[mirror_ubuntu-jammy-kernel.git] / arch / powerpc / mm / fault.c

/*
 *  PowerPC version
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Derived from "arch/i386/mm/fault.c"
 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  Modified by Cort Dougan and Paul Mackerras.
 *
 *  Modified for PPC64 by Dave Engebretsen (engebret@ibm.com)
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 */

#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/highmem.h>
#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <linux/perf_event.h>
#include <linux/magic.h>

#include <asm/firmware.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/tlbflush.h>
#include <asm/siginfo.h>
#include <mm/mmu_decl.h>

#ifdef CONFIG_KPROBES
static inline int notify_page_fault(struct pt_regs *regs)
{
	int ret = 0;

	/* kprobe_running() needs smp_processor_id() */
	if (!user_mode(regs)) {
		preempt_disable();
		if (kprobe_running() && kprobe_fault_handler(regs, 11))
			ret = 1;
		preempt_enable();
	}

	return ret;
}
#else
static inline int notify_page_fault(struct pt_regs *regs)
{
	return 0;
}
#endif

/*
 * Check whether the instruction at regs->nip is a store using
 * an update addressing form which will update r1.
 */
static int store_updates_sp(struct pt_regs *regs)
{
	unsigned int inst;

	if (get_user(inst, (unsigned int __user *)regs->nip))
		return 0;
	/* check for 1 in the rA field */
	if (((inst >> 16) & 0x1f) != 1)
		return 0;
	/* check major opcode */
	switch (inst >> 26) {
	case 37:	/* stwu */
	case 39:	/* stbu */
	case 45:	/* sthu */
	case 53:	/* stfsu */
	case 55:	/* stfdu */
		return 1;
	case 62:	/* std or stdu */
		return (inst & 3) == 1;
	case 31:
		/* check minor opcode */
		switch ((inst >> 1) & 0x3ff) {
		case 181:	/* stdux */
		case 183:	/* stwux */
		case 247:	/* stbux */
		case 439:	/* sthux */
		case 695:	/* stfsux */
		case 759:	/* stfdux */
			return 1;
		}
	}
	return 0;
}

/*
 * For 600- and 800-family processors, the error_code parameter is DSISR
 * for a data fault, SRR1 for an instruction fault. For 400-family processors
 * the error_code parameter is ESR for a data fault, 0 for an instruction
 * fault.
 * For 64-bit processors, the error_code parameter is
 *  - DSISR for a non-SLB data access fault,
 *  - SRR1 & 0x08000000 for a non-SLB instruction access fault
 *  - 0 any SLB fault.
 *
 * The return value is 0 if the fault was handled, or the signal
 * number if this is a kernel fault that can't be handled here.
 */
int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
			    unsigned long error_code)
{
	struct vm_area_struct * vma;
	struct mm_struct *mm = current->mm;
	siginfo_t info;
	int code = SEGV_MAPERR;
	int is_write = 0, ret;
	int trap = TRAP(regs);
 	int is_exec = trap == 0x400;

#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
	/*
	 * Fortunately the bit assignments in SRR1 for an instruction
	 * fault and DSISR for a data fault are mostly the same for the
	 * bits we are interested in.  But there are some bits which
	 * indicate errors in DSISR but can validly be set in SRR1.
	 */
	if (trap == 0x400)
		error_code &= 0x48200000;
	else
		is_write = error_code & DSISR_ISSTORE;
#else
	is_write = error_code & ESR_DST;
#endif /* CONFIG_4xx || CONFIG_BOOKE */

	if (notify_page_fault(regs))
		return 0;

	if (unlikely(debugger_fault_handler(regs)))
		return 0;

	/* On a kernel SLB miss we can only check for a valid exception entry */
	if (!user_mode(regs) && (address >= TASK_SIZE))
		return SIGSEGV;

#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE) || \
			     defined(CONFIG_PPC_BOOK3S_64))
  	if (error_code & DSISR_DABRMATCH) {
		/* DABR match */
		do_dabr(regs, address, error_code);
		return 0;
	}
#endif

	if (in_atomic() || mm == NULL) {
		if (!user_mode(regs))
			return SIGSEGV;
		/* in_atomic() in user mode is really bad,
		   as is current->mm == NULL. */
		printk(KERN_EMERG "Page fault in user mode with "
		       "in_atomic() = %d mm = %p\n", in_atomic(), mm);
		printk(KERN_EMERG "NIP = %lx  MSR = %lx\n",
		       regs->nip, regs->msr);
		die("Weird page fault", regs, SIGSEGV);
	}

	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);

	/* When running in the kernel we expect faults to occur only to
	 * addresses in user space.  All other faults represent errors in the
	 * kernel and should generate an OOPS.  Unfortunately, in the case of an
	 * erroneous fault occurring in a code path which already holds mmap_sem
	 * we will deadlock attempting to validate the fault against the
	 * address space.  Luckily the kernel only validly references user
	 * space from well defined areas of code, which are listed in the
	 * exceptions table.
	 *
	 * As the vast majority of faults will be valid we will only perform
	 * the source reference check when there is a possibility of a deadlock.
	 * Attempt to lock the address space, if we cannot we then validate the
	 * source.  If this is invalid we can skip the address space check,
	 * thus avoiding the deadlock.
	 */
	if (!down_read_trylock(&mm->mmap_sem)) {
		if (!user_mode(regs) && !search_exception_tables(regs->nip))
			goto bad_area_nosemaphore;

		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;

	/*
	 * N.B. The POWER/Open ABI allows programs to access up to
	 * 288 bytes below the stack pointer.
	 * The kernel signal delivery code writes up to about 1.5kB
	 * below the stack pointer (r1) before decrementing it.
	 * The exec code can write slightly over 640kB to the stack
	 * before setting the user r1.  Thus we allow the stack to
	 * expand to 1MB without further checks.
	 */
	if (address + 0x100000 < vma->vm_end) {
		/* get user regs even if this fault is in kernel mode */
		struct pt_regs *uregs = current->thread.regs;
		if (uregs == NULL)
			goto bad_area;

		/*
		 * A user-mode access to an address a long way below
		 * the stack pointer is only valid if the instruction
		 * is one which would update the stack pointer to the
		 * address accessed if the instruction completed,
		 * i.e. either stwu rs,n(r1) or stwux rs,r1,rb
		 * (or the byte, halfword, float or double forms).
		 *
		 * If we don't check this then any write to the area
		 * between the last mapped region and the stack will
		 * expand the stack rather than segfaulting.
		 */
		if (address + 2048 < uregs->gpr[1]
		    && (!user_mode(regs) || !store_updates_sp(regs)))
			goto bad_area;
	}
	if (expand_stack(vma, address))
		goto bad_area;

good_area:
	code = SEGV_ACCERR;
#if defined(CONFIG_6xx)
	if (error_code & 0x95700000)
		/* an error such as lwarx to I/O controller space,
		   address matching DABR, eciwx, etc. */
		goto bad_area;
#endif /* CONFIG_6xx */
#if defined(CONFIG_8xx)
	/* 8xx sometimes need to load a invalid/non-present TLBs.
	 * These must be invalidated separately as linux mm don't.
	 */
	if (error_code & 0x40000000) /* no translation? */
		_tlbil_va(address, 0, 0, 0);

        /* The MPC8xx seems to always set 0x80000000, which is
         * "undefined".  Of those that can be set, this is the only
         * one which seems bad.
         */
	if (error_code & 0x10000000)
                /* Guarded storage error. */
		goto bad_area;
#endif /* CONFIG_8xx */

	if (is_exec) {
#ifdef CONFIG_PPC_STD_MMU
		/* Protection fault on exec go straight to failure on
		 * Hash based MMUs as they either don't support per-page
		 * execute permission, or if they do, it's handled already
		 * at the hash level. This test would probably have to
		 * be removed if we change the way this works to make hash
		 * processors use the same I/D cache coherency mechanism
		 * as embedded.
		 */
		if (error_code & DSISR_PROTFAULT)
			goto bad_area;
#endif /* CONFIG_PPC_STD_MMU */

		/*
		 * Allow execution from readable areas if the MMU does not
		 * provide separate controls over reading and executing.
		 *
		 * Note: That code used to not be enabled for 4xx/BookE.
		 * It is now as I/D cache coherency for these is done at
		 * set_pte_at() time and I see no reason why the test
		 * below wouldn't be valid on those processors. This -may-
		 * break programs compiled with a really old ABI though.
		 */
		if (!(vma->vm_flags & VM_EXEC) &&
		    (cpu_has_feature(CPU_FTR_NOEXECUTE) ||
		     !(vma->vm_flags & (VM_READ | VM_WRITE))))
			goto bad_area;
	/* a write */
	} else if (is_write) {
		if (!(vma->vm_flags & VM_WRITE))
			goto bad_area;
	/* a read */
	} else {
		/* protection fault */
		if (error_code & 0x08000000)
			goto bad_area;
		if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
			goto bad_area;
	}

	/*
	 * If for any reason at all we couldn't handle the fault,
	 * make sure we exit gracefully rather than endlessly redo
	 * the fault.
	 */
	ret = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : 0);
	if (unlikely(ret & VM_FAULT_ERROR)) {
		if (ret & VM_FAULT_OOM)
			goto out_of_memory;
		else if (ret & VM_FAULT_SIGBUS)
			goto do_sigbus;
		BUG();
	}
	if (ret & VM_FAULT_MAJOR) {
		current->maj_flt++;
		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
				     regs, address);
#ifdef CONFIG_PPC_SMLPAR
		if (firmware_has_feature(FW_FEATURE_CMO)) {
			preempt_disable();
			get_lppaca()->page_ins += (1 << PAGE_FACTOR);
			preempt_enable();
		}
#endif
	} else {
		current->min_flt++;
		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
				     regs, address);
	}
	up_read(&mm->mmap_sem);
	return 0;

bad_area:
	up_read(&mm->mmap_sem);

bad_area_nosemaphore:
	/* User mode accesses cause a SIGSEGV */
	if (user_mode(regs)) {
		_exception(SIGSEGV, regs, code, address);
		return 0;
	}

	if (is_exec && (error_code & DSISR_PROTFAULT)
	    && printk_ratelimit())
		printk(KERN_CRIT "kernel tried to execute NX-protected"
		       " page (%lx) - exploit attempt? (uid: %d)\n",
		       address, current_uid());

	return SIGSEGV;

/*
 * 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))
		return SIGKILL;
	pagefault_out_of_memory();
	return 0;

do_sigbus:
	up_read(&mm->mmap_sem);
	if (user_mode(regs)) {
		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);
		return 0;
	}
	return SIGBUS;
}

/*
 * bad_page_fault is called when we have a bad access from the kernel.
 * It is called from the DSI and ISI handlers in head.S and from some
 * of the procedures in traps.c.
 */
void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
{
	const struct exception_table_entry *entry;
	unsigned long *stackend;

	/* Are we prepared to handle this fault?  */
	if ((entry = search_exception_tables(regs->nip)) != NULL) {
		regs->nip = entry->fixup;
		return;
	}

	/* kernel has accessed a bad area */

	switch (regs->trap) {
	case 0x300:
	case 0x380:
		printk(KERN_ALERT "Unable to handle kernel paging request for "
			"data at address 0x%08lx\n", regs->dar);
		break;
	case 0x400:
	case 0x480:
		printk(KERN_ALERT "Unable to handle kernel paging request for "
			"instruction fetch\n");
		break;
	default:
		printk(KERN_ALERT "Unable to handle kernel paging request for "
			"unknown fault\n");
		break;
	}
	printk(KERN_ALERT "Faulting instruction address: 0x%08lx\n",
		regs->nip);

	stackend = end_of_stack(current);
	if (current != &init_task && *stackend != STACK_END_MAGIC)
		printk(KERN_ALERT "Thread overran stack, or stack corrupted\n");

	die("Kernel access of bad area", regs, sig);
}
Commit	Line	Data
14cf11af	1	/*
14cf11af PM	2	* PowerPC version
	3	* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
	4	*
	5	* Derived from "arch/i386/mm/fault.c"
	6	* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
	7	*
	8	* Modified by Cort Dougan and Paul Mackerras.
	9	*
	10	* Modified for PPC64 by Dave Engebretsen (engebret@ibm.com)
	11	*
	12	* This program is free software; you can redistribute it and/or
	13	* modify it under the terms of the GNU General Public License
	14	* as published by the Free Software Foundation; either version
	15	* 2 of the License, or (at your option) any later version.
	16	*/
	17
14cf11af PM	18	#include <linux/signal.h>
	19	#include <linux/sched.h>
	20	#include <linux/kernel.h>
	21	#include <linux/errno.h>
	22	#include <linux/string.h>
	23	#include <linux/types.h>
	24	#include <linux/ptrace.h>
	25	#include <linux/mman.h>
	26	#include <linux/mm.h>
	27	#include <linux/interrupt.h>
	28	#include <linux/highmem.h>
	29	#include <linux/module.h>
	30	#include <linux/kprobes.h>
1eeb66a1	31	#include <linux/kdebug.h>
cdd6c482	32	#include <linux/perf_event.h>
28b54990	33	#include <linux/magic.h>
14cf11af	34
40900194	35	#include <asm/firmware.h>
14cf11af PM	36	#include <asm/page.h>
	37	#include <asm/pgtable.h>
	38	#include <asm/mmu.h>
	39	#include <asm/mmu_context.h>
	40	#include <asm/system.h>
	41	#include <asm/uaccess.h>
	42	#include <asm/tlbflush.h>
14cf11af	43	#include <asm/siginfo.h>
5efab4a0	44	#include <mm/mmu_decl.h>
4f9e87c0	45
9f90b997 CH	46	#ifdef CONFIG_KPROBES
9f90b997 CH	47	static inline int notify_page_fault(struct pt_regs *regs)
4f9e87c0	48	{
9f90b997 CH	49	int ret = 0;
	50
	51	/* kprobe_running() needs smp_processor_id() */
	52	if (!user_mode(regs)) {
	53	preempt_disable();
	54	if (kprobe_running() && kprobe_fault_handler(regs, 11))
	55	ret = 1;
	56	preempt_enable();
	57	}
4f9e87c0	58
9f90b997	59	return ret;
4f9e87c0 AK	60	}
4f9e87c0 AK	61	#else
9f90b997	62	static inline int notify_page_fault(struct pt_regs *regs)
4f9e87c0	63	{
9f90b997	64	return 0;
4f9e87c0 AK	65	}
	66	#endif
	67
14cf11af PM	68	/*
	69	* Check whether the instruction at regs->nip is a store using
	70	* an update addressing form which will update r1.
	71	*/
	72	static int store_updates_sp(struct pt_regs *regs)
	73	{
	74	unsigned int inst;
	75
	76	if (get_user(inst, (unsigned int __user *)regs->nip))
	77	return 0;
	78	/* check for 1 in the rA field */
	79	if (((inst >> 16) & 0x1f) != 1)
	80	return 0;
	81	/* check major opcode */
	82	switch (inst >> 26) {
	83	case 37: /* stwu */
	84	case 39: /* stbu */
	85	case 45: /* sthu */
	86	case 53: /* stfsu */
	87	case 55: /* stfdu */
	88	return 1;
	89	case 62: /* std or stdu */
	90	return (inst & 3) == 1;
	91	case 31:
	92	/* check minor opcode */
	93	switch ((inst >> 1) & 0x3ff) {
	94	case 181: /* stdux */
	95	case 183: /* stwux */
	96	case 247: /* stbux */
	97	case 439: /* sthux */
	98	case 695: /* stfsux */
	99	case 759: /* stfdux */
	100	return 1;
	101	}
	102	}
	103	return 0;
	104	}
	105
14cf11af PM	106	/*
	107	* For 600- and 800-family processors, the error_code parameter is DSISR
	108	* for a data fault, SRR1 for an instruction fault. For 400-family processors
	109	* the error_code parameter is ESR for a data fault, 0 for an instruction
	110	* fault.
	111	* For 64-bit processors, the error_code parameter is
	112	* - DSISR for a non-SLB data access fault,
	113	* - SRR1 & 0x08000000 for a non-SLB instruction access fault
	114	* - 0 any SLB fault.
	115	*
	116	* The return value is 0 if the fault was handled, or the signal
	117	* number if this is a kernel fault that can't be handled here.
	118	*/
	119	int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
	120	unsigned long error_code)
	121	{
	122	struct vm_area_struct * vma;
	123	struct mm_struct *mm = current->mm;
	124	siginfo_t info;
	125	int code = SEGV_MAPERR;
83c54070	126	int is_write = 0, ret;
14cf11af PM	127	int trap = TRAP(regs);
	128	int is_exec = trap == 0x400;
	129
	130	#if !(defined(CONFIG_4xx) \|\| defined(CONFIG_BOOKE))
	131	/*
	132	* Fortunately the bit assignments in SRR1 for an instruction
	133	* fault and DSISR for a data fault are mostly the same for the
	134	* bits we are interested in. But there are some bits which
	135	* indicate errors in DSISR but can validly be set in SRR1.
	136	*/
	137	if (trap == 0x400)
	138	error_code &= 0x48200000;
	139	else
	140	is_write = error_code & DSISR_ISSTORE;
	141	#else
	142	is_write = error_code & ESR_DST;
	143	#endif /* CONFIG_4xx \|\| CONFIG_BOOKE */
	144
9f90b997	145	if (notify_page_fault(regs))
14cf11af PM	146	return 0;
14cf11af PM	147
c3b75bd7 MN	148	if (unlikely(debugger_fault_handler(regs)))
c3b75bd7 MN	149	return 0;
14cf11af PM	150
	151	/* On a kernel SLB miss we can only check for a valid exception entry */
	152	if (!user_mode(regs) && (address >= TASK_SIZE))
	153	return SIGSEGV;
	154
9c7cc234 P	155	#if !(defined(CONFIG_4xx) \|\| defined(CONFIG_BOOKE) \|\| \
9c7cc234 P	156	defined(CONFIG_PPC_BOOK3S_64))
14cf11af PM	157	if (error_code & DSISR_DABRMATCH) {
14cf11af PM	158	/* DABR match */
bce6c5fd	159	do_dabr(regs, address, error_code);
14cf11af PM	160	return 0;
14cf11af PM	161	}
9c7cc234	162	#endif
14cf11af PM	163
	164	if (in_atomic() \|\| mm == NULL) {
	165	if (!user_mode(regs))
	166	return SIGSEGV;
	167	/* in_atomic() in user mode is really bad,
	168	as is current->mm == NULL. */
df3c9019	169	printk(KERN_EMERG "Page fault in user mode with "
14cf11af PM	170	"in_atomic() = %d mm = %p\n", in_atomic(), mm);
	171	printk(KERN_EMERG "NIP = %lx MSR = %lx\n",
	172	regs->nip, regs->msr);
	173	die("Weird page fault", regs, SIGSEGV);
	174	}
	175
cdd6c482	176	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);
7dd1fcc2	177
14cf11af PM	178	/* When running in the kernel we expect faults to occur only to
14cf11af PM	179	* addresses in user space. All other faults represent errors in the
fc5266ea AB	180	* kernel and should generate an OOPS. Unfortunately, in the case of an
fc5266ea AB	181	* erroneous fault occurring in a code path which already holds mmap_sem
14cf11af PM	182	* we will deadlock attempting to validate the fault against the
	183	* address space. Luckily the kernel only validly references user
	184	* space from well defined areas of code, which are listed in the
	185	* exceptions table.
	186	*
	187	* As the vast majority of faults will be valid we will only perform
fc5266ea	188	* the source reference check when there is a possibility of a deadlock.
14cf11af PM	189	* Attempt to lock the address space, if we cannot we then validate the
	190	* source. If this is invalid we can skip the address space check,
	191	* thus avoiding the deadlock.
	192	*/
	193	if (!down_read_trylock(&mm->mmap_sem)) {
	194	if (!user_mode(regs) && !search_exception_tables(regs->nip))
	195	goto bad_area_nosemaphore;
	196
	197	down_read(&mm->mmap_sem);
	198	}
	199
	200	vma = find_vma(mm, address);
	201	if (!vma)
	202	goto bad_area;
	203	if (vma->vm_start <= address)
	204	goto good_area;
	205	if (!(vma->vm_flags & VM_GROWSDOWN))
	206	goto bad_area;
	207
	208	/*
	209	* N.B. The POWER/Open ABI allows programs to access up to
	210	* 288 bytes below the stack pointer.
	211	* The kernel signal delivery code writes up to about 1.5kB
	212	* below the stack pointer (r1) before decrementing it.
	213	* The exec code can write slightly over 640kB to the stack
	214	* before setting the user r1. Thus we allow the stack to
	215	* expand to 1MB without further checks.
	216	*/
	217	if (address + 0x100000 < vma->vm_end) {
	218	/* get user regs even if this fault is in kernel mode */
	219	struct pt_regs *uregs = current->thread.regs;
	220	if (uregs == NULL)
	221	goto bad_area;
	222
	223	/*
	224	* A user-mode access to an address a long way below
	225	* the stack pointer is only valid if the instruction
	226	* is one which would update the stack pointer to the
	227	* address accessed if the instruction completed,
	228	* i.e. either stwu rs,n(r1) or stwux rs,r1,rb
	229	* (or the byte, halfword, float or double forms).
	230	*
	231	* If we don't check this then any write to the area
	232	* between the last mapped region and the stack will
	233	* expand the stack rather than segfaulting.
	234	*/
	235	if (address + 2048 < uregs->gpr[1]
	236	&& (!user_mode(regs) \|\| !store_updates_sp(regs)))
	237	goto bad_area;
	238	}
	239	if (expand_stack(vma, address))
	240	goto bad_area;
	241
	242	good_area:
	243	code = SEGV_ACCERR;
	244	#if defined(CONFIG_6xx)
	245	if (error_code & 0x95700000)
	246	/* an error such as lwarx to I/O controller space,
	247	address matching DABR, eciwx, etc. */
	248	goto bad_area;
	249	#endif /* CONFIG_6xx */
	250	#if defined(CONFIG_8xx)
5efab4a0 JT	251	/* 8xx sometimes need to load a invalid/non-present TLBs.
	252	* These must be invalidated separately as linux mm don't.
	253	*/
	254	if (error_code & 0x40000000) /* no translation? */
	255	_tlbil_va(address, 0, 0, 0);
	256
14cf11af PM	257	/* The MPC8xx seems to always set 0x80000000, which is
	258	* "undefined". Of those that can be set, this is the only
	259	* one which seems bad.
	260	*/
	261	if (error_code & 0x10000000)
	262	/* Guarded storage error. */
	263	goto bad_area;
	264	#endif /* CONFIG_8xx */
	265
	266	if (is_exec) {
8d30c14c BH	267	#ifdef CONFIG_PPC_STD_MMU
	268	/* Protection fault on exec go straight to failure on
	269	* Hash based MMUs as they either don't support per-page
	270	* execute permission, or if they do, it's handled already
	271	* at the hash level. This test would probably have to
	272	* be removed if we change the way this works to make hash
	273	* processors use the same I/D cache coherency mechanism
	274	* as embedded.
	275	*/
14cf11af PM	276	if (error_code & DSISR_PROTFAULT)
14cf11af PM	277	goto bad_area;
8d30c14c BH	278	#endif /* CONFIG_PPC_STD_MMU */
8d30c14c BH	279
08ae6cc1 PM	280	/*
	281	* Allow execution from readable areas if the MMU does not
	282	* provide separate controls over reading and executing.
8d30c14c BH	283	*
	284	* Note: That code used to not be enabled for 4xx/BookE.
	285	* It is now as I/D cache coherency for these is done at
	286	* set_pte_at() time and I see no reason why the test
	287	* below wouldn't be valid on those processors. This -may-
	288	* break programs compiled with a really old ABI though.
08ae6cc1 PM	289	*/
	290	if (!(vma->vm_flags & VM_EXEC) &&
	291	(cpu_has_feature(CPU_FTR_NOEXECUTE) \|\|
	292	!(vma->vm_flags & (VM_READ \| VM_WRITE))))
14cf11af	293	goto bad_area;
14cf11af PM	294	/* a write */
	295	} else if (is_write) {
	296	if (!(vma->vm_flags & VM_WRITE))
	297	goto bad_area;
	298	/* a read */
	299	} else {
	300	/* protection fault */
	301	if (error_code & 0x08000000)
	302	goto bad_area;
df67b3da	303	if (!(vma->vm_flags & (VM_READ \| VM_EXEC \| VM_WRITE)))
14cf11af PM	304	goto bad_area;
	305	}
	306
	307	/*
	308	* If for any reason at all we couldn't handle the fault,
	309	* make sure we exit gracefully rather than endlessly redo
	310	* the fault.
	311	*/
d06063cc	312	ret = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : 0);
83c54070 NP	313	if (unlikely(ret & VM_FAULT_ERROR)) {
	314	if (ret & VM_FAULT_OOM)
	315	goto out_of_memory;
	316	else if (ret & VM_FAULT_SIGBUS)
	317	goto do_sigbus;
14cf11af PM	318	BUG();
14cf11af PM	319	}
40900194	320	if (ret & VM_FAULT_MAJOR) {
83c54070	321	current->maj_flt++;
cdd6c482	322	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
78f13e95	323	regs, address);
40900194 BK	324	#ifdef CONFIG_PPC_SMLPAR
	325	if (firmware_has_feature(FW_FEATURE_CMO)) {
	326	preempt_disable();
a6326e98	327	get_lppaca()->page_ins += (1 << PAGE_FACTOR);
40900194 BK	328	preempt_enable();
	329	}
	330	#endif
ac17dc8e	331	} else {
83c54070	332	current->min_flt++;
cdd6c482	333	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
78f13e95	334	regs, address);
ac17dc8e	335	}
14cf11af PM	336	up_read(&mm->mmap_sem);
	337	return 0;
	338
	339	bad_area:
	340	up_read(&mm->mmap_sem);
	341
	342	bad_area_nosemaphore:
	343	/* User mode accesses cause a SIGSEGV */
	344	if (user_mode(regs)) {
	345	_exception(SIGSEGV, regs, code, address);
	346	return 0;
	347	}
	348
	349	if (is_exec && (error_code & DSISR_PROTFAULT)
	350	&& printk_ratelimit())
	351	printk(KERN_CRIT "kernel tried to execute NX-protected"
	352	" page (%lx) - exploit attempt? (uid: %d)\n",
1330deb0	353	address, current_uid());
14cf11af PM	354
	355	return SIGSEGV;
	356
	357	/*
	358	* We ran out of memory, or some other thing happened to us that made
	359	* us unable to handle the page fault gracefully.
	360	*/
	361	out_of_memory:
	362	up_read(&mm->mmap_sem);
e460c2c9 BH	363	if (!user_mode(regs))
	364	return SIGKILL;
	365	pagefault_out_of_memory();
	366	return 0;
14cf11af PM	367
	368	do_sigbus:
	369	up_read(&mm->mmap_sem);
	370	if (user_mode(regs)) {
	371	info.si_signo = SIGBUS;
	372	info.si_errno = 0;
	373	info.si_code = BUS_ADRERR;
	374	info.si_addr = (void __user *)address;
	375	force_sig_info(SIGBUS, &info, current);
	376	return 0;
	377	}
	378	return SIGBUS;
	379	}
	380
	381	/*
	382	* bad_page_fault is called when we have a bad access from the kernel.
	383	* It is called from the DSI and ISI handlers in head.S and from some
	384	* of the procedures in traps.c.
	385	*/
	386	void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
	387	{
	388	const struct exception_table_entry *entry;
28b54990	389	unsigned long *stackend;
14cf11af PM	390
	391	/* Are we prepared to handle this fault? */
	392	if ((entry = search_exception_tables(regs->nip)) != NULL) {
	393	regs->nip = entry->fixup;
	394	return;
	395	}
	396
	397	/* kernel has accessed a bad area */
723925b7	398
723925b7	399	switch (regs->trap) {
a416dd8d ME	400	case 0x300:
	401	case 0x380:
	402	printk(KERN_ALERT "Unable to handle kernel paging request for "
	403	"data at address 0x%08lx\n", regs->dar);
	404	break;
	405	case 0x400:
	406	case 0x480:
	407	printk(KERN_ALERT "Unable to handle kernel paging request for "
	408	"instruction fetch\n");
	409	break;
	410	default:
	411	printk(KERN_ALERT "Unable to handle kernel paging request for "
	412	"unknown fault\n");
	413	break;
723925b7 OJ	414	}
	415	printk(KERN_ALERT "Faulting instruction address: 0x%08lx\n",
	416	regs->nip);
	417
28b54990 AB	418	stackend = end_of_stack(current);
	419	if (current != &init_task && *stackend != STACK_END_MAGIC)
	420	printk(KERN_ALERT "Thread overran stack, or stack corrupted\n");
	421
14cf11af PM	422	die("Kernel access of bad area", regs, sig);
14cf11af PM	423	}