diff options
4 files changed, 282 insertions, 2 deletions
diff --git a/recipes-kernel/linux/linux-intel-rt_5.10.bb b/recipes-kernel/linux/linux-intel-rt_5.10.bb index b1a32c1a..ae0f45f2 100644 --- a/recipes-kernel/linux/linux-intel-rt_5.10.bb +++ b/recipes-kernel/linux/linux-intel-rt_5.10.bb @@ -11,7 +11,9 @@ python () { LIC_FILES_CHKSUM = "file://COPYING;md5=6bc538ed5bd9a7fc9398086aedcd7e46" SRC_URI_append = " file://0001-menuconfig-mconf-cfg-Allow-specification-of-ncurses-.patch \ -" + file://objtool-fix-segfault-with-clang.patch \ + file://x86-entry-Emit-a-symbol-for-register-restoring-thunk.patch \ + " KBRANCH = "5.10/preempt-rt" KMETA_BRANCH = "yocto-5.10" diff --git a/recipes-kernel/linux/linux-intel/objtool-fix-segfault-with-clang.patch b/recipes-kernel/linux/linux-intel/objtool-fix-segfault-with-clang.patch new file mode 100644 index 00000000..f4b1374f --- /dev/null +++ b/recipes-kernel/linux/linux-intel/objtool-fix-segfault-with-clang.patch @@ -0,0 +1,150 @@ +From 44f6a7c0755d8dd453c70557e11687bb080a6f21 Mon Sep 17 00:00:00 2001 +From: Josh Poimboeuf <jpoimboe@redhat.com> +Date: Mon, 14 Dec 2020 16:04:20 -0600 +Subject: [PATCH] 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@kernel.org> +Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> +Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> +Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> +Reviewed-by: Miroslav Benes <mbenes@suse.cz> +Link: https://github.com/ClangBuiltLinux/linux/issues/1207 +Link: https://lkml.kernel.org/r/ba6b6c0f0dd5acbba66e403955a967d9fdd1726a.1607983452.git.jpoimboe@redhat.com + +Upstream-Status: Backport +Signed-off-by: Anuj Mittal <anuj.mittal@intel.com> +--- + 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 c6ab44543c92a..5f8d3eed78a18 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 4e1d7460574b4..be89c741ba9a0 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 807f8c6700974..e6890cc70a25b 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 235663b96adc7..9ce68b385a1b8 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; diff --git a/recipes-kernel/linux/linux-intel/x86-entry-Emit-a-symbol-for-register-restoring-thunk.patch b/recipes-kernel/linux/linux-intel/x86-entry-Emit-a-symbol-for-register-restoring-thunk.patch new file mode 100644 index 00000000..3cd07c0a --- /dev/null +++ b/recipes-kernel/linux/linux-intel/x86-entry-Emit-a-symbol-for-register-restoring-thunk.patch @@ -0,0 +1,125 @@ +From 5e6dca82bcaa49348f9e5fcb48df4881f6d6c4ae Mon Sep 17 00:00:00 2001 +From: Nick Desaulniers <ndesaulniers@google.com> +Date: Tue, 12 Jan 2021 11:46:24 -0800 +Subject: [PATCH] x86/entry: Emit a symbol for register restoring thunk + +Arnd found a randconfig that produces the warning: + + arch/x86/entry/thunk_64.o: warning: objtool: missing symbol for insn at + offset 0x3e + +when building with LLVM_IAS=1 (Clang's integrated assembler). Josh +notes: + + With the LLVM assembler not generating section symbols, objtool has no + way to reference this code when it generates ORC unwinder entries, + because this code is outside of any ELF function. + + The limitation now being imposed by objtool is that all code must be + contained in an ELF symbol. And .L symbols don't create such symbols. + + So basically, you can use an .L symbol *inside* a function or a code + segment, you just can't use the .L symbol to contain the code using a + SYM_*_START/END annotation pair. + +Fangrui notes that this optimization is helpful for reducing image size +when compiling with -ffunction-sections and -fdata-sections. I have +observed on the order of tens of thousands of symbols for the kernel +images built with those flags. + +A patch has been authored against GNU binutils to match this behavior +of not generating unused section symbols ([1]), so this will +also become a problem for users of GNU binutils once they upgrade to 2.36. + +Omit the .L prefix on a label so that the assembler will emit an entry +into the symbol table for the label, with STB_LOCAL binding. This +enables objtool to generate proper unwind info here with LLVM_IAS=1 or +GNU binutils 2.36+. + + [ bp: Massage commit message. ] + +Reported-by: Arnd Bergmann <arnd@arndb.de> +Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> +Suggested-by: Borislav Petkov <bp@alien8.de> +Suggested-by: Mark Brown <broonie@kernel.org> +Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> +Signed-off-by: Borislav Petkov <bp@suse.de> +Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> +Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> +Link: https://lkml.kernel.org/r/20210112194625.4181814-1-ndesaulniers@google.com +Link: https://github.com/ClangBuiltLinux/linux/issues/1209 +Link: https://reviews.llvm.org/D93783 +Link: https://sourceware.org/binutils/docs/as/Symbol-Names.html +Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=d1bcae833b32f1408485ce69f844dcd7ded093a8 [1] + +Upstream-Status: Backport +Signed-off-by: Anuj Mittal <anuj.mittal@intel.com> +--- + Documentation/asm-annotations.rst | 5 +++++ + arch/x86/entry/thunk_64.S | 8 ++++---- + include/linux/linkage.h | 5 +++++ + 3 files changed, 14 insertions(+), 4 deletions(-) + +diff --git a/Documentation/asm-annotations.rst b/Documentation/asm-annotations.rst +index 32ea57483378d..76424e0431f4b 100644 +--- a/Documentation/asm-annotations.rst ++++ b/Documentation/asm-annotations.rst +@@ -100,6 +100,11 @@ Instruction Macros + ~~~~~~~~~~~~~~~~~~ + This section covers ``SYM_FUNC_*`` and ``SYM_CODE_*`` enumerated above. + ++``objtool`` requires that all code must be contained in an ELF symbol. Symbol ++names that have a ``.L`` prefix do not emit symbol table entries. ``.L`` ++prefixed symbols can be used within a code region, but should be avoided for ++denoting a range of code via ``SYM_*_START/END`` annotations. ++ + * ``SYM_FUNC_START`` and ``SYM_FUNC_START_LOCAL`` are supposed to be **the + most frequent markings**. They are used for functions with standard calling + conventions -- global and local. Like in C, they both align the functions to +diff --git a/arch/x86/entry/thunk_64.S b/arch/x86/entry/thunk_64.S +index ccd32877a3c41..c9a9fbf1655f3 100644 +--- a/arch/x86/entry/thunk_64.S ++++ b/arch/x86/entry/thunk_64.S +@@ -31,7 +31,7 @@ SYM_FUNC_START_NOALIGN(\name) + .endif + + call \func +- jmp .L_restore ++ jmp __thunk_restore + SYM_FUNC_END(\name) + _ASM_NOKPROBE(\name) + .endm +@@ -44,7 +44,7 @@ SYM_FUNC_END(\name) + #endif + + #ifdef CONFIG_PREEMPTION +-SYM_CODE_START_LOCAL_NOALIGN(.L_restore) ++SYM_CODE_START_LOCAL_NOALIGN(__thunk_restore) + popq %r11 + popq %r10 + popq %r9 +@@ -56,6 +56,6 @@ SYM_CODE_START_LOCAL_NOALIGN(.L_restore) + popq %rdi + popq %rbp + ret +- _ASM_NOKPROBE(.L_restore) +-SYM_CODE_END(.L_restore) ++ _ASM_NOKPROBE(__thunk_restore) ++SYM_CODE_END(__thunk_restore) + #endif +diff --git a/include/linux/linkage.h b/include/linux/linkage.h +index 5bcfbd972e970..dbf8506decca0 100644 +--- a/include/linux/linkage.h ++++ b/include/linux/linkage.h +@@ -178,6 +178,11 @@ + * Objtool generates debug info for both FUNC & CODE, but needs special + * annotations for each CODE's start (to describe the actual stack frame). + * ++ * Objtool requires that all code must be contained in an ELF symbol. Symbol ++ * names that have a .L prefix do not emit symbol table entries. .L ++ * prefixed symbols can be used within a code region, but should be avoided for ++ * denoting a range of code via ``SYM_*_START/END`` annotations. ++ * + * ALIAS -- does not generate debug info -- the aliased function will + */ + diff --git a/recipes-kernel/linux/linux-intel_5.10.bb b/recipes-kernel/linux/linux-intel_5.10.bb index caf2c899..585dea49 100644 --- a/recipes-kernel/linux/linux-intel_5.10.bb +++ b/recipes-kernel/linux/linux-intel_5.10.bb @@ -5,7 +5,10 @@ KMETA_BRANCH = "yocto-5.10" LIC_FILES_CHKSUM = "file://COPYING;md5=6bc538ed5bd9a7fc9398086aedcd7e46" -SRC_URI_append = " file://0001-menuconfig-mconf-cfg-Allow-specification-of-ncurses-.patch" +SRC_URI_append = " file://0001-menuconfig-mconf-cfg-Allow-specification-of-ncurses-.patch \ + file://objtool-fix-segfault-with-clang.patch \ + file://x86-entry-Emit-a-symbol-for-register-restoring-thunk.patch \ + " DEPENDS += "elfutils-native openssl-native util-linux-native" |