[mirror_ubuntu-zesty-kernel.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"
#ifdef CONFIG_MODE_SKAS
#include "skas.h"
#endif

/* 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) || SEGV_MAYBE_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"
1da177e4 LT	28	#include "mem_kern.h"
be662a18 PBG	29	#ifdef CONFIG_MODE_SKAS
	30	#include "skas.h"
	31	#endif
1da177e4	32
3b52166c	33	/* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */
1da177e4 LT	34	int handle_page_fault(unsigned long address, unsigned long ip,
	35	int is_write, int is_user, int *code_out)
	36	{
	37	struct mm_struct *mm = current->mm;
	38	struct vm_area_struct *vma;
	39	pgd_t *pgd;
	40	pud_t *pud;
	41	pmd_t *pmd;
	42	pte_t *pte;
1da177e4 LT	43	int err = -EFAULT;
	44
	45	*code_out = SEGV_MAPERR;
fea03cb4 PBG	46
	47	/* If the fault was during atomic operation, don't take the fault, just
	48	* fail. */
	49	if (in_atomic())
	50	goto out_nosemaphore;
	51
1da177e4 LT	52	down_read(&mm->mmap_sem);
	53	vma = find_vma(mm, address);
	54	if(!vma)
	55	goto out;
	56	else if(vma->vm_start <= address)
	57	goto good_area;
	58	else if(!(vma->vm_flags & VM_GROWSDOWN))
	59	goto out;
2d58cc9a	60	else if(is_user && !ARCH_IS_STACKGROW(address))
1da177e4 LT	61	goto out;
	62	else if(expand_stack(vma, address))
	63	goto out;
	64
3b52166c	65	good_area:
1da177e4 LT	66	*code_out = SEGV_ACCERR;
	67	if(is_write && !(vma->vm_flags & VM_WRITE))
	68	goto out;
13479d52	69
d129f312 PBG	70	/* Don't require VM_READ\|VM_EXEC for write faults! */
d129f312 PBG	71	if(!is_write && !(vma->vm_flags & (VM_READ \| VM_EXEC)))
13479d52 JD	72	goto out;
13479d52 JD	73
1da177e4	74	do {
3b52166c	75	survive:
1da177e4 LT	76	switch (handle_mm_fault(mm, vma, address, is_write)){
	77	case VM_FAULT_MINOR:
	78	current->min_flt++;
	79	break;
	80	case VM_FAULT_MAJOR:
	81	current->maj_flt++;
	82	break;
	83	case VM_FAULT_SIGBUS:
	84	err = -EACCES;
	85	goto out;
	86	case VM_FAULT_OOM:
	87	err = -ENOMEM;
	88	goto out_of_memory;
	89	default:
	90	BUG();
	91	}
3b52166c PBG	92	pgd = pgd_offset(mm, address);
	93	pud = pud_offset(pgd, address);
	94	pmd = pmd_offset(pud, address);
	95	pte = pte_offset_kernel(pmd, address);
1da177e4 LT	96	} while(!pte_present(*pte));
1da177e4 LT	97	err = 0;
16b03678	98	WARN_ON(!pte_young(pte) \|\| (is_write && !pte_dirty(pte)));
3b52166c PBG	99	flush_tlb_page(vma, address);
3b52166c PBG	100	out:
1da177e4	101	up_read(&mm->mmap_sem);
fea03cb4	102	out_nosemaphore:
1da177e4 LT	103	return(err);
	104
	105	/*
	106	* We ran out of memory, or some other thing happened to us that made
	107	* us unable to handle the page fault gracefully.
	108	*/
	109	out_of_memory:
	110	if (current->pid == 1) {
	111	up_read(&mm->mmap_sem);
	112	yield();
	113	down_read(&mm->mmap_sem);
	114	goto survive;
	115	}
	116	goto out;
	117	}
	118
c578455a BS	119	/*
	120	* We give a copy of the faultinfo in the regs to segv.
	121	* This must be done, since nesting SEGVs could overwrite
	122	* the info in the regs. A pointer to the info then would
	123	* give us bad data!
	124	*/
	125	unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
1da177e4 LT	126	{
	127	struct siginfo si;
	128	void *catcher;
	129	int err;
c578455a BS	130	int is_write = FAULT_WRITE(fi);
c578455a BS	131	unsigned long address = FAULT_ADDRESS(fi);
1da177e4 LT	132
	133	if(!is_user && (address >= start_vm) && (address < end_vm)){
	134	flush_tlb_kernel_vm();
	135	return(0);
	136	}
1da177e4 LT	137	else if(current->mm == NULL)
1da177e4 LT	138	panic("Segfault with no mm");
546fe1cb	139
be662a18	140	if (SEGV_IS_FIXABLE(&fi) \|\| SEGV_MAYBE_FIXABLE(&fi))
546fe1cb PBG	141	err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
	142	else {
	143	err = -EFAULT;
	144	/* A thread accessed NULL, we get a fault, but CR2 is invalid.
	145	* This code is used in __do_copy_from_user() of TT mode. */
	146	address = 0;
	147	}
1da177e4 LT	148
	149	catcher = current->thread.fault_catcher;
	150	if(!err)
	151	return(0);
	152	else if(catcher != NULL){
	153	current->thread.fault_addr = (void *) address;
	154	do_longjmp(catcher, 1);
	155	}
	156	else if(current->thread.fault_addr != NULL)
	157	panic("fault_addr set but no fault catcher");
c578455a	158	else if(!is_user && arch_fixup(ip, sc))
1da177e4 LT	159	return(0);
	160
	161	if(!is_user)
	162	panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
	163	address, ip);
	164
3b52166c	165	if (err == -EACCES) {
1da177e4 LT	166	si.si_signo = SIGBUS;
	167	si.si_errno = 0;
	168	si.si_code = BUS_ADRERR;
	169	si.si_addr = (void *)address;
c578455a	170	current->thread.arch.faultinfo = fi;
1da177e4	171	force_sig_info(SIGBUS, &si, current);
3b52166c	172	} else if (err == -ENOMEM) {
1da177e4 LT	173	printk("VM: killing process %s\n", current->comm);
1da177e4 LT	174	do_exit(SIGKILL);
3b52166c PBG	175	} else {
3b52166c PBG	176	BUG_ON(err != -EFAULT);
1da177e4 LT	177	si.si_signo = SIGSEGV;
1da177e4 LT	178	si.si_addr = (void *) address;
c578455a	179	current->thread.arch.faultinfo = fi;
1da177e4 LT	180	force_sig_info(SIGSEGV, &si, current);
	181	}
	182	return(0);
	183	}
	184
c578455a	185	void bad_segv(struct faultinfo fi, unsigned long ip)
1da177e4 LT	186	{
	187	struct siginfo si;
	188
	189	si.si_signo = SIGSEGV;
	190	si.si_code = SEGV_ACCERR;
c578455a BS	191	si.si_addr = (void *) FAULT_ADDRESS(fi);
c578455a BS	192	current->thread.arch.faultinfo = fi;
1da177e4 LT	193	force_sig_info(SIGSEGV, &si, current);
	194	}
	195
	196	void relay_signal(int sig, union uml_pt_regs *regs)
	197	{
	198	if(arch_handle_signal(sig, regs)) return;
	199	if(!UPT_IS_USER(regs))
	200	panic("Kernel mode signal %d", sig);
c578455a	201	current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
1da177e4 LT	202	force_sig(sig, current);
	203	}
	204
	205	void bus_handler(int sig, union uml_pt_regs *regs)
	206	{
	207	if(current->thread.fault_catcher != NULL)
	208	do_longjmp(current->thread.fault_catcher, 1);
	209	else relay_signal(sig, regs);
	210	}
	211
	212	void winch(int sig, union uml_pt_regs *regs)
	213	{
	214	do_IRQ(WINCH_IRQ, regs);
	215	}
	216
	217	void trap_init(void)
	218	{
	219	}