Hi all, The latest GNU assembler (binutils-2.36.1) is removing unused section symbols like Clang [1]. So linux-5.10.15 can't be built with binutils-2.36.1 now. It has been reported as https://bugzilla.kernel.org/show_bug.cgi?id=211693. I can confirm this commit fixes the issue. It should be cherry-picked into stable branches, so the following stable releases will be able to built with latest GNU toolchain. [1]: https://sourceware.org/pipermail/binutils/2020-December/114671.html At last, happy new lunar year guys :). On 2020-12-16 13:49 +0000, tip-bot2 for Josh Poimboeuf wrote: > The following commit has been merged into the objtool/urgent branch of tip: > > Commit-ID: 44f6a7c0755d8dd453c70557e11687bb080a6f21 > Gitweb: > https://git.kernel.org/tip/44f6a7c0755d8dd453c70557e11687bb080a6f21 > Author: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> > AuthorDate: Mon, 14 Dec 2020 16:04:20 -06:00 > Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > CommitterDate: Wed, 16 Dec 2020 14:35:46 +01:00 > > objtool: Fix seg fault with Clang non-section symbols > > The Clang assembler likes to strip section symbols, which means objtool > can't reference some text code by its section. This confuses objtool > greatly, causing it to seg fault. > > The fix is similar to what was done before, for ORC reloc generation: > > e81e07244325 ("objtool: Support Clang non-section symbols in ORC > generation") > > Factor out that code into a common helper and use it for static call > reloc generation as well. > > Reported-by: Arnd Bergmann <arnd@xxxxxxxxxx> > Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> > Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > Reviewed-by: Miroslav Benes <mbenes@xxxxxxx> > Link: https://github.com/ClangBuiltLinux/linux/issues/1207 > Link: > https://lkml.kernel.org/r/ba6b6c0f0dd5acbba66e403955a967d9fdd1726a.1607983452.git.jpoimboe@xxxxxxxxxx > --- > tools/objtool/check.c | 11 +++++++++-- > tools/objtool/elf.c | 26 ++++++++++++++++++++++++++ > tools/objtool/elf.h | 2 ++ > tools/objtool/orc_gen.c | 29 +++++------------------------ > 4 files changed, 42 insertions(+), 26 deletions(-) > > diff --git a/tools/objtool/check.c b/tools/objtool/check.c > index c6ab445..5f8d3ee 100644 > --- a/tools/objtool/check.c > +++ b/tools/objtool/check.c > @@ -467,13 +467,20 @@ static int create_static_call_sections(struct > objtool_file *file) > > /* populate reloc for 'addr' */ > reloc = malloc(sizeof(*reloc)); > + > if (!reloc) { > perror("malloc"); > return -1; > } > memset(reloc, 0, sizeof(*reloc)); > - reloc->sym = insn->sec->sym; > - reloc->addend = insn->offset; > + > + insn_to_reloc_sym_addend(insn->sec, insn->offset, reloc); > + if (!reloc->sym) { > + WARN_FUNC("static call tramp: missing containing > symbol", > + insn->sec, insn->offset); > + return -1; > + } > + > reloc->type = R_X86_64_PC32; > reloc->offset = idx * sizeof(struct static_call_site); > reloc->sec = reloc_sec; > diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c > index 4e1d746..be89c74 100644 > --- a/tools/objtool/elf.c > +++ b/tools/objtool/elf.c > @@ -262,6 +262,32 @@ struct reloc *find_reloc_by_dest(const struct elf *elf, > struct section *sec, uns > return find_reloc_by_dest_range(elf, sec, offset, 1); > } > > +void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset, > + struct reloc *reloc) > +{ > + if (sec->sym) { > + reloc->sym = sec->sym; > + reloc->addend = offset; > + return; > + } > + > + /* > + * The Clang assembler strips section symbols, so we have to reference > + * the function symbol instead: > + */ > + reloc->sym = find_symbol_containing(sec, offset); > + if (!reloc->sym) { > + /* > + * Hack alert. This happens when we need to reference the NOP > + * pad insn immediately after the function. > + */ > + reloc->sym = find_symbol_containing(sec, offset - 1); > + } > + > + if (reloc->sym) > + reloc->addend = offset - reloc->sym->offset; > +} > + > static int read_sections(struct elf *elf) > { > Elf_Scn *s = NULL; > diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h > index 807f8c6..e6890cc 100644 > --- a/tools/objtool/elf.h > +++ b/tools/objtool/elf.h > @@ -140,6 +140,8 @@ struct reloc *find_reloc_by_dest(const struct elf *elf, > struct section *sec, uns > struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section > *sec, > unsigned long offset, unsigned int len); > struct symbol *find_func_containing(struct section *sec, unsigned long > offset); > +void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset, > + struct reloc *reloc); > int elf_rebuild_reloc_section(struct elf *elf, struct section *sec); > > #define for_each_sec(file, > sec) \ > diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c > index 235663b..9ce68b3 100644 > --- a/tools/objtool/orc_gen.c > +++ b/tools/objtool/orc_gen.c > @@ -105,30 +105,11 @@ static int create_orc_entry(struct elf *elf, struct > section *u_sec, struct secti > } > memset(reloc, 0, sizeof(*reloc)); > > - if (insn_sec->sym) { > - reloc->sym = insn_sec->sym; > - reloc->addend = insn_off; > - } else { > - /* > - * The Clang assembler doesn't produce section symbols, so we > - * have to reference the function symbol instead: > - */ > - reloc->sym = find_symbol_containing(insn_sec, insn_off); > - if (!reloc->sym) { > - /* > - * Hack alert. This happens when we need to reference > - * the NOP pad insn immediately after the function. > - */ > - reloc->sym = find_symbol_containing(insn_sec, > - insn_off - 1); > - } > - if (!reloc->sym) { > - WARN("missing symbol for insn at offset 0x%lx\n", > - insn_off); > - return -1; > - } > - > - reloc->addend = insn_off - reloc->sym->offset; > + insn_to_reloc_sym_addend(insn_sec, insn_off, reloc); > + if (!reloc->sym) { > + WARN("missing symbol for insn at offset 0x%lx", > + insn_off); > + return -1; > } > > reloc->type = R_X86_64_PC32; -- Xi Ruoyao <xry111@xxxxxxxxxxxxxxxx> School of Aerospace Science and Technology, Xidian University
