Commit 534b0abc authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86_urgent_for_v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 fixes from Borislav Petkov:

 - Add the respective UP last level cache mask accessors in order not to
   cause segfaults when lscpu accesses their representation in sysfs

 - Fix for a race in the alternatives batch patching machinery when
   kprobes are set

* tag 'x86_urgent_for_v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cacheinfo: Add a cpu_llc_shared_mask() UP variant
  x86/alternative: Fix race in try_get_desc()
parents b357fd1c df5b035b

arch/x86/include/asm/smp.h

+15 −10
Original line number Diff line number Diff line
@@ -21,16 +21,6 @@ DECLARE_PER_CPU_READ_MOSTLY(u16, cpu_llc_id); 
DECLARE_PER_CPU_READ_MOSTLY(u16, cpu_l2c_id);

DECLARE_PER_CPU_READ_MOSTLY(int, cpu_number);



static inline struct cpumask *cpu_llc_shared_mask(int cpu)

{

	return per_cpu(cpu_llc_shared_map, cpu);

}



static inline struct cpumask *cpu_l2c_shared_mask(int cpu)

{

	return per_cpu(cpu_l2c_shared_map, cpu);

}



DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_cpu_to_apicid);

DECLARE_EARLY_PER_CPU_READ_MOSTLY(u32, x86_cpu_to_acpiid);

DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_bios_cpu_apicid);
@@ -172,6 +162,16 @@ extern int safe_smp_processor_id(void); 
# define safe_smp_processor_id()	smp_processor_id()

#endif



static inline struct cpumask *cpu_llc_shared_mask(int cpu)

{

	return per_cpu(cpu_llc_shared_map, cpu);

}



static inline struct cpumask *cpu_l2c_shared_mask(int cpu)

{

	return per_cpu(cpu_l2c_shared_map, cpu);

}



#else /* !CONFIG_SMP */

#define wbinvd_on_cpu(cpu)     wbinvd()

static inline int wbinvd_on_all_cpus(void)
@@ -179,6 +179,11 @@ static inline int wbinvd_on_all_cpus(void) 
	wbinvd();

	return 0;

}



static inline struct cpumask *cpu_llc_shared_mask(int cpu)

{

	return (struct cpumask *)cpumask_of(0);

}

#endif /* CONFIG_SMP */



extern unsigned disabled_cpus;

arch/x86/kernel/alternative.c

+23 −22
Original line number Diff line number Diff line
@@ -1319,22 +1319,23 @@ struct bp_patching_desc { 
	atomic_t refs;

};



static struct bp_patching_desc *bp_desc;

static struct bp_patching_desc bp_desc;



static __always_inline

struct bp_patching_desc *try_get_desc(struct bp_patching_desc **descp)

struct bp_patching_desc *try_get_desc(void)

{

	/* rcu_dereference */

	struct bp_patching_desc *desc = __READ_ONCE(*descp);

	struct bp_patching_desc *desc = &bp_desc;



	if (!desc || !arch_atomic_inc_not_zero(&desc->refs))

	if (!arch_atomic_inc_not_zero(&desc->refs))

		return NULL;



	return desc;

}



static __always_inline void put_desc(struct bp_patching_desc *desc)

static __always_inline void put_desc(void)

{

	struct bp_patching_desc *desc = &bp_desc;



	smp_mb__before_atomic();

	arch_atomic_dec(&desc->refs);

}
@@ -1367,15 +1368,15 @@ noinstr int poke_int3_handler(struct pt_regs *regs) 


	/*

	 * Having observed our INT3 instruction, we now must observe

	 * bp_desc:

	 * bp_desc with non-zero refcount:

	 *

	 *	bp_desc = desc			INT3

	 *	bp_desc.refs = 1		INT3

	 *	WMB				RMB

	 *	write INT3			if (desc)

	 *	write INT3			if (bp_desc.refs != 0)

	 */

	smp_rmb();



	desc = try_get_desc(&bp_desc);

	desc = try_get_desc();

	if (!desc)

		return 0;
@@ -1429,7 +1430,7 @@ noinstr int poke_int3_handler(struct pt_regs *regs) 
	ret = 1;



out_put:

	put_desc(desc);

	put_desc();

	return ret;

}
@@ -1460,18 +1461,20 @@ static int tp_vec_nr; 
 */

static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries)

{

	struct bp_patching_desc desc = {

		.vec = tp,

		.nr_entries = nr_entries,

		.refs = ATOMIC_INIT(1),

	};

	unsigned char int3 = INT3_INSN_OPCODE;

	unsigned int i;

	int do_sync;



	lockdep_assert_held(&text_mutex);



	smp_store_release(&bp_desc, &desc); /* rcu_assign_pointer */

	bp_desc.vec = tp;

	bp_desc.nr_entries = nr_entries;



	/*

	 * Corresponds to the implicit memory barrier in try_get_desc() to

	 * ensure reading a non-zero refcount provides up to date bp_desc data.

	 */

	atomic_set_release(&bp_desc.refs, 1);



	/*

	 * Corresponding read barrier in int3 notifier for making sure the
@@ -1559,12 +1562,10 @@ static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries 
		text_poke_sync();



	/*

	 * Remove and synchronize_rcu(), except we have a very primitive

	 * refcount based completion.

	 * Remove and wait for refs to be zero.

	 */

	WRITE_ONCE(bp_desc, NULL); /* RCU_INIT_POINTER */

	if (!atomic_dec_and_test(&desc.refs))

		atomic_cond_read_acquire(&desc.refs, !VAL);

	if (!atomic_dec_and_test(&bp_desc.refs))

		atomic_cond_read_acquire(&bp_desc.refs, !VAL);

}



static void text_poke_loc_init(struct text_poke_loc *tp, void *addr,