Commit c11878fd authored by Ingo Molnar's avatar Ingo Molnar
Browse files

Merge branch 'for-mingo-kcsan' of... 

Merge branch 'for-mingo-kcsan' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

 into locking/core

Pull KCSAN updates from Paul E. McKenney:

 "Kernel concurrency sanitizer (KCSAN) updates from Marco Elver."

Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parents 62137364 567a83e6

kernel/kcsan/core.c

+13 −13
Original line number Diff line number Diff line
@@ -12,7 +12,6 @@ 
#include <linux/moduleparam.h>

#include <linux/percpu.h>

#include <linux/preempt.h>

#include <linux/random.h>

#include <linux/sched.h>

#include <linux/uaccess.h>
@@ -101,7 +100,7 @@ static atomic_long_t watchpoints[CONFIG_KCSAN_NUM_WATCHPOINTS + NUM_SLOTS-1]; 
static DEFINE_PER_CPU(long, kcsan_skip);



/* For kcsan_prandom_u32_max(). */

static DEFINE_PER_CPU(struct rnd_state, kcsan_rand_state);

static DEFINE_PER_CPU(u32, kcsan_rand_state);



static __always_inline atomic_long_t *find_watchpoint(unsigned long addr,

						      size_t size,
@@ -275,20 +274,17 @@ should_watch(const volatile void *ptr, size_t size, int type, struct kcsan_ctx * 
}



/*

 * Returns a pseudo-random number in interval [0, ep_ro). See prandom_u32_max()

 * for more details.

 *

 * The open-coded version here is using only safe primitives for all contexts

 * where we can have KCSAN instrumentation. In particular, we cannot use

 * prandom_u32() directly, as its tracepoint could cause recursion.

 * Returns a pseudo-random number in interval [0, ep_ro). Simple linear

 * congruential generator, using constants from "Numerical Recipes".

 */

static u32 kcsan_prandom_u32_max(u32 ep_ro)

{

	struct rnd_state *state = &get_cpu_var(kcsan_rand_state);

	const u32 res = prandom_u32_state(state);

	u32 state = this_cpu_read(kcsan_rand_state);



	state = 1664525 * state + 1013904223;

	this_cpu_write(kcsan_rand_state, state);



	put_cpu_var(kcsan_rand_state);

	return (u32)(((u64) res * ep_ro) >> 32);

	return state % ep_ro;

}



static inline void reset_kcsan_skip(void)
@@ -639,10 +635,14 @@ static __always_inline void check_access(const volatile void *ptr, size_t size, 


void __init kcsan_init(void)

{

	int cpu;



	BUG_ON(!in_task());



	kcsan_debugfs_init();

	prandom_seed_full_state(&kcsan_rand_state);



	for_each_possible_cpu(cpu)

		per_cpu(kcsan_rand_state, cpu) = (u32)get_cycles();



	/*

	 * We are in the init task, and no other tasks should be running;

lib/Makefile

+0 −3
Original line number Diff line number Diff line
@@ -27,9 +27,6 @@ KASAN_SANITIZE_string.o := n 
CFLAGS_string.o += -fno-stack-protector

endif



# Used by KCSAN while enabled, avoid recursion.

KCSAN_SANITIZE_random32.o := n



lib-y := ctype.o string.o vsprintf.o cmdline.o \

	 rbtree.o radix-tree.o timerqueue.o xarray.o \

	 idr.o extable.o sha1.o irq_regs.o argv_split.o \