2 * Copyright (C) 1995 Linus Torvalds
4 * Pentium III FXSR, SSE support
5 * Gareth Hughes <gareth@valinux.com>, May 2000
9 * This file handles the architecture-dependent parts of process handling..
12 #include <linux/cpu.h>
13 #include <linux/errno.h>
14 #include <linux/sched.h>
16 #include <linux/kernel.h>
18 #include <linux/elfcore.h>
19 #include <linux/smp.h>
20 #include <linux/stddef.h>
21 #include <linux/slab.h>
22 #include <linux/vmalloc.h>
23 #include <linux/user.h>
24 #include <linux/interrupt.h>
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>
32 #include <linux/personality.h>
33 #include <linux/percpu.h>
34 #include <linux/prctl.h>
35 #include <linux/ftrace.h>
36 #include <linux/uaccess.h>
38 #include <linux/kdebug.h>
40 #include <asm/pgtable.h>
42 #include <asm/processor.h>
44 #include <asm/fpu-internal.h>
46 #ifdef CONFIG_MATH_EMULATION
47 #include <asm/math_emu.h>
50 #include <linux/err.h>
52 #include <asm/tlbflush.h>
55 #include <asm/syscalls.h>
56 #include <asm/debugreg.h>
57 #include <asm/switch_to.h>
59 asmlinkage
void ret_from_fork(void) __asm__("ret_from_fork");
60 asmlinkage
void ret_from_kernel_thread(void) __asm__("ret_from_kernel_thread");
63 * Return saved PC of a blocked thread.
65 unsigned long thread_saved_pc(struct task_struct
*tsk
)
67 return ((unsigned long *)tsk
->thread
.sp
)[3];
70 void __show_regs(struct pt_regs
*regs
, int all
)
72 unsigned long cr0
= 0L, cr2
= 0L, cr3
= 0L, cr4
= 0L;
73 unsigned long d0
, d1
, d2
, d3
, d6
, d7
;
75 unsigned short ss
, gs
;
77 if (user_mode_vm(regs
)) {
79 ss
= regs
->ss
& 0xffff;
80 gs
= get_user_gs(regs
);
82 sp
= kernel_stack_pointer(regs
);
87 printk(KERN_DEFAULT
"EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n",
88 (u16
)regs
->cs
, regs
->ip
, regs
->flags
,
90 print_symbol("EIP is at %s\n", regs
->ip
);
92 printk(KERN_DEFAULT
"EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
93 regs
->ax
, regs
->bx
, regs
->cx
, regs
->dx
);
94 printk(KERN_DEFAULT
"ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",
95 regs
->si
, regs
->di
, regs
->bp
, sp
);
96 printk(KERN_DEFAULT
" DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n",
97 (u16
)regs
->ds
, (u16
)regs
->es
, (u16
)regs
->fs
, gs
, ss
);
105 cr4
= read_cr4_safe();
106 printk(KERN_DEFAULT
"CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",
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))
121 printk(KERN_DEFAULT
"DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",
123 printk(KERN_DEFAULT
"DR6: %08lx DR7: %08lx\n",
127 void release_thread(struct task_struct
*dead_task
)
129 BUG_ON(dead_task
->mm
);
130 release_vm86_irqs(dead_task
);
133 int copy_thread(unsigned long clone_flags
, unsigned long sp
,
134 unsigned long arg
, struct task_struct
*p
)
136 struct pt_regs
*childregs
= task_pt_regs(p
);
137 struct task_struct
*tsk
;
140 p
->thread
.sp
= (unsigned long) childregs
;
141 p
->thread
.sp0
= (unsigned long) (childregs
+1);
143 if (unlikely(p
->flags
& PF_KTHREAD
)) {
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 */
153 childregs
->orig_ax
= -1;
154 childregs
->cs
= __KERNEL_CS
| get_kernel_rpl();
155 childregs
->flags
= X86_EFLAGS_IF
| X86_EFLAGS_FIXED
;
157 p
->thread
.io_bitmap_ptr
= NULL
;
158 memset(p
->thread
.ptrace_bps
, 0, sizeof(p
->thread
.ptrace_bps
));
161 *childregs
= *current_pt_regs();
166 p
->thread
.ip
= (unsigned long) ret_from_fork
;
167 task_user_gs(p
) = get_user_gs(current_pt_regs());
170 p
->thread
.io_bitmap_ptr
= NULL
;
174 memset(p
->thread
.ptrace_bps
, 0, sizeof(p
->thread
.ptrace_bps
));
176 if (unlikely(test_tsk_thread_flag(tsk
, TIF_IO_BITMAP
))) {
177 p
->thread
.io_bitmap_ptr
= kmemdup(tsk
->thread
.io_bitmap_ptr
,
178 IO_BITMAP_BYTES
, GFP_KERNEL
);
179 if (!p
->thread
.io_bitmap_ptr
) {
180 p
->thread
.io_bitmap_max
= 0;
183 set_tsk_thread_flag(p
, TIF_IO_BITMAP
);
189 * Set a new TLS for the child thread?
191 if (clone_flags
& CLONE_SETTLS
)
192 err
= do_set_thread_area(p
, -1,
193 (struct user_desc __user
*)childregs
->si
, 0);
195 if (err
&& p
->thread
.io_bitmap_ptr
) {
196 kfree(p
->thread
.io_bitmap_ptr
);
197 p
->thread
.io_bitmap_max
= 0;
203 start_thread(struct pt_regs
*regs
, unsigned long new_ip
, unsigned long new_sp
)
205 set_user_gs(regs
, 0);
207 regs
->ds
= __USER_DS
;
208 regs
->es
= __USER_DS
;
209 regs
->ss
= __USER_DS
;
210 regs
->cs
= __USER_CS
;
213 regs
->flags
= X86_EFLAGS_IF
;
215 * force it to the iret return path by making it look as if there was
218 set_thread_flag(TIF_NOTIFY_RESUME
);
220 EXPORT_SYMBOL_GPL(start_thread
);
224 * switch_to(x,y) should switch tasks from x to y.
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).
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.
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
246 * The return value (in %ax) will be the "prev" task after
247 * the task-switch, and shows up in ret_from_fork in entry.S,
250 __visible __notrace_funcgraph
struct task_struct
*
251 __switch_to(struct task_struct
*prev_p
, struct task_struct
*next_p
)
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
);
259 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
261 fpu
= switch_fpu_prepare(prev_p
, next_p
, cpu
);
269 * Save away %gs. No need to save %fs, as it was saved on the
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.
278 lazy_save_gs(prev
->gs
);
281 * Load the per-thread Thread-Local Storage descriptor.
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.
291 if (get_kernel_rpl() && unlikely(prev
->iopl
!= next
->iopl
))
292 set_iopl_mask(next
->iopl
);
295 * Now maybe handle debug registers and/or IO bitmaps
297 if (unlikely(task_thread_info(prev_p
)->flags
& _TIF_WORK_CTXSW_PREV
||
298 task_thread_info(next_p
)->flags
& _TIF_WORK_CTXSW_NEXT
))
299 __switch_to_xtra(prev_p
, next_p
, tss
);
302 * Leave lazy mode, flushing any hypercalls made here.
303 * This must be done before restoring TLS segments so
304 * the GDT and LDT are properly updated, and must be
305 * done before math_state_restore, so the TS bit is up
308 arch_end_context_switch(next_p
);
311 * Restore %gs if needed (which is common)
313 if (prev
->gs
| next
->gs
)
314 lazy_load_gs(next
->gs
);
316 switch_fpu_finish(next_p
, fpu
);
318 this_cpu_write(current_task
, next_p
);
323 #define top_esp (THREAD_SIZE - sizeof(unsigned long))
324 #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long))
326 unsigned long get_wchan(struct task_struct
*p
)
328 unsigned long bp
, sp
, ip
;
329 unsigned long stack_page
;
331 if (!p
|| p
== current
|| p
->state
== TASK_RUNNING
)
333 stack_page
= (unsigned long)task_stack_page(p
);
335 if (!stack_page
|| sp
< stack_page
|| sp
> top_esp
+stack_page
)
337 /* include/asm-i386/system.h:switch_to() pushes bp last. */
338 bp
= *(unsigned long *) sp
;
340 if (bp
< stack_page
|| bp
> top_ebp
+stack_page
)
342 ip
= *(unsigned long *) (bp
+4);
343 if (!in_sched_functions(ip
))
345 bp
= *(unsigned long *) bp
;
346 } while (count
++ < 16);