[mirror_ubuntu-focal-kernel.git] / arch / m68k / mm / fault.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/arch/m68k/mm/fault.c
 *
 *  Copyright (C) 1995  Hamish Macdonald
 */

#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/uaccess.h>

#include <asm/setup.h>
#include <asm/traps.h>
#include <asm/pgalloc.h>

extern void die_if_kernel(char *, struct pt_regs *, long);

int send_fault_sig(struct pt_regs *regs)
{
	int signo, si_code;
	void __user *addr;

	signo = current->thread.signo;
	si_code = current->thread.code;
	addr = (void __user *)current->thread.faddr;
	pr_debug("send_fault_sig: %p,%d,%d\n", addr, signo, si_code);

	if (user_mode(regs)) {
		force_sig_fault(signo, si_code, addr);
	} else {
		if (fixup_exception(regs))
			return -1;

		//if (signo == SIGBUS)
		//	force_sig_fault(si_signo, si_code, addr);

		/*
		 * Oops. The kernel tried to access some bad page. We'll have to
		 * terminate things with extreme prejudice.
		 */
		if ((unsigned long)addr < PAGE_SIZE)
			pr_alert("Unable to handle kernel NULL pointer dereference");
		else
			pr_alert("Unable to handle kernel access");
		pr_cont(" at virtual address %p\n", addr);
		die_if_kernel("Oops", regs, 0 /*error_code*/);
		do_exit(SIGKILL);
	}

	return 1;
}

/*
 * This routine handles page faults.  It determines the problem, and
 * then passes it off to one of the appropriate routines.
 *
 * error_code:
 *	bit 0 == 0 means no page found, 1 means protection fault
 *	bit 1 == 0 means read, 1 means write
 *
 * If this routine detects a bad access, it returns 1, otherwise it
 * returns 0.
 */
int do_page_fault(struct pt_regs *regs, unsigned long address,
			      unsigned long error_code)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct * vma;
	vm_fault_t fault;
	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

	pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
		regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL);

	/*
	 * If we're in an interrupt or have no user
	 * context, we must not take the fault..
	 */
	if (faulthandler_disabled() || !mm)
		goto no_context;

	if (user_mode(regs))
		flags |= FAULT_FLAG_USER;
retry:
	down_read(&mm->mmap_sem);

	vma = find_vma(mm, address);
	if (!vma)
		goto map_err;
	if (vma->vm_flags & VM_IO)
		goto acc_err;
	if (vma->vm_start <= address)
		goto good_area;
	if (!(vma->vm_flags & VM_GROWSDOWN))
		goto map_err;
	if (user_mode(regs)) {
		/* Accessing the stack below usp is always a bug.  The
		   "+ 256" is there due to some instructions doing
		   pre-decrement on the stack and that doesn't show up
		   until later.  */
		if (address + 256 < rdusp())
			goto map_err;
	}
	if (expand_stack(vma, address))
		goto map_err;

/*
 * Ok, we have a good vm_area for this memory access, so
 * we can handle it..
 */
good_area:
	pr_debug("do_page_fault: good_area\n");
	switch (error_code & 3) {
		default:	/* 3: write, present */
			/* fall through */
		case 2:		/* write, not present */
			if (!(vma->vm_flags & VM_WRITE))
				goto acc_err;
			flags |= FAULT_FLAG_WRITE;
			break;
		case 1:		/* read, present */
			goto acc_err;
		case 0:		/* read, not present */
			if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
				goto acc_err;
	}

	/*
	 * If for any reason at all we couldn't handle the fault,
	 * make sure we exit gracefully rather than endlessly redo
	 * the fault.
	 */

	fault = handle_mm_fault(vma, address, flags);
	pr_debug("handle_mm_fault returns %x\n", fault);

	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
		return 0;

	if (unlikely(fault & VM_FAULT_ERROR)) {
		if (fault & VM_FAULT_OOM)
			goto out_of_memory;
		else if (fault & VM_FAULT_SIGSEGV)
			goto map_err;
		else if (fault & VM_FAULT_SIGBUS)
			goto bus_err;
		BUG();
	}

	/*
	 * Major/minor page fault accounting is only done on the
	 * initial attempt. If we go through a retry, it is extremely
	 * likely that the page will be found in page cache at that point.
	 */
	if (flags & FAULT_FLAG_ALLOW_RETRY) {
		if (fault & VM_FAULT_MAJOR)
			current->maj_flt++;
		else
			current->min_flt++;
		if (fault & VM_FAULT_RETRY) {
			/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
			 * of starvation. */
			flags &= ~FAULT_FLAG_ALLOW_RETRY;
			flags |= FAULT_FLAG_TRIED;

			/*
			 * No need to up_read(&mm->mmap_sem) as we would
			 * have already released it in __lock_page_or_retry
			 * in mm/filemap.c.
			 */

			goto retry;
		}
	}

	up_read(&mm->mmap_sem);
	return 0;

/*
 * 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:
	up_read(&mm->mmap_sem);
	if (!user_mode(regs))
		goto no_context;
	pagefault_out_of_memory();
	return 0;

no_context:
	current->thread.signo = SIGBUS;
	current->thread.faddr = address;
	return send_fault_sig(regs);

bus_err:
	current->thread.signo = SIGBUS;
	current->thread.code = BUS_ADRERR;
	current->thread.faddr = address;
	goto send_sig;

map_err:
	current->thread.signo = SIGSEGV;
	current->thread.code = SEGV_MAPERR;
	current->thread.faddr = address;
	goto send_sig;

acc_err:
	current->thread.signo = SIGSEGV;
	current->thread.code = SEGV_ACCERR;
	current->thread.faddr = address;

send_sig:
	up_read(&mm->mmap_sem);
	return send_fault_sig(regs);
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
1da177e4 LT	2	/*
	3	* linux/arch/m68k/mm/fault.c
	4	*
	5	* Copyright (C) 1995 Hamish Macdonald
	6	*/
	7
	8	#include <linux/mman.h>
	9	#include <linux/mm.h>
	10	#include <linux/kernel.h>
	11	#include <linux/ptrace.h>
	12	#include <linux/interrupt.h>
	13	#include <linux/module.h>
70ffdb93	14	#include <linux/uaccess.h>
1da177e4 LT	15
	16	#include <asm/setup.h>
	17	#include <asm/traps.h>
1da177e4 LT	18	#include <asm/pgalloc.h>
	19
	20	extern void die_if_kernel(char , struct pt_regs , long);
1da177e4 LT	21
	22	int send_fault_sig(struct pt_regs *regs)
	23	{
3c67075d EB	24	int signo, si_code;
3c67075d EB	25	void __user *addr;
1da177e4	26
3c67075d EB	27	signo = current->thread.signo;
	28	si_code = current->thread.code;
	29	addr = (void __user *)current->thread.faddr;
	30	pr_debug("send_fault_sig: %p,%d,%d\n", addr, signo, si_code);
1da177e4 LT	31
1da177e4 LT	32	if (user_mode(regs)) {
2e1661d2	33	force_sig_fault(signo, si_code, addr);
1da177e4	34	} else {
68acfdcb	35	if (fixup_exception(regs))
1da177e4	36	return -1;
1da177e4	37
3c67075d	38	//if (signo == SIGBUS)
2e1661d2	39	// force_sig_fault(si_signo, si_code, addr);
1da177e4 LT	40
	41	/*
	42	* Oops. The kernel tried to access some bad page. We'll have to
	43	* terminate things with extreme prejudice.
	44	*/
3c67075d	45	if ((unsigned long)addr < PAGE_SIZE)
8e398f63	46	pr_alert("Unable to handle kernel NULL pointer dereference");
1da177e4	47	else
8e398f63	48	pr_alert("Unable to handle kernel access");
3c67075d	49	pr_cont(" at virtual address %p\n", addr);
1da177e4 LT	50	die_if_kernel("Oops", regs, 0 /error_code/);
	51	do_exit(SIGKILL);
	52	}
	53
	54	return 1;
	55	}
	56
	57	/*
	58	* This routine handles page faults. It determines the problem, and
	59	* then passes it off to one of the appropriate routines.
	60	*
	61	* error_code:
	62	* bit 0 == 0 means no page found, 1 means protection fault
	63	* bit 1 == 0 means read, 1 means write
	64	*
	65	* If this routine detects a bad access, it returns 1, otherwise it
	66	* returns 0.
	67	*/
	68	int do_page_fault(struct pt_regs *regs, unsigned long address,
	69	unsigned long error_code)
	70	{
	71	struct mm_struct *mm = current->mm;
	72	struct vm_area_struct * vma;
50a7ca3c	73	vm_fault_t fault;
b637a6b1	74	unsigned int flags = FAULT_FLAG_ALLOW_RETRY \| FAULT_FLAG_KILLABLE;
1da177e4	75
8e398f63	76	pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
4e25c0e9	77	regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL);
1da177e4 LT	78
	79	/*
	80	* If we're in an interrupt or have no user
	81	* context, we must not take the fault..
	82	*/
70ffdb93	83	if (faulthandler_disabled() \|\| !mm)
1da177e4 LT	84	goto no_context;
1da177e4 LT	85
759496ba JW	86	if (user_mode(regs))
759496ba JW	87	flags \|= FAULT_FLAG_USER;
b637a6b1	88	retry:
1da177e4 LT	89	down_read(&mm->mmap_sem);
	90
	91	vma = find_vma(mm, address);
	92	if (!vma)
	93	goto map_err;
	94	if (vma->vm_flags & VM_IO)
	95	goto acc_err;
	96	if (vma->vm_start <= address)
	97	goto good_area;
	98	if (!(vma->vm_flags & VM_GROWSDOWN))
	99	goto map_err;
	100	if (user_mode(regs)) {
	101	/* Accessing the stack below usp is always a bug. The
	102	"+ 256" is there due to some instructions doing
	103	pre-decrement on the stack and that doesn't show up
	104	until later. */
	105	if (address + 256 < rdusp())
	106	goto map_err;
	107	}
	108	if (expand_stack(vma, address))
	109	goto map_err;
	110
	111	/*
	112	* Ok, we have a good vm_area for this memory access, so
	113	* we can handle it..
	114	*/
	115	good_area:
8e398f63	116	pr_debug("do_page_fault: good_area\n");
1da177e4 LT	117	switch (error_code & 3) {
	118	default: /* 3: write, present */
	119	/* fall through */
	120	case 2: /* write, not present */
	121	if (!(vma->vm_flags & VM_WRITE))
	122	goto acc_err;
b637a6b1	123	flags \|= FAULT_FLAG_WRITE;
1da177e4 LT	124	break;
	125	case 1: /* read, present */
	126	goto acc_err;
	127	case 0: /* read, not present */
df67b3da	128	if (!(vma->vm_flags & (VM_READ \| VM_EXEC \| VM_WRITE)))
1da177e4 LT	129	goto acc_err;
	130	}
	131
	132	/*
	133	* If for any reason at all we couldn't handle the fault,
	134	* make sure we exit gracefully rather than endlessly redo
	135	* the fault.
	136	*/
	137
dcddffd4	138	fault = handle_mm_fault(vma, address, flags);
50a7ca3c	139	pr_debug("handle_mm_fault returns %x\n", fault);
b637a6b1 KC	140
	141	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
	142	return 0;
	143
83c54070 NP	144	if (unlikely(fault & VM_FAULT_ERROR)) {
	145	if (fault & VM_FAULT_OOM)
	146	goto out_of_memory;
33692f27 LT	147	else if (fault & VM_FAULT_SIGSEGV)
33692f27 LT	148	goto map_err;
83c54070 NP	149	else if (fault & VM_FAULT_SIGBUS)
	150	goto bus_err;
	151	BUG();
1da177e4	152	}
b637a6b1 KC	153
	154	/*
	155	* Major/minor page fault accounting is only done on the
	156	* initial attempt. If we go through a retry, it is extremely
	157	* likely that the page will be found in page cache at that point.
	158	*/
	159	if (flags & FAULT_FLAG_ALLOW_RETRY) {
	160	if (fault & VM_FAULT_MAJOR)
	161	current->maj_flt++;
	162	else
	163	current->min_flt++;
	164	if (fault & VM_FAULT_RETRY) {
	165	/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
	166	* of starvation. */
	167	flags &= ~FAULT_FLAG_ALLOW_RETRY;
45cac65b	168	flags \|= FAULT_FLAG_TRIED;
b637a6b1 KC	169
	170	/*
	171	* No need to up_read(&mm->mmap_sem) as we would
	172	* have already released it in __lock_page_or_retry
	173	* in mm/filemap.c.
	174	*/
	175
	176	goto retry;
	177	}
	178	}
1da177e4 LT	179
	180	up_read(&mm->mmap_sem);
	181	return 0;
	182
	183	/*
	184	* We ran out of memory, or some other thing happened to us that made
	185	* us unable to handle the page fault gracefully.
	186	*/
	187	out_of_memory:
	188	up_read(&mm->mmap_sem);
adbf6e69 NP	189	if (!user_mode(regs))
	190	goto no_context;
	191	pagefault_out_of_memory();
	192	return 0;
1da177e4 LT	193
	194	no_context:
	195	current->thread.signo = SIGBUS;
	196	current->thread.faddr = address;
	197	return send_fault_sig(regs);
	198
	199	bus_err:
	200	current->thread.signo = SIGBUS;
	201	current->thread.code = BUS_ADRERR;
	202	current->thread.faddr = address;
	203	goto send_sig;
	204
	205	map_err:
	206	current->thread.signo = SIGSEGV;
	207	current->thread.code = SEGV_MAPERR;
	208	current->thread.faddr = address;
	209	goto send_sig;
	210
	211	acc_err:
	212	current->thread.signo = SIGSEGV;
	213	current->thread.code = SEGV_ACCERR;
	214	current->thread.faddr = address;
	215
	216	send_sig:
	217	up_read(&mm->mmap_sem);
	218	return send_fault_sig(regs);
	219	}