This patch contains the perfmon2 system call interface.
The interface consist of 12 new system calls. The front-end
of each system call is implemented in perfmon_syscall.c.
The front-end takes care of copying the parameters into
kernel structures and also verifies that the perfmon state
is appropriate for each command. The back-end of each syscall
is implemented either in the core (perfmon.c) or in feature
specific file (e.g. perfmon_sets.c).
The system calls are defined as follows:
sys_pfm_create_context():
- create a new perfmon2 context and returns a file descriptor in
the pfarg_ctx_t parameters. This is the first call an application
must make to do monitoring
- rewritten to pass sampling format identification as a string
- file descriptor is now returned by call
sys_pfm_write_pmcs():
- program the PMU configuration registers. Accepts vector of arguments
of type pfarg_pmc_t
sys_pfm_write_pmds():
- program the PMU data registers. Accepts a vector of arguments of type
pfarg_pmd_t
sys_pfm_read_pmds():
- read the PMU data registers. Accepts a vector of arguments of type
pfarg_pmd_t
sys_pfm_restart():
- indicate that application is doing processing an overflow notification
sys_pfm_start():
- start monitoring
sys_pfm_stop():
- stop monitoring
sys_pfm_load_context():
- attach a perfmon2 context to a task or the current processor.
sys_pfm_unload_context():
- detach the perfmon2 context
sys_pfm_create_evtsets():
- create or change an event sets. By default a context is created with only one
set
sys_pfm_delete_evtsets():
- delete any explicitely created event set
sys_pfm_getinfo_evtsets():
- get information about event sets, such as the number of activations. Accepts
vector arguments of type pfarg_setinfo_t
There are other more indirect system calls related to the fact that a context uses a file
descriptor. Those system calls are in perfmon_file.c and part of another patch.
--- linux-2.6.19.base/perfmon/perfmon_syscalls.c 1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.19/perfmon/perfmon_syscalls.c 2006-12-03 14:15:48.000000000 -0800
@@ -0,0 +1,968 @@
+/*
+ * perfmon_syscalls.c: perfmon2 system call interface
+ *
+ * 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/kernel.h>
+#include <linux/perfmon.h>
+#include <linux/fs.h>
+#include <linux/ptrace.h>
+#include <asm/uaccess.h>
+
+/*
+ * Context locking rules:
+ * ---------------------
+ * - any thread with access to the file descriptor of a context can
+ * potentially issue perfmon calls
+ *
+ * - calls must be serialized to guarantee correctness
+ *
+ * - as soon as a context is attached to a thread or CPU, it may be
+ * actively monitoring. On some architectures, such as IA-64, this
+ * is true even though the pfm_start() call has not been made. This
+ * comes from the fact that on some architectures, it is possible to
+ * start/stop monitoring from userland.
+ *
+ * - If monitoring is active, then there can PMU interrupts. Because
+ * context accesses must be serialized, the perfmon system calls
+ * must mask interrupts as soon as the context is attached.
+ *
+ * - perfmon system calls that operate with the context unloaded cannot
+ * assume it is actually unloaded when they are called. They first need
+ * to check and for that they need interrupts masked. Then if the context
+ * is actually unloaded, they can unmask interrupts.
+ *
+ * - interrupt masking holds true for other internal perfmon functions as
+ * well. Except for PMU interrupt handler because those interrupts cannot
+ * be nested.
+ *
+ * - we mask ALL interrupts instead of just the PMU interrupt because we
+ * also need to protect against timer interrupts which could trigger
+ * a set switch.
+ */
+
+/*
+ * cannot attach if :
+ * - kernel task
+ * - task not owned by caller
+ * - task is dead or zombie
+ * - cannot use blocking notification when self-monitoring
+ */
+static int pfm_task_incompatible(struct pfm_context *ctx, struct task_struct *task)
+{
+ /*
+ * no kernel task or task not owned by caller
+ */
+ if (!task->mm) {
+ PFM_DBG("cannot attach to kernel thread [%d]", task->pid);
+ return -EPERM;
+ }
+
+ /*
+ * cannot block in self-monitoring mode
+ */
+ if (ctx->flags.block && task == current) {
+ PFM_DBG("cannot load a in blocking mode on self for [%d]",
+ task->pid);
+ return -EINVAL;
+ }
+
+ if (task->exit_state == EXIT_ZOMBIE || task->exit_state == EXIT_DEAD) {
+ PFM_DBG("cannot attach to zombie/dead task [%d]", task->pid);
+ return -EBUSY;
+ }
+ return 0;
+}
+
+/*
+ * This function is used in per-thread mode only AND when not
+ * self-monitoring. It finds the task to monitor and checks
+ * that the caller has persmissions to attach. It also checks
+ * that the task is stopped via ptrace so that we can safely
+ * modify its state.
+ *
+ * task refcount is increment when succesful.
+ */
+int pfm_get_task(struct pfm_context *ctx, pid_t pid, struct task_struct **task)
+{
+ struct task_struct *p;
+ int ret = 0, ret1 = 0;
+
+ /*
+ * When attaching to another thread we must ensure
+ * that the thread is actually stopped. Just like with
+ * perfmon system calls, we enforce that the thread
+ * be ptraced and STOPPED by using ptrace_check_attach().
+ *
+ * As a consequence, only the ptracing parent can actually
+ * attach a context to a thread. Obviously, this constraint
+ * does not exist for self-monitoring threads.
+ *
+ * We use ptrace_may_attach() to check for permission.
+ * No permission checking is needed for self monitoring.
+ */
+ read_lock(&tasklist_lock);
+
+ p = find_task_by_pid(pid);
+ if (p)
+ get_task_struct(p);
+
+ read_unlock(&tasklist_lock);
+
+ if (p == NULL)
+ return -ESRCH;
+
+ ret = -EPERM;
+
+ /*
+ * returns 0 if cannot attach
+ */
+ ret1 = ptrace_may_attach(p);
+ if (ret1)
+ ret = ptrace_check_attach(p, 0);
+
+ PFM_DBG("may_attach=%d check_attach=%d", ret1, ret);
+
+ if (ret || !ret1)
+ goto error;
+
+ ret = pfm_task_incompatible(ctx, p);
+ if (ret)
+ goto error;
+
+ *task = p;
+
+ return 0;
+error:
+ if (!(ret1 || ret))
+ ret = -EPERM;
+
+ put_task_struct(p);
+
+ return ret;
+}
+
+int pfm_check_task_state(struct pfm_context *ctx, int check_mask,
+ unsigned long *flags)
+{
+ struct task_struct *task;
+ unsigned long local_flags, new_flags;
+ int state, ret;
+
+recheck:
+ /*
+ * task is NULL for system-wide context
+ */
+ task = ctx->task;
+ state = ctx->state;
+ local_flags = *flags;
+
+ PFM_DBG("state=%d check_mask=0x%x", state, check_mask);
+ /*
+ * if the context is detached, then we do not touch
+ * hardware, therefore there is not restriction on when we can
+ * access it.
+ */
+ if (state == PFM_CTX_UNLOADED)
+ return 0;
+ /*
+ * no command can operate on a zombie context.
+ * A context becomes zombie when the file that identifies
+ * it is closed while the context is still attached to the
+ * thread it monitors.
+ */
+ if (state == PFM_CTX_ZOMBIE)
+ return -EINVAL;
+
+ /*
+ * at this point, state is PFM_CTX_LOADED or PFM_CTX_MASKED
+ */
+
+ /*
+ * some commands require the context to be unloaded to operate
+ */
+ if (check_mask & PFM_CMD_UNLOADED) {
+ PFM_DBG("state=%d, cmd needs context unloaded", state);
+ return -EBUSY;
+ }
+
+ /*
+ * self-monitoring always ok.
+ */
+ if (task == current)
+ return 0;
+
+ /*
+ * for syswide, the calling thread must be running on the cpu
+ * the context is bound to. There cannot be preemption as we
+ * check with interrupts disabled.
+ */
+ if (ctx->flags.system) {
+ if (ctx->cpu != smp_processor_id())
+ return -EBUSY;
+ return 0;
+ }
+
+ /*
+ * at this point, monitoring another thread
+ */
+
+ /*
+ * the pfm_unload_context() command is allowed on masked context
+ */
+ if (state == PFM_CTX_MASKED && !(check_mask & PFM_CMD_UNLOAD))
+ return 0;
+
+ /*
+ * When we operate on another thread, we must wait for it to be
+ * stopped and completely off any CPU as we need to access the
+ * PMU state (or machine state).
+ *
+ * A thread can be put in the STOPPED state in various ways
+ * including PTRACE_ATTACH, or when it receives a SIGSTOP signal.
+ * We enforce that the thread must be ptraced, so it is stopped
+ * AND it CANNOT Wake up while we operate on it because this
+ * would require an action for the ptracing parent which is the
+ * thread that is calling this function.
+ *
+ * The dependency on ptrace, imposes that only the ptracing
+ * parent can issue command on a thread. This is unfortunate
+ * but we do not know of a better way of doing this.
+ */
+ if (check_mask & PFM_CMD_STOPPED) {
+
+ spin_unlock_irqrestore(&ctx->lock, local_flags);
+
+ /*
+ * check that the thread is ptraced AND STOPPED
+ */
+ ret = ptrace_check_attach(task, 0);
+
+ spin_lock_irqsave(&ctx->lock, new_flags);
+
+ /*
+ * flags may be different than when we released the lock
+ */
+ *flags = new_flags;
+
+ if (ret)
+ return ret;
+ /*
+ * we must recheck to verify if state has changed
+ */
+ if (ctx->state != state) {
+ PFM_DBG("old_state=%d new_state=%d",
+ state,
+ ctx->state);
+ goto recheck;
+ }
+ }
+ return 0;
+}
+
+int pfm_get_args(void __user *ureq, size_t sz, size_t lsz, void *laddr,
+ void **req, void **ptr_free)
+{
+ void *addr;
+
+ /*
+ * check if we can get by with stack buffer
+ */
+ if (sz <= lsz) {
+ *req = laddr;
+ *ptr_free = NULL;
+ return copy_from_user(laddr, ureq, sz) ? -EFAULT : 0;
+ }
+
+ if (unlikely(sz > pfm_controls.arg_mem_max)) {
+ PFM_DBG("argument too big %zu max=%zu",
+ sz,
+ pfm_controls.arg_mem_max);
+ return -E2BIG;
+ }
+
+ addr = kmalloc(sz, GFP_KERNEL);
+ if (unlikely(addr == NULL))
+ return -ENOMEM;
+
+ if (copy_from_user(addr, ureq, sz)) {
+ kfree(addr);
+ return -EFAULT;
+ }
+ *req = *ptr_free = addr;
+
+ return 0;
+}
+
+int pfm_get_smpl_arg(char __user *fmt_uname, void __user *fmt_uarg, size_t usize, void **arg,
+ struct pfm_smpl_fmt **fmt)
+{
+ struct pfm_smpl_fmt *f;
+ char *fmt_name;
+ void *addr = NULL;
+ size_t sz;
+ int ret;
+
+ fmt_name = getname(fmt_uname);
+ if (!fmt_name) {
+ PFM_DBG("getname failed");
+ return -ENOMEM;
+ }
+
+ /*
+ * find fmt and increase refcount
+ */
+ f = pfm_smpl_fmt_get(fmt_name);
+
+ putname(fmt_name);
+
+ if (f == NULL) {
+ PFM_DBG("buffer format not found");
+ return -EINVAL;
+ }
+
+ /*
+ * expected format argument size
+ */
+ sz = f->fmt_arg_size;
+
+ /*
+ * check user size matches expected size
+ * usize = -1 is for IA-64 backward compatibility
+ */
+ ret = -EINVAL;
+ if (sz != usize && usize != -1) {
+ PFM_DBG("invalid arg size %zu, format expects %zu",
+ usize, sz);
+ goto error;
+ }
+
+ ret = -ENOMEM;
+ addr = kmalloc(sz, GFP_KERNEL);
+ if (addr == NULL)
+ goto error;
+
+ ret = -EFAULT;
+ if (copy_from_user(addr, fmt_uarg, sz))
+ goto error;
+
+ *arg = addr;
+ *fmt = f;
+ return 0;
+
+error:
+ kfree(addr);
+ pfm_smpl_fmt_put(f);
+ return ret;
+}
+
+/*
+ * unlike the other perfmon system calls, this one return a file descriptor
+ * or a value < 0 in case of error, very much like open() or socket()
+ */
+asmlinkage long sys_pfm_create_context(struct pfarg_ctx __user *ureq,
+ char __user *fmt_name,
+ void __user *fmt_uarg, size_t fmt_size)
+{
+ struct pfarg_ctx req;
+ struct pfm_context *new_ctx;
+ struct pfm_smpl_fmt *fmt = NULL;
+ void *fmt_arg = NULL;
+ int ret;
+
+ if (atomic_read(&perfmon_disabled))
+ return -ENOSYS;
+
+ if (copy_from_user(&req, ureq, sizeof(req)))
+ return -EFAULT;
+
+ if (fmt_name) {
+ ret = pfm_get_smpl_arg(fmt_name, fmt_uarg, fmt_size, &fmt_arg, &fmt);
+ if (ret)
+ goto abort;
+ }
+
+ ret = __pfm_create_context(&req, fmt, fmt_arg, PFM_NORMAL, &new_ctx);
+
+ kfree(fmt_arg);
+abort:
+ return ret;
+}
+
+asmlinkage long sys_pfm_write_pmcs(int fd, struct pfarg_pmc __user *ureq, int count)
+{
+ struct pfm_context *ctx;
+ struct file *filp;
+ struct pfarg_pmc pmcs[PFM_PMC_STK_ARG];
+ struct pfarg_pmc *req;
+ void *fptr;
+ unsigned long flags;
+ size_t sz;
+ int ret, fput_needed;
+
+ if (count < 0 || count >= PFM_MAX_ARG_COUNT(ureq))
+ return -EINVAL;
+
+ sz = count*sizeof(*ureq);
+
+ filp = fget_light(fd, &fput_needed);
+ if (unlikely(filp == NULL)) {
+ PFM_DBG("invalid fd %d", fd);
+ return -EBADF;
+ }
+
+ ctx = filp->private_data;
+ ret = -EBADF;
+
+ if (unlikely(!ctx || filp->f_op != &pfm_file_ops)) {
+ PFM_DBG("fd %d not related to perfmon", fd);
+ goto error;
+ }
+
+ ret = pfm_get_args(ureq, sz, sizeof(pmcs), pmcs, (void **)&req, &fptr);
+ if (ret)
+ goto error;
+
+ spin_lock_irqsave(&ctx->lock, flags);
+
+ ret = pfm_check_task_state(ctx, PFM_CMD_STOPPED, &flags);
+ if (!ret)
+ ret = __pfm_write_pmcs(ctx, req, count);
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+ if (copy_to_user(ureq, req, sz))
+ ret = -EFAULT;
+
+ /*
+ * This function may be on the critical path.
+ * We want to avoid the branch if unecessary.
+ */
+ if (fptr)
+ kfree(fptr);
+error:
+ fput_light(filp, fput_needed);
+
+ return ret;
+}
+
+asmlinkage long sys_pfm_write_pmds(int fd, struct pfarg_pmd __user *ureq, int count)
+{
+ struct pfm_context *ctx;
+ struct file *filp;
+ struct pfarg_pmd pmds[PFM_PMD_STK_ARG];
+ struct pfarg_pmd *req;
+ void *fptr;
+ unsigned long flags;
+ size_t sz;
+ int ret, fput_needed;
+
+ if (count < 0 || count >= PFM_MAX_ARG_COUNT(ureq))
+ return -EINVAL;
+
+ sz = count*sizeof(*ureq);
+
+ filp = fget_light(fd, &fput_needed);
+ if (unlikely(filp == NULL)) {
+ PFM_DBG("invalid fd %d", fd);
+ return -EBADF;
+ }
+
+ ctx = filp->private_data;
+ ret = -EBADF;
+
+ if (unlikely(!ctx || filp->f_op != &pfm_file_ops)) {
+ PFM_DBG("fd %d not related to perfmon", fd);
+ goto error;
+ }
+
+ ret = pfm_get_args(ureq, sz, sizeof(pmds), pmds, (void **)&req, &fptr);
+ if (ret)
+ goto error;
+
+ spin_lock_irqsave(&ctx->lock, flags);
+
+ ret = pfm_check_task_state(ctx, PFM_CMD_STOPPED, &flags);
+ if (!ret)
+ ret = __pfm_write_pmds(ctx, req, count, 0);
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+ if (copy_to_user(ureq, req, sz))
+ ret = -EFAULT;
+
+ if (fptr)
+ kfree(fptr);
+error:
+ fput_light(filp, fput_needed);
+
+ return ret;
+}
+
+asmlinkage long sys_pfm_read_pmds(int fd, struct pfarg_pmd __user *ureq, int count)
+{
+ struct pfm_context *ctx;
+ struct file *filp;
+ struct pfarg_pmd pmds[PFM_PMD_STK_ARG];
+ struct pfarg_pmd *req;
+ void *fptr;
+ unsigned long flags;
+ size_t sz;
+ int ret, fput_needed;
+
+ if (count < 0 || count >= PFM_MAX_ARG_COUNT(ureq))
+ return -EINVAL;
+
+ sz = count*sizeof(*ureq);
+
+ filp = fget_light(fd, &fput_needed);
+ if (unlikely(filp == NULL)) {
+ PFM_DBG("invalid fd %d", fd);
+ return -EBADF;
+ }
+
+ ctx = filp->private_data;
+ ret = -EBADF;
+
+ if (unlikely(!ctx || filp->f_op != &pfm_file_ops)) {
+ PFM_DBG("fd %d not related to perfmon", fd);
+ goto error;
+ }
+
+ ret = pfm_get_args(ureq, sz, sizeof(pmds), pmds, (void **)&req, &fptr);
+ if (ret)
+ goto error;
+
+ spin_lock_irqsave(&ctx->lock, flags);
+
+ ret = pfm_check_task_state(ctx, PFM_CMD_STOPPED, &flags);
+ if (!ret)
+ ret = __pfm_read_pmds(ctx, req, count);
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+ if (copy_to_user(ureq, req, sz))
+ ret = -EFAULT;
+
+ if (fptr)
+ kfree(req);
+error:
+ fput_light(filp, fput_needed);
+ return ret;
+}
+
+asmlinkage long sys_pfm_restart(int fd)
+{
+ struct pfm_context *ctx;
+ struct file *filp;
+ unsigned long flags;
+ int ret, fput_needed;
+
+ filp = fget_light(fd, &fput_needed);
+ if (unlikely(filp == NULL)) {
+ PFM_DBG("invalid fd %d", fd);
+ return -EBADF;
+ }
+
+ ctx = filp->private_data;
+ ret = -EBADF;
+
+ if (unlikely(!ctx || filp->f_op != &pfm_file_ops)) {
+ PFM_DBG("fd %d not related to perfmon", fd);
+ goto error;
+ }
+
+ spin_lock_irqsave(&ctx->lock, flags);
+
+ ret = pfm_check_task_state(ctx, 0, &flags);
+ if (!ret)
+ ret = __pfm_restart(ctx);
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+error:
+ fput_light(filp, fput_needed);
+ return ret;
+}
+
+asmlinkage long sys_pfm_stop(int fd)
+{
+ struct pfm_context *ctx;
+ struct file *filp;
+ unsigned long flags;
+ int ret, fput_needed;
+
+ filp = fget_light(fd, &fput_needed);
+ if (unlikely(filp == NULL)) {
+ PFM_DBG("invalid fd %d", fd);
+ return -EBADF;
+ }
+
+ ctx = filp->private_data;
+ ret = -EBADF;
+
+ if (unlikely(!ctx || filp->f_op != &pfm_file_ops)) {
+ PFM_DBG("fd %d not related to perfmon", fd);
+ goto error;
+ }
+
+ spin_lock_irqsave(&ctx->lock, flags);
+
+ ret = pfm_check_task_state(ctx, PFM_CMD_STOPPED, &flags);
+ if (!ret)
+ ret = __pfm_stop(ctx);
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+error:
+ fput_light(filp, fput_needed);
+ return ret;
+}
+
+asmlinkage long sys_pfm_start(int fd, struct pfarg_start __user *ureq)
+{
+ struct pfm_context *ctx;
+ struct file *filp;
+ struct pfarg_start req;
+ unsigned long flags;
+ int ret, fput_needed;
+
+ filp = fget_light(fd, &fput_needed);
+ if (unlikely(filp == NULL)) {
+ PFM_DBG("invalid fd %d", fd);
+ return -EBADF;
+ }
+
+ ctx = filp->private_data;
+ ret = -EBADF;
+
+ if (unlikely(!ctx || filp->f_op != &pfm_file_ops)) {
+ PFM_DBG("fd %d not related to perfmon", fd);
+ goto error;
+ }
+
+ /*
+ * the one argument is actually optional
+ */
+ if (ureq && copy_from_user(&req, ureq, sizeof(req)))
+ return -EFAULT;
+
+ spin_lock_irqsave(&ctx->lock, flags);
+
+ ret = pfm_check_task_state(ctx, PFM_CMD_STOPPED, &flags);
+ if (!ret)
+ ret = __pfm_start(ctx, ureq ? &req : NULL);
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+error:
+ fput_light(filp, fput_needed);
+ return ret;
+}
+
+asmlinkage long sys_pfm_load_context(int fd, struct pfarg_load __user *ureq)
+{
+ struct pfm_context *ctx;
+ struct task_struct *task;
+ struct file *filp;
+ unsigned long flags;
+ struct pfarg_load req;
+ int ret, fput_needed;
+
+ if (copy_from_user(&req, ureq, sizeof(req)))
+ return -EFAULT;
+
+ filp = fget_light(fd, &fput_needed);
+ if (unlikely(filp == NULL)) {
+ PFM_DBG("invalid fd %d", fd);
+ return -EBADF;
+ }
+
+ task = NULL;
+ ctx = filp->private_data;
+ ret = -EBADF;
+
+ if (unlikely(!ctx || filp->f_op != &pfm_file_ops)) {
+ PFM_DBG("fd %d not related to perfmon", fd);
+ goto error;
+ }
+
+ /*
+ * in per-thread mode (not self-monitoring), get a reference
+ * on task to monitor. This must be done with interrupts enabled
+ * Upon succesful return, refcount on task is increased.
+ *
+ * fget_light() is protecting the context.
+ */
+ if (!ctx->flags.system) {
+ if (req.load_pid != current->pid) {
+ ret = pfm_get_task(ctx, req.load_pid, &task);
+ if (ret)
+ goto error;
+ } else
+ task = current;
+ }
+
+ /*
+ * irqsave is required to avoid race in case context is already
+ * loaded or with switch timeout in the case of self-monitoring
+ */
+ spin_lock_irqsave(&ctx->lock, flags);
+
+ ret = pfm_check_task_state(ctx, PFM_CMD_UNLOADED, &flags);
+ if (!ret)
+ ret = __pfm_load_context(ctx, &req, task);
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+ /*
+ * in per-thread mode (not self-monitoring), we need
+ * to decrease refcount on task to monitor:
+ * - load successful: we have a reference to the task in ctx->task
+ * - load failed : undo the effect of pfm_get_task()
+ */
+ if (task && task != current)
+ put_task_struct(task);
+error:
+ fput_light(filp, fput_needed);
+ return ret;
+}
+
+asmlinkage long sys_pfm_unload_context(int fd)
+{
+ struct pfm_context *ctx;
+ struct file *filp;
+ unsigned long flags;
+ int ret, fput_needed;
+ int is_system, can_release = 0;
+ u32 cpu;
+
+ filp = fget_light(fd, &fput_needed);
+ if (unlikely(filp == NULL)) {
+ PFM_DBG("invalid fd %d", fd);
+ return -EBADF;
+ }
+
+ ctx = filp->private_data;
+ ret = -EBADF;
+ is_system = ctx->flags.system;
+ cpu = ctx->cpu;
+
+ if (unlikely(!ctx || filp->f_op != &pfm_file_ops)) {
+ PFM_DBG("fd %d not related to perfmon", fd);
+ goto error;
+ }
+
+ spin_lock_irqsave(&ctx->lock, flags);
+
+ ret = pfm_check_task_state(ctx, PFM_CMD_STOPPED|PFM_CMD_UNLOAD, &flags);
+ if (!ret)
+ ret = __pfm_unload_context(ctx, &can_release);
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+ if (can_release)
+ pfm_release_session(is_system, cpu);
+
+error:
+ fput_light(filp, fput_needed);
+ return ret;
+}
+
+asmlinkage long sys_pfm_create_evtsets(int fd, struct pfarg_setdesc __user *ureq, int count)
+{
+ struct pfm_context *ctx;
+ struct file *filp;
+ struct pfarg_setdesc *req;
+ void *fptr;
+ unsigned long flags;
+ size_t sz;
+ int ret, fput_needed;
+
+ if (count < 0 || count >= PFM_MAX_ARG_COUNT(ureq))
+ return -EINVAL;
+
+ sz = count*sizeof(*ureq);
+
+ filp = fget_light(fd, &fput_needed);
+ if (unlikely(filp == NULL)) {
+ PFM_DBG("invalid fd %d", fd);
+ return -EBADF;
+ }
+
+ ctx = filp->private_data;
+ ret = -EBADF;
+
+ if (unlikely(!ctx || filp->f_op != &pfm_file_ops)) {
+ PFM_DBG("fd %d not related to perfmon", fd);
+ goto error;
+ }
+
+ ret = pfm_get_args(ureq, sz, 0, NULL, (void **)&req, &fptr);
+ if (ret)
+ goto error;
+
+ /*
+ * must mask interrupts because we do not know the state of context,
+ * could be attached and we could be getting PMU interrupts. So
+ * we mask and lock context and we check and possibly relax masking
+ */
+ spin_lock_irqsave(&ctx->lock, flags);
+
+ ret = pfm_check_task_state(ctx, PFM_CMD_UNLOADED, &flags);
+ if (!ret)
+ ret = __pfm_create_evtsets(ctx, req, count);
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+ if (copy_to_user(ureq, req, sz))
+ ret = -EFAULT;
+
+ kfree(fptr);
+
+error:
+ fput_light(filp, fput_needed);
+ return ret;
+}
+
+asmlinkage long sys_pfm_getinfo_evtsets(int fd, struct pfarg_setinfo __user *ureq, int count)
+{
+ struct pfm_context *ctx;
+ struct file *filp;
+ struct pfarg_setinfo *req;
+ void *fptr;
+ unsigned long flags;
+ size_t sz;
+ int ret, fput_needed;
+
+ if (count < 0 || count >= PFM_MAX_ARG_COUNT(ureq))
+ return -EINVAL;
+
+ sz = count*sizeof(*ureq);
+
+ filp = fget_light(fd, &fput_needed);
+ if (unlikely(filp == NULL)) {
+ PFM_DBG("invalid fd %d", fd);
+ return -EBADF;
+ }
+
+ ctx = filp->private_data;
+ ret = -EBADF;
+
+ if (unlikely(!ctx || filp->f_op != &pfm_file_ops)) {
+ PFM_DBG("fd %d not related to perfmon", fd);
+ goto error;
+ }
+
+ ret = pfm_get_args(ureq, sz, 0, NULL, (void **)&req, &fptr);
+ if (ret)
+ goto error;
+
+ /*
+ * this command operate even when context is loaded, so we need
+ * to keep interrupts masked to avoid a race with PMU interrupt
+ * which may switch active set
+ */
+ spin_lock_irqsave(&ctx->lock, flags);
+
+ ret = pfm_check_task_state(ctx, 0, &flags);
+ if (!ret)
+ ret = __pfm_getinfo_evtsets(ctx, req, count);
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+ if (copy_to_user(ureq, req, sz))
+ ret = -EFAULT;
+
+ kfree(fptr);
+error:
+ fput_light(filp, fput_needed);
+ return ret;
+}
+
+asmlinkage long sys_pfm_delete_evtsets(int fd, struct pfarg_setinfo __user *ureq, int count)
+{
+ struct pfm_context *ctx;
+ struct file *filp;
+ struct pfarg_setinfo *req;
+ void *fptr;
+ unsigned long flags;
+ size_t sz;
+ int ret, fput_needed;
+
+ if (count < 0 || count >= PFM_MAX_ARG_COUNT(ureq))
+ return -EINVAL;
+
+ sz = count*sizeof(*ureq);
+
+ filp = fget_light(fd, &fput_needed);
+ if (unlikely(filp == NULL)) {
+ PFM_DBG("invalid fd %d", fd);
+ return -EBADF;
+ }
+
+ ctx = filp->private_data;
+ ret = -EBADF;
+
+ if (unlikely(!ctx || filp->f_op != &pfm_file_ops)) {
+ PFM_DBG("fd %d not related to perfmon", fd);
+ goto error;
+ }
+
+ ret = pfm_get_args(ureq, sz, 0, NULL, (void **)&req, &fptr);
+ if (ret)
+ goto error;
+
+ /*
+ * must mask interrupts because we do not know the state of context,
+ * could be attached and we could be getting PMU interrupts
+ */
+ spin_lock_irqsave(&ctx->lock, flags);
+
+ ret = pfm_check_task_state(ctx, PFM_CMD_UNLOADED, &flags);
+ if (!ret)
+ ret = __pfm_delete_evtsets(ctx, req, count);
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+ if (copy_to_user(ureq, req, sz))
+ ret = -EFAULT;
+
+ kfree(fptr);
+
+error:
+ fput_light(filp, fput_needed);
+ return ret;
+}
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