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Message-ID: <20080209195305.0d094a50@daedalus.pq.iki.fi>
Date: Sat, 9 Feb 2008 19:53:05 +0200
From: Pekka Paalanen <pq@....fi>
To: Ingo Molnar <mingo@...e.hu>
Cc: Eric Dumazet <dada1@...mosbay.com>, linux-kernel@...r.kernel.org,
pq@....fi
Subject: [PATCH] x86 mmiotrace: Use percpu instead of arrays.
Signed-off-by: Pekka Paalanen <pq@....fi>
---
arch/x86/mm/kmmio.c | 27 +++++++++-------
arch/x86/mm/mmio-mod.c | 80 +++++++++++++++++++++++++----------------------
2 files changed, 58 insertions(+), 49 deletions(-)
diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c
index e759f7c..5e239d0 100644
--- a/arch/x86/mm/kmmio.c
+++ b/arch/x86/mm/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/mm/mmio-mod.c b/arch/x86/mm/mmio-mod.c
index f492b65..ed62a95 100644
--- a/arch/x86/mm/mmio-mod.c
+++ b/arch/x86/mm/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) {
--
1.5.3.7
--
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