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>

2 files changed, 58 insertions, 49 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)
diff --git a/arch/x86/kernel/mmiotrace/mmio-mod.c b/arch/x86/kernel/mmiotrace/mmio-mod.c
index 0019dcdf6158..f9c609266d83 100644
--- a/arch/x86/kernel/mmiotrace/mmio-mod.c
+++ b/arch/x86/kernel/mmiotrace/mmio-mod.c
@@ -30,6 +30,7 @@
 #include <linux/mmiotrace.h>
 #include <asm/e820.h> /* for ISA_START_ADDRESS */
 #include <asm/atomic.h>
+#include <linux/percpu.h>
 
 #include "kmmio.h"
 #include "pf_in.h"
@@ -49,11 +50,11 @@ struct trap_reason {
 };
 
 /* Accessed per-cpu. */
-static struct trap_reason pf_reason[NR_CPUS];
-static struct mm_io_header_rw cpu_trace[NR_CPUS];
+static DEFINE_PER_CPU(struct trap_reason, pf_reason);
+static DEFINE_PER_CPU(struct mm_io_header_rw, cpu_trace);
 
 /* Access to this is not per-cpu. */
-static atomic_t dropped[NR_CPUS];
+static DEFINE_PER_CPU(atomic_t, dropped);
 
 static struct file_operations mmio_fops = {
         .owner = THIS_MODULE,
@@ -150,15 +151,15 @@ static void print_pte(unsigned long address)
  */
 static void die_kmmio_nesting_error(struct pt_regs *regs, unsigned long addr)
 {
-        const unsigned long cpu = smp_processor_id();
+        const struct trap_reason *my_reason = &get_cpu_var(pf_reason);
         printk(KERN_EMERG MODULE_NAME ": unexpected fault for address: %lx, "
                                         "last fault for address: %lx\n",
-                                        addr, pf_reason[cpu].addr);
+                                        addr, my_reason->addr);
         print_pte(addr);
 #ifdef __i386__
         print_symbol(KERN_EMERG "faulting EIP is at %s\n", regs->ip);
         print_symbol(KERN_EMERG "last faulting EIP was at %s\n",
-                                                        pf_reason[cpu].ip);
+                                                        my_reason->ip);
         printk(KERN_EMERG
                         "eax: %08lx   ebx: %08lx   ecx: %08lx   edx: %08lx\n",
                         regs->ax, regs->bx, regs->cx, regs->dx);
@@ -168,100 +169,105 @@ static void die_kmmio_nesting_error(struct pt_regs *regs, unsigned long addr)
 #else
         print_symbol(KERN_EMERG "faulting RIP is at %s\n", regs->ip);
         print_symbol(KERN_EMERG "last faulting RIP was at %s\n",
-                                                        pf_reason[cpu].ip);
+                                                        my_reason->ip);
         printk(KERN_EMERG "rax: %016lx   rcx: %016lx   rdx: %016lx\n",
                                         regs->ax, regs->cx, regs->dx);
         printk(KERN_EMERG "rsi: %016lx   rdi: %016lx   "
                                 "rbp: %016lx   rsp: %016lx\n",
                                 regs->si, regs->di, regs->bp, regs->sp);
 #endif
+        put_cpu_var(pf_reason);
         BUG();
 }
 
 static void pre(struct kmmio_probe *p, struct pt_regs *regs,
                                                 unsigned long addr)
 {
-        const unsigned long cpu = smp_processor_id();
+        struct trap_reason *my_reason = &get_cpu_var(pf_reason);
+        struct mm_io_header_rw *my_trace = &get_cpu_var(cpu_trace);
         const unsigned long instptr = instruction_pointer(regs);
         const enum reason_type type = get_ins_type(instptr);
 
         /* it doesn't make sense to have more than one active trace per cpu */
-        if (pf_reason[cpu].active_traces)
+        if (my_reason->active_traces)
                 die_kmmio_nesting_error(regs, addr);
         else
-                pf_reason[cpu].active_traces++;
+                my_reason->active_traces++;
 
-        pf_reason[cpu].type = type;
-        pf_reason[cpu].addr = addr;
-        pf_reason[cpu].ip = instptr;
+        my_reason->type = type;
+        my_reason->addr = addr;
+        my_reason->ip = instptr;
 
-        cpu_trace[cpu].header.type = MMIO_MAGIC;
-        cpu_trace[cpu].header.pid = 0;
-        cpu_trace[cpu].header.data_len = sizeof(struct mm_io_rw);
-        cpu_trace[cpu].rw.address = addr;
+        my_trace->header.type = MMIO_MAGIC;
+        my_trace->header.pid = 0;
+        my_trace->header.data_len = sizeof(struct mm_io_rw);
+        my_trace->rw.address = addr;
 
         /*
          * Only record the program counter when requested.
          * It may taint clean-room reverse engineering.
          */
         if (trace_pc)
-                cpu_trace[cpu].rw.pc = instptr;
+                my_trace->rw.pc = instptr;
         else
-                cpu_trace[cpu].rw.pc = 0;
+                my_trace->rw.pc = 0;
 
-        record_timestamp(&cpu_trace[cpu].header);
+        record_timestamp(&my_trace->header);
 
         switch (type) {
         case REG_READ:
-                cpu_trace[cpu].header.type |=
+                my_trace->header.type |=
                         (MMIO_READ << MMIO_OPCODE_SHIFT) |
                         (get_ins_mem_width(instptr) << MMIO_WIDTH_SHIFT);
                 break;
         case REG_WRITE:
-                cpu_trace[cpu].header.type |=
+                my_trace->header.type |=
                         (MMIO_WRITE << MMIO_OPCODE_SHIFT) |
                         (get_ins_mem_width(instptr) << MMIO_WIDTH_SHIFT);
-                cpu_trace[cpu].rw.value = get_ins_reg_val(instptr, regs);
+                my_trace->rw.value = get_ins_reg_val(instptr, regs);
                 break;
         case IMM_WRITE:
-                cpu_trace[cpu].header.type |=
+                my_trace->header.type |=
                         (MMIO_WRITE << MMIO_OPCODE_SHIFT) |
                         (get_ins_mem_width(instptr) << MMIO_WIDTH_SHIFT);
-                cpu_trace[cpu].rw.value = get_ins_imm_val(instptr);
+                my_trace->rw.value = get_ins_imm_val(instptr);
                 break;
         default:
                 {
                         unsigned char *ip = (unsigned char *)instptr;
-                        cpu_trace[cpu].header.type |=
+                        my_trace->header.type |=
                                         (MMIO_UNKNOWN_OP << MMIO_OPCODE_SHIFT);
-                        cpu_trace[cpu].rw.value = (*ip) << 16 |
-                                                        *(ip + 1) << 8 |
-                                                        *(ip + 2);
+                        my_trace->rw.value = (*ip) << 16 | *(ip + 1) << 8 |
+                                                                *(ip + 2);
                 }
         }
+        put_cpu_var(cpu_trace);
+        put_cpu_var(pf_reason);
 }
 
 static void post(struct kmmio_probe *p, unsigned long condition,
                                                         struct pt_regs *regs)
 {
-        const unsigned long cpu = smp_processor_id();
+        struct trap_reason *my_reason = &get_cpu_var(pf_reason);
+        struct mm_io_header_rw *my_trace = &get_cpu_var(cpu_trace);
 
         /* this should always return the active_trace count to 0 */
-        pf_reason[cpu].active_traces--;
-        if (pf_reason[cpu].active_traces) {
+        my_reason->active_traces--;
+        if (my_reason->active_traces) {
                 printk(KERN_EMERG MODULE_NAME ": unexpected post handler");
                 BUG();
         }
 
-        switch (pf_reason[cpu].type) {
+        switch (my_reason->type) {
         case REG_READ:
-                cpu_trace[cpu].rw.value = get_ins_reg_val(pf_reason[cpu].ip,
-                                                                        regs);
+                my_trace->rw.value = get_ins_reg_val(my_reason->ip, regs);
                 break;
         default:
                 break;
         }
-        relay_write(chan, &cpu_trace[cpu], sizeof(struct mm_io_header_rw));
+        relay_write(chan, my_trace, sizeof(*my_trace));
+        put_cpu_var(cpu_trace);
+        put_cpu_var(pf_reason);
 }
 
 /*
@@ -274,7 +280,7 @@ static int subbuf_start_handler(struct rchan_buf *buf, void *subbuf,
                                         void *prev_subbuf, size_t prev_padding)
 {
         unsigned int cpu = buf->cpu;
-        atomic_t *drop = &dropped[cpu];
+        atomic_t *drop = &per_cpu(dropped, cpu);
         int count;
         if (relay_buf_full(buf)) {
                 if (atomic_inc_return(drop) == 1) {