Commit f433cf21 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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
parents 5517a2ea 144b9152

kernel/kcsan/core.c

+50 −0
Original line number Diff line number Diff line
@@ -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

+3 −3
Original line number Diff line number Diff line
@@ -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

+10 −0
Original line number Diff line number Diff line
@@ -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",