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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, %0, c5, c0, 0"
  56.         : "=r"(fsu.dummy)
  57.     );
  58.     return fsu.fs;
  59. }
  60.  
  61. /** Returns FAR (fault address register) content.
  62.  *
  63.  * @return FAR (fault address register) content (address that caused a page
  64.  *     fault)
  65.  */
  66. static inline uintptr_t read_fault_address_register(void)
  67. {
  68.     uintptr_t ret;
  69.  
  70.     /* fault adress is stored in CP15 register 6 */
  71.     asm volatile (
  72.         "mrc p15, 0, %0, c6, c0, 0"
  73.         : "=r"(ret)
  74.     );
  75.     return ret;
  76. }
  77.  
  78. /** Decides whether the instruction is load/store or not.
  79.  *
  80.  * @param instr Instruction
  81.  *
  82.  * @return true when instruction is load/store, false otherwise
  83.  */
  84. static inline bool is_load_store_instruction(instruction_t instr)
  85. {
  86.     /* load store immediate offset */
  87.     if (instr.type == 0x2) {
  88.         return true;
  89.     }
  90.  
  91.     /* load store register offset */
  92.     if (instr.type == 0x3 && instr.bit4 == 0) {
  93.         return true;
  94.     }
  95.  
  96.     /* load store multiple */
  97.     if (instr.type == 0x4) {
  98.         return true;
  99.     }
  100.  
  101.     /* oprocessor load/store */
  102.     if (instr.type == 0x6) {
  103.         return true;
  104.     }
  105.  
  106.     return false;
  107. }
  108.  
  109. /** Decides whether the instruction is swap or not.
  110.  *
  111.  * @param instr Instruction
  112.  *
  113.  * @return true when instruction is swap, false otherwise
  114.  */
  115. static inline bool is_swap_instruction(instruction_t instr)
  116. {
  117.     /* swap, swapb instruction */
  118.     if (instr.type == 0x0 &&
  119.         (instr.opcode == 0x8 || instr.opcode == 0xa) &&
  120.         instr.access == 0x0 && instr.bits567 == 0x4 && instr.bit4 == 1) {
  121.         return true;
  122.     }
  123.  
  124.     return false;
  125. }
  126.  
  127. /** Decides whether read or write into memory is requested.
  128.  *
  129.  * @param instr_addr   Address of instruction which tries to access memory.
  130.  * @param badvaddr     Virtual address the instruction tries to access.
  131.  *
  132.  * @return Type of access into memory, PF_ACCESS_EXEC if no memory access is
  133.  *     requested.
  134.  */
  135. static pf_access_t get_memory_access_type(uint32_t instr_addr,
  136.     uintptr_t badvaddr)
  137. {
  138.     instruction_union_t instr_union;
  139.     instr_union.pc = instr_addr;
  140.  
  141.     instruction_t instr = *(instr_union.instr);
  142.  
  143.     /* undefined instructions */
  144.     if (instr.condition == 0xf) {
  145.         panic("page_fault - instruction doesn't access memory "
  146.             "(instr_code: %x, badvaddr:%x)", instr, badvaddr);
  147.         return PF_ACCESS_EXEC;
  148.     }
  149.  
  150.     /* load store instructions */
  151.     if (is_load_store_instruction(instr)) {
  152.         if (instr.access == 1) {
  153.             return PF_ACCESS_READ;
  154.         } else {
  155.             return PF_ACCESS_WRITE;
  156.         }
  157.     }
  158.  
  159.     /* swap, swpb instruction */
  160.     if (is_swap_instruction(instr)) {
  161.         return PF_ACCESS_WRITE;
  162.     }
  163.  
  164.     panic("page_fault - instruction doesn't access memory "
  165.         "(instr_code: %x, badvaddr:%x)", instr, badvaddr);
  166.  
  167.     return PF_ACCESS_EXEC;
  168. }
  169.  
  170. /** Handles "data abort" exception (load or store at invalid address).
  171.  *
  172.  * @param exc_no    Exception number.
  173.  * @param istate    CPU state when exception occured.
  174.  */
  175. void data_abort(int exc_no, istate_t *istate)
  176. {
  177.     fault_status_t fsr __attribute__ ((unused)) =
  178.         read_fault_status_register();
  179.     uintptr_t badvaddr = read_fault_address_register();
  180.  
  181.     pf_access_t access = get_memory_access_type(istate->pc, badvaddr);
  182.  
  183.     int ret = as_page_fault(badvaddr, access, istate);
  184.  
  185.     if (ret == AS_PF_FAULT) {
  186.         print_istate(istate);
  187.         dprintf("page fault - pc: %x, va: %x, status: %x(%x), "
  188.             "access:%d\n", istate->pc, badvaddr, fsr.status, fsr,
  189.             access);
  190.  
  191.         fault_if_from_uspace(istate, "Page fault: %#x", badvaddr);
  192.         panic("page fault\n");
  193.     }
  194. }
  195.  
  196. /** Check whether the abort was caused by a bkpt instruction.
  197.  *
  198.  * This must be called after (possibly) fetching the faulting page.
  199.  *
  200.  * TODO: When paging-out is implemented, make sure the page
  201.  * is still present when reading the instruction (we don't want
  202.  * to trigger another exception).
  203.  */
  204. static void bkpt_check(istate_t *istate)
  205. {
  206.     uint32_t *instr_addr = (uint32_t *) istate->pc;
  207.     uint32_t opcode = *instr_addr;
  208.  
  209.     if ((opcode & 0xfff000f0) == 0xe1200070) {
  210.         /* Bkpt */
  211.         if (istate_from_uspace(istate)) {
  212.             udebug_breakpoint_event(0);
  213.         } else {
  214.             panic("Unexpected BKPT instruction at 0x%x",
  215.                 istate->pc);
  216.         }
  217.     }
  218. }
  219.  
  220. /** Handles "prefetch abort" exception (instruction couldn't be executed).
  221.  *
  222.  * @param exc_no    Exception number.
  223.  * @param istate    CPU state when exception occured.
  224.  */
  225. void prefetch_abort(int exc_no, istate_t *istate)
  226. {
  227.     int ret = as_page_fault(istate->pc, PF_ACCESS_EXEC, istate);
  228.  
  229.     if (ret == AS_PF_FAULT) {
  230.         dprintf("prefetch_abort\n");
  231.         print_istate(istate);
  232.         panic("page fault - prefetch_abort at address: %x\n",
  233.             istate->pc);
  234.     }
  235.  
  236.     /* Now check if the abort was caused by a breakpoint instruction */
  237.     bkpt_check(istate);
  238. }
  239.  
  240. /** @}
  241.  */
  242.