diff options
| -rw-r--r-- | arch/ia64/kernel/traps.c | 50 |
1 files changed, 40 insertions, 10 deletions
diff --git a/arch/ia64/kernel/traps.c b/arch/ia64/kernel/traps.c index fffa9e0..ab68474 100644 --- a/arch/ia64/kernel/traps.c +++ b/arch/ia64/kernel/traps.c @@ -307,6 +307,15 @@ fp_emulate (int fp_fault, void *bundle, long *ipsr, long *fpsr, long *isr, long return ret.status; } +struct fpu_swa_msg { + unsigned long count; + unsigned long time; +}; +static DEFINE_PER_CPU(struct fpu_swa_msg, cpulast); +DECLARE_PER_CPU(struct fpu_swa_msg, cpulast); +static struct fpu_swa_msg last __cacheline_aligned; + + /* * Handle floating-point assist faults and traps. */ @@ -316,8 +325,6 @@ handle_fpu_swa (int fp_fault, struct pt_regs *regs, unsigned long isr) long exception, bundle[2]; unsigned long fault_ip; struct siginfo siginfo; - static int fpu_swa_count = 0; - static unsigned long last_time; fault_ip = regs->cr_iip; if (!fp_fault && (ia64_psr(regs)->ri == 0)) @@ -325,14 +332,37 @@ handle_fpu_swa (int fp_fault, struct pt_regs *regs, unsigned long isr) if (copy_from_user(bundle, (void __user *) fault_ip, sizeof(bundle))) return -1; - if (jiffies - last_time > 5*HZ) - fpu_swa_count = 0; - if ((fpu_swa_count < 4) && !(current->thread.flags & IA64_THREAD_FPEMU_NOPRINT)) { - last_time = jiffies; - ++fpu_swa_count; - printk(KERN_WARNING - "%s(%d): floating-point assist fault at ip %016lx, isr %016lx\n", - current->comm, current->pid, regs->cr_iip + ia64_psr(regs)->ri, isr); + if (!(current->thread.flags & IA64_THREAD_FPEMU_NOPRINT)) { + unsigned long count, current_jiffies = jiffies; + struct fpu_swa_msg *cp = &__get_cpu_var(cpulast); + + if (unlikely(current_jiffies > cp->time)) + cp->count = 0; + if (unlikely(cp->count < 5)) { + cp->count++; + cp->time = current_jiffies + 5 * HZ; + + /* minimize races by grabbing a copy of count BEFORE checking last.time. */ + count = last.count; + barrier(); + + /* + * Lower 4 bits are used as a count. Upper bits are a sequence + * number that is updated when count is reset. The cmpxchg will + * fail is seqno has changed. This minimizes mutiple cpus + * reseting the count. + */ + if (current_jiffies > last.time) + (void) cmpxchg_acq(&last.count, count, 16 + (count & ~15)); + + /* used fetchadd to atomically update the count */ + if ((last.count & 15) < 5 && (ia64_fetchadd(1, &last.count, acq) & 15) < 5) { + last.time = current_jiffies + 5 * HZ; + printk(KERN_WARNING + "%s(%d): floating-point assist fault at ip %016lx, isr %016lx\n", + current->comm, current->pid, regs->cr_iip + ia64_psr(regs)->ri, isr); + } + } } exception = fp_emulate(fp_fault, bundle, ®s->cr_ipsr, ®s->ar_fpsr, &isr, ®s->pr, |
