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-rw-r--r--arch/mips/kernel/mips-mt-fpaff.c176
1 files changed, 176 insertions, 0 deletions
diff --git a/arch/mips/kernel/mips-mt-fpaff.c b/arch/mips/kernel/mips-mt-fpaff.c
new file mode 100644
index 000000000000..ede5d73d652e
--- /dev/null
+++ b/arch/mips/kernel/mips-mt-fpaff.c
@@ -0,0 +1,176 @@
+/*
+ * General MIPS MT support routines, usable in AP/SP, SMVP, or SMTC kernels
+ * Copyright (C) 2005 Mips Technologies, Inc
+ */
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/security.h>
+#include <linux/types.h>
+#include <asm/uaccess.h>
+
+/*
+ * CPU mask used to set process affinity for MT VPEs/TCs with FPUs
+ */
+cpumask_t mt_fpu_cpumask;
+
+static int fpaff_threshold = -1;
+unsigned long mt_fpemul_threshold = 0;
+
+/*
+ * Replacement functions for the sys_sched_setaffinity() and
+ * sys_sched_getaffinity() system calls, so that we can integrate
+ * FPU affinity with the user's requested processor affinity.
+ * This code is 98% identical with the sys_sched_setaffinity()
+ * and sys_sched_getaffinity() system calls, and should be
+ * updated when kernel/sched.c changes.
+ */
+
+/*
+ * find_process_by_pid - find a process with a matching PID value.
+ * used in sys_sched_set/getaffinity() in kernel/sched.c, so
+ * cloned here.
+ */
+static inline struct task_struct *find_process_by_pid(pid_t pid)
+{
+ return pid ? find_task_by_pid(pid) : current;
+}
+
+
+/*
+ * mipsmt_sys_sched_setaffinity - set the cpu affinity of a process
+ */
+asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len,
+ unsigned long __user *user_mask_ptr)
+{
+ cpumask_t new_mask;
+ cpumask_t effective_mask;
+ int retval;
+ struct task_struct *p;
+
+ if (len < sizeof(new_mask))
+ return -EINVAL;
+
+ if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask)))
+ return -EFAULT;
+
+ lock_cpu_hotplug();
+ read_lock(&tasklist_lock);
+
+ p = find_process_by_pid(pid);
+ if (!p) {
+ read_unlock(&tasklist_lock);
+ unlock_cpu_hotplug();
+ return -ESRCH;
+ }
+
+ /*
+ * It is not safe to call set_cpus_allowed with the
+ * tasklist_lock held. We will bump the task_struct's
+ * usage count and drop tasklist_lock before invoking
+ * set_cpus_allowed.
+ */
+ get_task_struct(p);
+
+ retval = -EPERM;
+ if ((current->euid != p->euid) && (current->euid != p->uid) &&
+ !capable(CAP_SYS_NICE)) {
+ read_unlock(&tasklist_lock);
+ goto out_unlock;
+ }
+
+ retval = security_task_setscheduler(p, 0, NULL);
+ if (retval)
+ goto out_unlock;
+
+ /* Record new user-specified CPU set for future reference */
+ p->thread.user_cpus_allowed = new_mask;
+
+ /* Unlock the task list */
+ read_unlock(&tasklist_lock);
+
+ /* Compute new global allowed CPU set if necessary */
+ if ((p->thread.mflags & MF_FPUBOUND)
+ && cpus_intersects(new_mask, mt_fpu_cpumask)) {
+ cpus_and(effective_mask, new_mask, mt_fpu_cpumask);
+ retval = set_cpus_allowed(p, effective_mask);
+ } else {
+ p->thread.mflags &= ~MF_FPUBOUND;
+ retval = set_cpus_allowed(p, new_mask);
+ }
+
+
+out_unlock:
+ put_task_struct(p);
+ unlock_cpu_hotplug();
+ return retval;
+}
+
+/*
+ * mipsmt_sys_sched_getaffinity - get the cpu affinity of a process
+ */
+asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len,
+ unsigned long __user *user_mask_ptr)
+{
+ unsigned int real_len;
+ cpumask_t mask;
+ int retval;
+ struct task_struct *p;
+
+ real_len = sizeof(mask);
+ if (len < real_len)
+ return -EINVAL;
+
+ lock_cpu_hotplug();
+ read_lock(&tasklist_lock);
+
+ retval = -ESRCH;
+ p = find_process_by_pid(pid);
+ if (!p)
+ goto out_unlock;
+ retval = security_task_getscheduler(p);
+ if (retval)
+ goto out_unlock;
+
+ cpus_and(mask, p->thread.user_cpus_allowed, cpu_possible_map);
+
+out_unlock:
+ read_unlock(&tasklist_lock);
+ unlock_cpu_hotplug();
+ if (retval)
+ return retval;
+ if (copy_to_user(user_mask_ptr, &mask, real_len))
+ return -EFAULT;
+ return real_len;
+}
+
+
+static int __init fpaff_thresh(char *str)
+{
+ get_option(&str, &fpaff_threshold);
+ return 1;
+}
+__setup("fpaff=", fpaff_thresh);
+
+/*
+ * FPU Use Factor empirically derived from experiments on 34K
+ */
+#define FPUSEFACTOR 333
+
+static __init int mt_fp_affinity_init(void)
+{
+ if (fpaff_threshold >= 0) {
+ mt_fpemul_threshold = fpaff_threshold;
+ } else {
+ mt_fpemul_threshold =
+ (FPUSEFACTOR * (loops_per_jiffy/(500000/HZ))) / HZ;
+ }
+ printk(KERN_DEBUG "FPU Affinity set after %ld emulations\n",
+ mt_fpemul_threshold);
+
+ return 0;
+}
+arch_initcall(mt_fp_affinity_init);