From: Marco Elver <elver@google.com>
To: elver@google.com, "Paul E. McKenney" <paulmck@kernel.org>
Cc: Alexander Potapenko <glider@google.com>,
Boqun Feng <boqun.feng@gmail.com>, Borislav Petkov <bp@alien8.de>,
Dmitry Vyukov <dvyukov@google.com>,
Ingo Molnar <mingo@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Waiman Long <longman@redhat.com>, Will Deacon <will@kernel.org>,
kasan-dev@googlegroups.com, linux-arch@vger.kernel.org,
linux-doc@vger.kernel.org, linux-kbuild@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
llvm@lists.linux.dev, x86@kernel.org,
Josh Poimboeuf <jpoimboe@redhat.com>
Subject: [PATCH v3 23/25] objtool, kcsan: Remove memory barrier instrumentation from noinstr
Date: Tue, 30 Nov 2021 12:44:31 +0100 [thread overview]
Message-ID: <20211130114433.2580590-24-elver@google.com> (raw)
In-Reply-To: <20211130114433.2580590-1-elver@google.com>
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>
---
v3:
* s/removable_instr/profiling_func/ (suggested by Josh Poimboeuf)
* s/__kcsan_(mb|wmb|rmb|release)/__atomic_signal_fence/, because
Clang < 14.0 will still emit these in noinstr even with __no_kcsan.
* Fix and add more comments.
v2:
* Rewrite after rebase to v5.16-rc1.
---
tools/objtool/check.c | 37 ++++++++++++++++++++++++-----
tools/objtool/include/objtool/elf.h | 2 +-
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;
};
--
2.34.0.rc2.393.gf8c9666880-goog
next prev parent reply other threads:[~2021-11-30 11:47 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-30 11:44 [PATCH v3 00/25] kcsan: Support detecting a subset of missing memory barriers Marco Elver
2021-11-30 11:44 ` [PATCH v3 01/25] kcsan: Refactor reading of instrumented memory Marco Elver
2021-11-30 11:44 ` [PATCH v3 02/25] kcsan: Remove redundant zero-initialization of globals Marco Elver
2021-11-30 11:44 ` [PATCH v3 03/25] kcsan: Avoid checking scoped accesses from nested contexts Marco Elver
2021-11-30 11:44 ` [PATCH v3 04/25] kcsan: Add core support for a subset of weak memory modeling Marco Elver
2021-12-03 8:56 ` Marco Elver
2021-12-03 16:50 ` Paul E. McKenney
2021-12-03 21:08 ` Paul E. McKenney
2021-12-03 23:42 ` Marco Elver
2021-12-03 23:42 ` Paul E. McKenney
2021-12-03 23:45 ` Marco Elver
2021-12-04 1:14 ` Paul E. McKenney
2021-11-30 11:44 ` [PATCH v3 05/25] kcsan: Add core memory barrier instrumentation functions Marco Elver
2021-11-30 11:44 ` [PATCH v3 06/25] kcsan, kbuild: Add option for barrier instrumentation only Marco Elver
2021-11-30 11:44 ` [PATCH v3 07/25] kcsan: Call scoped accesses reordered in reports Marco Elver
2021-11-30 11:44 ` [PATCH v3 08/25] kcsan: Show location access was reordered to Marco Elver
2021-12-06 5:03 ` Boqun Feng
2021-12-06 7:16 ` Marco Elver
2021-12-06 14:31 ` Boqun Feng
2021-12-06 16:04 ` Marco Elver
2021-12-06 17:16 ` Boqun Feng
2021-12-06 17:38 ` Paul E. McKenney
2021-11-30 11:44 ` [PATCH v3 09/25] kcsan: Document modeling of weak memory Marco Elver
2021-11-30 11:44 ` [PATCH v3 10/25] kcsan: test: Match reordered or normal accesses Marco Elver
2021-11-30 11:44 ` [PATCH v3 11/25] kcsan: test: Add test cases for memory barrier instrumentation Marco Elver
2021-11-30 11:44 ` [PATCH v3 12/25] kcsan: Ignore GCC 11+ warnings about TSan runtime support Marco Elver
2021-11-30 11:44 ` [PATCH v3 13/25] kcsan: selftest: Add test case to check memory barrier instrumentation Marco Elver
2021-11-30 11:44 ` [PATCH v3 14/25] locking/barriers, kcsan: Add instrumentation for barriers Marco Elver
2021-11-30 11:44 ` [PATCH v3 15/25] locking/barriers, kcsan: Support generic instrumentation Marco Elver
2021-11-30 11:44 ` [PATCH v3 16/25] locking/atomics, kcsan: Add instrumentation for barriers Marco Elver
2021-11-30 11:44 ` [PATCH v3 17/25] asm-generic/bitops, " Marco Elver
2021-11-30 11:44 ` [PATCH v3 18/25] x86/barriers, kcsan: Use generic instrumentation for non-smp barriers Marco Elver
2021-11-30 11:44 ` [PATCH v3 19/25] x86/qspinlock, kcsan: Instrument barrier of pv_queued_spin_unlock() Marco Elver
2021-11-30 11:44 ` [PATCH v3 20/25] mm, kcsan: Enable barrier instrumentation Marco Elver
2021-11-30 11:44 ` [PATCH v3 21/25] sched, kcsan: Enable memory " Marco Elver
2021-11-30 11:44 ` [PATCH v3 22/25] objtool, kcsan: Add memory barrier instrumentation to whitelist Marco Elver
2021-11-30 11:44 ` Marco Elver [this message]
2021-11-30 11:44 ` [PATCH v3 24/25] compiler_attributes.h: Add __disable_sanitizer_instrumentation Marco Elver
2021-11-30 11:44 ` [PATCH v3 25/25] kcsan: Support WEAK_MEMORY with Clang where no objtool support exists Marco Elver
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