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
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-2.6.17.9.base/perfmon/perfmon_syscalls.c 1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.17.9/perfmon/perfmon_syscalls.c 2006-08-21 03:37:46.000000000 -0700
@@ -0,0 +1,712 @@
+/*
+ * 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://www.hpl.hp.com/research/linux/perfmon
+ */
+#include <linux/kernel.h>
+#include <linux/perfmon.h>
+#include <linux/fs.h>
+#include <asm/uaccess.h>
+
+struct pfm_context * pfm_get_ctx(int fd)
+{
+ struct file *filp;
+ struct pfm_context *ctx;
+
+ filp = fget(fd);
+ if (unlikely(filp == NULL)) {
+ PFM_DBG("invalid fd %d", fd);
+ return NULL;
+ }
+
+ if (unlikely(filp->f_op != &pfm_file_ops)) {
+ PFM_DBG("fd %d not related to perfmon", fd);
+ fput(filp);
+ return NULL;
+ }
+ ctx = filp->private_data;
+
+ /*
+ * sanity check
+ */
+ if (filp != ctx->filp && ctx->filp) {
+ PFM_DBG("filp is different");
+ }
+
+ /*
+ * update filp
+ */
+ ctx->filp = filp;
+ return ctx;
+}
+
+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, old_state;
+
+recheck:
+ /*
+ * task is NULL for system-wide context
+ */
+ task = ctx->task;
+ state = ctx->state;
+ local_flags = *flags;
+
+ PFM_DBG("state=%d [%d] task_state=%ld check_mask=0x%x",
+ state,
+ task ? task->pid : -1,
+ task ? task->state : -1, check_mask);
+
+ if (state == PFM_CTX_UNLOADED)
+ return 0;
+ /*
+ * no command can operate on a zombie context
+ */
+ 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 unloaded", state);
+ return -EBUSY;
+ }
+
+ /*
+ * self-monitoring always ok.
+ */
+ if (task == current)
+ return 0;
+
+ /*
+ * for syswide, we accept if running on the cpu the context is bound
+ * to. When monitoring another thread, must wait until stopped.
+ */
+ 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;
+
+ /*
+ * We could lift this restriction for UP but it would mean that
+ * the user has no guarantee the task would not run between
+ * two successive calls to perfmonctl(). That's probably OK.
+ * If this user wants to ensure the task does not run, then
+ * the task must be stopped.
+ */
+ if (check_mask & PFM_CMD_STOPPED) {
+ if ((task->state != TASK_STOPPED)
+ && (task->state != TASK_TRACED)) {
+ PFM_DBG("[%d] task not in stopped state", task->pid);
+ return -EBUSY;
+ }
+ /*
+ * task is now stopped, wait for ctxsw out
+ *
+ * This is an interesting point in the code.
+ * We need to unprotect the context because
+ * the pfm_ctxswout_thread() routines needs to grab
+ * the same lock. There are danger in doing
+ * this because it leaves a window open for
+ * another task to get access to the context
+ * and possibly change its state. The one thing
+ * that is not possible is for the context to disappear
+ * because we are protected by the VFS layer, i.e.,
+ * get_fd()/put_fd().
+ */
+ old_state = state;
+
+ PFM_DBG("going wait_inactive for [%d] state=%ld flags=0x%lx",
+ task->pid,
+ task->state,
+ local_flags);
+
+ spin_unlock_irqrestore(&ctx->lock, local_flags);
+
+ wait_task_inactive(task);
+
+ spin_lock_irqsave(&ctx->lock, new_flags);
+
+ /*
+ * flags may be different than when we released the lock
+ */
+ *flags = new_flags;
+
+ /*
+ * we must recheck to verify if state has changed
+ */
+ if (ctx->state != old_state) {
+ PFM_DBG("old_state=%d new_state=%d",
+ old_state,
+ ctx->state);
+ goto recheck;
+ }
+ }
+ return 0;
+}
+
+int pfm_get_args(void __user *ureq, size_t sz, size_t max_sz, void *laddr,
+ void **req)
+{
+ void *addr;
+
+ if (sz <= max_sz) {
+ *req = laddr;
+ return copy_from_user(laddr, ureq, sz);
+ }
+
+ if (unlikely(sz > pfm_controls.arg_size_max)) {
+ PFM_DBG("argument too big %zu max=%zu",
+ sz,
+ pfm_controls.arg_size_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 = addr;
+
+ return 0;
+}
+
+int pfm_get_smpl_arg(pfm_uuid_t uuid, void __user *uaddr, size_t usize, void **arg,
+ struct pfm_smpl_fmt **fmt)
+{
+ struct pfm_smpl_fmt *f;
+ void *addr = NULL;
+ size_t sz;
+ int ret;
+
+ if (!pfm_use_smpl_fmt(uuid))
+ return 0;
+
+ /*
+ * find fmt and increase refcount
+ */
+ f = pfm_smpl_fmt_get(uuid);
+ if (f == NULL) {
+ PFM_DBG("buffer format not found");
+ return -EINVAL;
+ }
+
+ sz = f->fmt_arg_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, uaddr, sz))
+ goto error;
+
+ *arg = addr;
+ *fmt = f;
+ return 0;
+
+error:
+ kfree(addr);
+ pfm_smpl_fmt_put(f);
+ return ret;
+}
+
+/*
+ * function invoked in case, pfm_context_create fails
+ * at the last operation, copy_to_user. It needs to
+ * undo memory allocations and free the file descriptor
+ */
+#ifndef CONFIG_IA64_PERFMON_COMPAT
+static
+#endif
+void pfm_undo_create_context_fd(int fd, struct pfm_context *ctx)
+{
+ struct files_struct *files = current->files;
+ struct file *file;
+
+ file = fget(fd);
+ /*
+ * there is no fd_uninstall(), so we do it
+ * here. put_unused_fd() does not remove the
+ * effect of fd_install().
+ */
+
+ spin_lock(&files->file_lock);
+ files->fd_array[fd] = NULL;
+ spin_unlock(&files->file_lock);
+
+ /*
+ * undo the fget()
+ */
+ fput(file);
+
+ /*
+ * decrement ref count and kill file
+ */
+ put_filp(file);
+
+ put_unused_fd(fd);
+
+ pfm_context_free(ctx);
+}
+
+asmlinkage long sys_pfm_create_context(struct pfarg_ctx __user *ureq,
+ void __user *uarg, size_t smpl_size)
+{
+ struct pfarg_ctx req;
+ struct pfm_context *new_ctx;
+ struct pfm_smpl_fmt *fmt = NULL;
+ void *smpl_arg = NULL;
+ int ret;
+
+ if (copy_from_user(&req, ureq, sizeof(req)))
+ return -EFAULT;
+
+ ret = pfm_get_smpl_arg(req.ctx_smpl_buf_id, uarg, smpl_size,
+ &smpl_arg, &fmt);
+ if (ret)
+ goto abort;
+
+ ret = __pfm_create_context(&req, fmt, smpl_arg, PFM_NORMAL, NULL, &new_ctx);
+
+ /*
+ * copy_user return value overrides command return value
+ */
+ if (!ret) {
+ if (copy_to_user(ureq, &req, sizeof(req))) {
+ pfm_undo_create_context_fd(req.ctx_fd, new_ctx);
+ ret = -EFAULT;
+ }
+ }
+ kfree(smpl_arg);
+abort:
+ return ret;
+}
+
+asmlinkage long sys_pfm_write_pmcs(int fd, struct pfarg_pmc __user *ureq, int count)
+{
+ struct pfm_context *ctx;
+ struct pfarg_pmc pmcs[PFM_PMC_STK_ARG];
+ struct pfarg_pmc *req;
+ unsigned long flags;
+ size_t sz;
+ int ret;
+
+ if (count < 0)
+ return -EINVAL;
+
+ ctx = pfm_get_ctx(fd);
+ if (unlikely(ctx == NULL))
+ return -EBADF;
+
+ sz = count*sizeof(*ureq);
+
+ ret = pfm_get_args(ureq, sz, sizeof(pmcs), pmcs, (void **)&req);
+ 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;
+
+ if (count > PFM_PMC_STK_ARG)
+ kfree(req);
+error:
+ pfm_put_ctx(ctx);
+
+ return ret;
+}
+
+asmlinkage long sys_pfm_write_pmds(int fd, struct pfarg_pmd __user *ureq, int count)
+{
+ struct pfm_context *ctx;
+ struct pfarg_pmd pmds[PFM_PMD_STK_ARG];
+ struct pfarg_pmd *req;
+ unsigned long flags;
+ size_t sz;
+ int ret;
+
+ if (count < 0)
+ return -EINVAL;
+
+ ctx = pfm_get_ctx(fd);
+ if (unlikely(ctx == NULL))
+ return -EBADF;
+
+ sz = count*sizeof(*ureq);
+
+ ret = pfm_get_args(ureq, sz, sizeof(pmds), pmds, (void **)&req);
+ 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 (count > PFM_PMD_STK_ARG)
+ kfree(req);
+error:
+ pfm_put_ctx(ctx);
+
+ return ret;
+}
+
+asmlinkage long sys_pfm_read_pmds(int fd, struct pfarg_pmd __user *ureq, int count)
+{
+ struct pfm_context *ctx;
+ struct pfarg_pmd pmds[PFM_PMD_STK_ARG];
+ struct pfarg_pmd *req;
+ unsigned long flags;
+ size_t sz;
+ int ret;
+
+ if (count < 0)
+ return -EINVAL;
+
+ ctx = pfm_get_ctx(fd);
+ if (unlikely(ctx == NULL))
+ return -EBADF;
+
+ sz = count*sizeof(*ureq);
+
+ ret = pfm_get_args(ureq, sz, sizeof(pmds), pmds, (void **)&req);
+ 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 (count > PFM_PMD_STK_ARG)
+ kfree(req);
+error:
+ pfm_put_ctx(ctx);
+
+ return ret;
+}
+
+asmlinkage long sys_pfm_restart(int fd)
+{
+ struct pfm_context *ctx;
+ unsigned long flags;
+ int ret = 0;
+
+ ctx = pfm_get_ctx(fd);
+ if (unlikely(ctx == NULL))
+ return -EBADF;
+
+ 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);
+
+ pfm_put_ctx(ctx);
+
+ return ret;
+}
+
+
+asmlinkage long sys_pfm_stop(int fd)
+{
+ struct pfm_context *ctx;
+ unsigned long flags;
+ int ret;
+
+ ctx = pfm_get_ctx(fd);
+ if (unlikely(ctx == NULL))
+ return -EBADF;
+
+ 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);
+
+ pfm_put_ctx(ctx);
+
+ return ret;
+}
+
+asmlinkage long sys_pfm_start(int fd, struct pfarg_start __user *ureq)
+{
+ struct pfm_context *ctx;
+ struct pfarg_start req;
+ unsigned long flags;
+ int ret = 0;
+
+ ctx = pfm_get_ctx(fd);
+ if (ctx == NULL)
+ return -EBADF;
+
+ /*
+ * 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);
+
+ pfm_put_ctx(ctx);
+
+ return ret;
+}
+
+
+
+asmlinkage long sys_pfm_load_context(int fd, struct pfarg_load __user *ureq)
+{
+ struct pfm_context *ctx;
+ unsigned long flags;
+ struct pfarg_load req;
+ int ret;
+
+ ctx = pfm_get_ctx(fd);
+ if (ctx == NULL)
+ return -EBADF;
+
+ if (copy_from_user(&req, ureq, sizeof(req)))
+ return -EFAULT;
+
+ /*
+ * 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_STOPPED, &flags);
+ if (!ret)
+ ret = __pfm_load_context(ctx, &req);
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+ pfm_put_ctx(ctx);
+
+ return ret;
+}
+
+
+asmlinkage long sys_pfm_unload_context(int fd)
+{
+ struct pfm_context *ctx;
+ unsigned long flags;
+ int ret = 0;
+
+ ctx = pfm_get_ctx(fd);
+ if (ctx == NULL)
+ return -EBADF;
+
+ 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, 0);
+
+ spin_unlock_irqrestore(&ctx->lock, flags);
+
+ pfm_put_ctx(ctx);
+
+ return ret;
+}
+
+asmlinkage long sys_pfm_delete_evtsets(int fd, struct pfarg_setinfo __user *ureq, int count)
+{
+ struct pfm_context *ctx;
+ struct pfarg_setinfo *req;
+ unsigned long flags;
+ size_t sz;
+ int ret;
+
+ if (count < 0)
+ return -EINVAL;
+
+ ctx = pfm_get_ctx(fd);
+ if (ctx == NULL)
+ return -EBADF;
+
+ sz = count*sizeof(*ureq);
+
+ ret = pfm_get_args(ureq, sz, 0, NULL, (void **)&req);
+ if (ret)
+ goto error;
+
+ 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(req);
+
+error:
+ pfm_put_ctx(ctx);
+
+ return ret;
+}
+
+asmlinkage long sys_pfm_create_evtsets(int fd, struct pfarg_setdesc __user *ureq, int count)
+{
+ struct pfm_context *ctx;
+ struct pfarg_setdesc *req;
+ unsigned long flags;
+ size_t sz;
+ int ret;
+
+ if (count < 0)
+ return -EINVAL;
+
+ ctx = pfm_get_ctx(fd);
+ if (ctx == NULL)
+ return -EBADF;
+
+ sz = count*sizeof(*ureq);
+
+ ret = pfm_get_args(ureq, sz, 0, NULL, (void **)&req);
+ if (ret)
+ goto error;
+
+ 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(req);
+
+error:
+ pfm_put_ctx(ctx);
+
+ return ret;
+}
+
+asmlinkage long sys_pfm_getinfo_evtsets(int fd, struct pfarg_setinfo __user *ureq, int count)
+{
+ struct pfm_context *ctx;
+ struct pfarg_setinfo *req;
+ unsigned long flags;
+ size_t sz;
+ int ret;
+
+ if (count < 0)
+ return -EINVAL;
+
+ ctx = pfm_get_ctx(fd);
+ if (ctx == NULL)
+ return -EBADF;
+
+ sz = count*sizeof(*ureq);
+
+ ret = pfm_get_args(ureq, sz, 0, NULL, (void **)&req);
+ if (ret)
+ goto error;
+
+ 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(req);
+error:
+ pfm_put_ctx(ctx);
+
+ return ret;
+}
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
