x86 mmiotrace: Use percpu instead of arrays.

Signed-off-by: Pekka Paalanen <pq@iki.fi>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: pq@iki.fi
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 15 insertions, 12 deletions

diff --git a/arch/x86/kernel/mmiotrace/kmmio.c b/arch/x86/kernel/mmiotrace/kmmio.c
index e759f7c3878f..5e239d0b8467 100644
--- a/arch/x86/kernel/mmiotrace/kmmio.c
+++ b/arch/x86/kernel/mmiotrace/kmmio.c
@@ -16,6 +16,7 @@
 #include <linux/uaccess.h>
 #include <linux/ptrace.h>
 #include <linux/preempt.h>
+#include <linux/percpu.h>
 #include <asm/io.h>
 #include <asm/cacheflush.h>
 #include <asm/errno.h>
@@ -49,7 +50,8 @@ static unsigned int handler_registered;
 static struct list_head kmmio_page_table[KMMIO_PAGE_TABLE_SIZE];
 static LIST_HEAD(kmmio_probes);
 
-static struct kmmio_context kmmio_ctx[NR_CPUS];
+/* Accessed per-cpu */
+static DEFINE_PER_CPU(struct kmmio_context, kmmio_ctx);
 
 static struct notifier_block nb_die = {
         .notifier_call = kmmio_die_notifier
@@ -173,8 +175,7 @@ static void disarm_kmmio_fault_page(unsigned long page, int *page_level)
  */
 static int kmmio_handler(struct pt_regs *regs, unsigned long addr)
 {
-        struct kmmio_context *ctx;
-        int cpu;
+        struct kmmio_context *ctx = &get_cpu_var(kmmio_ctx);
 
         /*
          * Preemption is now disabled to prevent process switch during
@@ -187,8 +188,6 @@ static int kmmio_handler(struct pt_regs *regs, unsigned long addr)
          * And that interrupt triggers a kmmio trap?
          */
         preempt_disable();
-        cpu = smp_processor_id();
-        ctx = &kmmio_ctx[cpu];
 
         /* interrupts disabled and CPU-local data => atomicity guaranteed. */
         if (ctx->active) {
@@ -199,7 +198,7 @@ static int kmmio_handler(struct pt_regs *regs, unsigned long addr)
                  */
                 printk(KERN_EMERG "mmiotrace: recursive probe hit on CPU %d, "
                                         "for address %lu. Ignoring.\n",
-                                        cpu, addr);
+                                        smp_processor_id(), addr);
                 goto no_kmmio;
         }
         ctx->active++;
@@ -231,6 +230,7 @@ static int kmmio_handler(struct pt_regs *regs, unsigned long addr)
         /* We hold lock, now we set present bit in PTE and single step. */
         disarm_kmmio_fault_page(ctx->fpage->page, NULL);
 
+        put_cpu_var(kmmio_ctx);
         return 1;
 
 no_kmmio_locked:
@@ -238,6 +238,7 @@ no_kmmio_locked:
         ctx->active--;
 no_kmmio:
         preempt_enable_no_resched();
+        put_cpu_var(kmmio_ctx);
         /* page fault not handled by kmmio */
         return 0;
 }
@@ -249,11 +250,11 @@ no_kmmio:
  */
 static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs)
 {
-        int cpu = smp_processor_id();
-        struct kmmio_context *ctx = &kmmio_ctx[cpu];
+        int ret = 0;
+        struct kmmio_context *ctx = &get_cpu_var(kmmio_ctx);
 
         if (!ctx->active)
-                return 0;
+                goto out;
 
         if (ctx->probe && ctx->probe->post_handler)
                 ctx->probe->post_handler(ctx->probe, condition, regs);
@@ -273,10 +274,12 @@ static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs)
          * will have TF set, in which case, continue the remaining processing
          * of do_debug, as if this is not a probe hit.
          */
-        if (regs->flags & TF_MASK)
-                return 0;
+        if (!(regs->flags & TF_MASK))
+                ret = 1;
 
-        return 1;
+out:
+        put_cpu_var(kmmio_ctx);
+        return ret;
 }
 
 static int add_kmmio_fault_page(unsigned long page)