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);