From 0525bd82f6a9b5860ed3ea53520ac11ebfa09d5b Mon Sep 17 00:00:00 2001 From: Marco Elver Date: Tue, 30 Nov 2021 12:44:30 +0100 Subject: objtool, kcsan: Add memory barrier instrumentation to whitelist Adds KCSAN's memory barrier instrumentation to objtool's uaccess whitelist. Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney --- tools/objtool/check.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'tools/objtool') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 21735829b860..61dfb66b30b6 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -849,6 +849,10 @@ static const char *uaccess_safe_builtin[] = { "__asan_report_store16_noabort", /* KCSAN */ "__kcsan_check_access", + "__kcsan_mb", + "__kcsan_wmb", + "__kcsan_rmb", + "__kcsan_release", "kcsan_found_watchpoint", "kcsan_setup_watchpoint", "kcsan_check_scoped_accesses", -- cgit v1.2.3 From 0509811952e41ad1e04c50d2378078250b6b7be3 Mon Sep 17 00:00:00 2001 From: Marco Elver Date: Tue, 30 Nov 2021 12:44:31 +0100 Subject: objtool, kcsan: Remove memory barrier instrumentation from noinstr Teach objtool to turn instrumentation required for memory barrier modeling into nops in noinstr text. The __tsan_func_entry/exit calls are still emitted by compilers even with the __no_sanitize_thread attribute. The memory barrier instrumentation will be inserted explicitly (without compiler help), and thus needs to also explicitly be removed. Signed-off-by: Marco Elver Acked-by: Josh Poimboeuf Signed-off-by: Paul E. McKenney --- tools/objtool/check.c | 37 +++++++++++++++++++++++++++++++------ tools/objtool/include/objtool/elf.h | 2 +- 2 files changed, 32 insertions(+), 7 deletions(-) (limited to 'tools/objtool') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 61dfb66b30b6..a9a1f7259d62 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1072,11 +1072,11 @@ static void annotate_call_site(struct objtool_file *file, } /* - * Many compilers cannot disable KCOV with a function attribute - * so they need a little help, NOP out any KCOV calls from noinstr - * text. + * Many compilers cannot disable KCOV or sanitizer calls with a function + * attribute so they need a little help, NOP out any such calls from + * noinstr text. */ - if (insn->sec->noinstr && sym->kcov) { + if (insn->sec->noinstr && sym->profiling_func) { if (reloc) { reloc->type = R_NONE; elf_write_reloc(file->elf, reloc); @@ -1991,6 +1991,31 @@ static int read_intra_function_calls(struct objtool_file *file) return 0; } +/* + * Return true if name matches an instrumentation function, where calls to that + * function from noinstr code can safely be removed, but compilers won't do so. + */ +static bool is_profiling_func(const char *name) +{ + /* + * Many compilers cannot disable KCOV with a function attribute. + */ + if (!strncmp(name, "__sanitizer_cov_", 16)) + return true; + + /* + * Some compilers currently do not remove __tsan_func_entry/exit nor + * __tsan_atomic_signal_fence (used for barrier instrumentation) with + * the __no_sanitize_thread attribute, remove them. Once the kernel's + * minimum Clang version is 14.0, this can be removed. + */ + if (!strncmp(name, "__tsan_func_", 12) || + !strcmp(name, "__tsan_atomic_signal_fence")) + return true; + + return false; +} + static int classify_symbols(struct objtool_file *file) { struct section *sec; @@ -2011,8 +2036,8 @@ static int classify_symbols(struct objtool_file *file) if (!strcmp(func->name, "__fentry__")) func->fentry = true; - if (!strncmp(func->name, "__sanitizer_cov_", 16)) - func->kcov = true; + if (is_profiling_func(func->name)) + func->profiling_func = true; } } diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h index cdc739fa9a6f..d22336781401 100644 --- a/tools/objtool/include/objtool/elf.h +++ b/tools/objtool/include/objtool/elf.h @@ -58,7 +58,7 @@ struct symbol { u8 static_call_tramp : 1; u8 retpoline_thunk : 1; u8 fentry : 1; - u8 kcov : 1; + u8 profiling_func : 1; struct list_head pv_target; }; -- cgit v1.2.3