diff options
| -rw-r--r-- | arch/x86/kernel/cpu/intel.c | 63 | ||||
| -rw-r--r-- | include/linux/sched.h | 3 | ||||
| -rw-r--r-- | kernel/fork.c | 5 |
3 files changed, 61 insertions, 10 deletions
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index f7a5370a9b3b..be2a0bdb9527 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -7,10 +7,13 @@ #include <linux/smp.h> #include <linux/sched.h> #include <linux/sched/clock.h> +#include <linux/semaphore.h> #include <linux/thread_info.h> #include <linux/init.h> #include <linux/uaccess.h> +#include <linux/workqueue.h> #include <linux/delay.h> +#include <linux/cpuhotplug.h> #include <asm/cpufeature.h> #include <asm/msr.h> @@ -999,6 +1002,8 @@ static const struct { static struct ratelimit_state bld_ratelimit; +static DEFINE_SEMAPHORE(buslock_sem); + static inline bool match_option(const char *arg, int arglen, const char *opt) { int len = strlen(opt), ratelimit; @@ -1109,18 +1114,52 @@ static void split_lock_init(void) split_lock_verify_msr(sld_state != sld_off); } +static void __split_lock_reenable(struct work_struct *work) +{ + sld_update_msr(true); + up(&buslock_sem); +} + +/* + * If a CPU goes offline with pending delayed work to re-enable split lock + * detection then the delayed work will be executed on some other CPU. That + * handles releasing the buslock_sem, but because it executes on a + * different CPU probably won't re-enable split lock detection. This is a + * problem on HT systems since the sibling CPU on the same core may then be + * left running with split lock detection disabled. + * + * Unconditionally re-enable detection here. + */ +static int splitlock_cpu_offline(unsigned int cpu) +{ + sld_update_msr(true); + + return 0; +} + +static DECLARE_DELAYED_WORK(split_lock_reenable, __split_lock_reenable); + static void split_lock_warn(unsigned long ip) { - pr_warn_ratelimited("#AC: %s/%d took a split_lock trap at address: 0x%lx\n", - current->comm, current->pid, ip); + int cpu; - /* - * Disable the split lock detection for this task so it can make - * progress and set TIF_SLD so the detection is re-enabled via - * switch_to_sld() when the task is scheduled out. - */ + if (!current->reported_split_lock) + pr_warn_ratelimited("#AC: %s/%d took a split_lock trap at address: 0x%lx\n", + current->comm, current->pid, ip); + current->reported_split_lock = 1; + + /* misery factor #1, sleep 10ms before trying to execute split lock */ + if (msleep_interruptible(10) > 0) + return; + /* Misery factor #2, only allow one buslocked disabled core at a time */ + if (down_interruptible(&buslock_sem) == -EINTR) + return; + cpu = get_cpu(); + schedule_delayed_work_on(cpu, &split_lock_reenable, 2); + + /* Disable split lock detection on this CPU to make progress */ sld_update_msr(false); - set_tsk_thread_flag(current, TIF_SLD); + put_cpu(); } bool handle_guest_split_lock(unsigned long ip) @@ -1274,10 +1313,14 @@ static void sld_state_show(void) pr_info("disabled\n"); break; case sld_warn: - if (boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT)) + if (boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT)) { pr_info("#AC: crashing the kernel on kernel split_locks and warning on user-space split_locks\n"); - else if (boot_cpu_has(X86_FEATURE_BUS_LOCK_DETECT)) + if (cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, + "x86/splitlock", NULL, splitlock_cpu_offline) < 0) + pr_warn("No splitlock CPU offline handler\n"); + } else if (boot_cpu_has(X86_FEATURE_BUS_LOCK_DETECT)) { pr_info("#DB: warning on user-space bus_locks\n"); + } break; case sld_fatal: if (boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT)) { diff --git a/include/linux/sched.h b/include/linux/sched.h index a8911b1f35aa..23e03c7824c4 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -941,6 +941,9 @@ struct task_struct { #ifdef CONFIG_IOMMU_SVA unsigned pasid_activated:1; #endif +#ifdef CONFIG_CPU_SUP_INTEL + unsigned reported_split_lock:1; +#endif unsigned long atomic_flags; /* Flags requiring atomic access. */ diff --git a/kernel/fork.c b/kernel/fork.c index 9796897560ab..f39795f372c2 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1045,6 +1045,11 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node) #ifdef CONFIG_MEMCG tsk->active_memcg = NULL; #endif + +#ifdef CONFIG_CPU_SUP_INTEL + tsk->reported_split_lock = 0; +#endif + return tsk; free_stack: |