1 /* 2 * Memory fault handling for Hexagon 3 * 4 * Copyright (c) 2010-2011 Code Aurora Forum. All rights reserved. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 and 8 * only version 2 as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, write to the Free Software 17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 18 * 02110-1301, USA. 19 */ 20 21 /* 22 * Page fault handling for the Hexagon Virtual Machine. 23 * Can also be called by a native port emulating the HVM 24 * execptions. 25 */ 26 27 #include <asm/pgtable.h> 28 #include <asm/traps.h> 29 #include <asm/uaccess.h> 30 #include <linux/mm.h> 31 #include <linux/signal.h> 32 #include <linux/module.h> 33 #include <linux/hardirq.h> 34 35 /* 36 * Decode of hardware exception sends us to one of several 37 * entry points. At each, we generate canonical arguments 38 * for handling by the abstract memory management code. 39 */ 40 #define FLT_IFETCH -1 41 #define FLT_LOAD 0 42 #define FLT_STORE 1 43 44 45 /* 46 * Canonical page fault handler 47 */ 48 void do_page_fault(unsigned long address, long cause, struct pt_regs *regs) 49 { 50 struct vm_area_struct *vma; 51 struct mm_struct *mm = current->mm; 52 siginfo_t info; 53 int si_code = SEGV_MAPERR; 54 int fault; 55 const struct exception_table_entry *fixup; 56 57 /* 58 * If we're in an interrupt or have no user context, 59 * then must not take the fault. 60 */ 61 if (unlikely(in_interrupt() || !mm)) 62 goto no_context; 63 64 local_irq_enable(); 65 66 down_read(&mm->mmap_sem); 67 vma = find_vma(mm, address); 68 if (!vma) 69 goto bad_area; 70 71 if (vma->vm_start <= address) 72 goto good_area; 73 74 if (!(vma->vm_flags & VM_GROWSDOWN)) 75 goto bad_area; 76 77 if (expand_stack(vma, address)) 78 goto bad_area; 79 80 good_area: 81 /* Address space is OK. Now check access rights. */ 82 si_code = SEGV_ACCERR; 83 84 switch (cause) { 85 case FLT_IFETCH: 86 if (!(vma->vm_flags & VM_EXEC)) 87 goto bad_area; 88 break; 89 case FLT_LOAD: 90 if (!(vma->vm_flags & VM_READ)) 91 goto bad_area; 92 break; 93 case FLT_STORE: 94 if (!(vma->vm_flags & VM_WRITE)) 95 goto bad_area; 96 break; 97 } 98 99 fault = handle_mm_fault(mm, vma, address, (cause > 0)); 100 101 /* The most common case -- we are done. */ 102 if (likely(!(fault & VM_FAULT_ERROR))) { 103 if (fault & VM_FAULT_MAJOR) 104 current->maj_flt++; 105 else 106 current->min_flt++; 107 108 up_read(&mm->mmap_sem); 109 return; 110 } 111 112 up_read(&mm->mmap_sem); 113 114 /* Handle copyin/out exception cases */ 115 if (!user_mode(regs)) 116 goto no_context; 117 118 if (fault & VM_FAULT_OOM) { 119 pagefault_out_of_memory(); 120 return; 121 } 122 123 /* User-mode address is in the memory map, but we are 124 * unable to fix up the page fault. 125 */ 126 if (fault & VM_FAULT_SIGBUS) { 127 info.si_signo = SIGBUS; 128 info.si_code = BUS_ADRERR; 129 } 130 /* Address is not in the memory map */ 131 else { 132 info.si_signo = SIGSEGV; 133 info.si_code = SEGV_ACCERR; 134 } 135 info.si_errno = 0; 136 info.si_addr = (void __user *)address; 137 force_sig_info(info.si_code, &info, current); 138 return; 139 140 bad_area: 141 up_read(&mm->mmap_sem); 142 143 if (user_mode(regs)) { 144 info.si_signo = SIGSEGV; 145 info.si_errno = 0; 146 info.si_code = si_code; 147 info.si_addr = (void *)address; 148 force_sig_info(SIGSEGV, &info, current); 149 return; 150 } 151 /* Kernel-mode fault falls through */ 152 153 no_context: 154 fixup = search_exception_tables(pt_elr(regs)); 155 if (fixup) { 156 pt_set_elr(regs, fixup->fixup); 157 return; 158 } 159 160 /* Things are looking very, very bad now */ 161 bust_spinlocks(1); 162 printk(KERN_EMERG "Unable to handle kernel paging request at " 163 "virtual address 0x%08lx, regs %p\n", address, regs); 164 die("Bad Kernel VA", regs, SIGKILL); 165 } 166 167 168 void read_protection_fault(struct pt_regs *regs) 169 { 170 unsigned long badvadr = pt_badva(regs); 171 172 do_page_fault(badvadr, FLT_LOAD, regs); 173 } 174 175 void write_protection_fault(struct pt_regs *regs) 176 { 177 unsigned long badvadr = pt_badva(regs); 178 179 do_page_fault(badvadr, FLT_STORE, regs); 180 } 181 182 void execute_protection_fault(struct pt_regs *regs) 183 { 184 unsigned long badvadr = pt_badva(regs); 185 186 do_page_fault(badvadr, FLT_IFETCH, regs); 187 } 188