Merge tag 'kcsan.2022.12.02a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull KCSAN updates from Paul McKenney:

 - Add instrumentation for memcpy(), memset(), and memmove() for Clang
   v16+'s new function names that are used when the -fsanitize=thread
   argument is given

 - Fix objtool warnings from KCSAN's volatile instrumentation, and typos
   in a pair of Kconfig options' help clauses

* tag 'kcsan.2022.12.02a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  kcsan: Fix trivial typo in Kconfig help comments
  objtool, kcsan: Add volatile read/write instrumentation to whitelist
  kcsan: Instrument memcpy/memset/memmove with newer Clang

Author: torvalds

kernel/kcsan/core.c

@@ -14,10 +14,12 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
+#include <linux/minmax.h>
 #include <linux/moduleparam.h>
 #include <linux/percpu.h>
 #include <linux/preempt.h>
 #include <linux/sched.h>
+#include <linux/string.h>
 #include <linux/uaccess.h>
 
 #include "encoding.h"
@@ -1308,3 +1310,51 @@ noinline void __tsan_atomic_signal_fence(int memorder)
 	}
 }
 EXPORT_SYMBOL(__tsan_atomic_signal_fence);
+
+#ifdef __HAVE_ARCH_MEMSET
+void *__tsan_memset(void *s, int c, size_t count);
+noinline void *__tsan_memset(void *s, int c, size_t count)
+{
+	/*
+	 * Instead of not setting up watchpoints where accessed size is greater
+	 * than MAX_ENCODABLE_SIZE, truncate checked size to MAX_ENCODABLE_SIZE.
+	 */
+	size_t check_len = min_t(size_t, count, MAX_ENCODABLE_SIZE);
+
+	check_access(s, check_len, KCSAN_ACCESS_WRITE, _RET_IP_);
+	return memset(s, c, count);
+}
+#else
+void *__tsan_memset(void *s, int c, size_t count) __alias(memset);
+#endif
+EXPORT_SYMBOL(__tsan_memset);
+
+#ifdef __HAVE_ARCH_MEMMOVE
+void *__tsan_memmove(void *dst, const void *src, size_t len);
+noinline void *__tsan_memmove(void *dst, const void *src, size_t len)
+{
+	size_t check_len = min_t(size_t, len, MAX_ENCODABLE_SIZE);
+
+	check_access(dst, check_len, KCSAN_ACCESS_WRITE, _RET_IP_);
+	check_access(src, check_len, 0, _RET_IP_);
+	return memmove(dst, src, len);
+}
+#else
+void *__tsan_memmove(void *dst, const void *src, size_t len) __alias(memmove);
+#endif
+EXPORT_SYMBOL(__tsan_memmove);
+
+#ifdef __HAVE_ARCH_MEMCPY
+void *__tsan_memcpy(void *dst, const void *src, size_t len);
+noinline void *__tsan_memcpy(void *dst, const void *src, size_t len)
+{
+	size_t check_len = min_t(size_t, len, MAX_ENCODABLE_SIZE);
+
+	check_access(dst, check_len, KCSAN_ACCESS_WRITE, _RET_IP_);
+	check_access(src, check_len, 0, _RET_IP_);
+	return memcpy(dst, src, len);
+}
+#else
+void *__tsan_memcpy(void *dst, const void *src, size_t len) __alias(memcpy);
+#endif
+EXPORT_SYMBOL(__tsan_memcpy);

lib/Kconfig.kcsan

@@ -125,7 +125,7 @@ config KCSAN_SKIP_WATCH
 	default 4000
 	help
 	  The number of per-CPU memory operations to skip, before another
-	  watchpoint is set up, i.e. one in KCSAN_WATCH_SKIP per-CPU
+	  watchpoint is set up, i.e. one in KCSAN_SKIP_WATCH per-CPU
 	  memory operations are used to set up a watchpoint. A smaller value
 	  results in more aggressive race detection, whereas a larger value
 	  improves system performance at the cost of missing some races.
@@ -135,8 +135,8 @@ config KCSAN_SKIP_WATCH_RANDOMIZE
 	default y
 	help
 	  If instruction skip count should be randomized, where the maximum is
-	  KCSAN_WATCH_SKIP. If false, the chosen value is always
-	  KCSAN_WATCH_SKIP.
+	  KCSAN_SKIP_WATCH. If false, the chosen value is always
+	  KCSAN_SKIP_WATCH.
 
 config KCSAN_INTERRUPT_WATCHER
 	bool "Interruptible watchers" if !KCSAN_STRICT

tools/objtool/check.c

@@ -999,6 +999,16 @@ static const char *uaccess_safe_builtin[] = {
 	"__tsan_read_write4",
 	"__tsan_read_write8",
 	"__tsan_read_write16",
+	"__tsan_volatile_read1",
+	"__tsan_volatile_read2",
+	"__tsan_volatile_read4",
+	"__tsan_volatile_read8",
+	"__tsan_volatile_read16",
+	"__tsan_volatile_write1",
+	"__tsan_volatile_write2",
+	"__tsan_volatile_write4",
+	"__tsan_volatile_write8",
+	"__tsan_volatile_write16",
 	"__tsan_atomic8_load",
 	"__tsan_atomic16_load",
 	"__tsan_atomic32_load",