From ff05ab2305aaeb21a3002ae95a17e176c198b71b Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 18 Mar 2019 14:33:07 +0100 Subject: [PATCH] x86/nospec, objtool: Introduce ANNOTATE_IGNORE_ALTERNATIVE To facillitate other usage of ignoring alternatives; rename ANNOTATE_NOSPEC_IGNORE to ANNOTATE_IGNORE_ALTERNATIVE. Signed-off-by: Peter Zijlstra (Intel) Cc: Borislav Petkov Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar --- arch/x86/include/asm/alternative-asm.h | 11 ++++++++++ arch/x86/include/asm/alternative.h | 10 +++++++++ arch/x86/include/asm/nospec-branch.h | 28 +++++++++----------------- tools/objtool/check.c | 8 ++++---- 4 files changed, 34 insertions(+), 23 deletions(-) diff --git a/arch/x86/include/asm/alternative-asm.h b/arch/x86/include/asm/alternative-asm.h index 31b627b43a8e..464034db299f 100644 --- a/arch/x86/include/asm/alternative-asm.h +++ b/arch/x86/include/asm/alternative-asm.h @@ -19,6 +19,17 @@ .endm #endif +/* + * objtool annotation to ignore the alternatives and only consider the original + * instruction(s). + */ +.macro ANNOTATE_IGNORE_ALTERNATIVE + .Lannotate_\@: + .pushsection .discard.ignore_alts + .long .Lannotate_\@ - . + .popsection +.endm + /* * Issue one struct alt_instr descriptor entry (need to put it into * the section .altinstructions, see below). This entry contains diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index 4c74073a19cc..094fbc9c0b1c 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -45,6 +45,16 @@ #define LOCK_PREFIX "" #endif +/* + * objtool annotation to ignore the alternatives and only consider the original + * instruction(s). + */ +#define ANNOTATE_IGNORE_ALTERNATIVE \ + "999:\n\t" \ + ".pushsection .discard.ignore_alts\n\t" \ + ".long 999b - .\n\t" \ + ".popsection\n\t" + struct alt_instr { s32 instr_offset; /* original instruction */ s32 repl_offset; /* offset to replacement instruction */ diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index dad12b767ba0..daf25b60c9e3 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -10,6 +10,15 @@ #include #include +/* + * This should be used immediately before a retpoline alternative. It tells + * objtool where the retpolines are so that it can make sense of the control + * flow by just reading the original instruction(s) and ignoring the + * alternatives. + */ +#define ANNOTATE_NOSPEC_ALTERNATIVE \ + ANNOTATE_IGNORE_ALTERNATIVE + /* * Fill the CPU return stack buffer. * @@ -56,19 +65,6 @@ #ifdef __ASSEMBLY__ -/* - * This should be used immediately before a retpoline alternative. It tells - * objtool where the retpolines are so that it can make sense of the control - * flow by just reading the original instruction(s) and ignoring the - * alternatives. - */ -.macro ANNOTATE_NOSPEC_ALTERNATIVE - .Lannotate_\@: - .pushsection .discard.nospec - .long .Lannotate_\@ - . - .popsection -.endm - /* * This should be used immediately before an indirect jump/call. It tells * objtool the subsequent indirect jump/call is vouched safe for retpoline @@ -152,12 +148,6 @@ #else /* __ASSEMBLY__ */ -#define ANNOTATE_NOSPEC_ALTERNATIVE \ - "999:\n\t" \ - ".pushsection .discard.nospec\n\t" \ - ".long 999b - .\n\t" \ - ".popsection\n\t" - #define ANNOTATE_RETPOLINE_SAFE \ "999:\n\t" \ ".pushsection .discard.retpoline_safe\n\t" \ diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 5dde107083c6..110ea3d84772 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -457,13 +457,13 @@ static void add_ignores(struct objtool_file *file) * But it at least allows objtool to understand the control flow *around* the * retpoline. */ -static int add_nospec_ignores(struct objtool_file *file) +static int add_ignore_alternatives(struct objtool_file *file) { struct section *sec; struct rela *rela; struct instruction *insn; - sec = find_section_by_name(file->elf, ".rela.discard.nospec"); + sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts"); if (!sec) return 0; @@ -475,7 +475,7 @@ static int add_nospec_ignores(struct objtool_file *file) insn = find_insn(file, rela->sym->sec, rela->addend); if (!insn) { - WARN("bad .discard.nospec entry"); + WARN("bad .discard.ignore_alts entry"); return -1; } @@ -1239,7 +1239,7 @@ static int decode_sections(struct objtool_file *file) add_ignores(file); - ret = add_nospec_ignores(file); + ret = add_ignore_alternatives(file); if (ret) return ret;