[mirror_ubuntu-kernels.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 "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;
	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);
	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");
	err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);

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