shared/start/pgtbl_setup.c

0001 #include <sys/param.h>
0002 #include <rtems.h>
0003 #include <libcpu/mmu.h>
0004 #include <rtems/bspIo.h>
0005 #include <libcpu/pte121.h>
0006
0007 /* Default setup of the page tables. This is a weak
0008  * alias, so applications may easily override this
0009  * default setup.
0010  *
0011  * NOTE: while it is possible to change the individual
0012  *       mappings, the page table itself MUST be
0013  *       allocated at the top of the physical memory!
0014  *       bspstart.c RELIES on this.
0015  *       Also, the 'setup' routine must reduce
0016  *       *pmemsize by the size of the page table.
0017  */
0018 /* to align the pointer to the (next) page boundary */
0019 #define PAGE_ALIGN(addr)    (((addr) + PAGE_MASK) & ~PAGE_MASK)
0020
0021
0022 /*
0023  * Authorship
0024  * ----------
0025  * This software was created by
0026  *     Till Straumann <strauman@slac.stanford.edu>, 4/2002,
0027  *     Stanford Linear Accelerator Center, Stanford University.
0028  *
0029  * Acknowledgement of sponsorship
0030  * ------------------------------
0031  * This software was produced by
0032  *     the Stanford Linear Accelerator Center, Stanford University,
0033  *     under Contract DE-AC03-76SFO0515 with the Department of Energy.
0034  *
0035  * Government disclaimer of liability
0036  * ----------------------------------
0037  * Neither the United States nor the United States Department of Energy,
0038  * nor any of their employees, makes any warranty, express or implied, or
0039  * assumes any legal liability or responsibility for the accuracy,
0040  * completeness, or usefulness of any data, apparatus, product, or process
0041  * disclosed, or represents that its use would not infringe privately owned
0042  * rights.
0043  *
0044  * Stanford disclaimer of liability
0045  * --------------------------------
0046  * Stanford University makes no representations or warranties, express or
0047  * implied, nor assumes any liability for the use of this software.
0048  *
0049  * Stanford disclaimer of copyright
0050  * --------------------------------
0051  * Stanford University, owner of the copyright, hereby disclaims its
0052  * copyright and all other rights in this software.  Hence, anyone may
0053  * freely use it for any purpose without restriction.
0054  *
0055  * Maintenance of notices
0056  * ----------------------
0057  * In the interest of clarity regarding the origin and status of this
0058  * SLAC software, this and all the preceding Stanford University notices
0059  * are to remain affixed to any copy or derivative of this software made
0060  * or distributed by the recipient and are to be affixed to any copy of
0061  * software made or distributed by the recipient that contains a copy or
0062  * derivative of this software.
0063  *
0064  * ------------------ SLAC Software Notices, Set 4 OTT.002a, 2004 FEB 03
0065  */
0066
0067 Triv121PgTbl __BSP_default_pgtbl_setup(unsigned int *pmemsize);
0068 Triv121PgTbl BSP_pgtbl_setup(unsigned int *)
0069   __attribute__ (( weak, alias("__BSP_default_pgtbl_setup") ));
0070
0071 /* get those from the linker script.
0072  * NOTE THAT THE CORRECTNESS OF THE LINKER SCRIPT IS CRUCIAL
0073  */
0074 extern unsigned long __DATA_START__[], _etext[];
0075
0076 Triv121PgTbl
0077 __BSP_default_pgtbl_setup(unsigned int *pmemsize)
0078 {
0079 Triv121PgTbl    pt;
0080 unsigned        ldPtSize,tmp;
0081
0082   /* Allocate a page table large enough to map
0083    * the entire physical memory. We put the page
0084    * table at the top of the physical memory.
0085    */
0086
0087   /* get minimal size (log base 2) of PT for
0088    * this board's memory
0089    */
0090   ldPtSize = triv121PgTblLdMinSize(*pmemsize);
0091   ldPtSize++; /* double this amount -- then why? */
0092
0093   /* allocate the page table at the top of the physical
0094    * memory - THIS IS NOT AN OPTION - bspstart.c RELIES
0095    * ON THIS LAYOUT! (the size, however may be changed)
0096    */
0097   if ( (pt = triv121PgTblInit(*pmemsize - (1<<ldPtSize), ldPtSize)) ) {
0098     /* map text and RO data read-only */
0099     tmp = triv121PgTblMap(
0100                         pt,
0101                         TRIV121_121_VSID,
0102                         0,
0103                         (PAGE_ALIGN((unsigned long)_etext) - 0) >> PG_SHIFT,
0104                         0, /* WIMG */
0105                         TRIV121_PP_RO_PAGE);
0106     if (TRIV121_MAP_SUCCESS != tmp) {
0107         printk("Unable to map page index %i; reverting to BAT0\n",
0108                 tmp);
0109         pt = 0;
0110     } else {
0111         /* map the rest (without the page table itself) RW */
0112         tmp = triv121PgTblMap(
0113                         pt,
0114                         TRIV121_121_VSID,
0115                         (unsigned long)__DATA_START__,
0116                         (*pmemsize - (1<<ldPtSize) -  (unsigned long)__DATA_START__ )>> PG_SHIFT,
0117                         0, /* WIMG */
0118                         TRIV121_PP_RW_PAGE);
0119         if (TRIV121_MAP_SUCCESS != tmp) {
0120             printk("Unable to map page index %i; reverting to BAT0\n",
0121                     tmp);
0122             pt = 0;
0123         }
0124     }
0125   } else {
0126     printk("WARNING: unable to allocate page table, keeping DBAT0\n");
0127   }
0128   if (pt) {
0129 #ifdef SHOW_MORE_INIT_SETTINGS
0130     printk("Setting up page table mappings; protecting text/read-only data from write access\n");
0131 #endif
0132     /* SUCCESS; reduce available memory by size of the page table */
0133     *pmemsize -= (1<<ldPtSize);
0134   }
0135   return pt;
0136 }