Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | * Copyright (C) 1995 Linus Torvalds |
| 3 | * |
| 4 | * Pentium III FXSR, SSE support |
| 5 | * Gareth Hughes <gareth@valinux.com>, May 2000 |
| 6 | */ |
| 7 | |
| 8 | /* |
| 9 | * This file handles the architecture-dependent parts of process handling.. |
| 10 | */ |
| 11 | |
Zwane Mwaikambo | f370513 | 2005-06-25 14:54:50 -0700 | [diff] [blame] | 12 | #include <linux/cpu.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 13 | #include <linux/errno.h> |
| 14 | #include <linux/sched.h> |
| 15 | #include <linux/fs.h> |
| 16 | #include <linux/kernel.h> |
| 17 | #include <linux/mm.h> |
| 18 | #include <linux/elfcore.h> |
| 19 | #include <linux/smp.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 20 | #include <linux/stddef.h> |
| 21 | #include <linux/slab.h> |
| 22 | #include <linux/vmalloc.h> |
| 23 | #include <linux/user.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 24 | #include <linux/interrupt.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 25 | #include <linux/delay.h> |
| 26 | #include <linux/reboot.h> |
| 27 | #include <linux/init.h> |
| 28 | #include <linux/mc146818rtc.h> |
| 29 | #include <linux/module.h> |
| 30 | #include <linux/kallsyms.h> |
| 31 | #include <linux/ptrace.h> |
Andi Kleen | c16b63e0 | 2006-09-26 10:52:28 +0200 | [diff] [blame] | 32 | #include <linux/personality.h> |
Jeremy Fitzhardinge | 7c3576d | 2007-05-02 19:27:16 +0200 | [diff] [blame] | 33 | #include <linux/percpu.h> |
Erik Bosman | 529e25f | 2008-04-14 00:24:18 +0200 | [diff] [blame] | 34 | #include <linux/prctl.h> |
Frederic Weisbecker | 8b96f01 | 2008-12-06 03:40:00 +0100 | [diff] [blame] | 35 | #include <linux/ftrace.h> |
Jaswinder Singh Rajput | befa9e7 | 2009-01-04 16:18:56 +0530 | [diff] [blame] | 36 | #include <linux/uaccess.h> |
| 37 | #include <linux/io.h> |
| 38 | #include <linux/kdebug.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 39 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 40 | #include <asm/pgtable.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 41 | #include <asm/ldt.h> |
| 42 | #include <asm/processor.h> |
| 43 | #include <asm/i387.h> |
Linus Torvalds | 1361b83 | 2012-02-21 13:19:22 -0800 | [diff] [blame] | 44 | #include <asm/fpu-internal.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | #include <asm/desc.h> |
| 46 | #ifdef CONFIG_MATH_EMULATION |
| 47 | #include <asm/math_emu.h> |
| 48 | #endif |
| 49 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 50 | #include <linux/err.h> |
| 51 | |
Zwane Mwaikambo | f370513 | 2005-06-25 14:54:50 -0700 | [diff] [blame] | 52 | #include <asm/tlbflush.h> |
| 53 | #include <asm/cpu.h> |
Marc Dionne | 1eda814 | 2008-09-23 22:40:02 -0400 | [diff] [blame] | 54 | #include <asm/idle.h> |
Jaswinder Singh | bbc1f69 | 2008-07-21 21:34:13 +0530 | [diff] [blame] | 55 | #include <asm/syscalls.h> |
K.Prasad | 66cb591 | 2009-06-01 23:44:55 +0530 | [diff] [blame] | 56 | #include <asm/debugreg.h> |
David Howells | f05e798 | 2012-03-28 18:11:12 +0100 | [diff] [blame] | 57 | #include <asm/switch_to.h> |
Zwane Mwaikambo | f370513 | 2005-06-25 14:54:50 -0700 | [diff] [blame] | 58 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 59 | asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); |
Al Viro | 7076aad | 2012-09-10 16:44:54 -0400 | [diff] [blame] | 60 | asmlinkage void ret_from_kernel_thread(void) __asm__("ret_from_kernel_thread"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 61 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 62 | /* |
| 63 | * Return saved PC of a blocked thread. |
| 64 | */ |
| 65 | unsigned long thread_saved_pc(struct task_struct *tsk) |
| 66 | { |
H. Peter Anvin | faca622 | 2008-01-30 13:31:02 +0100 | [diff] [blame] | 67 | return ((unsigned long *)tsk->thread.sp)[3]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 68 | } |
| 69 | |
Pekka Enberg | e2ce07c | 2008-04-03 16:40:48 +0300 | [diff] [blame] | 70 | void __show_regs(struct pt_regs *regs, int all) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 71 | { |
| 72 | unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L; |
Alan Stern | bb1995d | 2007-07-21 17:10:42 +0200 | [diff] [blame] | 73 | unsigned long d0, d1, d2, d3, d6, d7; |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 74 | unsigned long sp; |
Pavel Emelyanov | 9d975eb | 2007-10-19 20:35:03 +0200 | [diff] [blame] | 75 | unsigned short ss, gs; |
| 76 | |
| 77 | if (user_mode_vm(regs)) { |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 78 | sp = regs->sp; |
| 79 | ss = regs->ss & 0xffff; |
Tejun Heo | d9a89a2 | 2009-02-09 22:17:40 +0900 | [diff] [blame] | 80 | gs = get_user_gs(regs); |
Pavel Emelyanov | 9d975eb | 2007-10-19 20:35:03 +0200 | [diff] [blame] | 81 | } else { |
H. Peter Anvin | def3c5d | 2009-10-12 14:09:07 -0700 | [diff] [blame] | 82 | sp = kernel_stack_pointer(regs); |
Pavel Emelyanov | 9d975eb | 2007-10-19 20:35:03 +0200 | [diff] [blame] | 83 | savesegment(ss, ss); |
| 84 | savesegment(gs, gs); |
| 85 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 86 | |
Pekka Enberg | d015a09 | 2009-12-28 10:26:59 +0200 | [diff] [blame] | 87 | printk(KERN_DEFAULT "EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n", |
Harvey Harrison | 92bc205 | 2008-02-08 12:09:56 -0800 | [diff] [blame] | 88 | (u16)regs->cs, regs->ip, regs->flags, |
Pavel Emelyanov | 9d975eb | 2007-10-19 20:35:03 +0200 | [diff] [blame] | 89 | smp_processor_id()); |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 90 | print_symbol("EIP is at %s\n", regs->ip); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 91 | |
Pekka Enberg | d015a09 | 2009-12-28 10:26:59 +0200 | [diff] [blame] | 92 | printk(KERN_DEFAULT "EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n", |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 93 | regs->ax, regs->bx, regs->cx, regs->dx); |
Pekka Enberg | d015a09 | 2009-12-28 10:26:59 +0200 | [diff] [blame] | 94 | printk(KERN_DEFAULT "ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n", |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 95 | regs->si, regs->di, regs->bp, sp); |
Pekka Enberg | d015a09 | 2009-12-28 10:26:59 +0200 | [diff] [blame] | 96 | printk(KERN_DEFAULT " DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n", |
Harvey Harrison | 92bc205 | 2008-02-08 12:09:56 -0800 | [diff] [blame] | 97 | (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss); |
Pavel Emelyanov | 9d975eb | 2007-10-19 20:35:03 +0200 | [diff] [blame] | 98 | |
| 99 | if (!all) |
| 100 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | |
Zachary Amsden | 4bb0d3e | 2005-09-03 15:56:36 -0700 | [diff] [blame] | 102 | cr0 = read_cr0(); |
| 103 | cr2 = read_cr2(); |
| 104 | cr3 = read_cr3(); |
Zachary Amsden | ff6e8c0 | 2006-01-06 00:11:50 -0800 | [diff] [blame] | 105 | cr4 = read_cr4_safe(); |
Pekka Enberg | d015a09 | 2009-12-28 10:26:59 +0200 | [diff] [blame] | 106 | printk(KERN_DEFAULT "CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", |
Pavel Emelyanov | 9d975eb | 2007-10-19 20:35:03 +0200 | [diff] [blame] | 107 | cr0, cr2, cr3, cr4); |
Alan Stern | bb1995d | 2007-07-21 17:10:42 +0200 | [diff] [blame] | 108 | |
| 109 | get_debugreg(d0, 0); |
| 110 | get_debugreg(d1, 1); |
| 111 | get_debugreg(d2, 2); |
| 112 | get_debugreg(d3, 3); |
Alan Stern | bb1995d | 2007-07-21 17:10:42 +0200 | [diff] [blame] | 113 | get_debugreg(d6, 6); |
| 114 | get_debugreg(d7, 7); |
Dave Jones | 4338774c | 2013-06-18 12:09:11 -0400 | [diff] [blame] | 115 | |
| 116 | /* Only print out debug registers if they are in their non-default state. */ |
| 117 | if ((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && |
| 118 | (d6 == DR6_RESERVED) && (d7 == 0x400)) |
| 119 | return; |
| 120 | |
| 121 | printk(KERN_DEFAULT "DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", |
| 122 | d0, d1, d2, d3); |
Pekka Enberg | d015a09 | 2009-12-28 10:26:59 +0200 | [diff] [blame] | 123 | printk(KERN_DEFAULT "DR6: %08lx DR7: %08lx\n", |
Pavel Emelyanov | 9d975eb | 2007-10-19 20:35:03 +0200 | [diff] [blame] | 124 | d6, d7); |
| 125 | } |
Alan Stern | bb1995d | 2007-07-21 17:10:42 +0200 | [diff] [blame] | 126 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 127 | void release_thread(struct task_struct *dead_task) |
| 128 | { |
Zachary Amsden | 2684927 | 2006-01-06 00:11:59 -0800 | [diff] [blame] | 129 | BUG_ON(dead_task->mm); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 130 | release_vm86_irqs(dead_task); |
| 131 | } |
| 132 | |
Alexey Dobriyan | 6f2c55b | 2009-04-02 16:56:59 -0700 | [diff] [blame] | 133 | int copy_thread(unsigned long clone_flags, unsigned long sp, |
Al Viro | afa86fc | 2012-10-22 22:51:14 -0400 | [diff] [blame] | 134 | unsigned long arg, struct task_struct *p) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 135 | { |
Al Viro | 7076aad | 2012-09-10 16:44:54 -0400 | [diff] [blame] | 136 | struct pt_regs *childregs = task_pt_regs(p); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 137 | struct task_struct *tsk; |
| 138 | int err; |
| 139 | |
H. Peter Anvin | faca622 | 2008-01-30 13:31:02 +0100 | [diff] [blame] | 140 | p->thread.sp = (unsigned long) childregs; |
| 141 | p->thread.sp0 = (unsigned long) (childregs+1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 142 | |
Al Viro | 1d4b4b2 | 2012-10-22 22:34:11 -0400 | [diff] [blame] | 143 | if (unlikely(p->flags & PF_KTHREAD)) { |
Al Viro | 7076aad | 2012-09-10 16:44:54 -0400 | [diff] [blame] | 144 | /* kernel thread */ |
| 145 | memset(childregs, 0, sizeof(struct pt_regs)); |
| 146 | p->thread.ip = (unsigned long) ret_from_kernel_thread; |
| 147 | task_user_gs(p) = __KERNEL_STACK_CANARY; |
| 148 | childregs->ds = __USER_DS; |
| 149 | childregs->es = __USER_DS; |
| 150 | childregs->fs = __KERNEL_PERCPU; |
| 151 | childregs->bx = sp; /* function */ |
| 152 | childregs->bp = arg; |
| 153 | childregs->orig_ax = -1; |
| 154 | childregs->cs = __KERNEL_CS | get_kernel_rpl(); |
H. Peter Anvin | 1adfa76 | 2013-04-27 16:10:11 -0700 | [diff] [blame] | 155 | childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_FIXED; |
Vineet Gupta | c375f15 | 2013-11-12 15:08:46 -0800 | [diff] [blame] | 156 | p->thread.fpu_counter = 0; |
Al Viro | 7076aad | 2012-09-10 16:44:54 -0400 | [diff] [blame] | 157 | p->thread.io_bitmap_ptr = NULL; |
| 158 | memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps)); |
| 159 | return 0; |
| 160 | } |
Al Viro | 1d4b4b2 | 2012-10-22 22:34:11 -0400 | [diff] [blame] | 161 | *childregs = *current_pt_regs(); |
Al Viro | 7076aad | 2012-09-10 16:44:54 -0400 | [diff] [blame] | 162 | childregs->ax = 0; |
Al Viro | 1d4b4b2 | 2012-10-22 22:34:11 -0400 | [diff] [blame] | 163 | if (sp) |
| 164 | childregs->sp = sp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 165 | |
Al Viro | 7076aad | 2012-09-10 16:44:54 -0400 | [diff] [blame] | 166 | p->thread.ip = (unsigned long) ret_from_fork; |
Al Viro | 1d4b4b2 | 2012-10-22 22:34:11 -0400 | [diff] [blame] | 167 | task_user_gs(p) = get_user_gs(current_pt_regs()); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 168 | |
Vineet Gupta | c375f15 | 2013-11-12 15:08:46 -0800 | [diff] [blame] | 169 | p->thread.fpu_counter = 0; |
K.Prasad | 66cb591 | 2009-06-01 23:44:55 +0530 | [diff] [blame] | 170 | p->thread.io_bitmap_ptr = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 171 | tsk = current; |
K.Prasad | 66cb591 | 2009-06-01 23:44:55 +0530 | [diff] [blame] | 172 | err = -ENOMEM; |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame] | 173 | |
| 174 | memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps)); |
K.Prasad | 66cb591 | 2009-06-01 23:44:55 +0530 | [diff] [blame] | 175 | |
Stephane Eranian | b3cf257 | 2006-07-09 21:12:39 -0400 | [diff] [blame] | 176 | if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) { |
Alexey Dobriyan | 52978be | 2006-09-30 23:27:21 -0700 | [diff] [blame] | 177 | p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr, |
| 178 | IO_BITMAP_BYTES, GFP_KERNEL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 179 | if (!p->thread.io_bitmap_ptr) { |
| 180 | p->thread.io_bitmap_max = 0; |
| 181 | return -ENOMEM; |
| 182 | } |
Stephane Eranian | b3cf257 | 2006-07-09 21:12:39 -0400 | [diff] [blame] | 183 | set_tsk_thread_flag(p, TIF_IO_BITMAP); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 184 | } |
| 185 | |
Roland McGrath | efd1ca5 | 2008-01-30 13:30:46 +0100 | [diff] [blame] | 186 | err = 0; |
| 187 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 188 | /* |
| 189 | * Set a new TLS for the child thread? |
| 190 | */ |
Roland McGrath | efd1ca5 | 2008-01-30 13:30:46 +0100 | [diff] [blame] | 191 | if (clone_flags & CLONE_SETTLS) |
| 192 | err = do_set_thread_area(p, -1, |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 193 | (struct user_desc __user *)childregs->si, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 194 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 195 | if (err && p->thread.io_bitmap_ptr) { |
| 196 | kfree(p->thread.io_bitmap_ptr); |
| 197 | p->thread.io_bitmap_max = 0; |
| 198 | } |
| 199 | return err; |
| 200 | } |
| 201 | |
Ingo Molnar | 513ad84 | 2008-02-21 05:18:40 +0100 | [diff] [blame] | 202 | void |
| 203 | start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp) |
| 204 | { |
Tejun Heo | d9a89a2 | 2009-02-09 22:17:40 +0900 | [diff] [blame] | 205 | set_user_gs(regs, 0); |
Ingo Molnar | 513ad84 | 2008-02-21 05:18:40 +0100 | [diff] [blame] | 206 | regs->fs = 0; |
Ingo Molnar | 513ad84 | 2008-02-21 05:18:40 +0100 | [diff] [blame] | 207 | regs->ds = __USER_DS; |
| 208 | regs->es = __USER_DS; |
| 209 | regs->ss = __USER_DS; |
| 210 | regs->cs = __USER_CS; |
| 211 | regs->ip = new_ip; |
| 212 | regs->sp = new_sp; |
Al Viro | 6783eaa2 | 2012-08-02 23:05:11 +0400 | [diff] [blame] | 213 | regs->flags = X86_EFLAGS_IF; |
Suresh Siddha | aa283f4 | 2008-03-10 15:28:05 -0700 | [diff] [blame] | 214 | /* |
Al Viro | e76623d | 2012-08-02 22:12:06 +0400 | [diff] [blame] | 215 | * force it to the iret return path by making it look as if there was |
| 216 | * some work pending. |
| 217 | */ |
| 218 | set_thread_flag(TIF_NOTIFY_RESUME); |
Ingo Molnar | 513ad84 | 2008-02-21 05:18:40 +0100 | [diff] [blame] | 219 | } |
| 220 | EXPORT_SYMBOL_GPL(start_thread); |
| 221 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 222 | |
| 223 | /* |
Kamalesh Babulal | ea70ef3 | 2011-04-28 14:32:08 +0530 | [diff] [blame] | 224 | * switch_to(x,y) should switch tasks from x to y. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 225 | * |
| 226 | * We fsave/fwait so that an exception goes off at the right time |
| 227 | * (as a call from the fsave or fwait in effect) rather than to |
| 228 | * the wrong process. Lazy FP saving no longer makes any sense |
| 229 | * with modern CPU's, and this simplifies a lot of things (SMP |
| 230 | * and UP become the same). |
| 231 | * |
| 232 | * NOTE! We used to use the x86 hardware context switching. The |
| 233 | * reason for not using it any more becomes apparent when you |
| 234 | * try to recover gracefully from saved state that is no longer |
| 235 | * valid (stale segment register values in particular). With the |
| 236 | * hardware task-switch, there is no way to fix up bad state in |
| 237 | * a reasonable manner. |
| 238 | * |
| 239 | * The fact that Intel documents the hardware task-switching to |
| 240 | * be slow is a fairly red herring - this code is not noticeably |
| 241 | * faster. However, there _is_ some room for improvement here, |
| 242 | * so the performance issues may eventually be a valid point. |
| 243 | * More important, however, is the fact that this allows us much |
| 244 | * more flexibility. |
| 245 | * |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 246 | * The return value (in %ax) will be the "prev" task after |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 247 | * the task-switch, and shows up in ret_from_fork in entry.S, |
| 248 | * for example. |
| 249 | */ |
Andi Kleen | 35ea7903 | 2013-08-05 15:02:39 -0700 | [diff] [blame] | 250 | __visible __notrace_funcgraph struct task_struct * |
Frederic Weisbecker | 8b96f01 | 2008-12-06 03:40:00 +0100 | [diff] [blame] | 251 | __switch_to(struct task_struct *prev_p, struct task_struct *next_p) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 252 | { |
| 253 | struct thread_struct *prev = &prev_p->thread, |
| 254 | *next = &next_p->thread; |
| 255 | int cpu = smp_processor_id(); |
| 256 | struct tss_struct *tss = &per_cpu(init_tss, cpu); |
Linus Torvalds | 34ddc81 | 2012-02-18 12:56:35 -0800 | [diff] [blame] | 257 | fpu_switch_t fpu; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 258 | |
| 259 | /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */ |
| 260 | |
Linus Torvalds | 7e16838 | 2012-02-19 13:27:00 -0800 | [diff] [blame] | 261 | fpu = switch_fpu_prepare(prev_p, next_p, cpu); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 262 | |
| 263 | /* |
Zachary Amsden | e7a2ff5 | 2005-09-03 15:56:39 -0700 | [diff] [blame] | 264 | * Reload esp0. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 265 | */ |
H. Peter Anvin | faca622 | 2008-01-30 13:31:02 +0100 | [diff] [blame] | 266 | load_sp0(tss, next); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 267 | |
| 268 | /* |
Jeremy Fitzhardinge | 464d1a7 | 2007-02-13 13:26:20 +0100 | [diff] [blame] | 269 | * Save away %gs. No need to save %fs, as it was saved on the |
Jeremy Fitzhardinge | f95d47c | 2006-12-07 02:14:02 +0100 | [diff] [blame] | 270 | * stack on entry. No need to save %es and %ds, as those are |
| 271 | * always kernel segments while inside the kernel. Doing this |
| 272 | * before setting the new TLS descriptors avoids the situation |
| 273 | * where we temporarily have non-reloadable segments in %fs |
| 274 | * and %gs. This could be an issue if the NMI handler ever |
| 275 | * used %fs or %gs (it does not today), or if the kernel is |
| 276 | * running inside of a hypervisor layer. |
Zachary Amsden | e7a2ff5 | 2005-09-03 15:56:39 -0700 | [diff] [blame] | 277 | */ |
Tejun Heo | ccbeed3 | 2009-02-09 22:17:40 +0900 | [diff] [blame] | 278 | lazy_save_gs(prev->gs); |
Zachary Amsden | e7a2ff5 | 2005-09-03 15:56:39 -0700 | [diff] [blame] | 279 | |
| 280 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 281 | * Load the per-thread Thread-Local Storage descriptor. |
| 282 | */ |
| 283 | load_TLS(next, cpu); |
| 284 | |
| 285 | /* |
Zachary Amsden | 8b15114 | 2007-02-13 13:26:21 +0100 | [diff] [blame] | 286 | * Restore IOPL if needed. In normal use, the flags restore |
| 287 | * in the switch assembly will handle this. But if the kernel |
| 288 | * is running virtualized at a non-zero CPL, the popf will |
| 289 | * not restore flags, so it must be done in a separate step. |
| 290 | */ |
| 291 | if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl)) |
| 292 | set_iopl_mask(next->iopl); |
| 293 | |
| 294 | /* |
Peter Zijlstra | c2daa3b | 2013-08-14 14:51:00 +0200 | [diff] [blame] | 295 | * If it were not for PREEMPT_ACTIVE we could guarantee that the |
| 296 | * preempt_count of all tasks was equal here and this would not be |
| 297 | * needed. |
| 298 | */ |
| 299 | task_thread_info(prev_p)->saved_preempt_count = this_cpu_read(__preempt_count); |
| 300 | this_cpu_write(__preempt_count, task_thread_info(next_p)->saved_preempt_count); |
| 301 | |
| 302 | /* |
Stephane Eranian | b3cf257 | 2006-07-09 21:12:39 -0400 | [diff] [blame] | 303 | * Now maybe handle debug registers and/or IO bitmaps |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 304 | */ |
Andrea Arcangeli | cf99aba | 2007-07-15 23:41:33 -0700 | [diff] [blame] | 305 | if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV || |
| 306 | task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT)) |
| 307 | __switch_to_xtra(prev_p, next_p, tss); |
Andrea Arcangeli | ffaa8bd | 2005-06-27 14:36:36 -0700 | [diff] [blame] | 308 | |
Zachary Amsden | 9226d12 | 2007-02-13 13:26:21 +0100 | [diff] [blame] | 309 | /* |
| 310 | * Leave lazy mode, flushing any hypercalls made here. |
| 311 | * This must be done before restoring TLS segments so |
| 312 | * the GDT and LDT are properly updated, and must be |
| 313 | * done before math_state_restore, so the TS bit is up |
| 314 | * to date. |
| 315 | */ |
Jeremy Fitzhardinge | 224101e | 2009-02-18 11:18:57 -0800 | [diff] [blame] | 316 | arch_end_context_switch(next_p); |
Zachary Amsden | 9226d12 | 2007-02-13 13:26:21 +0100 | [diff] [blame] | 317 | |
Zachary Amsden | 9226d12 | 2007-02-13 13:26:21 +0100 | [diff] [blame] | 318 | /* |
| 319 | * Restore %gs if needed (which is common) |
| 320 | */ |
| 321 | if (prev->gs | next->gs) |
Tejun Heo | ccbeed3 | 2009-02-09 22:17:40 +0900 | [diff] [blame] | 322 | lazy_load_gs(next->gs); |
Zachary Amsden | 9226d12 | 2007-02-13 13:26:21 +0100 | [diff] [blame] | 323 | |
Linus Torvalds | 34ddc81 | 2012-02-18 12:56:35 -0800 | [diff] [blame] | 324 | switch_fpu_finish(next_p, fpu); |
| 325 | |
Alex Shi | c6ae41e | 2012-05-11 15:35:27 +0800 | [diff] [blame] | 326 | this_cpu_write(current_task, next_p); |
Zachary Amsden | 9226d12 | 2007-02-13 13:26:21 +0100 | [diff] [blame] | 327 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 328 | return prev_p; |
| 329 | } |
| 330 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 331 | #define top_esp (THREAD_SIZE - sizeof(unsigned long)) |
| 332 | #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long)) |
| 333 | |
| 334 | unsigned long get_wchan(struct task_struct *p) |
| 335 | { |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 336 | unsigned long bp, sp, ip; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 337 | unsigned long stack_page; |
| 338 | int count = 0; |
| 339 | if (!p || p == current || p->state == TASK_RUNNING) |
| 340 | return 0; |
Al Viro | 65e0fdf | 2006-01-12 01:05:41 -0800 | [diff] [blame] | 341 | stack_page = (unsigned long)task_stack_page(p); |
H. Peter Anvin | faca622 | 2008-01-30 13:31:02 +0100 | [diff] [blame] | 342 | sp = p->thread.sp; |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 343 | if (!stack_page || sp < stack_page || sp > top_esp+stack_page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 344 | return 0; |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 345 | /* include/asm-i386/system.h:switch_to() pushes bp last. */ |
| 346 | bp = *(unsigned long *) sp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 347 | do { |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 348 | if (bp < stack_page || bp > top_ebp+stack_page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 349 | return 0; |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 350 | ip = *(unsigned long *) (bp+4); |
| 351 | if (!in_sched_functions(ip)) |
| 352 | return ip; |
| 353 | bp = *(unsigned long *) bp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 354 | } while (count++ < 16); |
| 355 | return 0; |
| 356 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 357 | |