[linux-block.git] / arch / alpha / mm / fault.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/arch/alpha/mm/fault.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 */

#include <linux/sched/signal.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <asm/io.h>

#define __EXTERN_INLINE inline
#include <asm/mmu_context.h>
#include <asm/tlbflush.h>
#undef  __EXTERN_INLINE

#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/extable.h>
#include <linux/uaccess.h>

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


/*
 * Force a new ASN for a task.
 */

#ifndef CONFIG_SMP
unsigned long last_asn = ASN_FIRST_VERSION;
#endif

void
__load_new_mm_context(struct mm_struct *next_mm)
{
	unsigned long mmc;
	struct pcb_struct *pcb;

	mmc = __get_new_mm_context(next_mm, smp_processor_id());
	next_mm->context[smp_processor_id()] = mmc;

	pcb = &current_thread_info()->pcb;
	pcb->asn = mmc & HARDWARE_ASN_MASK;
	pcb->ptbr = ((unsigned long) next_mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;

	__reload_thread(pcb);
}


/*
 * This routine handles page faults.  It determines the address,
 * and the problem, and then passes it off to handle_mm_fault().
 *
 * mmcsr:
 *	0 = translation not valid
 *	1 = access violation
 *	2 = fault-on-read
 *	3 = fault-on-execute
 *	4 = fault-on-write
 *
 * cause:
 *	-1 = instruction fetch
 *	0 = load
 *	1 = store
 *
 * Registers $9 through $15 are saved in a block just prior to `regs' and
 * are saved and restored around the call to allow exception code to
 * modify them.
 */

/* Macro for exception fixup code to access integer registers.  */
#define dpf_reg(r)							\
	(((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 :	\
				 (r) <= 18 ? (r)+8 : (r)-10])

asmlinkage void
do_page_fault(unsigned long address, unsigned long mmcsr,
	      long cause, struct pt_regs *regs)
{
	struct vm_area_struct * vma;
	struct mm_struct *mm = current->mm;
	const struct exception_table_entry *fixup;
	int fault, si_code = SEGV_MAPERR;
	siginfo_t info;
	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

	/* As of EV6, a load into $31/$f31 is a prefetch, and never faults
	   (or is suppressed by the PALcode).  Support that for older CPUs
	   by ignoring such an instruction.  */
	if (cause == 0) {
		unsigned int insn;
		__get_user(insn, (unsigned int __user *)regs->pc);
		if ((insn >> 21 & 0x1f) == 0x1f &&
		    /* ldq ldl ldt lds ldg ldf ldwu ldbu */
		    (1ul << (insn >> 26) & 0x30f00001400ul)) {
			regs->pc += 4;
			return;
		}
	}

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

#ifdef CONFIG_ALPHA_LARGE_VMALLOC
	if (address >= TASK_SIZE)
		goto vmalloc_fault;
#endif
	if (user_mode(regs))
		flags |= FAULT_FLAG_USER;
retry:
	down_read(&mm->mmap_sem);
	vma = find_vma(mm, address);
	if (!vma)
		goto bad_area;
	if (vma->vm_start <= address)
		goto good_area;
	if (!(vma->vm_flags & VM_GROWSDOWN))
		goto bad_area;
	if (expand_stack(vma, address))
		goto bad_area;

	/* Ok, we have a good vm_area for this memory access, so
	   we can handle it.  */
 good_area:
	si_code = SEGV_ACCERR;
	if (cause < 0) {
		if (!(vma->vm_flags & VM_EXEC))
			goto bad_area;
	} else if (!cause) {
		/* Allow reads even for write-only mappings */
		if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
			goto bad_area;
	} else {
		if (!(vma->vm_flags & VM_WRITE))
			goto bad_area;
		flags |= FAULT_FLAG_WRITE;
	}

	/* 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);

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

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

	if (flags & FAULT_FLAG_ALLOW_RETRY) {
		if (fault & VM_FAULT_MAJOR)
			current->maj_flt++;
		else
			current->min_flt++;
		if (fault & VM_FAULT_RETRY) {
			flags &= ~FAULT_FLAG_ALLOW_RETRY;

			 /* 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;

	/* Something tried to access memory that isn't in our memory map.
	   Fix it, but check if it's kernel or user first.  */
 bad_area:
	up_read(&mm->mmap_sem);

	if (user_mode(regs))
		goto do_sigsegv;

 no_context:
	/* Are we prepared to handle this fault as an exception?  */
	if ((fixup = search_exception_tables(regs->pc)) != 0) {
		unsigned long newpc;
		newpc = fixup_exception(dpf_reg, fixup, regs->pc);
		regs->pc = newpc;
		return;
	}

	/* Oops. The kernel tried to access some bad page. We'll have to
	   terminate things with extreme prejudice.  */
	printk(KERN_ALERT "Unable to handle kernel paging request at "
	       "virtual address %016lx\n", address);
	die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16);
	do_exit(SIGKILL);

	/* 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;

 do_sigbus:
	up_read(&mm->mmap_sem);
	/* Send a sigbus, regardless of whether we were in kernel
	   or user mode.  */
	info.si_signo = SIGBUS;
	info.si_errno = 0;
	info.si_code = BUS_ADRERR;
	info.si_addr = (void __user *) address;
	force_sig_info(SIGBUS, &info, current);
	if (!user_mode(regs))
		goto no_context;
	return;

 do_sigsegv:
	info.si_signo = SIGSEGV;
	info.si_errno = 0;
	info.si_code = si_code;
	info.si_addr = (void __user *) address;
	force_sig_info(SIGSEGV, &info, current);
	return;

#ifdef CONFIG_ALPHA_LARGE_VMALLOC
 vmalloc_fault:
	if (user_mode(regs))
		goto do_sigsegv;
	else {
		/* Synchronize this task's top level page-table
		   with the "reference" page table from init.  */
		long index = pgd_index(address);
		pgd_t *pgd, *pgd_k;

		pgd = current->active_mm->pgd + index;
		pgd_k = swapper_pg_dir + index;
		if (!pgd_present(*pgd) && pgd_present(*pgd_k)) {
			pgd_val(*pgd) = pgd_val(*pgd_k);
			return;
		}
		goto no_context;
	}
#endif
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
1da177e4 LT	2	/*
	3	* linux/arch/alpha/mm/fault.c
	4	*
	5	* Copyright (C) 1995 Linus Torvalds
	6	*/
	7
3f07c014	8	#include <linux/sched/signal.h>
1da177e4 LT	9	#include <linux/kernel.h>
	10	#include <linux/mm.h>
	11	#include <asm/io.h>
	12
	13	#define __EXTERN_INLINE inline
	14	#include <asm/mmu_context.h>
	15	#include <asm/tlbflush.h>
	16	#undef __EXTERN_INLINE
	17
	18	#include <linux/signal.h>
	19	#include <linux/errno.h>
	20	#include <linux/string.h>
	21	#include <linux/types.h>
	22	#include <linux/ptrace.h>
	23	#include <linux/mman.h>
	24	#include <linux/smp.h>
1da177e4	25	#include <linux/interrupt.h>
9c14f835	26	#include <linux/extable.h>
70ffdb93	27	#include <linux/uaccess.h>
1da177e4 LT	28
	29	extern void die_if_kernel(char ,struct pt_regs ,long, unsigned long *);
	30
	31
	32	/*
	33	* Force a new ASN for a task.
	34	*/
	35
	36	#ifndef CONFIG_SMP
	37	unsigned long last_asn = ASN_FIRST_VERSION;
	38	#endif
	39
	40	void
	41	__load_new_mm_context(struct mm_struct *next_mm)
	42	{
	43	unsigned long mmc;
	44	struct pcb_struct *pcb;
	45
	46	mmc = __get_new_mm_context(next_mm, smp_processor_id());
	47	next_mm->context[smp_processor_id()] = mmc;
	48
	49	pcb = &current_thread_info()->pcb;
	50	pcb->asn = mmc & HARDWARE_ASN_MASK;
	51	pcb->ptbr = ((unsigned long) next_mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
	52
	53	__reload_thread(pcb);
	54	}
	55
	56
	57	/*
	58	* This routine handles page faults. It determines the address,
	59	* and the problem, and then passes it off to handle_mm_fault().
	60	*
	61	* mmcsr:
	62	* 0 = translation not valid
	63	* 1 = access violation
	64	* 2 = fault-on-read
	65	* 3 = fault-on-execute
	66	* 4 = fault-on-write
	67	*
	68	* cause:
	69	* -1 = instruction fetch
	70	* 0 = load
	71	* 1 = store
	72	*
	73	* Registers $9 through $15 are saved in a block just prior to `regs' and
	74	* are saved and restored around the call to allow exception code to
	75	* modify them.
	76	*/
	77
	78	/* Macro for exception fixup code to access integer registers. */
	79	#define dpf_reg(r) \
	80	(((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 : \
	81	(r) <= 18 ? (r)+8 : (r)-10])
	82
	83	asmlinkage void
	84	do_page_fault(unsigned long address, unsigned long mmcsr,
	85	long cause, struct pt_regs *regs)
	86	{
	87	struct vm_area_struct * vma;
	88	struct mm_struct *mm = current->mm;
	89	const struct exception_table_entry *fixup;
	90	int fault, si_code = SEGV_MAPERR;
	91	siginfo_t info;
759496ba	92	unsigned int flags = FAULT_FLAG_ALLOW_RETRY \| FAULT_FLAG_KILLABLE;
1da177e4 LT	93
	94	/* As of EV6, a load into $31/$f31 is a prefetch, and never faults
	95	(or is suppressed by the PALcode). Support that for older CPUs
	96	by ignoring such an instruction. */
	97	if (cause == 0) {
	98	unsigned int insn;
	99	__get_user(insn, (unsigned int __user *)regs->pc);
	100	if ((insn >> 21 & 0x1f) == 0x1f &&
	101	/* ldq ldl ldt lds ldg ldf ldwu ldbu */
	102	(1ul << (insn >> 26) & 0x30f00001400ul)) {
	103	regs->pc += 4;
	104	return;
	105	}
	106	}
	107
	108	/* If we're in an interrupt context, or have no user context,
	109	we must not take the fault. */
70ffdb93	110	if (!mm \|\| faulthandler_disabled())
1da177e4 LT	111	goto no_context;
	112
	113	#ifdef CONFIG_ALPHA_LARGE_VMALLOC
	114	if (address >= TASK_SIZE)
	115	goto vmalloc_fault;
	116	#endif
759496ba JW	117	if (user_mode(regs))
759496ba JW	118	flags \|= FAULT_FLAG_USER;
0bcc426b	119	retry:
1da177e4 LT	120	down_read(&mm->mmap_sem);
	121	vma = find_vma(mm, address);
	122	if (!vma)
	123	goto bad_area;
	124	if (vma->vm_start <= address)
	125	goto good_area;
	126	if (!(vma->vm_flags & VM_GROWSDOWN))
	127	goto bad_area;
	128	if (expand_stack(vma, address))
	129	goto bad_area;
	130
	131	/* Ok, we have a good vm_area for this memory access, so
	132	we can handle it. */
	133	good_area:
	134	si_code = SEGV_ACCERR;
	135	if (cause < 0) {
	136	if (!(vma->vm_flags & VM_EXEC))
	137	goto bad_area;
	138	} else if (!cause) {
	139	/* Allow reads even for write-only mappings */
	140	if (!(vma->vm_flags & (VM_READ \| VM_WRITE)))
	141	goto bad_area;
	142	} else {
	143	if (!(vma->vm_flags & VM_WRITE))
	144	goto bad_area;
759496ba	145	flags \|= FAULT_FLAG_WRITE;
1da177e4 LT	146	}
1da177e4 LT	147
1da177e4 LT	148	/* If for any reason at all we couldn't handle the fault,
	149	make sure we exit gracefully rather than endlessly redo
	150	the fault. */
dcddffd4	151	fault = handle_mm_fault(vma, address, flags);
0bcc426b KC	152
	153	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
	154	return;
	155
83c54070 NP	156	if (unlikely(fault & VM_FAULT_ERROR)) {
	157	if (fault & VM_FAULT_OOM)
	158	goto out_of_memory;
33692f27 LT	159	else if (fault & VM_FAULT_SIGSEGV)
33692f27 LT	160	goto bad_area;
83c54070 NP	161	else if (fault & VM_FAULT_SIGBUS)
83c54070 NP	162	goto do_sigbus;
1da177e4 LT	163	BUG();
1da177e4 LT	164	}
0bcc426b KC	165
	166	if (flags & FAULT_FLAG_ALLOW_RETRY) {
	167	if (fault & VM_FAULT_MAJOR)
	168	current->maj_flt++;
	169	else
	170	current->min_flt++;
	171	if (fault & VM_FAULT_RETRY) {
	172	flags &= ~FAULT_FLAG_ALLOW_RETRY;
	173
	174	/* No need to up_read(&mm->mmap_sem) as we would
	175	* have already released it in __lock_page_or_retry
	176	* in mm/filemap.c.
	177	*/
	178
	179	goto retry;
	180	}
	181	}
	182
	183	up_read(&mm->mmap_sem);
	184
1da177e4 LT	185	return;
	186
	187	/* Something tried to access memory that isn't in our memory map.
	188	Fix it, but check if it's kernel or user first. */
	189	bad_area:
	190	up_read(&mm->mmap_sem);
	191
	192	if (user_mode(regs))
	193	goto do_sigsegv;
	194
	195	no_context:
	196	/* Are we prepared to handle this fault as an exception? */
	197	if ((fixup = search_exception_tables(regs->pc)) != 0) {
	198	unsigned long newpc;
	199	newpc = fixup_exception(dpf_reg, fixup, regs->pc);
	200	regs->pc = newpc;
	201	return;
	202	}
	203
	204	/* Oops. The kernel tried to access some bad page. We'll have to
	205	terminate things with extreme prejudice. */
	206	printk(KERN_ALERT "Unable to handle kernel paging request at "
	207	"virtual address %016lx\n", address);
	208	die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16);
	209	do_exit(SIGKILL);
	210
	211	/* We ran out of memory, or some other thing happened to us that
	212	made us unable to handle the page fault gracefully. */
	213	out_of_memory:
0bcc426b	214	up_read(&mm->mmap_sem);
1da177e4 LT	215	if (!user_mode(regs))
1da177e4 LT	216	goto no_context;
1cb3d8e2 NP	217	pagefault_out_of_memory();
1cb3d8e2 NP	218	return;
1da177e4 LT	219
1da177e4 LT	220	do_sigbus:
0bcc426b	221	up_read(&mm->mmap_sem);
1da177e4 LT	222	/* Send a sigbus, regardless of whether we were in kernel
	223	or user mode. */
	224	info.si_signo = SIGBUS;
	225	info.si_errno = 0;
	226	info.si_code = BUS_ADRERR;
	227	info.si_addr = (void __user *) address;
	228	force_sig_info(SIGBUS, &info, current);
	229	if (!user_mode(regs))
	230	goto no_context;
	231	return;
	232
	233	do_sigsegv:
	234	info.si_signo = SIGSEGV;
	235	info.si_errno = 0;
	236	info.si_code = si_code;
	237	info.si_addr = (void __user *) address;
	238	force_sig_info(SIGSEGV, &info, current);
	239	return;
	240
	241	#ifdef CONFIG_ALPHA_LARGE_VMALLOC
	242	vmalloc_fault:
	243	if (user_mode(regs))
	244	goto do_sigsegv;
	245	else {
	246	/* Synchronize this task's top level page-table
	247	with the "reference" page table from init. */
	248	long index = pgd_index(address);
	249	pgd_t pgd, pgd_k;
	250
	251	pgd = current->active_mm->pgd + index;
	252	pgd_k = swapper_pg_dir + index;
	253	if (!pgd_present(pgd) && pgd_present(pgd_k)) {
	254	pgd_val(pgd) = pgd_val(pgd_k);
	255	return;
	256	}
	257	goto no_context;
	258	}
	259	#endif
	260	}