objtool creates the .altinstructions section, it sets the SHF_WRITE flag to make the section writable -- unless the section had already been previously created by the kernel. The mismatch between kernel-created and objtool-created section flags can cause failures with external tooling (kpatch-build). And the section doesn't need to be writable anyway. Make the section flags consistent with the kernel's. Fixes: 9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls") Reported-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/6c284ae89717889ea136f9f0064d914cd8329d31.1624462939.git.jpoimboe@redhat.com
2021-06-14objtool: Improve reloc hash size guestimatePeter Zijlstra2-7/+5
Nathan reported that LLVM ThinLTO builds have a performance regression with commit 25cf0d8aa2a3 ("objtool: Rewrite hashtable sizing"). Sami was quick to note that this is due to their use of -ffunction-sections. As a result the .text section is small and basing the number of relocs off of that no longer works. Instead have read_sections() compute the sum of all SHF_EXECINSTR sections and use that. Fixes: 25cf0d8aa2a3 ("objtool: Rewrite hashtable sizing") Reported-by: Nathan Chancellor <nathan@kernel.org> Debugged-by: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Link: https://lkml.kernel.org/r/YMJpGLuGNsGtA5JJ@hirez.programming.kicks-ass.net
2021-06-11objtool: Only rewrite unconditional retpoline thunk callsPeter Zijlstra1-0/+4
It turns out that the compilers generate conditional branches to the retpoline thunks like: 5d5: 0f 85 00 00 00 00 jne 5db <cpuidle_reflect+0x22> 5d7: R_X86_64_PLT32 __x86_indirect_thunk_r11-0x4 while the rewrite can only handle JMP/CALL to the thunks. The result is the alternative wrecking the code. Make sure to skip writing the alternatives for conditional branches. Fixes: 9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls") Reported-by: Lukasz Majczak <lma@semihalf.com> Reported-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Nathan Chancellor <nathan@kernel.org>
2021-06-10objtool: Fix .symtab_shndx handling for elf_create_undef_symbol()Peter Zijlstra1-1/+24
When an ELF object uses extended symbol section indexes (IOW it has a .symtab_shndx section), these must be kept in sync with the regular symbol table (.symtab). So for every new symbol we emit, make sure to also emit a .symtab_shndx value to keep the arrays of equal size. Note: since we're writing an UNDEF symbol, most GElf_Sym fields will be 0 and we can repurpose one (st_size) to host the 0 for the xshndx value. Fixes: 2f2f7e47f052 ("objtool: Add elf_create_undef_symbol()") Reported-by: Nick Desaulniers <ndesaulniers@google.com> Suggested-by: Fangrui Song <maskray@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Link: https://lkml.kernel.org/r/YL3q1qFO9QIRL/BA@hirez.programming.kicks-ass.net
2021-05-14objtool: Reflow handle_jump_alt()Peter Zijlstra1-11/+11
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/x86: Fix elf_add_alternative() endiannessVasily Gorbik1-1/+2
Currently x86 kernel cross-compiled on big endian system fails at boot with: kernel BUG at arch/x86/kernel/alternative.c:258! Corresponding bug condition look like the following: BUG_ON(feature >= (NCAPINTS + NBUGINTS) * 32); Fix that by converting alternative feature/cpuid to target endianness. Fixes: 9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls") Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: https://lore.kernel.org/r/patch-2.thread-6c9df9.git-6c9df9a8098d.your-ad-here.call-01620841104-ext-2554@work.hours
2021-05-12objtool: Fix elf_create_undef_symbol() endiannessVasily Gorbik1-0/+1
Currently x86 cross-compilation fails on big endian system with: x86_64-cross-ld: init/main.o: invalid string offset 488112128 >= 6229 for section `.strtab' Mark new ELF data in elf_create_undef_symbol() as symbol, so that libelf does endianness handling correctly. Fixes: 2f2f7e47f052 ("objtool: Add elf_create_undef_symbol()") Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: https://lore.kernel.org/r/patch-1.thread-6c9df9.git-d39264656387.your-ad-here.call-01620841104-ext-2554@work.hours
2021-05-12objtool: Provide stats for jump_labelsPeter Zijlstra2-2/+23
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 Zijlstra1-0/+14
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
2021-05-12objtool: Decode jump_entry::key addendPeter Zijlstra3-0/+16
Teach objtool about the the low bits in the struct static_key pointer. That is, the low two bits of @key in: struct jump_entry { s32 code; s32 target; long key; } as found in the __jump_table section. Since @key has a relocation to the variable (to be resolved by the linker), the low two bits will be reflected in the relocation's addend. As such, find the reloc and store the addend, such that we can access these bits. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210506194158.028024143@infradead.org
2021-05-12objtool: Rewrite hashtable sizingPeter Zijlstra2-47/+83
Currently objtool has 5 hashtables and sizes them 16 or 20 bits depending on the --vmlinux argument. However, a single side doesn't really work well for the 5 tables, which among them, cover 3 different uses. Also, while vmlinux is larger, there is still a very wide difference between a defconfig and allyesconfig build, which again isn't optimally covered by a single size. Another aspect is the cost of elf_hash_init(), which for large tables dominates the runtime for small input files. It turns out that all it does it assign NULL, something that is required when using malloc(). However, when we allocate memory using mmap(), we're guaranteed to get zero filled pages. Therefore, rewrite the whole thing to: 1) use more dynamic sized tables, depending on the input file, 2) avoid the need for elf_hash_init() entirely by using mmap(). This speeds up a regular kernel build (100s to 98s for x86_64-defconfig), and potentially dramatically speeds up vmlinux processing. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210506194157.452881700@infradead.org
2021-04-28Merge tag 'objtool-core-2021-04-28' of ↵Linus Torvalds8-166/+299
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 Poimboeuf1-1/+13
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
2021-04-02objtool/x86: Rewrite retpoline thunk callsPeter Zijlstra1-0/+117
When the compiler emits: "CALL __x86_indirect_thunk_\reg" for an indirect call, have objtool rewrite it to: ALTERNATIVE "call __x86_indirect_thunk_\reg", "call *%reg", ALT_NOT(X86_FEATURE_RETPOLINE) Additionally, in order to not emit endless identical .altinst_replacement chunks, use a global symbol for them, see __x86_indirect_alt_*. This also avoids objtool from having to do code generation. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lkml.kernel.org/r/20210326151300.320177914@infradead.org
2021-04-02objtool: Skip magical retpoline .altinstr_replacementPeter Zijlstra1-1/+11
When the .altinstr_replacement is a retpoline, skip the alternative. We already special case retpolines anyway. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lkml.kernel.org/r/20210326151300.259429287@infradead.org
2021-04-02objtool: Cache instruction relocsPeter Zijlstra2-6/+23
Track the reloc of instructions in the new instruction->reloc field to avoid having to look them up again later. ( Technically x86 instructions can have two relocations, but not jumps and calls, for which we're using this. ) Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lkml.kernel.org/r/20210326151300.195441549@infradead.org
2021-04-02objtool: Keep track of retpoline call sitesPeter Zijlstra5-6/+34
Provide infrastructure for architectures to rewrite/augment compiler generated retpoline calls. Similar to what we do for static_call()s, keep track of the instructions that are retpoline calls. Use the same list_head, since a retpoline call cannot also be a static_call. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lkml.kernel.org/r/20210326151300.130805730@infradead.org
2021-04-02objtool: Add elf_create_undef_symbol()Peter Zijlstra2-0/+61
Allow objtool to create undefined symbols; this allows creating relocations to symbols not currently in the symbol table. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lkml.kernel.org/r/20210326151300.064743095@infradead.org
2021-04-02objtool: Extract elf_symbol_add()Peter Zijlstra1-25/+31
Create a common helper to add symbols. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lkml.kernel.org/r/20210326151300.003468981@infradead.org
generated by cgit v1.2.3 (git 2.39.0) at 2026-01-19 12:03:19 +0300