Ralf Baechle | 295cbf6 | 2007-07-03 14:37:43 +0100 | [diff] [blame] | 1 | /* |
| 2 | * General MIPS MT support routines, usable in AP/SP, SMVP, or SMTC kernels |
| 3 | * Copyright (C) 2005 Mips Technologies, Inc |
| 4 | */ |
| 5 | #include <linux/cpu.h> |
| 6 | #include <linux/cpumask.h> |
| 7 | #include <linux/delay.h> |
| 8 | #include <linux/kernel.h> |
| 9 | #include <linux/init.h> |
| 10 | #include <linux/sched.h> |
| 11 | #include <linux/security.h> |
| 12 | #include <linux/types.h> |
| 13 | #include <asm/uaccess.h> |
| 14 | |
| 15 | /* |
| 16 | * CPU mask used to set process affinity for MT VPEs/TCs with FPUs |
| 17 | */ |
| 18 | cpumask_t mt_fpu_cpumask; |
| 19 | |
| 20 | static int fpaff_threshold = -1; |
| 21 | unsigned long mt_fpemul_threshold = 0; |
| 22 | |
| 23 | /* |
| 24 | * Replacement functions for the sys_sched_setaffinity() and |
| 25 | * sys_sched_getaffinity() system calls, so that we can integrate |
| 26 | * FPU affinity with the user's requested processor affinity. |
| 27 | * This code is 98% identical with the sys_sched_setaffinity() |
| 28 | * and sys_sched_getaffinity() system calls, and should be |
| 29 | * updated when kernel/sched.c changes. |
| 30 | */ |
| 31 | |
| 32 | /* |
| 33 | * find_process_by_pid - find a process with a matching PID value. |
| 34 | * used in sys_sched_set/getaffinity() in kernel/sched.c, so |
| 35 | * cloned here. |
| 36 | */ |
| 37 | static inline struct task_struct *find_process_by_pid(pid_t pid) |
| 38 | { |
Pavel Emelyanov | 0e56853 | 2008-02-04 23:44:24 -0800 | [diff] [blame] | 39 | return pid ? find_task_by_vpid(pid) : current; |
Ralf Baechle | 295cbf6 | 2007-07-03 14:37:43 +0100 | [diff] [blame] | 40 | } |
| 41 | |
| 42 | |
| 43 | /* |
| 44 | * mipsmt_sys_sched_setaffinity - set the cpu affinity of a process |
| 45 | */ |
| 46 | asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len, |
| 47 | unsigned long __user *user_mask_ptr) |
| 48 | { |
| 49 | cpumask_t new_mask; |
| 50 | cpumask_t effective_mask; |
| 51 | int retval; |
| 52 | struct task_struct *p; |
Ralf Baechle | 293c5bd | 2007-07-25 16:19:33 +0100 | [diff] [blame] | 53 | struct thread_info *ti; |
Ralf Baechle | 295cbf6 | 2007-07-03 14:37:43 +0100 | [diff] [blame] | 54 | |
| 55 | if (len < sizeof(new_mask)) |
| 56 | return -EINVAL; |
| 57 | |
| 58 | if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask))) |
| 59 | return -EFAULT; |
| 60 | |
Gautham R Shenoy | 86ef5c9 | 2008-01-25 21:08:02 +0100 | [diff] [blame] | 61 | get_online_cpus(); |
Ralf Baechle | 295cbf6 | 2007-07-03 14:37:43 +0100 | [diff] [blame] | 62 | read_lock(&tasklist_lock); |
| 63 | |
| 64 | p = find_process_by_pid(pid); |
| 65 | if (!p) { |
| 66 | read_unlock(&tasklist_lock); |
Gautham R Shenoy | 86ef5c9 | 2008-01-25 21:08:02 +0100 | [diff] [blame] | 67 | put_online_cpus(); |
Ralf Baechle | 295cbf6 | 2007-07-03 14:37:43 +0100 | [diff] [blame] | 68 | return -ESRCH; |
| 69 | } |
| 70 | |
| 71 | /* |
| 72 | * It is not safe to call set_cpus_allowed with the |
| 73 | * tasklist_lock held. We will bump the task_struct's |
| 74 | * usage count and drop tasklist_lock before invoking |
| 75 | * set_cpus_allowed. |
| 76 | */ |
| 77 | get_task_struct(p); |
| 78 | |
| 79 | retval = -EPERM; |
| 80 | if ((current->euid != p->euid) && (current->euid != p->uid) && |
| 81 | !capable(CAP_SYS_NICE)) { |
| 82 | read_unlock(&tasklist_lock); |
| 83 | goto out_unlock; |
| 84 | } |
| 85 | |
| 86 | retval = security_task_setscheduler(p, 0, NULL); |
| 87 | if (retval) |
| 88 | goto out_unlock; |
| 89 | |
| 90 | /* Record new user-specified CPU set for future reference */ |
| 91 | p->thread.user_cpus_allowed = new_mask; |
| 92 | |
| 93 | /* Unlock the task list */ |
| 94 | read_unlock(&tasklist_lock); |
| 95 | |
| 96 | /* Compute new global allowed CPU set if necessary */ |
Ralf Baechle | 293c5bd | 2007-07-25 16:19:33 +0100 | [diff] [blame] | 97 | ti = task_thread_info(p); |
| 98 | if (test_ti_thread_flag(ti, TIF_FPUBOUND) && |
| 99 | cpus_intersects(new_mask, mt_fpu_cpumask)) { |
Ralf Baechle | 295cbf6 | 2007-07-03 14:37:43 +0100 | [diff] [blame] | 100 | cpus_and(effective_mask, new_mask, mt_fpu_cpumask); |
| 101 | retval = set_cpus_allowed(p, effective_mask); |
| 102 | } else { |
Ralf Baechle | 293c5bd | 2007-07-25 16:19:33 +0100 | [diff] [blame] | 103 | clear_ti_thread_flag(ti, TIF_FPUBOUND); |
Ralf Baechle | 295cbf6 | 2007-07-03 14:37:43 +0100 | [diff] [blame] | 104 | retval = set_cpus_allowed(p, new_mask); |
| 105 | } |
| 106 | |
Ralf Baechle | 295cbf6 | 2007-07-03 14:37:43 +0100 | [diff] [blame] | 107 | out_unlock: |
| 108 | put_task_struct(p); |
Gautham R Shenoy | 86ef5c9 | 2008-01-25 21:08:02 +0100 | [diff] [blame] | 109 | put_online_cpus(); |
Ralf Baechle | 295cbf6 | 2007-07-03 14:37:43 +0100 | [diff] [blame] | 110 | return retval; |
| 111 | } |
| 112 | |
| 113 | /* |
| 114 | * mipsmt_sys_sched_getaffinity - get the cpu affinity of a process |
| 115 | */ |
| 116 | asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len, |
| 117 | unsigned long __user *user_mask_ptr) |
| 118 | { |
| 119 | unsigned int real_len; |
| 120 | cpumask_t mask; |
| 121 | int retval; |
| 122 | struct task_struct *p; |
| 123 | |
| 124 | real_len = sizeof(mask); |
| 125 | if (len < real_len) |
| 126 | return -EINVAL; |
| 127 | |
Gautham R Shenoy | 86ef5c9 | 2008-01-25 21:08:02 +0100 | [diff] [blame] | 128 | get_online_cpus(); |
Ralf Baechle | 295cbf6 | 2007-07-03 14:37:43 +0100 | [diff] [blame] | 129 | read_lock(&tasklist_lock); |
| 130 | |
| 131 | retval = -ESRCH; |
| 132 | p = find_process_by_pid(pid); |
| 133 | if (!p) |
| 134 | goto out_unlock; |
| 135 | retval = security_task_getscheduler(p); |
| 136 | if (retval) |
| 137 | goto out_unlock; |
| 138 | |
| 139 | cpus_and(mask, p->thread.user_cpus_allowed, cpu_possible_map); |
| 140 | |
| 141 | out_unlock: |
| 142 | read_unlock(&tasklist_lock); |
Gautham R Shenoy | 86ef5c9 | 2008-01-25 21:08:02 +0100 | [diff] [blame] | 143 | put_online_cpus(); |
Ralf Baechle | 295cbf6 | 2007-07-03 14:37:43 +0100 | [diff] [blame] | 144 | if (retval) |
| 145 | return retval; |
| 146 | if (copy_to_user(user_mask_ptr, &mask, real_len)) |
| 147 | return -EFAULT; |
| 148 | return real_len; |
| 149 | } |
| 150 | |
| 151 | |
| 152 | static int __init fpaff_thresh(char *str) |
| 153 | { |
| 154 | get_option(&str, &fpaff_threshold); |
| 155 | return 1; |
| 156 | } |
| 157 | __setup("fpaff=", fpaff_thresh); |
| 158 | |
| 159 | /* |
| 160 | * FPU Use Factor empirically derived from experiments on 34K |
| 161 | */ |
Kevin D. Kissell | 9cc1236 | 2008-09-09 21:33:36 +0200 | [diff] [blame] | 162 | #define FPUSEFACTOR 2000 |
Ralf Baechle | 295cbf6 | 2007-07-03 14:37:43 +0100 | [diff] [blame] | 163 | |
| 164 | static __init int mt_fp_affinity_init(void) |
| 165 | { |
| 166 | if (fpaff_threshold >= 0) { |
| 167 | mt_fpemul_threshold = fpaff_threshold; |
| 168 | } else { |
| 169 | mt_fpemul_threshold = |
| 170 | (FPUSEFACTOR * (loops_per_jiffy/(500000/HZ))) / HZ; |
| 171 | } |
| 172 | printk(KERN_DEBUG "FPU Affinity set after %ld emulations\n", |
| 173 | mt_fpemul_threshold); |
| 174 | |
| 175 | return 0; |
| 176 | } |
| 177 | arch_initcall(mt_fp_affinity_init); |