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> |
Ingo Molnar | 2993002 | 2017-02-08 18:51:36 +0100 | [diff] [blame] | 15 | #include <linux/sched/task.h> |
Ingo Molnar | 68db0cf | 2017-02-08 18:51:37 +0100 | [diff] [blame] | 16 | #include <linux/sched/task_stack.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 17 | #include <linux/fs.h> |
| 18 | #include <linux/kernel.h> |
| 19 | #include <linux/mm.h> |
| 20 | #include <linux/elfcore.h> |
| 21 | #include <linux/smp.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 22 | #include <linux/stddef.h> |
| 23 | #include <linux/slab.h> |
| 24 | #include <linux/vmalloc.h> |
| 25 | #include <linux/user.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 26 | #include <linux/interrupt.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 27 | #include <linux/delay.h> |
| 28 | #include <linux/reboot.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | #include <linux/mc146818rtc.h> |
Paul Gortmaker | 186f436 | 2016-07-13 20:18:56 -0400 | [diff] [blame] | 30 | #include <linux/export.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | #include <linux/kallsyms.h> |
| 32 | #include <linux/ptrace.h> |
Andi Kleen | c16b63e0 | 2006-09-26 10:52:28 +0200 | [diff] [blame] | 33 | #include <linux/personality.h> |
Jeremy Fitzhardinge | 7c3576d | 2007-05-02 19:27:16 +0200 | [diff] [blame] | 34 | #include <linux/percpu.h> |
Erik Bosman | 529e25f | 2008-04-14 00:24:18 +0200 | [diff] [blame] | 35 | #include <linux/prctl.h> |
Frederic Weisbecker | 8b96f01 | 2008-12-06 03:40:00 +0100 | [diff] [blame] | 36 | #include <linux/ftrace.h> |
Jaswinder Singh Rajput | befa9e7 | 2009-01-04 16:18:56 +0530 | [diff] [blame] | 37 | #include <linux/uaccess.h> |
| 38 | #include <linux/io.h> |
| 39 | #include <linux/kdebug.h> |
Kyle Huey | 79170fd | 2017-03-20 01:16:24 -0700 | [diff] [blame] | 40 | #include <linux/syscalls.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 41 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 42 | #include <asm/pgtable.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | #include <asm/ldt.h> |
| 44 | #include <asm/processor.h> |
Ingo Molnar | 78f7f1e | 2015-04-24 02:54:44 +0200 | [diff] [blame] | 45 | #include <asm/fpu/internal.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 46 | #include <asm/desc.h> |
| 47 | #ifdef CONFIG_MATH_EMULATION |
| 48 | #include <asm/math_emu.h> |
| 49 | #endif |
| 50 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 51 | #include <linux/err.h> |
| 52 | |
Zwane Mwaikambo | f370513 | 2005-06-25 14:54:50 -0700 | [diff] [blame] | 53 | #include <asm/tlbflush.h> |
| 54 | #include <asm/cpu.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> |
Brian Gerst | ba3e127 | 2015-07-29 01:41:21 -0400 | [diff] [blame] | 58 | #include <asm/vm86.h> |
Fenghua Yu | 4f341a5 | 2016-10-28 15:04:48 -0700 | [diff] [blame] | 59 | #include <asm/intel_rdt.h> |
Kyle Huey | 79170fd | 2017-03-20 01:16:24 -0700 | [diff] [blame] | 60 | #include <asm/proto.h> |
Zwane Mwaikambo | f370513 | 2005-06-25 14:54:50 -0700 | [diff] [blame] | 61 | |
Pekka Enberg | e2ce07c | 2008-04-03 16:40:48 +0300 | [diff] [blame] | 62 | void __show_regs(struct pt_regs *regs, int all) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 63 | { |
| 64 | unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L; |
Alan Stern | bb1995d | 2007-07-21 17:10:42 +0200 | [diff] [blame] | 65 | unsigned long d0, d1, d2, d3, d6, d7; |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 66 | unsigned long sp; |
Pavel Emelyanov | 9d975eb | 2007-10-19 20:35:03 +0200 | [diff] [blame] | 67 | unsigned short ss, gs; |
| 68 | |
Andy Lutomirski | f39b6f0 | 2015-03-18 18:33:33 -0700 | [diff] [blame] | 69 | if (user_mode(regs)) { |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 70 | sp = regs->sp; |
| 71 | ss = regs->ss & 0xffff; |
Tejun Heo | d9a89a2 | 2009-02-09 22:17:40 +0900 | [diff] [blame] | 72 | gs = get_user_gs(regs); |
Pavel Emelyanov | 9d975eb | 2007-10-19 20:35:03 +0200 | [diff] [blame] | 73 | } else { |
H. Peter Anvin | def3c5d | 2009-10-12 14:09:07 -0700 | [diff] [blame] | 74 | sp = kernel_stack_pointer(regs); |
Pavel Emelyanov | 9d975eb | 2007-10-19 20:35:03 +0200 | [diff] [blame] | 75 | savesegment(ss, ss); |
| 76 | savesegment(gs, gs); |
| 77 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 78 | |
Josh Poimboeuf | bb5e5ce | 2016-10-25 09:51:12 -0500 | [diff] [blame] | 79 | printk(KERN_DEFAULT "EIP: %pS\n", (void *)regs->ip); |
| 80 | printk(KERN_DEFAULT "EFLAGS: %08lx CPU: %d\n", regs->flags, |
Borislav Petkov | 5d9070b | 2017-05-28 11:03:42 +0200 | [diff] [blame] | 81 | raw_smp_processor_id()); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 82 | |
Pekka Enberg | d015a09 | 2009-12-28 10:26:59 +0200 | [diff] [blame] | 83 | 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] | 84 | regs->ax, regs->bx, regs->cx, regs->dx); |
Pekka Enberg | d015a09 | 2009-12-28 10:26:59 +0200 | [diff] [blame] | 85 | 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] | 86 | regs->si, regs->di, regs->bp, sp); |
Pekka Enberg | d015a09 | 2009-12-28 10:26:59 +0200 | [diff] [blame] | 87 | 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] | 88 | (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss); |
Pavel Emelyanov | 9d975eb | 2007-10-19 20:35:03 +0200 | [diff] [blame] | 89 | |
| 90 | if (!all) |
| 91 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 92 | |
Zachary Amsden | 4bb0d3e | 2005-09-03 15:56:36 -0700 | [diff] [blame] | 93 | cr0 = read_cr0(); |
| 94 | cr2 = read_cr2(); |
Andy Lutomirski | 6c690ee | 2017-06-12 10:26:14 -0700 | [diff] [blame] | 95 | cr3 = __read_cr3(); |
Andy Lutomirski | 1ef55be1 | 2016-09-29 12:48:12 -0700 | [diff] [blame] | 96 | cr4 = __read_cr4(); |
Pekka Enberg | d015a09 | 2009-12-28 10:26:59 +0200 | [diff] [blame] | 97 | printk(KERN_DEFAULT "CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", |
Pavel Emelyanov | 9d975eb | 2007-10-19 20:35:03 +0200 | [diff] [blame] | 98 | cr0, cr2, cr3, cr4); |
Alan Stern | bb1995d | 2007-07-21 17:10:42 +0200 | [diff] [blame] | 99 | |
| 100 | get_debugreg(d0, 0); |
| 101 | get_debugreg(d1, 1); |
| 102 | get_debugreg(d2, 2); |
| 103 | get_debugreg(d3, 3); |
Alan Stern | bb1995d | 2007-07-21 17:10:42 +0200 | [diff] [blame] | 104 | get_debugreg(d6, 6); |
| 105 | get_debugreg(d7, 7); |
Dave Jones | 4338774 | 2013-06-18 12:09:11 -0400 | [diff] [blame] | 106 | |
| 107 | /* Only print out debug registers if they are in their non-default state. */ |
| 108 | if ((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && |
| 109 | (d6 == DR6_RESERVED) && (d7 == 0x400)) |
| 110 | return; |
| 111 | |
| 112 | printk(KERN_DEFAULT "DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", |
| 113 | d0, d1, d2, d3); |
Pekka Enberg | d015a09 | 2009-12-28 10:26:59 +0200 | [diff] [blame] | 114 | printk(KERN_DEFAULT "DR6: %08lx DR7: %08lx\n", |
Pavel Emelyanov | 9d975eb | 2007-10-19 20:35:03 +0200 | [diff] [blame] | 115 | d6, d7); |
| 116 | } |
Alan Stern | bb1995d | 2007-07-21 17:10:42 +0200 | [diff] [blame] | 117 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 118 | void release_thread(struct task_struct *dead_task) |
| 119 | { |
Zachary Amsden | 2684927 | 2006-01-06 00:11:59 -0800 | [diff] [blame] | 120 | BUG_ON(dead_task->mm); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 121 | release_vm86_irqs(dead_task); |
| 122 | } |
| 123 | |
Josh Triplett | c1bd55f | 2015-06-30 15:00:00 -0700 | [diff] [blame] | 124 | int copy_thread_tls(unsigned long clone_flags, unsigned long sp, |
| 125 | unsigned long arg, struct task_struct *p, unsigned long tls) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 126 | { |
Al Viro | 7076aad | 2012-09-10 16:44:54 -0400 | [diff] [blame] | 127 | struct pt_regs *childregs = task_pt_regs(p); |
Brian Gerst | 0100301 | 2016-08-13 12:38:19 -0400 | [diff] [blame] | 128 | struct fork_frame *fork_frame = container_of(childregs, struct fork_frame, regs); |
| 129 | struct inactive_task_frame *frame = &fork_frame->frame; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 130 | struct task_struct *tsk; |
| 131 | int err; |
| 132 | |
Brian Gerst | 0100301 | 2016-08-13 12:38:19 -0400 | [diff] [blame] | 133 | frame->bp = 0; |
Brian Gerst | 616d248 | 2016-08-13 12:38:20 -0400 | [diff] [blame] | 134 | frame->ret_addr = (unsigned long) ret_from_fork; |
Brian Gerst | 0100301 | 2016-08-13 12:38:19 -0400 | [diff] [blame] | 135 | p->thread.sp = (unsigned long) fork_frame; |
H. Peter Anvin | faca622 | 2008-01-30 13:31:02 +0100 | [diff] [blame] | 136 | p->thread.sp0 = (unsigned long) (childregs+1); |
Oleg Nesterov | 6f46b3a | 2014-09-02 19:57:33 +0200 | [diff] [blame] | 137 | memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 138 | |
Al Viro | 1d4b4b2 | 2012-10-22 22:34:11 -0400 | [diff] [blame] | 139 | if (unlikely(p->flags & PF_KTHREAD)) { |
Al Viro | 7076aad | 2012-09-10 16:44:54 -0400 | [diff] [blame] | 140 | /* kernel thread */ |
| 141 | memset(childregs, 0, sizeof(struct pt_regs)); |
Brian Gerst | 616d248 | 2016-08-13 12:38:20 -0400 | [diff] [blame] | 142 | frame->bx = sp; /* function */ |
| 143 | frame->di = arg; |
Al Viro | 7076aad | 2012-09-10 16:44:54 -0400 | [diff] [blame] | 144 | p->thread.io_bitmap_ptr = NULL; |
Al Viro | 7076aad | 2012-09-10 16:44:54 -0400 | [diff] [blame] | 145 | return 0; |
| 146 | } |
Brian Gerst | 616d248 | 2016-08-13 12:38:20 -0400 | [diff] [blame] | 147 | frame->bx = 0; |
Al Viro | 1d4b4b2 | 2012-10-22 22:34:11 -0400 | [diff] [blame] | 148 | *childregs = *current_pt_regs(); |
Al Viro | 7076aad | 2012-09-10 16:44:54 -0400 | [diff] [blame] | 149 | childregs->ax = 0; |
Al Viro | 1d4b4b2 | 2012-10-22 22:34:11 -0400 | [diff] [blame] | 150 | if (sp) |
| 151 | childregs->sp = sp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 152 | |
Al Viro | 1d4b4b2 | 2012-10-22 22:34:11 -0400 | [diff] [blame] | 153 | task_user_gs(p) = get_user_gs(current_pt_regs()); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 154 | |
K.Prasad | 66cb591 | 2009-06-01 23:44:55 +0530 | [diff] [blame] | 155 | p->thread.io_bitmap_ptr = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 156 | tsk = current; |
K.Prasad | 66cb591 | 2009-06-01 23:44:55 +0530 | [diff] [blame] | 157 | err = -ENOMEM; |
Frederic Weisbecker | 24f1e32c | 2009-09-09 19:22:48 +0200 | [diff] [blame] | 158 | |
Stephane Eranian | b3cf257 | 2006-07-09 21:12:39 -0400 | [diff] [blame] | 159 | if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) { |
Alexey Dobriyan | 52978be | 2006-09-30 23:27:21 -0700 | [diff] [blame] | 160 | p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr, |
| 161 | IO_BITMAP_BYTES, GFP_KERNEL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 162 | if (!p->thread.io_bitmap_ptr) { |
| 163 | p->thread.io_bitmap_max = 0; |
| 164 | return -ENOMEM; |
| 165 | } |
Stephane Eranian | b3cf257 | 2006-07-09 21:12:39 -0400 | [diff] [blame] | 166 | set_tsk_thread_flag(p, TIF_IO_BITMAP); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 167 | } |
| 168 | |
Roland McGrath | efd1ca5 | 2008-01-30 13:30:46 +0100 | [diff] [blame] | 169 | err = 0; |
| 170 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 171 | /* |
| 172 | * Set a new TLS for the child thread? |
| 173 | */ |
Roland McGrath | efd1ca5 | 2008-01-30 13:30:46 +0100 | [diff] [blame] | 174 | if (clone_flags & CLONE_SETTLS) |
| 175 | err = do_set_thread_area(p, -1, |
Josh Triplett | c1bd55f | 2015-06-30 15:00:00 -0700 | [diff] [blame] | 176 | (struct user_desc __user *)tls, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 177 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 178 | if (err && p->thread.io_bitmap_ptr) { |
| 179 | kfree(p->thread.io_bitmap_ptr); |
| 180 | p->thread.io_bitmap_max = 0; |
| 181 | } |
| 182 | return err; |
| 183 | } |
| 184 | |
Ingo Molnar | 513ad84 | 2008-02-21 05:18:40 +0100 | [diff] [blame] | 185 | void |
| 186 | start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp) |
| 187 | { |
Tejun Heo | d9a89a2 | 2009-02-09 22:17:40 +0900 | [diff] [blame] | 188 | set_user_gs(regs, 0); |
Ingo Molnar | 513ad84 | 2008-02-21 05:18:40 +0100 | [diff] [blame] | 189 | regs->fs = 0; |
Ingo Molnar | 513ad84 | 2008-02-21 05:18:40 +0100 | [diff] [blame] | 190 | regs->ds = __USER_DS; |
| 191 | regs->es = __USER_DS; |
| 192 | regs->ss = __USER_DS; |
| 193 | regs->cs = __USER_CS; |
| 194 | regs->ip = new_ip; |
| 195 | regs->sp = new_sp; |
Al Viro | 6783eaa | 2012-08-02 23:05:11 +0400 | [diff] [blame] | 196 | regs->flags = X86_EFLAGS_IF; |
Brian Gerst | 1daeaa3 | 2015-03-21 18:54:21 -0400 | [diff] [blame] | 197 | force_iret(); |
Ingo Molnar | 513ad84 | 2008-02-21 05:18:40 +0100 | [diff] [blame] | 198 | } |
| 199 | EXPORT_SYMBOL_GPL(start_thread); |
| 200 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 201 | |
| 202 | /* |
Kamalesh Babulal | ea70ef3 | 2011-04-28 14:32:08 +0530 | [diff] [blame] | 203 | * switch_to(x,y) should switch tasks from x to y. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 204 | * |
| 205 | * We fsave/fwait so that an exception goes off at the right time |
| 206 | * (as a call from the fsave or fwait in effect) rather than to |
| 207 | * the wrong process. Lazy FP saving no longer makes any sense |
| 208 | * with modern CPU's, and this simplifies a lot of things (SMP |
| 209 | * and UP become the same). |
| 210 | * |
| 211 | * NOTE! We used to use the x86 hardware context switching. The |
| 212 | * reason for not using it any more becomes apparent when you |
| 213 | * try to recover gracefully from saved state that is no longer |
| 214 | * valid (stale segment register values in particular). With the |
| 215 | * hardware task-switch, there is no way to fix up bad state in |
| 216 | * a reasonable manner. |
| 217 | * |
| 218 | * The fact that Intel documents the hardware task-switching to |
| 219 | * be slow is a fairly red herring - this code is not noticeably |
| 220 | * faster. However, there _is_ some room for improvement here, |
| 221 | * so the performance issues may eventually be a valid point. |
| 222 | * More important, however, is the fact that this allows us much |
| 223 | * more flexibility. |
| 224 | * |
H. Peter Anvin | 65ea5b0 | 2008-01-30 13:30:56 +0100 | [diff] [blame] | 225 | * The return value (in %ax) will be the "prev" task after |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 226 | * the task-switch, and shows up in ret_from_fork in entry.S, |
| 227 | * for example. |
| 228 | */ |
Andi Kleen | 35ea7903 | 2013-08-05 15:02:39 -0700 | [diff] [blame] | 229 | __visible __notrace_funcgraph struct task_struct * |
Frederic Weisbecker | 8b96f01 | 2008-12-06 03:40:00 +0100 | [diff] [blame] | 230 | __switch_to(struct task_struct *prev_p, struct task_struct *next_p) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 231 | { |
| 232 | struct thread_struct *prev = &prev_p->thread, |
Ingo Molnar | 384a23f | 2015-04-23 17:43:27 +0200 | [diff] [blame] | 233 | *next = &next_p->thread; |
| 234 | struct fpu *prev_fpu = &prev->fpu; |
| 235 | struct fpu *next_fpu = &next->fpu; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 236 | int cpu = smp_processor_id(); |
Andy Lutomirski | 24933b8 | 2015-03-05 19:19:05 -0800 | [diff] [blame] | 237 | struct tss_struct *tss = &per_cpu(cpu_tss, cpu); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 238 | |
| 239 | /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */ |
| 240 | |
Rik van Riel | c474e50 | 2016-10-14 08:15:31 -0400 | [diff] [blame] | 241 | switch_fpu_prepare(prev_fpu, cpu); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 242 | |
| 243 | /* |
Jeremy Fitzhardinge | 464d1a7 | 2007-02-13 13:26:20 +0100 | [diff] [blame] | 244 | * 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] | 245 | * stack on entry. No need to save %es and %ds, as those are |
| 246 | * always kernel segments while inside the kernel. Doing this |
| 247 | * before setting the new TLS descriptors avoids the situation |
| 248 | * where we temporarily have non-reloadable segments in %fs |
| 249 | * and %gs. This could be an issue if the NMI handler ever |
| 250 | * used %fs or %gs (it does not today), or if the kernel is |
| 251 | * running inside of a hypervisor layer. |
Zachary Amsden | e7a2ff5 | 2005-09-03 15:56:39 -0700 | [diff] [blame] | 252 | */ |
Tejun Heo | ccbeed3 | 2009-02-09 22:17:40 +0900 | [diff] [blame] | 253 | lazy_save_gs(prev->gs); |
Zachary Amsden | e7a2ff5 | 2005-09-03 15:56:39 -0700 | [diff] [blame] | 254 | |
| 255 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 256 | * Load the per-thread Thread-Local Storage descriptor. |
| 257 | */ |
| 258 | load_TLS(next, cpu); |
| 259 | |
| 260 | /* |
Zachary Amsden | 8b15114 | 2007-02-13 13:26:21 +0100 | [diff] [blame] | 261 | * Restore IOPL if needed. In normal use, the flags restore |
| 262 | * in the switch assembly will handle this. But if the kernel |
| 263 | * is running virtualized at a non-zero CPL, the popf will |
| 264 | * not restore flags, so it must be done in a separate step. |
| 265 | */ |
| 266 | if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl)) |
| 267 | set_iopl_mask(next->iopl); |
| 268 | |
| 269 | /* |
Stephane Eranian | b3cf257 | 2006-07-09 21:12:39 -0400 | [diff] [blame] | 270 | * Now maybe handle debug registers and/or IO bitmaps |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 271 | */ |
Andrea Arcangeli | cf99aba | 2007-07-15 23:41:33 -0700 | [diff] [blame] | 272 | if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV || |
| 273 | task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT)) |
| 274 | __switch_to_xtra(prev_p, next_p, tss); |
Andrea Arcangeli | ffaa8bd | 2005-06-27 14:36:36 -0700 | [diff] [blame] | 275 | |
Zachary Amsden | 9226d12 | 2007-02-13 13:26:21 +0100 | [diff] [blame] | 276 | /* |
| 277 | * Leave lazy mode, flushing any hypercalls made here. |
| 278 | * This must be done before restoring TLS segments so |
| 279 | * the GDT and LDT are properly updated, and must be |
Ingo Molnar | 3a0aee4 | 2015-04-22 13:16:47 +0200 | [diff] [blame] | 280 | * done before fpu__restore(), so the TS bit is up |
Zachary Amsden | 9226d12 | 2007-02-13 13:26:21 +0100 | [diff] [blame] | 281 | * to date. |
| 282 | */ |
Jeremy Fitzhardinge | 224101e | 2009-02-18 11:18:57 -0800 | [diff] [blame] | 283 | arch_end_context_switch(next_p); |
Zachary Amsden | 9226d12 | 2007-02-13 13:26:21 +0100 | [diff] [blame] | 284 | |
Andy Lutomirski | b27559a | 2015-03-06 17:50:18 -0800 | [diff] [blame] | 285 | /* |
Denys Vlasenko | fed7c3f | 2015-04-24 17:31:34 +0200 | [diff] [blame] | 286 | * Reload esp0 and cpu_current_top_of_stack. This changes |
Andy Lutomirski | a7fcf28 | 2015-03-06 17:50:19 -0800 | [diff] [blame] | 287 | * current_thread_info(). |
Andy Lutomirski | b27559a | 2015-03-06 17:50:18 -0800 | [diff] [blame] | 288 | */ |
| 289 | load_sp0(tss, next); |
Andy Lutomirski | a7fcf28 | 2015-03-06 17:50:19 -0800 | [diff] [blame] | 290 | this_cpu_write(cpu_current_top_of_stack, |
| 291 | (unsigned long)task_stack_page(next_p) + |
| 292 | THREAD_SIZE); |
Steven Rostedt | 198d208 | 2014-02-06 09:41:31 -0500 | [diff] [blame] | 293 | |
Zachary Amsden | 9226d12 | 2007-02-13 13:26:21 +0100 | [diff] [blame] | 294 | /* |
| 295 | * Restore %gs if needed (which is common) |
| 296 | */ |
| 297 | if (prev->gs | next->gs) |
Tejun Heo | ccbeed3 | 2009-02-09 22:17:40 +0900 | [diff] [blame] | 298 | lazy_load_gs(next->gs); |
Zachary Amsden | 9226d12 | 2007-02-13 13:26:21 +0100 | [diff] [blame] | 299 | |
Rik van Riel | c474e50 | 2016-10-14 08:15:31 -0400 | [diff] [blame] | 300 | switch_fpu_finish(next_fpu, cpu); |
Linus Torvalds | 34ddc81 | 2012-02-18 12:56:35 -0800 | [diff] [blame] | 301 | |
Alex Shi | c6ae41e | 2012-05-11 15:35:27 +0800 | [diff] [blame] | 302 | this_cpu_write(current_task, next_p); |
Zachary Amsden | 9226d12 | 2007-02-13 13:26:21 +0100 | [diff] [blame] | 303 | |
Fenghua Yu | 4f341a5 | 2016-10-28 15:04:48 -0700 | [diff] [blame] | 304 | /* Load the Intel cache allocation PQR MSR. */ |
| 305 | intel_rdt_sched_in(); |
| 306 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 307 | return prev_p; |
| 308 | } |
Kyle Huey | 79170fd | 2017-03-20 01:16:24 -0700 | [diff] [blame] | 309 | |
| 310 | SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2) |
| 311 | { |
| 312 | return do_arch_prctl_common(current, option, arg2); |
| 313 | } |