[deliverable/linux.git] / arch / um / kernel / trap_kern.c

/* 
 * Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
 * Licensed under the GPL
 */

#include "linux/kernel.h"
#include "asm/errno.h"
#include "linux/sched.h"
#include "linux/mm.h"
#include "linux/spinlock.h"
#include "linux/config.h"
#include "linux/init.h"
#include "linux/ptrace.h"
#include "asm/semaphore.h"
#include "asm/pgtable.h"
#include "asm/pgalloc.h"
#include "asm/tlbflush.h"
#include "asm/a.out.h"
#include "asm/current.h"
#include "asm/irq.h"
#include "sysdep/sigcontext.h"
#include "user_util.h"
#include "kern_util.h"
#include "kern.h"
#include "chan_kern.h"
#include "mconsole_kern.h"
#include "mem.h"
#include "mem_kern.h"

/* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */
int handle_page_fault(unsigned long address, unsigned long ip, 
		      int is_write, int is_user, int *code_out)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;
	int err = -EFAULT;

	*code_out = SEGV_MAPERR;

	/* If the fault was during atomic operation, don't take the fault, just
	 * fail. */
	if (in_atomic())
		goto out_nosemaphore;

	down_read(&mm->mmap_sem);
	vma = find_vma(mm, address);
	if(!vma) 
		goto out;
	else if(vma->vm_start <= address) 
		goto good_area;
	else if(!(vma->vm_flags & VM_GROWSDOWN)) 
		goto out;
	else if(is_user && !ARCH_IS_STACKGROW(address))
		goto out;
	else if(expand_stack(vma, address)) 
		goto out;

good_area:
	*code_out = SEGV_ACCERR;
	if(is_write && !(vma->vm_flags & VM_WRITE)) 
		goto out;

	/* Don't require VM_READ|VM_EXEC for write faults! */
        if(!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
                goto out;

	do {
survive:
		switch (handle_mm_fault(mm, vma, address, is_write)){
		case VM_FAULT_MINOR:
			current->min_flt++;
			break;
		case VM_FAULT_MAJOR:
			current->maj_flt++;
			break;
		case VM_FAULT_SIGBUS:
			err = -EACCES;
			goto out;
		case VM_FAULT_OOM:
			err = -ENOMEM;
			goto out_of_memory;
		default:
			BUG();
		}
		pgd = pgd_offset(mm, address);
		pud = pud_offset(pgd, address);
		pmd = pmd_offset(pud, address);
		pte = pte_offset_kernel(pmd, address);
	} while(!pte_present(*pte));
	err = 0;
	WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
	flush_tlb_page(vma, address);
out:
	up_read(&mm->mmap_sem);
out_nosemaphore:
	return(err);

/*
 * We ran out of memory, or some other thing happened to us that made
 * us unable to handle the page fault gracefully.
 */
out_of_memory:
	if (current->pid == 1) {
		up_read(&mm->mmap_sem);
		yield();
		down_read(&mm->mmap_sem);
		goto survive;
	}
	goto out;
}

/*
 * We give a *copy* of the faultinfo in the regs to segv.
 * This must be done, since nesting SEGVs could overwrite
 * the info in the regs. A pointer to the info then would
 * give us bad data!
 */
unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
{
	struct siginfo si;
	void *catcher;
	int err;
        int is_write = FAULT_WRITE(fi);
        unsigned long address = FAULT_ADDRESS(fi);

        if(!is_user && (address >= start_vm) && (address < end_vm)){
                flush_tlb_kernel_vm();
                return(0);
        }
	else if(current->mm == NULL)
		panic("Segfault with no mm");

	if (SEGV_IS_FIXABLE(&fi))
		err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
	else {
		err = -EFAULT;
		/* A thread accessed NULL, we get a fault, but CR2 is invalid.
		 * This code is used in __do_copy_from_user() of TT mode. */
		address = 0;
	}

	catcher = current->thread.fault_catcher;
	if(!err)
		return(0);
	else if(catcher != NULL){
		current->thread.fault_addr = (void *) address;
		do_longjmp(catcher, 1);
	} 
	else if(current->thread.fault_addr != NULL)
		panic("fault_addr set but no fault catcher");
        else if(!is_user && arch_fixup(ip, sc))
		return(0);

 	if(!is_user) 
		panic("Kernel mode fault at addr 0x%lx, ip 0x%lx", 
		      address, ip);

	if (err == -EACCES) {
		si.si_signo = SIGBUS;
		si.si_errno = 0;
		si.si_code = BUS_ADRERR;
		si.si_addr = (void *)address;
                current->thread.arch.faultinfo = fi;
		force_sig_info(SIGBUS, &si, current);
	} else if (err == -ENOMEM) {
		printk("VM: killing process %s\n", current->comm);
		do_exit(SIGKILL);
	} else {
		BUG_ON(err != -EFAULT);
		si.si_signo = SIGSEGV;
		si.si_addr = (void *) address;
                current->thread.arch.faultinfo = fi;
		force_sig_info(SIGSEGV, &si, current);
	}
	return(0);
}

void bad_segv(struct faultinfo fi, unsigned long ip)
{
	struct siginfo si;

	si.si_signo = SIGSEGV;
	si.si_code = SEGV_ACCERR;
        si.si_addr = (void *) FAULT_ADDRESS(fi);
        current->thread.arch.faultinfo = fi;
	force_sig_info(SIGSEGV, &si, current);
}

void relay_signal(int sig, union uml_pt_regs *regs)
{
	if(arch_handle_signal(sig, regs)) return;
	if(!UPT_IS_USER(regs))
		panic("Kernel mode signal %d", sig);
        current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
	force_sig(sig, current);
}

void bus_handler(int sig, union uml_pt_regs *regs)
{
	if(current->thread.fault_catcher != NULL)
		do_longjmp(current->thread.fault_catcher, 1);
	else relay_signal(sig, regs);
}

void winch(int sig, union uml_pt_regs *regs)
{
	do_IRQ(WINCH_IRQ, regs);
}

void trap_init(void)
{
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Copyright (C) 2000, 2001 Jeff Dike (jdike@karaya.com)
	3	* Licensed under the GPL
	4	*/
	5
	6	#include "linux/kernel.h"
	7	#include "asm/errno.h"
	8	#include "linux/sched.h"
	9	#include "linux/mm.h"
	10	#include "linux/spinlock.h"
	11	#include "linux/config.h"
	12	#include "linux/init.h"
	13	#include "linux/ptrace.h"
	14	#include "asm/semaphore.h"
	15	#include "asm/pgtable.h"
	16	#include "asm/pgalloc.h"
	17	#include "asm/tlbflush.h"
	18	#include "asm/a.out.h"
	19	#include "asm/current.h"
	20	#include "asm/irq.h"
546fe1cb	21	#include "sysdep/sigcontext.h"
1da177e4 LT	22	#include "user_util.h"
	23	#include "kern_util.h"
	24	#include "kern.h"
	25	#include "chan_kern.h"
	26	#include "mconsole_kern.h"
1da177e4 LT	27	#include "mem.h"
	28	#include "mem_kern.h"
	29
3b52166c	30	/* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */
1da177e4 LT	31	int handle_page_fault(unsigned long address, unsigned long ip,
	32	int is_write, int is_user, int *code_out)
	33	{
	34	struct mm_struct *mm = current->mm;
	35	struct vm_area_struct *vma;
	36	pgd_t *pgd;
	37	pud_t *pud;
	38	pmd_t *pmd;
	39	pte_t *pte;
1da177e4 LT	40	int err = -EFAULT;
	41
	42	*code_out = SEGV_MAPERR;
fea03cb4 PBG	43
	44	/* If the fault was during atomic operation, don't take the fault, just
	45	* fail. */
	46	if (in_atomic())
	47	goto out_nosemaphore;
	48
1da177e4 LT	49	down_read(&mm->mmap_sem);
	50	vma = find_vma(mm, address);
	51	if(!vma)
	52	goto out;
	53	else if(vma->vm_start <= address)
	54	goto good_area;
	55	else if(!(vma->vm_flags & VM_GROWSDOWN))
	56	goto out;
2d58cc9a	57	else if(is_user && !ARCH_IS_STACKGROW(address))
1da177e4 LT	58	goto out;
	59	else if(expand_stack(vma, address))
	60	goto out;
	61
3b52166c	62	good_area:
1da177e4 LT	63	*code_out = SEGV_ACCERR;
	64	if(is_write && !(vma->vm_flags & VM_WRITE))
	65	goto out;
13479d52	66
d129f312 PBG	67	/* Don't require VM_READ\|VM_EXEC for write faults! */
d129f312 PBG	68	if(!is_write && !(vma->vm_flags & (VM_READ \| VM_EXEC)))
13479d52 JD	69	goto out;
13479d52 JD	70
1da177e4	71	do {
3b52166c	72	survive:
1da177e4 LT	73	switch (handle_mm_fault(mm, vma, address, is_write)){
	74	case VM_FAULT_MINOR:
	75	current->min_flt++;
	76	break;
	77	case VM_FAULT_MAJOR:
	78	current->maj_flt++;
	79	break;
	80	case VM_FAULT_SIGBUS:
	81	err = -EACCES;
	82	goto out;
	83	case VM_FAULT_OOM:
	84	err = -ENOMEM;
	85	goto out_of_memory;
	86	default:
	87	BUG();
	88	}
3b52166c PBG	89	pgd = pgd_offset(mm, address);
	90	pud = pud_offset(pgd, address);
	91	pmd = pmd_offset(pud, address);
	92	pte = pte_offset_kernel(pmd, address);
1da177e4 LT	93	} while(!pte_present(*pte));
1da177e4 LT	94	err = 0;
16b03678	95	WARN_ON(!pte_young(pte) \|\| (is_write && !pte_dirty(pte)));
3b52166c PBG	96	flush_tlb_page(vma, address);
3b52166c PBG	97	out:
1da177e4	98	up_read(&mm->mmap_sem);
fea03cb4	99	out_nosemaphore:
1da177e4 LT	100	return(err);
	101
	102	/*
	103	* We ran out of memory, or some other thing happened to us that made
	104	* us unable to handle the page fault gracefully.
	105	*/
	106	out_of_memory:
	107	if (current->pid == 1) {
	108	up_read(&mm->mmap_sem);
	109	yield();
	110	down_read(&mm->mmap_sem);
	111	goto survive;
	112	}
	113	goto out;
	114	}
	115
c578455a BS	116	/*
	117	* We give a copy of the faultinfo in the regs to segv.
	118	* This must be done, since nesting SEGVs could overwrite
	119	* the info in the regs. A pointer to the info then would
	120	* give us bad data!
	121	*/
	122	unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
1da177e4 LT	123	{
	124	struct siginfo si;
	125	void *catcher;
	126	int err;
c578455a BS	127	int is_write = FAULT_WRITE(fi);
c578455a BS	128	unsigned long address = FAULT_ADDRESS(fi);
1da177e4 LT	129
	130	if(!is_user && (address >= start_vm) && (address < end_vm)){
	131	flush_tlb_kernel_vm();
	132	return(0);
	133	}
1da177e4 LT	134	else if(current->mm == NULL)
1da177e4 LT	135	panic("Segfault with no mm");
546fe1cb PBG	136
	137	if (SEGV_IS_FIXABLE(&fi))
	138	err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
	139	else {
	140	err = -EFAULT;
	141	/* A thread accessed NULL, we get a fault, but CR2 is invalid.
	142	* This code is used in __do_copy_from_user() of TT mode. */
	143	address = 0;
	144	}
1da177e4 LT	145
	146	catcher = current->thread.fault_catcher;
	147	if(!err)
	148	return(0);
	149	else if(catcher != NULL){
	150	current->thread.fault_addr = (void *) address;
	151	do_longjmp(catcher, 1);
	152	}
	153	else if(current->thread.fault_addr != NULL)
	154	panic("fault_addr set but no fault catcher");
c578455a	155	else if(!is_user && arch_fixup(ip, sc))
1da177e4 LT	156	return(0);
	157
	158	if(!is_user)
	159	panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
	160	address, ip);
	161
3b52166c	162	if (err == -EACCES) {
1da177e4 LT	163	si.si_signo = SIGBUS;
	164	si.si_errno = 0;
	165	si.si_code = BUS_ADRERR;
	166	si.si_addr = (void *)address;
c578455a	167	current->thread.arch.faultinfo = fi;
1da177e4	168	force_sig_info(SIGBUS, &si, current);
3b52166c	169	} else if (err == -ENOMEM) {
1da177e4 LT	170	printk("VM: killing process %s\n", current->comm);
1da177e4 LT	171	do_exit(SIGKILL);
3b52166c PBG	172	} else {
3b52166c PBG	173	BUG_ON(err != -EFAULT);
1da177e4 LT	174	si.si_signo = SIGSEGV;
1da177e4 LT	175	si.si_addr = (void *) address;
c578455a	176	current->thread.arch.faultinfo = fi;
1da177e4 LT	177	force_sig_info(SIGSEGV, &si, current);
	178	}
	179	return(0);
	180	}
	181
c578455a	182	void bad_segv(struct faultinfo fi, unsigned long ip)
1da177e4 LT	183	{
	184	struct siginfo si;
	185
	186	si.si_signo = SIGSEGV;
	187	si.si_code = SEGV_ACCERR;
c578455a BS	188	si.si_addr = (void *) FAULT_ADDRESS(fi);
c578455a BS	189	current->thread.arch.faultinfo = fi;
1da177e4 LT	190	force_sig_info(SIGSEGV, &si, current);
	191	}
	192
	193	void relay_signal(int sig, union uml_pt_regs *regs)
	194	{
	195	if(arch_handle_signal(sig, regs)) return;
	196	if(!UPT_IS_USER(regs))
	197	panic("Kernel mode signal %d", sig);
c578455a	198	current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
1da177e4 LT	199	force_sig(sig, current);
	200	}
	201
	202	void bus_handler(int sig, union uml_pt_regs *regs)
	203	{
	204	if(current->thread.fault_catcher != NULL)
	205	do_longjmp(current->thread.fault_catcher, 1);
	206	else relay_signal(sig, regs);
	207	}
	208
	209	void winch(int sig, union uml_pt_regs *regs)
	210	{
	211	do_IRQ(WINCH_IRQ, regs);
	212	}
	213
	214	void trap_init(void)
	215	{
	216	}