/*
* Copyright (c) 2007 Pavel Jancik, Michal Kebrt
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup arm32mm
* @{
*/
/** @file
* @brief Page fault related functions.
*/
#include <panic.h>
#include <arch/exception.h>
#include <arch/debug/print.h>
#include <arch/mm/page_fault.h>
#include <mm/as.h>
#include <genarch/mm/page_pt.h>
#include <arch.h>
#include <interrupt.h>
/** Returns value stored in fault status register.
* FSR contain reason of page fault
*
* @return Value stored in CP15 fault status register (FSR).
*/
static inline fault_status_t read_fault_status_register(void)
{
fault_status_union_t fsu;
// fault adress is stored in CP15 register 5
asm volatile (
"mrc p15, 0, %0, c5, c0, 0"
: "=r"(fsu.dummy)
);
return fsu.fs;
}
/** Returns FAR (fault address register) content.
*
* @return FAR (fault address register) content (address that caused a page fault)
*/
static inline uintptr_t read_fault_address_register(void)
{
uintptr_t ret;
// fault adress is stored in CP15 register 6
asm volatile (
"mrc p15, 0, %0, c6, c0, 0"
: "=r"(ret)
);
return ret;
}
/** Decides whether the instructions is load/store or not.
*
* @param instr Instruction
*
* @return true when instruction is load/store, false otherwise
*/
static inline bool is_load_store_instruction(instruction_t instr)
{
// load store immediate offset
if (instr.type == 0x2) {
return true;
}
// load store register offset
if (instr.type == 0x3 && instr.bit4 == 0) {
return true;
}
// load store multiple
if (instr.type == 0x4) {
return true;
}
// coprocessor load/store
if (instr.type == 0x6) {
return true;
}
return false;
}
/** Decides whether the instructions is swap or not.
*
* @param instr Instruction
*
* @return true when instruction is swap, false otherwise
*/
static inline bool is_swap_instruction(instruction_t instr)
{
// swap, swapb instruction
if (instr.type == 0x0 &&
(instr.opcode == 0x8 || instr.opcode == 0xa) &&
instr.access == 0x0 && instr.bits567 == 0x4 && instr.bit4 == 1) {
return true;
}
return false;
}
/** Decides whether read or write into memory is requested.
*
* @param instr_addr Address of instruction which tries to access memory
* @param badvaddr Virtual address the instruction tries to access
*
* @return Type of access into memmory
* Note: Returns #PF_ACCESS_EXEC if no memory access is requested
*/
static pf_access_t get_memory_access_type(uint32_t instr_addr, uintptr_t badvaddr)
{
instruction_union_t instr_union;
instr_union.pc = instr_addr;
instruction_t instr = *(instr_union.instr);
// undefined instructions
if (instr.condition == 0xf) {
panic("page_fault - instruction not access memmory (instr_code: %x, badvaddr:%x)",
instr, badvaddr);
return PF_ACCESS_EXEC;
}
// load store instructions
if (is_load_store_instruction(instr)) {
if (instr.access == 1) {
return PF_ACCESS_READ;
} else {
return PF_ACCESS_WRITE;
}
}
// swap, swpb instruction
if (is_swap_instruction(instr)) {
/* Swap instructions make read and write in one step.
* Type of access that caused exception have to page tables
* and access rights.
*/
pte_level1_t* pte = (pte_level1_t*)
pt_mapping_operations.mapping_find(AS, badvaddr);
if ( pte == NULL ) {
return PF_ACCESS_READ;
}
/* check if read possible
* Note: Don't check PTE_READABLE because it returns 1 everytimes */
if ( !PTE_PRESENT(pte) ) {
return PF_ACCESS_READ;
}
if ( !PTE_WRITABLE(pte) ) {
return PF_ACCESS_WRITE;
} else {
// badvaddr is present readable and writeable but error occured ... why?
panic("page_fault - swap instruction, but address readable and writeable"
"(instr_code:%X, badvaddr:%X)", instr, badvaddr);
}
}
panic("page_fault - instruction not access memory (instr_code: %x, badvaddr:%x)",
instr, badvaddr);
return PF_ACCESS_EXEC;
}
/** Handles "data abort" exception (load or store at invalid address).
*
* @param exc_no exception number
* @param istate CPU state when exception occured
*/
void data_abort(int exc_no, istate_t *istate)
{
fault_status_t fsr = read_fault_status_register();
uintptr_t badvaddr = read_fault_address_register();
pf_access_t access = get_memory_access_type(istate->pc, badvaddr);
int ret = as_page_fault(badvaddr, access, istate);
if (ret == AS_PF_FAULT) {
print_istate(istate);
dprintf("page fault - pc: %x, va: %x, status: %x(%x), access:%d\n",
istate->pc, badvaddr, fsr.status, fsr, access);
fault_if_from_uspace(istate, "Page fault: %#x", badvaddr);
panic("page fault\n");
}
}
/** Handles "prefetch abort" exception (instruction couldn't be executed).
*
* @param exc_no exception number
* @param istate CPU state when exception occured
*/
void prefetch_abort(int exc_no, istate_t *istate)
{
int ret = as_page_fault(istate->pc, PF_ACCESS_EXEC, istate);
if (ret == AS_PF_FAULT) {
dprintf("prefetch_abort\n");
print_istate(istate);
panic("page fault - prefetch_abort at address: %x\n", istate->pc);
}
}
/** @}
*/