[linux-2.6-block.git] / arch / arc / mm / fault.c

// SPDX-License-Identifier: GPL-2.0-only
/* Page Fault Handling for ARC (TLB Miss / ProtV)
 *
 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
 */

#include <linux/signal.h>
#include <linux/interrupt.h>
#include <linux/sched/signal.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/uaccess.h>
#include <linux/kdebug.h>
#include <linux/perf_event.h>
#include <linux/mm_types.h>
#include <asm/entry.h>
#include <asm/mmu.h>

/*
 * kernel virtual address is required to implement vmalloc/pkmap/fixmap
 * Refer to asm/processor.h for System Memory Map
 *
 * It simply copies the PMD entry (pointer to 2nd level page table or hugepage)
 * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared
 */
noinline static int handle_kernel_vaddr_fault(unsigned long address)
{
	/*
	 * Synchronize this task's top level page-table
	 * with the 'reference' page table.
	 */
	pgd_t *pgd, *pgd_k;
	p4d_t *p4d, *p4d_k;
	pud_t *pud, *pud_k;
	pmd_t *pmd, *pmd_k;

	pgd = pgd_offset(current->active_mm, address);
	pgd_k = pgd_offset_k(address);

	if (pgd_none (*pgd_k))
		goto bad_area;
	if (!pgd_present(*pgd))
		set_pgd(pgd, *pgd_k);

	p4d = p4d_offset(pgd, address);
	p4d_k = p4d_offset(pgd_k, address);
	if (p4d_none(*p4d_k))
		goto bad_area;
	if (!p4d_present(*p4d))
		set_p4d(p4d, *p4d_k);

	pud = pud_offset(p4d, address);
	pud_k = pud_offset(p4d_k, address);
	if (pud_none(*pud_k))
		goto bad_area;
	if (!pud_present(*pud))
		set_pud(pud, *pud_k);

	pmd = pmd_offset(pud, address);
	pmd_k = pmd_offset(pud_k, address);
	if (pmd_none(*pmd_k))
		goto bad_area;
	if (!pmd_present(*pmd))
		set_pmd(pmd, *pmd_k);

	/* XXX: create the TLB entry here */
	return 0;

bad_area:
	return 1;
}

void do_page_fault(unsigned long address, struct pt_regs *regs)
{
	struct vm_area_struct *vma = NULL;
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	int sig, si_code = SEGV_MAPERR;
	unsigned int write = 0, exec = 0, mask;
	vm_fault_t fault = VM_FAULT_SIGSEGV;	/* handle_mm_fault() output */
	unsigned int flags;			/* handle_mm_fault() input */

	/*
	 * NOTE! We MUST NOT take any locks for this case. We may
	 * be in an interrupt or a critical region, and should
	 * only copy the information from the master page table,
	 * nothing more.
	 */
	if (address >= VMALLOC_START && !user_mode(regs)) {
		if (unlikely(handle_kernel_vaddr_fault(address)))
			goto no_context;
		else
			return;
	}

	/*
	 * 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 (regs->ecr.cause & ECR_C_PROTV_STORE)	/* ST/EX */
		write = 1;
	else if ((regs->ecr.vec == ECR_V_PROTV) &&
	         (regs->ecr.cause == ECR_C_PROTV_INST_FETCH))
		exec = 1;

	flags = FAULT_FLAG_DEFAULT;
	if (user_mode(regs))
		flags |= FAULT_FLAG_USER;
	if (write)
		flags |= FAULT_FLAG_WRITE;

	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
retry:
	vma = lock_mm_and_find_vma(mm, address, regs);
	if (!vma)
		goto bad_area_nosemaphore;

	/*
	 * vm_area is good, now check permissions for this memory access
	 */
	mask = VM_READ;
	if (write)
		mask = VM_WRITE;
	if (exec)
		mask = VM_EXEC;

	if (!(vma->vm_flags & mask)) {
		si_code = SEGV_ACCERR;
		goto bad_area;
	}

	fault = handle_mm_fault(vma, address, flags, regs);

	/* Quick path to respond to signals */
	if (fault_signal_pending(fault, regs)) {
		if (!user_mode(regs))
			goto no_context;
		return;
	}

	/* The fault is fully completed (including releasing mmap lock) */
	if (fault & VM_FAULT_COMPLETED)
		return;

	/*
	 * Fault retry nuances, mmap_lock already relinquished by core mm
	 */
	if (unlikely(fault & VM_FAULT_RETRY)) {
		flags |= FAULT_FLAG_TRIED;
		goto retry;
	}

bad_area:
	mmap_read_unlock(mm);

bad_area_nosemaphore:
	/*
	 * Major/minor page fault accounting
	 * (in case of retry we only land here once)
	 */
	if (likely(!(fault & VM_FAULT_ERROR)))
		/* Normal return path: fault Handled Gracefully */
		return;

	if (!user_mode(regs))
		goto no_context;

	if (fault & VM_FAULT_OOM) {
		pagefault_out_of_memory();
		return;
	}

	if (fault & VM_FAULT_SIGBUS) {
		sig = SIGBUS;
		si_code = BUS_ADRERR;
	}
	else {
		sig = SIGSEGV;
	}

	tsk->thread.fault_address = address;
	force_sig_fault(sig, si_code, (void __user *)address);
	return;

no_context:
	if (fixup_exception(regs))
		return;

	die("Oops", regs, address);
}
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0-only
	2	/* Page Fault Handling for ARC (TLB Miss / ProtV)
	3	*
	4	* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
	5	*/
	6
	7	#include <linux/signal.h>
	8	#include <linux/interrupt.h>
	9	#include <linux/sched/signal.h>
	10	#include <linux/errno.h>
	11	#include <linux/ptrace.h>
	12	#include <linux/uaccess.h>
	13	#include <linux/kdebug.h>
	14	#include <linux/perf_event.h>
	15	#include <linux/mm_types.h>
	16	#include <asm/entry.h>
	17	#include <asm/mmu.h>
	18
	19	/*
	20	* kernel virtual address is required to implement vmalloc/pkmap/fixmap
	21	* Refer to asm/processor.h for System Memory Map
	22	*
	23	* It simply copies the PMD entry (pointer to 2nd level page table or hugepage)
	24	* from swapper pgdir to task pgdir. The 2nd level table/page is thus shared
	25	*/
	26	noinline static int handle_kernel_vaddr_fault(unsigned long address)
	27	{
	28	/*
	29	* Synchronize this task's top level page-table
	30	* with the 'reference' page table.
	31	*/
	32	pgd_t pgd, pgd_k;
	33	p4d_t p4d, p4d_k;
	34	pud_t pud, pud_k;
	35	pmd_t pmd, pmd_k;
	36
	37	pgd = pgd_offset(current->active_mm, address);
	38	pgd_k = pgd_offset_k(address);
	39
	40	if (pgd_none (*pgd_k))
	41	goto bad_area;
	42	if (!pgd_present(*pgd))
	43	set_pgd(pgd, *pgd_k);
	44
	45	p4d = p4d_offset(pgd, address);
	46	p4d_k = p4d_offset(pgd_k, address);
	47	if (p4d_none(*p4d_k))
	48	goto bad_area;
	49	if (!p4d_present(*p4d))
	50	set_p4d(p4d, *p4d_k);
	51
	52	pud = pud_offset(p4d, address);
	53	pud_k = pud_offset(p4d_k, address);
	54	if (pud_none(*pud_k))
	55	goto bad_area;
	56	if (!pud_present(*pud))
	57	set_pud(pud, *pud_k);
	58
	59	pmd = pmd_offset(pud, address);
	60	pmd_k = pmd_offset(pud_k, address);
	61	if (pmd_none(*pmd_k))
	62	goto bad_area;
	63	if (!pmd_present(*pmd))
	64	set_pmd(pmd, *pmd_k);
	65
	66	/* XXX: create the TLB entry here */
	67	return 0;
	68
	69	bad_area:
	70	return 1;
	71	}
	72
	73	void do_page_fault(unsigned long address, struct pt_regs *regs)
	74	{
	75	struct vm_area_struct *vma = NULL;
	76	struct task_struct *tsk = current;
	77	struct mm_struct *mm = tsk->mm;
	78	int sig, si_code = SEGV_MAPERR;
	79	unsigned int write = 0, exec = 0, mask;
	80	vm_fault_t fault = VM_FAULT_SIGSEGV; /* handle_mm_fault() output */
	81	unsigned int flags; /* handle_mm_fault() input */
	82
	83	/*
	84	* NOTE! We MUST NOT take any locks for this case. We may
	85	* be in an interrupt or a critical region, and should
	86	* only copy the information from the master page table,
	87	* nothing more.
	88	*/
	89	if (address >= VMALLOC_START && !user_mode(regs)) {
	90	if (unlikely(handle_kernel_vaddr_fault(address)))
	91	goto no_context;
	92	else
	93	return;
	94	}
	95
	96	/*
	97	* If we're in an interrupt or have no user
	98	* context, we must not take the fault..
	99	*/
	100	if (faulthandler_disabled() \|\| !mm)
	101	goto no_context;
	102
	103	if (regs->ecr.cause & ECR_C_PROTV_STORE) /* ST/EX */
	104	write = 1;
	105	else if ((regs->ecr.vec == ECR_V_PROTV) &&
	106	(regs->ecr.cause == ECR_C_PROTV_INST_FETCH))
	107	exec = 1;
	108
	109	flags = FAULT_FLAG_DEFAULT;
	110	if (user_mode(regs))
	111	flags \|= FAULT_FLAG_USER;
	112	if (write)
	113	flags \|= FAULT_FLAG_WRITE;
	114
	115	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
	116	retry:
	117	vma = lock_mm_and_find_vma(mm, address, regs);
	118	if (!vma)
	119	goto bad_area_nosemaphore;
	120
	121	/*
	122	* vm_area is good, now check permissions for this memory access
	123	*/
	124	mask = VM_READ;
	125	if (write)
	126	mask = VM_WRITE;
	127	if (exec)
	128	mask = VM_EXEC;
	129
	130	if (!(vma->vm_flags & mask)) {
	131	si_code = SEGV_ACCERR;
	132	goto bad_area;
	133	}
	134
	135	fault = handle_mm_fault(vma, address, flags, regs);
	136
	137	/* Quick path to respond to signals */
	138	if (fault_signal_pending(fault, regs)) {
	139	if (!user_mode(regs))
	140	goto no_context;
	141	return;
	142	}
	143
	144	/* The fault is fully completed (including releasing mmap lock) */
	145	if (fault & VM_FAULT_COMPLETED)
	146	return;
	147
	148	/*
	149	* Fault retry nuances, mmap_lock already relinquished by core mm
	150	*/
	151	if (unlikely(fault & VM_FAULT_RETRY)) {
	152	flags \|= FAULT_FLAG_TRIED;
	153	goto retry;
	154	}
	155
	156	bad_area:
	157	mmap_read_unlock(mm);
	158
	159	bad_area_nosemaphore:
	160	/*
	161	* Major/minor page fault accounting
	162	* (in case of retry we only land here once)
	163	*/
	164	if (likely(!(fault & VM_FAULT_ERROR)))
	165	/* Normal return path: fault Handled Gracefully */
	166	return;
	167
	168	if (!user_mode(regs))
	169	goto no_context;
	170
	171	if (fault & VM_FAULT_OOM) {
	172	pagefault_out_of_memory();
	173	return;
	174	}
	175
	176	if (fault & VM_FAULT_SIGBUS) {
	177	sig = SIGBUS;
	178	si_code = BUS_ADRERR;
	179	}
	180	else {
	181	sig = SIGSEGV;
	182	}
	183
	184	tsk->thread.fault_address = address;
	185	force_sig_fault(sig, si_code, (void __user *)address);
	186	return;
	187
	188	no_context:
	189	if (fixup_exception(regs))
	190	return;
	191
	192	die("Oops", regs, address);
	193	}