source: rtems/bsps/powerpc/shared/start/pgtbl_setup.c @ 9964895

#include <rtems.h>
#include <libcpu/mmu.h>
#include <rtems/bspIo.h>
#include <libcpu/pte121.h>

/* Default setup of the page tables. This is a weak
 * alias, so applications may easily override this
 * default setup.
 *
 * NOTE: while it is possible to change the individual
 *       mappings, the page table itself MUST be
 *       allocated at the top of the physical memory!
 *       bspstart.c RELIES on this.
 *       Also, the 'setup' routine must reduce
 *       *pmemsize by the size of the page table.
 */
/* to align the pointer to the (next) page boundary */
#define PAGE_ALIGN(addr)        (((addr)+PAGE_SIZE-1)&PAGE_MASK)


/*
 * Authorship
 * ----------
 * This software was created by
 *     Till Straumann <strauman@slac.stanford.edu>, 4/2002,
 *         Stanford Linear Accelerator Center, Stanford University.
 *
 * Acknowledgement of sponsorship
 * ------------------------------
 * This software was produced by
 *     the Stanford Linear Accelerator Center, Stanford University,
 *         under Contract DE-AC03-76SFO0515 with the Department of Energy.
 *
 * Government disclaimer of liability
 * ----------------------------------
 * Neither the United States nor the United States Department of Energy,
 * nor any of their employees, makes any warranty, express or implied, or
 * assumes any legal liability or responsibility for the accuracy,
 * completeness, or usefulness of any data, apparatus, product, or process
 * disclosed, or represents that its use would not infringe privately owned
 * rights.
 *
 * Stanford disclaimer of liability
 * --------------------------------
 * Stanford University makes no representations or warranties, express or
 * implied, nor assumes any liability for the use of this software.
 *
 * Stanford disclaimer of copyright
 * --------------------------------
 * Stanford University, owner of the copyright, hereby disclaims its
 * copyright and all other rights in this software.  Hence, anyone may
 * freely use it for any purpose without restriction.
 *
 * Maintenance of notices
 * ----------------------
 * In the interest of clarity regarding the origin and status of this
 * SLAC software, this and all the preceding Stanford University notices
 * are to remain affixed to any copy or derivative of this software made
 * or distributed by the recipient and are to be affixed to any copy of
 * software made or distributed by the recipient that contains a copy or
 * derivative of this software.
 *
 * ------------------ SLAC Software Notices, Set 4 OTT.002a, 2004 FEB 03
 */

Triv121PgTbl __BSP_default_pgtbl_setup(unsigned int *pmemsize);
Triv121PgTbl BSP_pgtbl_setup(unsigned int *)
  __attribute__ (( weak, alias("__BSP_default_pgtbl_setup") ));

/* get those from the linker script.
 * NOTE THAT THE CORRECTNESS OF THE LINKER SCRIPT IS CRUCIAL
 */
extern unsigned long __DATA_START__[], _etext[];

Triv121PgTbl
__BSP_default_pgtbl_setup(unsigned int *pmemsize)
{
Triv121PgTbl    pt;
unsigned                ldPtSize,tmp;

  /* Allocate a page table large enough to map
   * the entire physical memory. We put the page
   * table at the top of the physical memory.
   */

  /* get minimal size (log base 2) of PT for
   * this board's memory
   */
  ldPtSize = triv121PgTblLdMinSize(*pmemsize);
  ldPtSize++; /* double this amount -- then why? */

  /* allocate the page table at the top of the physical
   * memory - THIS IS NOT AN OPTION - bspstart.c RELIES
   * ON THIS LAYOUT! (the size, however may be changed)
   */
  if ( (pt = triv121PgTblInit(*pmemsize - (1<<ldPtSize), ldPtSize)) ) {
        /* map text and RO data read-only */
        tmp = triv121PgTblMap(
                                                pt,
                                                TRIV121_121_VSID,
                                                0,
                                                (PAGE_ALIGN((unsigned long)_etext) - 0) >> PG_SHIFT,
                                                0, /* WIMG */
                                                TRIV121_PP_RO_PAGE);
        if (TRIV121_MAP_SUCCESS != tmp) {
                printk("Unable to map page index %i; reverting to BAT0\n",
                                tmp);
                pt = 0;
        } else {
                /* map the rest (without the page table itself) RW */
                tmp = triv121PgTblMap(
                                                pt,
                                                TRIV121_121_VSID,
                                                (unsigned long)__DATA_START__,
                                                (*pmemsize - (1<<ldPtSize) -  (unsigned long)__DATA_START__ )>> PG_SHIFT,
                                                0, /* WIMG */
                                                TRIV121_PP_RW_PAGE);
                if (TRIV121_MAP_SUCCESS != tmp) {
                        printk("Unable to map page index %i; reverting to BAT0\n",
                                        tmp);
                        pt = 0;
                }
        }
  } else {
        printk("WARNING: unable to allocate page table, keeping DBAT0\n");
  }
  if (pt) {
#ifdef SHOW_MORE_INIT_SETTINGS
        printk("Setting up page table mappings; protecting text/read-only data from write access\n");
#endif
        /* SUCCESS; reduce available memory by size of the page table */
        *pmemsize -= (1<<ldPtSize);
  }
  return pt;
}