[mirror_ubuntu-bionic-kernel.git] / arch / um / kernel / trap.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/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"
#include "sysdep/sigcontext.h"
#include "sysdep/ptrace.h"
#include "os.h"
#ifdef CONFIG_MODE_SKAS
#include "skas.h"
#endif
#include "os.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;
	/* The below warning was added in place of
	 *	pte_mkyoung(); if (is_write) pte_mkdirty();
	 * If it's triggered, we'd see normally a hang here (a clean pte is
	 * marked read-only to emulate the dirty bit).
	 * However, the generic code can mark a PTE writable but clean on a
	 * concurrent read fault, triggering this harmlessly. So comment it out.
	 */
#if 0
	WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
#endif
	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 (is_init(current)) {
		up_read(&mm->mmap_sem);
		yield();
		down_read(&mm->mmap_sem);
		goto survive;
	}
	goto out;
}

void segv_handler(int sig, union uml_pt_regs *regs)
{
	struct faultinfo * fi = UPT_FAULTINFO(regs);

	if(UPT_IS_USER(regs) && !SEGV_IS_FIXABLE(fi)){
		bad_segv(*fi, UPT_IP(regs));
		return;
	}
	segv(*fi, UPT_IP(regs), UPT_IS_USER(regs), regs);
}

/*
 * 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 __user *)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 __user *) 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 __user *) 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)){
		if(sig == SIGBUS)
			printk("Bus error - the /dev/shm or /tmp mount likely "
			       "just ran out of space\n");
		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);
}

const struct kern_handlers handlinfo_kern = {
	.relay_signal = relay_signal,
	.winch = winch,
	.bus_handler = bus_handler,
	.page_fault = segv_handler,
	.sigio_handler = sigio_handler,
	.timer_handler = timer_handler
};

void trap_init(void)
{
}
Commit	Line	Data
ea2ba7dc	1	/*
1da177e4 LT	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"
1da177e4 LT	11	#include "linux/init.h"
	12	#include "linux/ptrace.h"
	13	#include "asm/semaphore.h"
	14	#include "asm/pgtable.h"
	15	#include "asm/pgalloc.h"
	16	#include "asm/tlbflush.h"
	17	#include "asm/a.out.h"
	18	#include "asm/current.h"
	19	#include "asm/irq.h"
546fe1cb	20	#include "sysdep/sigcontext.h"
1da177e4 LT	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"
1da177e4 LT	27	#include "mem_kern.h"
c66fdd5e GS	28	#include "sysdep/sigcontext.h"
	29	#include "sysdep/ptrace.h"
	30	#include "os.h"
be662a18 PBG	31	#ifdef CONFIG_MODE_SKAS
	32	#include "skas.h"
	33	#endif
ea2ba7dc	34	#include "os.h"
1da177e4	35
3b52166c	36	/* Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by segv(). */
1d3468a6	37	int handle_page_fault(unsigned long address, unsigned long ip,
1da177e4 LT	38	int is_write, int is_user, int *code_out)
	39	{
	40	struct mm_struct *mm = current->mm;
	41	struct vm_area_struct *vma;
	42	pgd_t *pgd;
	43	pud_t *pud;
	44	pmd_t *pmd;
	45	pte_t *pte;
1da177e4 LT	46	int err = -EFAULT;
	47
	48	*code_out = SEGV_MAPERR;
fea03cb4 PBG	49
	50	/* If the fault was during atomic operation, don't take the fault, just
	51	* fail. */
	52	if (in_atomic())
	53	goto out_nosemaphore;
	54
1da177e4 LT	55	down_read(&mm->mmap_sem);
1da177e4 LT	56	vma = find_vma(mm, address);
1d3468a6	57	if(!vma)
1da177e4	58	goto out;
1d3468a6	59	else if(vma->vm_start <= address)
1da177e4	60	goto good_area;
1d3468a6	61	else if(!(vma->vm_flags & VM_GROWSDOWN))
1da177e4	62	goto out;
2d58cc9a	63	else if(is_user && !ARCH_IS_STACKGROW(address))
1da177e4	64	goto out;
1d3468a6	65	else if(expand_stack(vma, address))
1da177e4 LT	66	goto out;
1da177e4 LT	67
3b52166c	68	good_area:
1da177e4	69	*code_out = SEGV_ACCERR;
1d3468a6	70	if(is_write && !(vma->vm_flags & VM_WRITE))
1da177e4	71	goto out;
13479d52	72
d129f312 PBG	73	/* Don't require VM_READ\|VM_EXEC for write faults! */
d129f312 PBG	74	if(!is_write && !(vma->vm_flags & (VM_READ \| VM_EXEC)))
13479d52 JD	75	goto out;
13479d52 JD	76
1da177e4	77	do {
3b52166c	78	survive:
1da177e4 LT	79	switch (handle_mm_fault(mm, vma, address, is_write)){
	80	case VM_FAULT_MINOR:
	81	current->min_flt++;
	82	break;
	83	case VM_FAULT_MAJOR:
	84	current->maj_flt++;
	85	break;
	86	case VM_FAULT_SIGBUS:
	87	err = -EACCES;
	88	goto out;
	89	case VM_FAULT_OOM:
	90	err = -ENOMEM;
	91	goto out_of_memory;
	92	default:
	93	BUG();
	94	}
3b52166c PBG	95	pgd = pgd_offset(mm, address);
	96	pud = pud_offset(pgd, address);
	97	pmd = pmd_offset(pud, address);
	98	pte = pte_offset_kernel(pmd, address);
1da177e4 LT	99	} while(!pte_present(*pte));
1da177e4 LT	100	err = 0;
cbc24afa PBG	101	/* The below warning was added in place of
	102	* pte_mkyoung(); if (is_write) pte_mkdirty();
	103	* If it's triggered, we'd see normally a hang here (a clean pte is
	104	* marked read-only to emulate the dirty bit).
	105	* However, the generic code can mark a PTE writable but clean on a
	106	* concurrent read fault, triggering this harmlessly. So comment it out.
	107	*/
	108	#if 0
16b03678	109	WARN_ON(!pte_young(pte) \|\| (is_write && !pte_dirty(pte)));
cbc24afa	110	#endif
3b52166c PBG	111	flush_tlb_page(vma, address);
3b52166c PBG	112	out:
1da177e4	113	up_read(&mm->mmap_sem);
fea03cb4	114	out_nosemaphore:
1da177e4 LT	115	return(err);
	116
	117	/*
	118	* We ran out of memory, or some other thing happened to us that made
	119	* us unable to handle the page fault gracefully.
	120	*/
	121	out_of_memory:
f400e198	122	if (is_init(current)) {
1da177e4 LT	123	up_read(&mm->mmap_sem);
	124	yield();
	125	down_read(&mm->mmap_sem);
	126	goto survive;
	127	}
	128	goto out;
	129	}
	130
c66fdd5e GS	131	void segv_handler(int sig, union uml_pt_regs *regs)
	132	{
	133	struct faultinfo * fi = UPT_FAULTINFO(regs);
	134
	135	if(UPT_IS_USER(regs) && !SEGV_IS_FIXABLE(fi)){
	136	bad_segv(*fi, UPT_IP(regs));
	137	return;
	138	}
	139	segv(*fi, UPT_IP(regs), UPT_IS_USER(regs), regs);
	140	}
	141
c578455a BS	142	/*
	143	* We give a copy of the faultinfo in the regs to segv.
	144	* This must be done, since nesting SEGVs could overwrite
	145	* the info in the regs. A pointer to the info then would
	146	* give us bad data!
	147	*/
	148	unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
1da177e4 LT	149	{
	150	struct siginfo si;
	151	void *catcher;
	152	int err;
c578455a BS	153	int is_write = FAULT_WRITE(fi);
c578455a BS	154	unsigned long address = FAULT_ADDRESS(fi);
1da177e4 LT	155
	156	if(!is_user && (address >= start_vm) && (address < end_vm)){
	157	flush_tlb_kernel_vm();
	158	return(0);
	159	}
1da177e4 LT	160	else if(current->mm == NULL)
1da177e4 LT	161	panic("Segfault with no mm");
546fe1cb	162
be662a18	163	if (SEGV_IS_FIXABLE(&fi) \|\| SEGV_MAYBE_FIXABLE(&fi))
546fe1cb PBG	164	err = handle_page_fault(address, ip, is_write, is_user, &si.si_code);
	165	else {
	166	err = -EFAULT;
	167	/* A thread accessed NULL, we get a fault, but CR2 is invalid.
	168	* This code is used in __do_copy_from_user() of TT mode. */
	169	address = 0;
	170	}
1da177e4 LT	171
	172	catcher = current->thread.fault_catcher;
	173	if(!err)
	174	return(0);
	175	else if(catcher != NULL){
	176	current->thread.fault_addr = (void *) address;
	177	do_longjmp(catcher, 1);
1d3468a6	178	}
1da177e4 LT	179	else if(current->thread.fault_addr != NULL)
1da177e4 LT	180	panic("fault_addr set but no fault catcher");
c578455a	181	else if(!is_user && arch_fixup(ip, sc))
1da177e4 LT	182	return(0);
1da177e4 LT	183
1d3468a6 JD	184	if(!is_user)
1d3468a6 JD	185	panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
1da177e4 LT	186	address, ip);
1da177e4 LT	187
3b52166c	188	if (err == -EACCES) {
1da177e4 LT	189	si.si_signo = SIGBUS;
	190	si.si_errno = 0;
	191	si.si_code = BUS_ADRERR;
4d338e1a	192	si.si_addr = (void __user *)address;
c578455a	193	current->thread.arch.faultinfo = fi;
1da177e4	194	force_sig_info(SIGBUS, &si, current);
3b52166c	195	} else if (err == -ENOMEM) {
1da177e4 LT	196	printk("VM: killing process %s\n", current->comm);
1da177e4 LT	197	do_exit(SIGKILL);
3b52166c PBG	198	} else {
3b52166c PBG	199	BUG_ON(err != -EFAULT);
1da177e4	200	si.si_signo = SIGSEGV;
4d338e1a	201	si.si_addr = (void __user *) address;
c578455a	202	current->thread.arch.faultinfo = fi;
1da177e4 LT	203	force_sig_info(SIGSEGV, &si, current);
	204	}
	205	return(0);
	206	}
	207
c578455a	208	void bad_segv(struct faultinfo fi, unsigned long ip)
1da177e4 LT	209	{
	210	struct siginfo si;
	211
	212	si.si_signo = SIGSEGV;
	213	si.si_code = SEGV_ACCERR;
4d338e1a AV	214	si.si_addr = (void __user *) FAULT_ADDRESS(fi);
4d338e1a AV	215	current->thread.arch.faultinfo = fi;
1da177e4 LT	216	force_sig_info(SIGSEGV, &si, current);
	217	}
	218
	219	void relay_signal(int sig, union uml_pt_regs *regs)
	220	{
6edf428e JD	221	if(arch_handle_signal(sig, regs))
	222	return;
	223
	224	if(!UPT_IS_USER(regs)){
	225	if(sig == SIGBUS)
	226	printk("Bus error - the /dev/shm or /tmp mount likely "
	227	"just ran out of space\n");
1da177e4	228	panic("Kernel mode signal %d", sig);
6edf428e JD	229	}
6edf428e JD	230
c578455a	231	current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
1da177e4 LT	232	force_sig(sig, current);
	233	}
	234
	235	void bus_handler(int sig, union uml_pt_regs *regs)
	236	{
	237	if(current->thread.fault_catcher != NULL)
	238	do_longjmp(current->thread.fault_catcher, 1);
	239	else relay_signal(sig, regs);
	240	}
	241
	242	void winch(int sig, union uml_pt_regs *regs)
	243	{
	244	do_IRQ(WINCH_IRQ, regs);
	245	}
	246
53dd2b55 JD	247	const struct kern_handlers handlinfo_kern = {
	248	.relay_signal = relay_signal,
	249	.winch = winch,
	250	.bus_handler = bus_handler,
	251	.page_fault = segv_handler,
	252	.sigio_handler = sigio_handler,
	253	.timer_handler = timer_handler
	254	};
	255
1da177e4 LT	256	void trap_init(void)
	257	{
	258	}