Hi Bruce Yeah :) it was my local series and as mentioned temp hack. I think we will wait for your SRCREV bumps for final fix. but perhaps this can help to temporarily testing master-next a bit.
On Tue, Feb 2, 2021 at 7:12 PM Bruce Ashfield <[email protected]> wrote: > > Richard, > > Obviously ignore this patch. > > It'll fail to apply as soon as my SRCREVs are bumped, and honestly, > it's a hassle to have to wonder if this has been applied, have a > failure, sent a revert, etc. > > I'm not even sure why it was sent. > > Bruce > > On Tue, Feb 2, 2021 at 8:36 PM Khem Raj <[email protected]> wrote: > > > > This is for master-next testing only !! > > > > Signed-off-by: Khem Raj <[email protected]> > > --- > > ...fault-with-Clang-non-section-symbols.patch | 150 ++++++++++++++++++ > > ...-symbol-for-register-restoring-thunk.patch | 125 +++++++++++++++ > > meta/recipes-kernel/linux/linux-yocto_5.10.bb | 5 + > > 3 files changed, 280 insertions(+) > > create mode 100644 > > meta/recipes-kernel/linux/files/0001-objtool-Fix-seg-fault-with-Clang-non-section-symbols.patch > > create mode 100644 > > meta/recipes-kernel/linux/files/0001-x86-entry-Emit-a-symbol-for-register-restoring-thunk.patch > > > > diff --git > > a/meta/recipes-kernel/linux/files/0001-objtool-Fix-seg-fault-with-Clang-non-section-symbols.patch > > > > b/meta/recipes-kernel/linux/files/0001-objtool-Fix-seg-fault-with-Clang-non-section-symbols.patch > > new file mode 100644 > > index 0000000000..f606e3ee6d > > --- /dev/null > > +++ > > b/meta/recipes-kernel/linux/files/0001-objtool-Fix-seg-fault-with-Clang-non-section-symbols.patch > > @@ -0,0 +1,150 @@ > > +From 44f6a7c0755d8dd453c70557e11687bb080a6f21 Mon Sep 17 00:00:00 2001 > > +From: Josh Poimboeuf <[email protected]> > > +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 <[email protected]> > > +Signed-off-by: Josh Poimboeuf <[email protected]> > > +Signed-off-by: Peter Zijlstra (Intel) <[email protected]> > > +Reviewed-by: Nick Desaulniers <[email protected]> > > +Reviewed-by: Miroslav Benes <[email protected]> > > +Link: https://github.com/ClangBuiltLinux/linux/issues/1207 > > +Link: > > https://lkml.kernel.org/r/ba6b6c0f0dd5acbba66e403955a967d9fdd1726a.1607983452.git.jpoim...@redhat.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 c6ab44543c92..5f8d3eed78a1 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 4e1d7460574b..be89c741ba9a 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 807f8c670097..e6890cc70a25 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 235663b96adc..9ce68b385a1b 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; > > +-- > > +2.30.0 > > + > > diff --git > > a/meta/recipes-kernel/linux/files/0001-x86-entry-Emit-a-symbol-for-register-restoring-thunk.patch > > > > b/meta/recipes-kernel/linux/files/0001-x86-entry-Emit-a-symbol-for-register-restoring-thunk.patch > > new file mode 100644 > > index 0000000000..320d7e929c > > --- /dev/null > > +++ > > b/meta/recipes-kernel/linux/files/0001-x86-entry-Emit-a-symbol-for-register-restoring-thunk.patch > > @@ -0,0 +1,125 @@ > > +From de98d14b7f4511380a9d9b784a12507c790d8a54 Mon Sep 17 00:00:00 2001 > > +From: Nick Desaulniers <[email protected]> > > +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 <[email protected]> > > +Suggested-by: Josh Poimboeuf <[email protected]> > > +Suggested-by: Borislav Petkov <[email protected]> > > +Suggested-by: Mark Brown <[email protected]> > > +Signed-off-by: Nick Desaulniers <[email protected]> > > +Signed-off-by: Borislav Petkov <[email protected]> > > +Acked-by: Peter Zijlstra (Intel) <[email protected]> > > +Acked-by: Josh Poimboeuf <[email protected]> > > +Link: > > https://lkml.kernel.org/r/[email protected] > > +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] > > +--- > > + 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 32ea57483378..76424e0431f4 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 ccd32877a3c4..c9a9fbf1655f 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 5bcfbd972e97..dbf8506decca 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 > > + */ > > + > > +-- > > +2.30.0 > > + > > diff --git a/meta/recipes-kernel/linux/linux-yocto_5.10.bb > > b/meta/recipes-kernel/linux/linux-yocto_5.10.bb > > index 7e570b04f5..aa328aff52 100644 > > --- a/meta/recipes-kernel/linux/linux-yocto_5.10.bb > > +++ b/meta/recipes-kernel/linux/linux-yocto_5.10.bb > > @@ -29,6 +29,11 @@ SRCREV_meta ?= "47c7a3148a4d7653cec536ba202b25148d1952ad" > > SRC_URI = > > "git://git.yoctoproject.org/linux-yocto.git;name=machine;branch=${KBRANCH}; > > \ > > > > git://git.yoctoproject.org/yocto-kernel-cache;type=kmeta;name=meta;branch=yocto-5.10;destsuffix=${KMETA}" > > > > +SRC_URI += "\ > > + > > file://0001-objtool-Fix-seg-fault-with-Clang-non-section-symbols.patch \ > > + > > file://0001-x86-entry-Emit-a-symbol-for-register-restoring-thunk.patch \ > > +" > > + > > LIC_FILES_CHKSUM = "file://COPYING;md5=6bc538ed5bd9a7fc9398086aedcd7e46" > > LINUX_VERSION ?= "5.10.5" > > > > -- > > 2.30.0 > > > > > > > > > > > -- > - Thou shalt not follow the NULL pointer, for chaos and madness await > thee at its end > - "Use the force Harry" - Gandalf, Star Trek II
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