/*
* linux/arch/i386/kernel/process.c
*
* Copyright (C) 1995 Linus Torvalds
*
* Pentium III FXSR, SSE support
* Gareth Hughes <gareth@valinux.com>, May 2000
*/
/*
* This file handles the architecture-dependent parts of process handling..
*/
#define __KERNEL_SYSCALLS__
#include <stdarg.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/malloc.h>
#include <linux/vmalloc.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/interrupt.h>
#include <linux/config.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/mc146818rtc.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/ldt.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/desc.h>
#include <asm/mmu_context.h>
#ifdef CONFIG_MATH_EMULATION
#include <asm/math_emu.h>
#endif
#include <linux/irq.h>
asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
int hlt_counter;
/*
* Powermanagement idle function, if any..
*/
void (*pm_idle)(void);
/*
* Power off function, if any
*/
void (*pm_power_off)(void);
66 void disable_hlt(void)
{
hlt_counter++;
}
71 void enable_hlt(void)
{
hlt_counter--;
}
/*
* We use this if we don't have any better
* idle routine..
*/
80 static void default_idle(void)
{
82 if (current_cpu_data.hlt_works_ok && !hlt_counter) {
__cli();
84 if (!current->need_resched)
safe_halt();
86 else
__sti();
}
}
/*
* On SMP it's slightly faster (but much more power-consuming!)
* to poll the ->need_resched flag instead of waiting for the
* cross-CPU IPI to arrive. Use this option with caution.
*/
96 static void poll_idle (void)
{
int oldval;
__sti();
/*
* Deal with another CPU just having chosen a thread to
* run here:
*/
oldval = xchg(¤t->need_resched, -1);
108 if (!oldval)
asm volatile(
"2:"
"cmpl $-1, %0;"
"rep; nop;"
"je 2b;"
: :"m" (current->need_resched));
}
/*
* The idle thread. There's no useful work to be
* done, so just try to conserve power and have a
* low exit latency (ie sit in a loop waiting for
* somebody to say that they'd like to reschedule)
*/
123 void cpu_idle (void)
{
/* endless idle loop with no priority at all */
init_idle();
current->nice = 20;
current->counter = -100;
130 while (1) {
void (*idle)(void) = pm_idle;
132 if (!idle)
idle = default_idle;
134 while (!current->need_resched)
idle();
schedule();
check_pgt_cache();
}
}
141 static int __init idle_setup (char *str)
{
143 if (!strncmp(str, "poll", 4)) {
printk("using polling idle threads.\n");
pm_idle = poll_idle;
}
148 return 1;
}
__setup("idle=", idle_setup);
static long no_idt[2];
static int reboot_mode;
static int reboot_thru_bios;
157 static int __init reboot_setup(char *str)
{
159 while(1) {
160 switch (*str) {
161 case 'w': /* "warm" reboot (no memory testing etc) */
reboot_mode = 0x1234;
163 break;
164 case 'c': /* "cold" reboot (with memory testing etc) */
reboot_mode = 0x0;
166 break;
167 case 'b': /* "bios" reboot by jumping through the BIOS */
reboot_thru_bios = 1;
169 break;
170 case 'h': /* "hard" reboot by toggling RESET and/or crashing the CPU */
reboot_thru_bios = 0;
172 break;
}
174 if((str = strchr(str,',')) != NULL)
str++;
176 else
177 break;
}
179 return 1;
}
__setup("reboot=", reboot_setup);
/* The following code and data reboots the machine by switching to real
mode and jumping to the BIOS reset entry point, as if the CPU has
really been reset. The previous version asked the keyboard
controller to pulse the CPU reset line, which is more thorough, but
doesn't work with at least one type of 486 motherboard. It is easy
to stop this code working; hence the copious comments. */
static unsigned long long
real_mode_gdt_entries [3] =
{
0x0000000000000000ULL, /* Null descriptor */
0x00009a000000ffffULL, /* 16-bit real-mode 64k code at 0x00000000 */
0x000092000100ffffULL /* 16-bit real-mode 64k data at 0x00000100 */
};
static struct
{
unsigned short size __attribute__ ((packed));
unsigned long long * base __attribute__ ((packed));
}
real_mode_gdt = { sizeof (real_mode_gdt_entries) - 1, real_mode_gdt_entries },
real_mode_idt = { 0x3ff, 0 };
/* This is 16-bit protected mode code to disable paging and the cache,
switch to real mode and jump to the BIOS reset code.
The instruction that switches to real mode by writing to CR0 must be
followed immediately by a far jump instruction, which set CS to a
valid value for real mode, and flushes the prefetch queue to avoid
running instructions that have already been decoded in protected
mode.
Clears all the flags except ET, especially PG (paging), PE
(protected-mode enable) and TS (task switch for coprocessor state
save). Flushes the TLB after paging has been disabled. Sets CD and
NW, to disable the cache on a 486, and invalidates the cache. This
is more like the state of a 486 after reset. I don't know if
something else should be done for other chips.
More could be done here to set up the registers as if a CPU reset had
occurred; hopefully real BIOSs don't assume much. */
static unsigned char real_mode_switch [] =
{
0x66, 0x0f, 0x20, 0xc0, /* movl %cr0,%eax */
0x66, 0x83, 0xe0, 0x11, /* andl $0x00000011,%eax */
0x66, 0x0d, 0x00, 0x00, 0x00, 0x60, /* orl $0x60000000,%eax */
0x66, 0x0f, 0x22, 0xc0, /* movl %eax,%cr0 */
0x66, 0x0f, 0x22, 0xd8, /* movl %eax,%cr3 */
0x66, 0x0f, 0x20, 0xc3, /* movl %cr0,%ebx */
0x66, 0x81, 0xe3, 0x00, 0x00, 0x00, 0x60, /* andl $0x60000000,%ebx */
0x74, 0x02, /* jz f */
0x0f, 0x08, /* invd */
0x24, 0x10, /* f: andb $0x10,al */
0x66, 0x0f, 0x22, 0xc0 /* movl %eax,%cr0 */
};
static unsigned char jump_to_bios [] =
{
0xea, 0x00, 0x00, 0xff, 0xff /* ljmp $0xffff,$0x0000 */
};
245 static inline void kb_wait(void)
{
int i;
249 for (i=0; i<0x10000; i++)
250 if ((inb_p(0x64) & 0x02) == 0)
251 break;
}
/*
* Switch to real mode and then execute the code
* specified by the code and length parameters.
* We assume that length will aways be less that 100!
*/
259 void machine_real_restart(unsigned char *code, int length)
{
unsigned long flags;
cli();
/* Write zero to CMOS register number 0x0f, which the BIOS POST
routine will recognize as telling it to do a proper reboot. (Well
that's what this book in front of me says -- it may only apply to
the Phoenix BIOS though, it's not clear). At the same time,
disable NMIs by setting the top bit in the CMOS address register,
as we're about to do peculiar things to the CPU. I'm not sure if
`outb_p' is needed instead of just `outb'. Use it to be on the
safe side. (Yes, CMOS_WRITE does outb_p's. - Paul G.)
*/
275 spin_lock_irqsave(&rtc_lock, flags);
CMOS_WRITE(0x00, 0x8f);
277 spin_unlock_irqrestore(&rtc_lock, flags);
/* Remap the kernel at virtual address zero, as well as offset zero
from the kernel segment. This assumes the kernel segment starts at
virtual address PAGE_OFFSET. */
memcpy (swapper_pg_dir, swapper_pg_dir + USER_PGD_PTRS,
sizeof (swapper_pg_dir [0]) * KERNEL_PGD_PTRS);
/* Make sure the first page is mapped to the start of physical memory.
It is normally not mapped, to trap kernel NULL pointer dereferences. */
pg0[0] = _PAGE_RW | _PAGE_PRESENT;
/*
* Use `swapper_pg_dir' as our page directory.
*/
asm volatile("movl %0,%%cr3": :"r" (__pa(swapper_pg_dir)));
/* Write 0x1234 to absolute memory location 0x472. The BIOS reads
this on booting to tell it to "Bypass memory test (also warm
boot)". This seems like a fairly standard thing that gets set by
REBOOT.COM programs, and the previous reset routine did this
too. */
*((unsigned short *)0x472) = reboot_mode;
/* For the switch to real mode, copy some code to low memory. It has
to be in the first 64k because it is running in 16-bit mode, and it
has to have the same physical and virtual address, because it turns
off paging. Copy it near the end of the first page, out of the way
of BIOS variables. */
memcpy ((void *) (0x1000 - sizeof (real_mode_switch) - 100),
real_mode_switch, sizeof (real_mode_switch));
memcpy ((void *) (0x1000 - 100), code, length);
/* Set up the IDT for real mode. */
__asm__ __volatile__ ("lidt %0" : : "m" (real_mode_idt));
/* Set up a GDT from which we can load segment descriptors for real
mode. The GDT is not used in real mode; it is just needed here to
prepare the descriptors. */
__asm__ __volatile__ ("lgdt %0" : : "m" (real_mode_gdt));
/* Load the data segment registers, and thus the descriptors ready for
real mode. The base address of each segment is 0x100, 16 times the
selector value being loaded here. This is so that the segment
registers don't have to be reloaded after switching to real mode:
the values are consistent for real mode operation already. */
__asm__ __volatile__ ("movl $0x0010,%%eax\n"
"\tmovl %%eax,%%ds\n"
"\tmovl %%eax,%%es\n"
"\tmovl %%eax,%%fs\n"
"\tmovl %%eax,%%gs\n"
"\tmovl %%eax,%%ss" : : : "eax");
/* Jump to the 16-bit code that we copied earlier. It disables paging
and the cache, switches to real mode, and jumps to the BIOS reset
entry point. */
__asm__ __volatile__ ("ljmp $0x0008,%0"
:
: "i" ((void *) (0x1000 - sizeof (real_mode_switch) - 100)));
}
346 void machine_restart(char * __unused)
{
#if CONFIG_SMP
/*
* Stop all CPUs and turn off local APICs and the IO-APIC, so
* other OSs see a clean IRQ state.
*/
smp_send_stop();
disable_IO_APIC();
#endif
357 if(!reboot_thru_bios) {
/* rebooting needs to touch the page at absolute addr 0 */
*((unsigned short *)__va(0x472)) = reboot_mode;
360 for (;;) {
int i;
362 for (i=0; i<100; i++) {
kb_wait();
udelay(50);
outb(0xfe,0x64); /* pulse reset low */
udelay(50);
}
/* That didn't work - force a triple fault.. */
__asm__ __volatile__("lidt %0": :"m" (no_idt));
__asm__ __volatile__("int3");
}
}
machine_real_restart(jump_to_bios, sizeof(jump_to_bios));
}
377 void machine_halt(void)
{
}
381 void machine_power_off(void)
{
383 if (pm_power_off)
pm_power_off();
}
extern void show_trace(unsigned long* esp);
389 void show_regs(struct pt_regs * regs)
{
unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
printk("\n");
printk("EIP: %04x:[<%08lx>] CPU: %d",0xffff & regs->xcs,regs->eip, smp_processor_id());
395 if (regs->xcs & 3)
printk(" ESP: %04x:%08lx",0xffff & regs->xss,regs->esp);
printk(" EFLAGS: %08lx\n",regs->eflags);
printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
regs->eax,regs->ebx,regs->ecx,regs->edx);
printk("ESI: %08lx EDI: %08lx EBP: %08lx",
regs->esi, regs->edi, regs->ebp);
printk(" DS: %04x ES: %04x\n",
0xffff & regs->xds,0xffff & regs->xes);
__asm__("movl %%cr0, %0": "=r" (cr0));
__asm__("movl %%cr2, %0": "=r" (cr2));
__asm__("movl %%cr3, %0": "=r" (cr3));
/* This could fault if %cr4 does not exist */
__asm__("1: movl %%cr4, %0 \n"
"2: \n"
".section __ex_table,\"a\" \n"
".long 1b,2b \n"
".previous \n"
: "=r" (cr4): "0" (0));
printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0, cr2, cr3, cr4);
show_trace(®s->esp);
}
/*
* No need to lock the MM as we are the last user
*/
422 void release_segments(struct mm_struct *mm)
{
void * ldt = mm->context.segments;
/*
* free the LDT
*/
429 if (ldt) {
mm->context.segments = NULL;
clear_LDT();
vfree(ldt);
}
}
/*
* Create a kernel thread
*/
439 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
long retval, d0;
__asm__ __volatile__(
"movl %%esp,%%esi\n\t"
"int $0x80\n\t" /* Linux/i386 system call */
"cmpl %%esp,%%esi\n\t" /* child or parent? */
"je 1f\n\t" /* parent - jump */
/* Load the argument into eax, and push it. That way, it does
* not matter whether the called function is compiled with
* -mregparm or not. */
"movl %4,%%eax\n\t"
"pushl %%eax\n\t"
"call *%5\n\t" /* call fn */
"movl %3,%0\n\t" /* exit */
"int $0x80\n"
"1:\t"
:"=&a" (retval), "=&S" (d0)
:"0" (__NR_clone), "i" (__NR_exit),
"r" (arg), "r" (fn),
"b" (flags | CLONE_VM)
: "memory");
462 return retval;
}
/*
* Free current thread data structures etc..
*/
468 void exit_thread(void)
{
/* nothing to do ... */
}
473 void flush_thread(void)
{
struct task_struct *tsk = current;
memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8);
/*
* Forget coprocessor state..
*/
481 clear_fpu(tsk);
tsk->used_math = 0;
}
485 void release_thread(struct task_struct *dead_task)
{
487 if (dead_task->mm) {
void * ldt = dead_task->mm->context.segments;
// temporary debugging check
491 if (ldt) {
printk("WARNING: dead process %8s still has LDT? <%p>\n",
dead_task->comm, ldt);
494 BUG();
}
}
}
/*
* we do not have to muck with descriptors here, that is
* done in switch_mm() as needed.
*/
503 void copy_segments(struct task_struct *p, struct mm_struct *new_mm)
{
struct mm_struct * old_mm;
void *old_ldt, *ldt;
ldt = NULL;
old_mm = current->mm;
510 if (old_mm && (old_ldt = old_mm->context.segments) != NULL) {
/*
* Completely new LDT, we initialize it from the parent:
*/
ldt = vmalloc(LDT_ENTRIES*LDT_ENTRY_SIZE);
515 if (!ldt)
printk(KERN_WARNING "ldt allocation failed\n");
517 else
memcpy(ldt, old_ldt, LDT_ENTRIES*LDT_ENTRY_SIZE);
}
new_mm->context.segments = ldt;
}
/*
* Save a segment.
*/
#define savesegment(seg,value) \
asm volatile("movl %%" #seg ",%0":"=m" (*(int *)&(value)))
529 int copy_thread(int nr, unsigned long clone_flags, unsigned long esp,
unsigned long unused,
struct task_struct * p, struct pt_regs * regs)
{
struct pt_regs * childregs;
childregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) p)) - 1;
struct_cpy(childregs, regs);
childregs->eax = 0;
childregs->esp = esp;
p->thread.esp = (unsigned long) childregs;
p->thread.esp0 = (unsigned long) (childregs+1);
p->thread.eip = (unsigned long) ret_from_fork;
savesegment(fs,p->thread.fs);
savesegment(gs,p->thread.gs);
548 unlazy_fpu(current);
struct_cpy(&p->thread.i387, ¤t->thread.i387);
551 return 0;
}
/*
* fill in the user structure for a core dump..
*/
557 void dump_thread(struct pt_regs * regs, struct user * dump)
{
int i;
/* changed the size calculations - should hopefully work better. lbt */
dump->magic = CMAGIC;
dump->start_code = 0;
dump->start_stack = regs->esp & ~(PAGE_SIZE - 1);
dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT;
dump->u_dsize -= dump->u_tsize;
dump->u_ssize = 0;
569 for (i = 0; i < 8; i++)
dump->u_debugreg[i] = current->thread.debugreg[i];
572 if (dump->start_stack < TASK_SIZE)
dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT;
dump->regs.ebx = regs->ebx;
dump->regs.ecx = regs->ecx;
dump->regs.edx = regs->edx;
dump->regs.esi = regs->esi;
dump->regs.edi = regs->edi;
dump->regs.ebp = regs->ebp;
dump->regs.eax = regs->eax;
dump->regs.ds = regs->xds;
dump->regs.es = regs->xes;
savesegment(fs,dump->regs.fs);
savesegment(gs,dump->regs.gs);
dump->regs.orig_eax = regs->orig_eax;
dump->regs.eip = regs->eip;
dump->regs.cs = regs->xcs;
dump->regs.eflags = regs->eflags;
dump->regs.esp = regs->esp;
dump->regs.ss = regs->xss;
dump->u_fpvalid = dump_fpu (regs, &dump->i387);
}
/*
* This special macro can be used to load a debugging register
*/
#define loaddebug(thread,register) \
__asm__("movl %0,%%db" #register \
: /* no output */ \
:"r" (thread->debugreg[register]))
/*
* switch_to(x,yn) should switch tasks from x to y.
*
* We fsave/fwait so that an exception goes off at the right time
* (as a call from the fsave or fwait in effect) rather than to
* the wrong process. Lazy FP saving no longer makes any sense
* with modern CPU's, and this simplifies a lot of things (SMP
* and UP become the same).
*
* NOTE! We used to use the x86 hardware context switching. The
* reason for not using it any more becomes apparent when you
* try to recover gracefully from saved state that is no longer
* valid (stale segment register values in particular). With the
* hardware task-switch, there is no way to fix up bad state in
* a reasonable manner.
*
* The fact that Intel documents the hardware task-switching to
* be slow is a fairly red herring - this code is not noticeably
* faster. However, there _is_ some room for improvement here,
* so the performance issues may eventually be a valid point.
* More important, however, is the fact that this allows us much
* more flexibility.
*/
627 void __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
{
struct thread_struct *prev = &prev_p->thread,
*next = &next_p->thread;
struct tss_struct *tss = init_tss + smp_processor_id();
633 unlazy_fpu(prev_p);
/*
* Reload esp0, LDT and the page table pointer:
*/
tss->esp0 = next->esp0;
/*
* Save away %fs and %gs. No need to save %es and %ds, as
* those are always kernel segments while inside the kernel.
*/
asm volatile("movl %%fs,%0":"=m" (*(int *)&prev->fs));
asm volatile("movl %%gs,%0":"=m" (*(int *)&prev->gs));
/*
* Restore %fs and %gs.
*/
loadsegment(fs, next->fs);
loadsegment(gs, next->gs);
/*
* Now maybe reload the debug registers
*/
656 if (next->debugreg[7]){
loaddebug(next, 0);
loaddebug(next, 1);
loaddebug(next, 2);
loaddebug(next, 3);
/* no 4 and 5 */
loaddebug(next, 6);
loaddebug(next, 7);
}
666 if (prev->ioperm || next->ioperm) {
667 if (next->ioperm) {
/*
* 4 cachelines copy ... not good, but not that
* bad either. Anyone got something better?
* This only affects processes which use ioperm().
* [Putting the TSSs into 4k-tlb mapped regions
* and playing VM tricks to switch the IO bitmap
* is not really acceptable.]
*/
memcpy(tss->io_bitmap, next->io_bitmap,
IO_BITMAP_SIZE*sizeof(unsigned long));
tss->bitmap = IO_BITMAP_OFFSET;
679 } else
/*
* a bitmap offset pointing outside of the TSS limit
* causes a nicely controllable SIGSEGV if a process
* tries to use a port IO instruction. The first
* sys_ioperm() call sets up the bitmap properly.
*/
tss->bitmap = INVALID_IO_BITMAP_OFFSET;
}
}
690 asmlinkage int sys_fork(struct pt_regs regs)
{
692 return do_fork(SIGCHLD, regs.esp, ®s, 0);
}
695 asmlinkage int sys_clone(struct pt_regs regs)
{
unsigned long clone_flags;
unsigned long newsp;
clone_flags = regs.ebx;
newsp = regs.ecx;
702 if (!newsp)
newsp = regs.esp;
704 return do_fork(clone_flags, newsp, ®s, 0);
}
/*
* This is trivial, and on the face of it looks like it
* could equally well be done in user mode.
*
* Not so, for quite unobvious reasons - register pressure.
* In user mode vfork() cannot have a stack frame, and if
* done by calling the "clone()" system call directly, you
* do not have enough call-clobbered registers to hold all
* the information you need.
*/
717 asmlinkage int sys_vfork(struct pt_regs regs)
{
719 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, ®s, 0);
}
/*
* sys_execve() executes a new program.
*/
725 asmlinkage int sys_execve(struct pt_regs regs)
{
int error;
char * filename;
filename = getname((char *) regs.ebx);
error = PTR_ERR(filename);
732 if (IS_ERR(filename))
733 goto out;
error = do_execve(filename, (char **) regs.ecx, (char **) regs.edx, ®s);
735 if (error == 0)
current->ptrace &= ~PT_DTRACE;
putname(filename);
out:
739 return error;
}
/*
* These bracket the sleeping functions..
*/
extern void scheduling_functions_start_here(void);
extern void scheduling_functions_end_here(void);
#define first_sched ((unsigned long) scheduling_functions_start_here)
#define last_sched ((unsigned long) scheduling_functions_end_here)
750 unsigned long get_wchan(struct task_struct *p)
{
unsigned long ebp, esp, eip;
unsigned long stack_page;
int count = 0;
755 if (!p || p == current || p->state == TASK_RUNNING)
756 return 0;
stack_page = (unsigned long)p;
esp = p->thread.esp;
759 if (!stack_page || esp < stack_page || esp > 8188+stack_page)
760 return 0;
/* include/asm-i386/system.h:switch_to() pushes ebp last. */
ebp = *(unsigned long *) esp;
763 do {
764 if (ebp < stack_page || ebp > 8184+stack_page)
765 return 0;
eip = *(unsigned long *) (ebp+4);
767 if (eip < first_sched || eip >= last_sched)
768 return eip;
ebp = *(unsigned long *) ebp;
770 } while (count++ < 16);
771 return 0;
}
#undef last_sched
#undef first_sched