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authorMarco Elver <elver@google.com>2021-11-30 14:44:31 +0300
committerPaul E. McKenney <paulmck@kernel.org>2021-12-10 03:42:28 +0300
commit0509811952e41ad1e04c50d2378078250b6b7be3 (patch)
tree44e74157c55812b237dcf6cf9ce2d20caea4e458 /tools/objtool
parent0525bd82f6a9b5860ed3ea53520ac11ebfa09d5b (diff)
downloadlinux-0509811952e41ad1e04c50d2378078250b6b7be3.tar.xz
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 <elver@google.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'tools/objtool')
-rw-r--r--tools/objtool/check.c37
-rw-r--r--tools/objtool/include/objtool/elf.h2
2 files changed, 32 insertions, 7 deletions
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;
};