This file contains some resource accounting functions for:
- sampling buffer memory managment
- context management
pfm_reserve_buf_space(size_t size), pfm_release_buf_space(size_t size):
- keep track of memory used for sampling buffers
- there is a per process limit set using the RLIMIT_MEMLOCK attribute
- there is a global limit controlled by perfmon and configurable via /sys/kernel/perfmon/buf_size_max
pfm_reserve_session(struct pfm_context *ctx, u32 cpu), pfm_release_session(struct pfm_context *ctx, u32 cpu):
- keep track of per-thread and system-wide sessions
- handles mutual exclusion between per-thread and system-wide context
- ensure no two system-wide context can be bound to the same CPU
(this patch was missing from my previous posting on LKML).
--- linux-2.6.18.base/perfmon/perfmon_res.c 1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.18/perfmon/perfmon_res.c 2006-09-25 12:10:13.000000000 -0700
@@ -0,0 +1,318 @@
+/*
+ * perfmon_res.c: perfmon2 resource allocations
+ *
+ * This file implements the perfmon2 interface which
+ * provides access to the hardware performance counters
+ * of the host processor.
+ *
+ * The initial version of perfmon.c was written by
+ * Ganesh Venkitachalam, IBM Corp.
+ *
+ * Then it was modified for perfmon-1.x by Stephane Eranian and
+ * David Mosberger, Hewlett Packard Co.
+ *
+ * Version Perfmon-2.x is a complete rewrite of perfmon-1.x
+ * by Stephane Eranian, Hewlett Packard Co.
+ *
+ * Copyright (c) 1999-2006 Hewlett-Packard Development Company, L.P.
+ * Contributed by Stephane Eranian <[email protected]>
+ * David Mosberger-Tang <[email protected]>
+ *
+ * More information about perfmon available at:
+ * http://perfmon2.sf.net
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ * 02111-1307 USA
+ */
+#include <linux/spinlock.h>
+#include <linux/perfmon.h>
+#include <linux/module.h>
+
+static struct pfm_sessions pfm_sessions;
+
+static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pfm_sessions_lock);
+
+/*
+ * sampling buffer allocated by perfmon must be
+ * checked against max usage thresholds for security
+ * reasons.
+ *
+ * The first level check is against the system wide limit
+ * as indicated by the system administrator in /proc/sys/kernel/perfmon
+ *
+ * The second level check is on a per-process basis using
+ * RLIMIT_MEMLOCK limit.
+ *
+ * Operating on the current task only.
+ */
+int pfm_reserve_buf_space(size_t size)
+{
+ struct mm_struct *mm;
+ unsigned long locked;
+ unsigned long buf_mem, buf_mem_max;
+
+ spin_lock(&pfm_sessions_lock);
+
+ /*
+ * check against global buffer limit
+ */
+ buf_mem_max = pfm_controls.smpl_buf_size_max;
+ buf_mem = pfm_sessions.pfs_cur_smpl_buf_mem + size;
+
+ if (buf_mem <= buf_mem_max) {
+ pfm_sessions.pfs_cur_smpl_buf_mem = buf_mem;
+
+ PFM_DBG("buf_mem_max=%lu current_buf_mem=%lu",
+ buf_mem_max,
+ buf_mem);
+ }
+ spin_unlock(&pfm_sessions_lock);
+
+ if (buf_mem > buf_mem_max) {
+ PFM_DBG("smpl buffer memory threshold reached");
+ return -ENOMEM;
+ }
+
+ /*
+ * check against RLIMIT_MEMLOCK
+ */
+ mm = get_task_mm(current);
+
+ down_write(&mm->mmap_sem);
+
+ locked = mm->locked_vm << PAGE_SHIFT;
+ locked += size;
+
+ if (locked > current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur) {
+
+ PFM_DBG("RLIMIT_MEMLOCK reached ask_locked=%lu rlim_cur=%lu",
+ locked,
+ current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur);
+
+ up_write(&mm->mmap_sem);
+ mmput(mm);
+ goto unres;
+ }
+
+ mm->locked_vm = locked >> PAGE_SHIFT;
+
+ up_write(&mm->mmap_sem);
+
+ mmput(mm);
+
+ return 0;
+
+unres:
+ /*
+ * remove global buffer memory allocation
+ */
+ spin_lock(&pfm_sessions_lock);
+
+ pfm_sessions.pfs_cur_smpl_buf_mem -= size;
+
+ spin_unlock(&pfm_sessions_lock);
+
+ return -ENOMEM;
+}
+
+void pfm_release_buf_space(size_t size)
+{
+ struct mm_struct *mm;
+
+ mm = get_task_mm(current);
+ if (mm) {
+ down_write(&mm->mmap_sem);
+
+ mm->locked_vm -= size >> PAGE_SHIFT;
+ PFM_DBG("locked_vm=%lu size=%zu", mm->locked_vm, size);
+ up_write(&mm->mmap_sem);
+
+ mmput(mm);
+ }
+
+ spin_lock(&pfm_sessions_lock);
+
+ pfm_sessions.pfs_cur_smpl_buf_mem -= size;
+
+ spin_unlock(&pfm_sessions_lock);
+}
+
+int pfm_reserve_session(struct pfm_context *ctx, u32 cpu)
+{
+ int is_system;
+
+ is_system = ctx->flags.system;
+
+ /*
+ * validy checks on cpu_mask have been done upstream
+ */
+ spin_lock(&pfm_sessions_lock);
+
+ PFM_DBG("in sys_sessions=%u task_sessions=%u syswide=%d cpu=%u",
+ pfm_sessions.pfs_sys_sessions,
+ pfm_sessions.pfs_task_sessions,
+ is_system,
+ cpu);
+
+ if (pfm_arch_reserve_session(&pfm_sessions, ctx, cpu))
+ goto abort;
+
+ if (is_system) {
+
+ BUG_ON(cpu != smp_processor_id());
+
+ /*
+ * cannot mix system wide and per-task sessions
+ */
+ if (pfm_sessions.pfs_task_sessions > 0) {
+ PFM_DBG("system wide imppossible, %u conflicting"
+ "task_sessions\n",
+ pfm_sessions.pfs_task_sessions);
+ goto abort_undo;
+ }
+
+ if (cpu_isset(cpu, pfm_sessions.pfs_sys_cpumask)) {
+ PFM_DBG("syswide not possible, conflicting session "
+ "on CPU%u\n", cpu);
+ goto abort_undo;
+ }
+
+ PFM_DBG("reserving syswide session on CPU%u currently "
+ "on CPU%u\n",
+ cpu,
+ smp_processor_id());
+
+ cpu_set(cpu, pfm_sessions.pfs_sys_cpumask);
+
+ pfm_sessions.pfs_sys_sessions++ ;
+ } else {
+ if (pfm_sessions.pfs_sys_sessions)
+ goto abort_undo;
+ pfm_sessions.pfs_task_sessions++;
+ }
+
+ PFM_DBG("out sys_sessions=%u task_sessions=%u syswide=%d cpu=%u",
+ pfm_sessions.pfs_sys_sessions,
+ pfm_sessions.pfs_task_sessions,
+ is_system,
+ cpu);
+
+ spin_unlock(&pfm_sessions_lock);
+
+ return 0;
+
+abort_undo:
+ /*
+ * must undo arch-specific reservation
+ */
+ pfm_arch_release_session(&pfm_sessions, ctx, cpu);
+abort:
+ spin_unlock(&pfm_sessions_lock);
+
+ return -EBUSY;
+}
+
+int pfm_release_session(struct pfm_context *ctx, u32 cpu)
+{
+ int is_system;
+
+ is_system = ctx->flags.system;
+
+ /*
+ * validy checks on cpu_mask have been done upstream
+ */
+ spin_lock(&pfm_sessions_lock);
+
+ PFM_DBG("in sys_sessions=%u task_sessions=%u syswide=%d cpu=%u",
+ pfm_sessions.pfs_sys_sessions,
+ pfm_sessions.pfs_task_sessions,
+ is_system, cpu);
+
+ if (is_system) {
+ cpu_clear(cpu, pfm_sessions.pfs_sys_cpumask);
+
+ pfm_sessions.pfs_sys_sessions--;
+ } else {
+ pfm_sessions.pfs_task_sessions--;
+ }
+
+ pfm_arch_release_session(&pfm_sessions, ctx, cpu);
+
+ PFM_DBG("out sys_sessions=%u task_sessions=%u syswide=%d cpu=%u",
+ pfm_sessions.pfs_sys_sessions,
+ pfm_sessions.pfs_task_sessions,
+ is_system, cpu);
+
+ spin_unlock(&pfm_sessions_lock);
+
+ return 0;
+}
+
+static struct _pfm_pmu_config empty_config={
+ .pmu_name = "Unknown",
+ .version = "0.0"
+};
+
+ssize_t pfm_sysfs_session_show(char *buf, size_t sz, int what)
+{
+ struct _pfm_pmu_config *p;
+ ssize_t ret = -EINVAL;
+
+ spin_lock(&pfm_sessions_lock);
+
+ if (pfm_pmu_conf)
+ p = pfm_pmu_conf;
+ else
+ p = &empty_config;
+
+ switch(what) {
+ case 0: ret = snprintf(buf, sz, "%u\n", pfm_sessions.pfs_task_sessions);
+ break;
+ case 1: ret = snprintf(buf, sz, "%u\n", pfm_sessions.pfs_sys_sessions);
+ break;
+ case 2: ret = snprintf(buf, sz, "%zu\n", pfm_sessions.pfs_cur_smpl_buf_mem);
+ break;
+ }
+
+ spin_unlock(&pfm_sessions_lock);
+
+ return ret;
+}
+int pfm_sessions_block(void)
+{
+ int ret = 0;
+
+ spin_lock(&pfm_sessions_lock);
+
+ if (pfm_sessions.pfs_task_sessions || pfm_sessions.pfs_sys_sessions)
+ ret = -1;
+
+ pfm_pmu_conf_get(0);
+
+ /* disable creation of new contexts */
+ atomic_inc(&perfmon_disabled);
+
+ spin_unlock(&pfm_sessions_lock);
+ return ret;
+}
+EXPORT_SYMBOL(pfm_sessions_block);
+
+void pfm_sessions_unblock(void)
+{
+ atomic_dec(&perfmon_disabled);
+ pfm_pmu_conf_put();
+}
+EXPORT_SYMBOL(pfm_sessions_unblock);
+
+
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