[linux-2.6-block.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)
{
	siginfo_t siginfo = { 0, 0, 0, };

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

	if (user_mode(regs)) {
		force_sig_info(siginfo.si_signo,
			       &siginfo, current);
	} else {
		if (fixup_exception(regs))
			return -1;

		//if (siginfo.si_signo == SIGBUS)
		//	force_sig_info(siginfo.si_signo,
		//		       &siginfo, current);

		/*
		 * Oops. The kernel tried to access some bad page. We'll have to
		 * terminate things with extreme prejudice.
		 */
		if ((unsigned long)siginfo.si_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", siginfo.si_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;
	int 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 %d\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	{
	24	siginfo_t siginfo = { 0, 0, 0, };
	25
	26	siginfo.si_signo = current->thread.signo;
	27	siginfo.si_code = current->thread.code;
	28	siginfo.si_addr = (void *)current->thread.faddr;
8e398f63 GU	29	pr_debug("send_fault_sig: %p,%d,%d\n", siginfo.si_addr,
8e398f63 GU	30	siginfo.si_signo, siginfo.si_code);
1da177e4 LT	31
	32	if (user_mode(regs)) {
	33	force_sig_info(siginfo.si_signo,
	34	&siginfo, current);
	35	} else {
68acfdcb	36	if (fixup_exception(regs))
1da177e4	37	return -1;
1da177e4 LT	38
	39	//if (siginfo.si_signo == SIGBUS)
	40	// force_sig_info(siginfo.si_signo,
	41	// &siginfo, current);
	42
	43	/*
	44	* Oops. The kernel tried to access some bad page. We'll have to
	45	* terminate things with extreme prejudice.
	46	*/
	47	if ((unsigned long)siginfo.si_addr < PAGE_SIZE)
8e398f63	48	pr_alert("Unable to handle kernel NULL pointer dereference");
1da177e4	49	else
8e398f63 GU	50	pr_alert("Unable to handle kernel access");
8e398f63 GU	51	pr_cont(" at virtual address %p\n", siginfo.si_addr);
1da177e4 LT	52	die_if_kernel("Oops", regs, 0 /error_code/);
	53	do_exit(SIGKILL);
	54	}
	55
	56	return 1;
	57	}
	58
	59	/*
	60	* This routine handles page faults. It determines the problem, and
	61	* then passes it off to one of the appropriate routines.
	62	*
	63	* error_code:
	64	* bit 0 == 0 means no page found, 1 means protection fault
	65	* bit 1 == 0 means read, 1 means write
	66	*
	67	* If this routine detects a bad access, it returns 1, otherwise it
	68	* returns 0.
	69	*/
	70	int do_page_fault(struct pt_regs *regs, unsigned long address,
	71	unsigned long error_code)
	72	{
	73	struct mm_struct *mm = current->mm;
	74	struct vm_area_struct * vma;
b637a6b1 KC	75	int fault;
b637a6b1 KC	76	unsigned int flags = FAULT_FLAG_ALLOW_RETRY \| FAULT_FLAG_KILLABLE;
1da177e4	77
8e398f63	78	pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
4e25c0e9	79	regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL);
1da177e4 LT	80
	81	/*
	82	* If we're in an interrupt or have no user
	83	* context, we must not take the fault..
	84	*/
70ffdb93	85	if (faulthandler_disabled() \|\| !mm)
1da177e4 LT	86	goto no_context;
1da177e4 LT	87
759496ba JW	88	if (user_mode(regs))
759496ba JW	89	flags \|= FAULT_FLAG_USER;
b637a6b1	90	retry:
1da177e4 LT	91	down_read(&mm->mmap_sem);
	92
	93	vma = find_vma(mm, address);
	94	if (!vma)
	95	goto map_err;
	96	if (vma->vm_flags & VM_IO)
	97	goto acc_err;
	98	if (vma->vm_start <= address)
	99	goto good_area;
	100	if (!(vma->vm_flags & VM_GROWSDOWN))
	101	goto map_err;
	102	if (user_mode(regs)) {
	103	/* Accessing the stack below usp is always a bug. The
	104	"+ 256" is there due to some instructions doing
	105	pre-decrement on the stack and that doesn't show up
	106	until later. */
	107	if (address + 256 < rdusp())
	108	goto map_err;
	109	}
	110	if (expand_stack(vma, address))
	111	goto map_err;
	112
	113	/*
	114	* Ok, we have a good vm_area for this memory access, so
	115	* we can handle it..
	116	*/
	117	good_area:
8e398f63	118	pr_debug("do_page_fault: good_area\n");
1da177e4 LT	119	switch (error_code & 3) {
	120	default: /* 3: write, present */
	121	/* fall through */
	122	case 2: /* write, not present */
	123	if (!(vma->vm_flags & VM_WRITE))
	124	goto acc_err;
b637a6b1	125	flags \|= FAULT_FLAG_WRITE;
1da177e4 LT	126	break;
	127	case 1: /* read, present */
	128	goto acc_err;
	129	case 0: /* read, not present */
df67b3da	130	if (!(vma->vm_flags & (VM_READ \| VM_EXEC \| VM_WRITE)))
1da177e4 LT	131	goto acc_err;
	132	}
	133
	134	/*
	135	* If for any reason at all we couldn't handle the fault,
	136	* make sure we exit gracefully rather than endlessly redo
	137	* the fault.
	138	*/
	139
dcddffd4	140	fault = handle_mm_fault(vma, address, flags);
8e398f63	141	pr_debug("handle_mm_fault returns %d\n", fault);
b637a6b1 KC	142
	143	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
	144	return 0;
	145
83c54070 NP	146	if (unlikely(fault & VM_FAULT_ERROR)) {
	147	if (fault & VM_FAULT_OOM)
	148	goto out_of_memory;
33692f27 LT	149	else if (fault & VM_FAULT_SIGSEGV)
33692f27 LT	150	goto map_err;
83c54070 NP	151	else if (fault & VM_FAULT_SIGBUS)
	152	goto bus_err;
	153	BUG();
1da177e4	154	}
b637a6b1 KC	155
	156	/*
	157	* Major/minor page fault accounting is only done on the
	158	* initial attempt. If we go through a retry, it is extremely
	159	* likely that the page will be found in page cache at that point.
	160	*/
	161	if (flags & FAULT_FLAG_ALLOW_RETRY) {
	162	if (fault & VM_FAULT_MAJOR)
	163	current->maj_flt++;
	164	else
	165	current->min_flt++;
	166	if (fault & VM_FAULT_RETRY) {
	167	/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
	168	* of starvation. */
	169	flags &= ~FAULT_FLAG_ALLOW_RETRY;
45cac65b	170	flags \|= FAULT_FLAG_TRIED;
b637a6b1 KC	171
	172	/*
	173	* No need to up_read(&mm->mmap_sem) as we would
	174	* have already released it in __lock_page_or_retry
	175	* in mm/filemap.c.
	176	*/
	177
	178	goto retry;
	179	}
	180	}
1da177e4 LT	181
	182	up_read(&mm->mmap_sem);
	183	return 0;
	184
	185	/*
	186	* We ran out of memory, or some other thing happened to us that made
	187	* us unable to handle the page fault gracefully.
	188	*/
	189	out_of_memory:
	190	up_read(&mm->mmap_sem);
adbf6e69 NP	191	if (!user_mode(regs))
	192	goto no_context;
	193	pagefault_out_of_memory();
	194	return 0;
1da177e4 LT	195
	196	no_context:
	197	current->thread.signo = SIGBUS;
	198	current->thread.faddr = address;
	199	return send_fault_sig(regs);
	200
	201	bus_err:
	202	current->thread.signo = SIGBUS;
	203	current->thread.code = BUS_ADRERR;
	204	current->thread.faddr = address;
	205	goto send_sig;
	206
	207	map_err:
	208	current->thread.signo = SIGSEGV;
	209	current->thread.code = SEGV_MAPERR;
	210	current->thread.faddr = address;
	211	goto send_sig;
	212
	213	acc_err:
	214	current->thread.signo = SIGSEGV;
	215	current->thread.code = SEGV_ACCERR;
	216	current->thread.faddr = address;
	217
	218	send_sig:
	219	up_read(&mm->mmap_sem);
	220	return send_fault_sig(regs);
	221	}