Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932212AbXBKUDh (ORCPT ); Sun, 11 Feb 2007 15:03:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932327AbXBKUDg (ORCPT ); Sun, 11 Feb 2007 15:03:36 -0500 Received: from tomts5-srv.bellnexxia.net ([209.226.175.25]:57624 "EHLO tomts5-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932212AbXBKUDd (ORCPT ); Sun, 11 Feb 2007 15:03:33 -0500 From: Mathieu Desnoyers To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Mathieu Desnoyers , Christoph Hellwig , Ingo Molnar , systemtap@sources.redhat.com, ltt-dev@shafik.org Subject: [PATCH 04/05] Linux Kernel Markers : i386 optimization Date: Sun, 11 Feb 2007 15:03:26 -0500 Message-Id: <11712242082031-git-send-email-mathieu.desnoyers@polymtl.ca> X-Mailer: git-send-email 1.4.4.4 In-Reply-To: <1171224207118-git-send-email-mathieu.desnoyers@polymtl.ca> References: <1171224207118-git-send-email-mathieu.desnoyers@polymtl.ca> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4861 Lines: 165 Linux Kernel Markers : i386 optimization Signed-off-by: Mathieu Desnoyers --- /dev/null +++ b/include/asm-i386/marker.h @@ -0,0 +1,47 @@ +/* + * marker.h + * + * Code markup for dynamic and static tracing. i386 architecture optimisations. + * + * (C) Copyright 2006 Mathieu Desnoyers + * + * This file is released under the GPLv2. + * See the file COPYING for more details. + */ + + +#ifdef CONFIG_MARKERS +#define MARK(name, format, args...) \ + do { \ + static marker_probe_func *__mark_call_##name = \ + __mark_empty_function; \ + static const struct __mark_marker_c __mark_c_##name \ + __attribute__((section(".markers.c"))) = \ + { #name, &__mark_call_##name, format, \ + MARKER_OPTIMIZED } ; \ + char condition; \ + asm volatile( ".section .markers, \"a\";\n\t" \ + ".long %1, 0f;\n\t" \ + ".previous;\n\t" \ + ".align 2\n\t" \ + "0:\n\t" \ + "movb $0,%0;\n\t" \ + : "=r" (condition) \ + : "m" (__mark_c_##name)); \ + __mark_check_format(format, ## args); \ + if (unlikely(condition)) { \ + preempt_disable(); \ + (*__mark_call_##name)(format, ## args); \ + preempt_enable(); \ + } \ + } while (0) + +/* Offset of the immediate value from the start of the movb instruction, in + * bytes. */ +#define MARK_ENABLE_IMMEDIATE_OFFSET 1 +#define MARK_ENABLE_TYPE char +#define MARK_POLYMORPHIC + +extern int arch_marker_set_ins_enable(void *address, char enable); + +#endif --- /dev/null +++ b/arch/i386/kernel/marker.c @@ -0,0 +1,93 @@ +/* marker.c + * + * Erratum 49 fix for Intel PIII and higher. + * + * Permits marker activation by XMC with correct serialization. + * + * Reentrant for NMI and trap handler instrumentation. :-) + * + * Mathieu Desnoyers + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#define BREAKPOINT_INSTRUCTION 0xcc +#define BREAKPOINT_INS_LEN 1 + +static DEFINE_MUTEX(mark_mutex); +static long target_eip = 0; + +static void mark_synchronize_core(void *info) +{ + sync_core(); /* use cpuid to stop speculative execution */ +} + +/* We simply skip the 2 bytes load immediate here, leaving the register in an + * undefined state. We don't care about the content (0 or !0), because we are + * changing the value 0->1 or 1->0. This small window of undefined value + * doesn't matter. + */ +static int mark_notifier(struct notifier_block *nb, + unsigned long val, void *data) +{ + enum die_val die_val = (enum die_val) val; + struct die_args *args = (struct die_args *)data; + + if (!args->regs || user_mode_vm(args->regs)) + return NOTIFY_DONE; + + if (die_val == DIE_INT3 && args->regs->eip == target_eip) { + args->regs->eip += 1; /* Skip the next byte of load immediate */ + return NOTIFY_STOP; + } + return NOTIFY_DONE; +} + +static struct notifier_block mark_notify = { + .notifier_call = mark_notifier, + .priority = 0x7fffffff, /* we need to be notified first */ +}; + +int arch_marker_set_ins_enable(void *address, char enable) +{ + char saved_byte; + int ret; + char *dest = address; + + mutex_lock(&mark_mutex); + BUG_ON(!(enable ^ dest[1])); /* Must be a state change 0<->1 */ + target_eip = (long)address + BREAKPOINT_INS_LEN; + /* register_die_notifier has memory barriers */ + register_die_notifier(&mark_notify); + saved_byte = *dest; + *dest = BREAKPOINT_INSTRUCTION; + wmb(); + /* Execute serializing instruction on each CPU. + * Acts as a memory barrier. */ + ret = on_each_cpu(mark_synchronize_core, NULL, 1, 1); + BUG_ON(ret != 0); + + dest[1] = enable; + wmb(); + *dest = saved_byte; + /* Wait for all int3 handlers to end + (interrupts are disabled in int3). + This CPU is clearly not in a int3 handler + (not preemptible). + synchronize_sched has memory barriers */ + synchronize_sched(); + unregister_die_notifier(&mark_notify); + /* unregister_die_notifier has memory barriers */ + target_eip = 0; + mutex_unlock(&mark_mutex); + flush_icache_range(address, size); + return 0; +} +EXPORT_SYMBOL(arch_marker_set_ins_enable); --- a/arch/i386/kernel/Makefile +++ b/arch/i386/kernel/Makefile @@ -39,6 +39,7 @@ obj-$(CONFIG_VM86) += vm86.o obj-$(CONFIG_EARLY_PRINTK) += early_printk.o obj-$(CONFIG_HPET_TIMER) += hpet.o obj-$(CONFIG_K8_NB) += k8.o +obj-$(CONFIG_MARKERS_ENABLE_OPTIMIZATION) += marker.o # Make sure this is linked after any other paravirt_ops structs: see head.S obj-$(CONFIG_PARAVIRT) += paravirt.o - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/