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  1. /*
  2.  * Copyright (c) 2007 Pavel Jancik, Michal Kebrt
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup arm32mm
  30.  * @{
  31.  */
  32. /** @file
  33.  *  @brief Page fault related functions.
  34.  */
  35. #include <panic.h>
  36. #include <arch/exception.h>
  37. #include <arch/debug/print.h>
  38. #include <arch/mm/page_fault.h>
  39. #include <mm/as.h>
  40. #include <genarch/mm/page_pt.h>
  41. #include <arch.h>
  42. #include <interrupt.h>
  43. #include <print.h>
  44.  
  45. /** Returns value stored in fault status register.
  46.  *
  47.  *  @return Value stored in CP15 fault status register (FSR).
  48.  */
  49. static inline fault_status_t read_fault_status_register(void)
  50. {
  51.     fault_status_union_t fsu;
  52.    
  53.     /* fault status is stored in CP15 register 5 */
  54.     asm volatile (
  55.         "mrc p15, 0, %[dummy], c5, c0, 0"
  56.         : [dummy] "=r" (fsu.dummy)
  57.     );
  58.    
  59.     return fsu.fs;
  60. }
  61.  
  62. /** Returns FAR (fault address register) content.
  63.  *
  64.  * @return FAR (fault address register) content (address that caused a page
  65.  *         fault)
  66.  */
  67. static inline uintptr_t read_fault_address_register(void)
  68. {
  69.     uintptr_t ret;
  70.    
  71.     /* fault adress is stored in CP15 register 6 */
  72.     asm volatile (
  73.         "mrc p15, 0, %[ret], c6, c0, 0"
  74.         : [ret] "=r" (ret)
  75.     );
  76.    
  77.     return ret;
  78. }
  79.  
  80. /** Decides whether the instruction is load/store or not.
  81.  *
  82.  * @param instr Instruction
  83.  *
  84.  * @return true when instruction is load/store, false otherwise
  85.  *
  86.  */
  87. static inline bool is_load_store_instruction(instruction_t instr)
  88. {
  89.     /* load store immediate offset */
  90.     if (instr.type == 0x2)
  91.         return true;
  92.    
  93.     /* load store register offset */
  94.     if ((instr.type == 0x3) && (instr.bit4 == 0))
  95.         return true;
  96.    
  97.     /* load store multiple */
  98.     if (instr.type == 0x4)
  99.         return true;
  100.    
  101.     /* oprocessor load/store */
  102.     if (instr.type == 0x6)
  103.         return true;
  104.    
  105.     return false;
  106. }
  107.  
  108. /** Decides whether the instruction is swap or not.
  109.  *
  110.  * @param instr Instruction
  111.  *
  112.  * @return true when instruction is swap, false otherwise
  113.  */
  114. static inline bool is_swap_instruction(instruction_t instr)
  115. {
  116.     /* swap, swapb instruction */
  117.     if ((instr.type == 0x0) &&
  118.         ((instr.opcode == 0x8) || (instr.opcode == 0xa)) &&
  119.         (instr.access == 0x0) && (instr.bits567 == 0x4) && (instr.bit4 == 1))
  120.         return true;
  121.    
  122.     return false;
  123. }
  124.  
  125. /** Decides whether read or write into memory is requested.
  126.  *
  127.  * @param instr_addr   Address of instruction which tries to access memory.
  128.  * @param badvaddr     Virtual address the instruction tries to access.
  129.  *
  130.  * @return Type of access into memory, PF_ACCESS_EXEC if no memory access is
  131.  *     requested.
  132.  */
  133. static pf_access_t get_memory_access_type(uint32_t instr_addr,
  134.     uintptr_t badvaddr)
  135. {
  136.     instruction_union_t instr_union;
  137.     instr_union.pc = instr_addr;
  138.  
  139.     instruction_t instr = *(instr_union.instr);
  140.  
  141.     /* undefined instructions */
  142.     if (instr.condition == 0xf) {
  143.         panic("page_fault - instruction does not access memory "
  144.             "(instr_code: %x, badvaddr:%x).", instr, badvaddr);
  145.         return PF_ACCESS_EXEC;
  146.     }
  147.  
  148.     /* load store instructions */
  149.     if (is_load_store_instruction(instr)) {
  150.         if (instr.access == 1) {
  151.             return PF_ACCESS_READ;
  152.         } else {
  153.             return PF_ACCESS_WRITE;
  154.         }
  155.     }
  156.  
  157.     /* swap, swpb instruction */
  158.     if (is_swap_instruction(instr)) {
  159.         return PF_ACCESS_WRITE;
  160.     }
  161.  
  162.     panic("page_fault - instruction doesn't access memory "
  163.         "(instr_code: %x, badvaddr:%x).", instr, badvaddr);
  164.  
  165.     return PF_ACCESS_EXEC;
  166. }
  167.  
  168. /** Handles "data abort" exception (load or store at invalid address).
  169.  *
  170.  * @param exc_no    Exception number.
  171.  * @param istate    CPU state when exception occured.
  172.  */
  173. void data_abort(int exc_no, istate_t *istate)
  174. {
  175.     fault_status_t fsr __attribute__ ((unused)) =
  176.         read_fault_status_register();
  177.     uintptr_t badvaddr = read_fault_address_register();
  178.  
  179.     pf_access_t access = get_memory_access_type(istate->pc, badvaddr);
  180.  
  181.     int ret = as_page_fault(badvaddr, access, istate);
  182.  
  183.     if (ret == AS_PF_FAULT) {
  184.         print_istate(istate);
  185.         dprintf("page fault - pc: %x, va: %x, status: %x(%x), "
  186.             "access:%d\n", istate->pc, badvaddr, fsr.status, fsr,
  187.             access);
  188.  
  189.         fault_if_from_uspace(istate, "Page fault: %#x.", badvaddr);
  190.         panic("Page fault.");
  191.     }
  192. }
  193.  
  194. /** Handles "prefetch abort" exception (instruction couldn't be executed).
  195.  *
  196.  * @param exc_no    Exception number.
  197.  * @param istate    CPU state when exception occured.
  198.  */
  199. void prefetch_abort(int exc_no, istate_t *istate)
  200. {
  201.     int ret = as_page_fault(istate->pc, PF_ACCESS_EXEC, istate);
  202.  
  203.     if (ret == AS_PF_FAULT) {
  204.         dprintf("prefetch_abort\n");
  205.         print_istate(istate);
  206.         panic("page fault - prefetch_abort at address: %x.",
  207.             istate->pc);
  208.     }
  209. }
  210.  
  211. /** @}
  212.  */
  213.