[linux.git] / arch / csky / mm / fault.c

// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.

#include <linux/signal.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/interrupt.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/smp.h>
#include <linux/version.h>
#include <linux/vt_kern.h>
#include <linux/kernel.h>
#include <linux/extable.h>
#include <linux/uaccess.h>

#include <asm/hardirq.h>
#include <asm/mmu_context.h>
#include <asm/traps.h>
#include <asm/page.h>

int fixup_exception(struct pt_regs *regs)
{
	const struct exception_table_entry *fixup;

	fixup = search_exception_tables(instruction_pointer(regs));
	if (fixup) {
		regs->pc = fixup->nextinsn;

		return 1;
	}

	return 0;
}

/*
 * This routine handles page faults. It determines the address,
 * and the problem, and then passes it off to one of the appropriate
 * routines.
 */
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
			      unsigned long mmu_meh)
{
	struct vm_area_struct *vma = NULL;
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	int si_code;
	int fault;
	unsigned long address = mmu_meh & PAGE_MASK;

	si_code = SEGV_MAPERR;

#ifndef CONFIG_CPU_HAS_TLBI
	/*
	 * We fault-in kernel-space virtual memory on-demand. The
	 * 'reference' page table is init_mm.pgd.
	 *
	 * 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 (unlikely(address >= VMALLOC_START) &&
	    unlikely(address <= VMALLOC_END)) {
		/*
		 * Synchronize this task's top level page-table
		 * with the 'reference' page table.
		 *
		 * Do _not_ use "tsk" here. We might be inside
		 * an interrupt in the middle of a task switch..
		 */
		int offset = __pgd_offset(address);
		pgd_t *pgd, *pgd_k;
		pud_t *pud, *pud_k;
		pmd_t *pmd, *pmd_k;
		pte_t *pte_k;

		unsigned long pgd_base;

		pgd_base = tlb_get_pgd();
		pgd = (pgd_t *)pgd_base + offset;
		pgd_k = init_mm.pgd + offset;

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

		pud = (pud_t *)pgd;
		pud_k = (pud_t *)pgd_k;
		if (!pud_present(*pud_k))
			goto no_context;

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

		pte_k = pte_offset_kernel(pmd_k, address);
		if (!pte_present(*pte_k))
			goto no_context;
		return;
	}
#endif
	/*
	 * If we're in an interrupt or have no user
	 * context, we must not take the fault..
	 */
	if (in_atomic() || !mm)
		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;
	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 (write) {
		if (!(vma->vm_flags & VM_WRITE))
			goto bad_area;
	} else {
		if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
			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.
	 */
	fault = handle_mm_fault(vma, address, write ? FAULT_FLAG_WRITE : 0);
	if (unlikely(fault & VM_FAULT_ERROR)) {
		if (fault & VM_FAULT_OOM)
			goto out_of_memory;
		else if (fault & VM_FAULT_SIGBUS)
			goto do_sigbus;
		else if (fault & VM_FAULT_SIGSEGV)
			goto bad_area;
		BUG();
	}
	if (fault & VM_FAULT_MAJOR)
		tsk->maj_flt++;
	else
		tsk->min_flt++;

	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);

bad_area_nosemaphore:
	/* User mode accesses just cause a SIGSEGV */
	if (user_mode(regs)) {
		force_sig_fault(SIGSEGV, si_code, (void __user *)address, current);
		return;
	}

no_context:
	/* Are we prepared to handle this kernel fault? */
	if (fixup_exception(regs))
		return;

	/*
	 * Oops. The kernel tried to access some bad page. We'll have to
	 * terminate things with extreme prejudice.
	 */
	bust_spinlocks(1);
	pr_alert("Unable to handle kernel paging request at virtual "
		 "address 0x%08lx, pc: 0x%08lx\n", address, regs->pc);
	die_if_kernel("Oops", regs, write);

out_of_memory:
	/*
	 * We ran out of memory, call the OOM killer, and return the userspace
	 * (which will retry the fault, or kill us if we got oom-killed).
	 */
	pagefault_out_of_memory();
	return;

do_sigbus:
	up_read(&mm->mmap_sem);

	/* Kernel mode? Handle exceptions or die */
	if (!user_mode(regs))
		goto no_context;

	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, current);
}
Commit	Line	Data
081860b9 GR	1	// SPDX-License-Identifier: GPL-2.0
	2	// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
	3
	4	#include <linux/signal.h>
	5	#include <linux/module.h>
	6	#include <linux/sched.h>
	7	#include <linux/interrupt.h>
	8	#include <linux/kernel.h>
	9	#include <linux/errno.h>
	10	#include <linux/string.h>
	11	#include <linux/types.h>
	12	#include <linux/ptrace.h>
	13	#include <linux/mman.h>
	14	#include <linux/mm.h>
	15	#include <linux/smp.h>
	16	#include <linux/version.h>
	17	#include <linux/vt_kern.h>
	18	#include <linux/kernel.h>
	19	#include <linux/extable.h>
	20	#include <linux/uaccess.h>
	21
	22	#include <asm/hardirq.h>
	23	#include <asm/mmu_context.h>
	24	#include <asm/traps.h>
	25	#include <asm/page.h>
	26
	27	int fixup_exception(struct pt_regs *regs)
	28	{
	29	const struct exception_table_entry *fixup;
	30
	31	fixup = search_exception_tables(instruction_pointer(regs));
	32	if (fixup) {
	33	regs->pc = fixup->nextinsn;
	34
	35	return 1;
	36	}
	37
	38	return 0;
	39	}
	40
	41	/*
	42	* This routine handles page faults. It determines the address,
	43	* and the problem, and then passes it off to one of the appropriate
	44	* routines.
	45	*/
	46	asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
	47	unsigned long mmu_meh)
	48	{
	49	struct vm_area_struct *vma = NULL;
	50	struct task_struct *tsk = current;
	51	struct mm_struct *mm = tsk->mm;
	52	int si_code;
	53	int fault;
	54	unsigned long address = mmu_meh & PAGE_MASK;
	55
	56	si_code = SEGV_MAPERR;
	57
	58	#ifndef CONFIG_CPU_HAS_TLBI
	59	/*
	60	* We fault-in kernel-space virtual memory on-demand. The
	61	* 'reference' page table is init_mm.pgd.
	62	*
	63	* NOTE! We MUST NOT take any locks for this case. We may
	64	* be in an interrupt or a critical region, and should
65	* only copy the information from the master page table,
66	* nothing more.
67	*/
68	if (unlikely(address >= VMALLOC_START) &&
69	unlikely(address <= VMALLOC_END)) {
70	/*
71	* Synchronize this task's top level page-table
72	* with the 'reference' page table.
73	*
74	* Do _not_ use "tsk" here. We might be inside
75	* an interrupt in the middle of a task switch..
76	*/
77	int offset = __pgd_offset(address);
78	pgd_t pgd, pgd_k;
79	pud_t pud, pud_k;
80	pmd_t pmd, pmd_k;
81	pte_t *pte_k;
82
83	unsigned long pgd_base;
84
85	pgd_base = tlb_get_pgd();
86	pgd = (pgd_t *)pgd_base + offset;
87	pgd_k = init_mm.pgd + offset;
88
89	if (!pgd_present(*pgd_k))
90	goto no_context;
91	set_pgd(pgd, *pgd_k);
92
93	pud = (pud_t *)pgd;
94	pud_k = (pud_t *)pgd_k;
95	if (!pud_present(*pud_k))
96	goto no_context;
97
98	pmd = pmd_offset(pud, address);
99	pmd_k = pmd_offset(pud_k, address);
100	if (!pmd_present(*pmd_k))
101	goto no_context;
102	set_pmd(pmd, *pmd_k);
103
104	pte_k = pte_offset_kernel(pmd_k, address);
105	if (!pte_present(*pte_k))
106	goto no_context;
107	return;
108	}
109	#endif
110	/*
111	* If we're in an interrupt or have no user
112	* context, we must not take the fault..
113	*/
114	if (in_atomic() \|\| !mm)
115	goto bad_area_nosemaphore;
116
117	down_read(&mm->mmap_sem);
118	vma = find_vma(mm, address);
119	if (!vma)
120	goto bad_area;
121	if (vma->vm_start <= address)
122	goto good_area;
123	if (!(vma->vm_flags & VM_GROWSDOWN))
124	goto bad_area;
125	if (expand_stack(vma, address))
126	goto bad_area;
127	/*
128	* Ok, we have a good vm_area for this memory access, so
129	* we can handle it..
130	*/
131	good_area:
132	si_code = SEGV_ACCERR;
133
134	if (write) {
135	if (!(vma->vm_flags & VM_WRITE))
136	goto bad_area;
137	} else {
138	if (!(vma->vm_flags & (VM_READ \| VM_WRITE \| VM_EXEC)))
139	goto bad_area;
140	}
141
142	/*
143	* If for any reason at all we couldn't handle the fault,
144	* make sure we exit gracefully rather than endlessly redo
145	* the fault.
146	*/
147	fault = handle_mm_fault(vma, address, write ? FAULT_FLAG_WRITE : 0);
148	if (unlikely(fault & VM_FAULT_ERROR)) {
149	if (fault & VM_FAULT_OOM)
150	goto out_of_memory;
151	else if (fault & VM_FAULT_SIGBUS)
152	goto do_sigbus;
153	else if (fault & VM_FAULT_SIGSEGV)
154	goto bad_area;
155	BUG();
156	}
157	if (fault & VM_FAULT_MAJOR)
158	tsk->maj_flt++;
159	else
160	tsk->min_flt++;
161
162	up_read(&mm->mmap_sem);
163	return;
164
165	/*
166	* Something tried to access memory that isn't in our memory map..
167	* Fix it, but check if it's kernel or user first..
168	*/
169	bad_area:
170	up_read(&mm->mmap_sem);
171
172	bad_area_nosemaphore:
173	/* User mode accesses just cause a SIGSEGV */
174	if (user_mode(regs)) {
081860b9 GR	175	force_sig_fault(SIGSEGV, si_code, (void __user *)address, current);
	176	return;
	177	}
	178
	179	no_context:
	180	/* Are we prepared to handle this kernel fault? */
	181	if (fixup_exception(regs))
	182	return;
	183
	184	/*
	185	* Oops. The kernel tried to access some bad page. We'll have to
	186	* terminate things with extreme prejudice.
	187	*/
	188	bust_spinlocks(1);
8f4f1639 GR	189	pr_alert("Unable to handle kernel paging request at virtual "
8f4f1639 GR	190	"address 0x%08lx, pc: 0x%08lx\n", address, regs->pc);
081860b9 GR	191	die_if_kernel("Oops", regs, write);
	192
	193	out_of_memory:
	194	/*
	195	* We ran out of memory, call the OOM killer, and return the userspace
	196	* (which will retry the fault, or kill us if we got oom-killed).
	197	*/
	198	pagefault_out_of_memory();
	199	return;
	200
	201	do_sigbus:
	202	up_read(&mm->mmap_sem);
	203
	204	/* Kernel mode? Handle exceptions or die */
	205	if (!user_mode(regs))
	206	goto no_context;
	207
081860b9 GR	208	force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, current);
081860b9 GR	209	}