src/runtime/gencgc-internal.h

   1 /*
   2  * Generational Conservative Garbage Collector for SBCL x86
   3  *
   4  * inline functions that gc-common.c needs sight of
   5  */
   6
   7
   8 /*
   9  * This software is part of the SBCL system. See the README file for
  10  * more information.
  11  *
  12  * This software is derived from the CMU CL system, which was
  13  * written at Carnegie Mellon University and released into the
  14  * public domain. The software is in the public domain and is
  15  * provided with absolutely no warranty. See the COPYING and CREDITS
  16  * files for more information.
  17  */
  18
  19 #ifndef _GENCGC_INTERNAL_H_
  20 #define _GENCGC_INTERNAL_H_
  21
  22 #include <limits.h>
  23 #include "gc.h"
  24 #include "gencgc-alloc-region.h"
  25 #include "genesis/code.h"
  26
  27 void gc_free_heap(void);
  28 extern page_index_t find_page_index(void *);
  29 extern void *page_address(page_index_t);
  30 int gencgc_handle_wp_violation(void *);
  31 \f
  32
  33 #if GENCGC_CARD_BYTES > USHRT_MAX
  34 # if GENCGC_CARD_BYTES > UINT_MAX
  35 #   error "GENCGC_CARD_BYTES unexpectedly large."
  36 # else
  37 #   define PAGE_BYTES_FMT "u"
  38     typedef unsigned int page_bytes_t;
  39 # endif
  40 #else
  41 # define PAGE_BYTES_FMT "hu"
  42   typedef unsigned short page_bytes_t;
  43 #endif
  44
  45 /* Note that this structure is also used from Lisp-side in
  46  * src/code/room.lisp, and the Lisp-side structure layout is currently
  47  * not groveled from C code but hardcoded. Any changes to the
  48  * structure layout need to be also made there.
  49  *
  50  * FIXME: We should probably just define this structure in Lisp, and
  51  * output the C version in genesis. -- JES, 2006-12-30.
  52  */
  53 struct page {
  54     /* This is the offset from the first byte of some object in memory
  55      * prior to and no closer than the start of the page to the start
  56      * of the page.  Lower values here are better, 0 is ideal.  This
  57      * is useful for determining where to start when scanning forward
  58      * through a heap page (either for conservative root validation or
  59      * for scavenging).
  60      */
  61     os_vm_size_t scan_start_offset;
  62
  63     /* the number of bytes of this page that are used. This may be less
  64      * than the actual bytes used for pages within the current
  65      * allocation regions. It should be 0 for all unallocated pages (not
  66      * hard to achieve).
  67      */
  68     page_bytes_t bytes_used;
  69
  70     unsigned char
  71         /* This is set when the page is write-protected. This should
  72          * always reflect the actual write_protect status of a page.
  73          * (If the page is written into, we catch the exception, make
  74          * the page writable, and clear this flag.) */
  75         write_protected :1,
  76         /* This flag is set when the above write_protected flag is
  77          * cleared by the SIGBUS handler (or SIGSEGV handler, for some
  78          * OSes). This is useful for re-scavenging pages that are
  79          * written during a GC. */
  80         write_protected_cleared :1,
  81         /*  000 free
  82          *  ?01 boxed data
  83          *  ?10 unboxed data
  84          *  ?11 code
  85          *  1?? open region
  86          *
  87          * Constants for this field are defined in gc-internal.h, the
  88          * xxx_PAGE_FLAG definitions.
  89          *
  90          * If the page is free the following slots are invalid, except
  91          * for the bytes_used which must be zero. */
  92         allocated :3,
  93         /* If this page should not be moved during a GC then this flag
  94          * is set. It's only valid during a GC for allocated pages. */
  95         dont_move :1,
  96         /* If the page is part of a large object then this flag is
  97          * set. No other objects should be allocated to these pages.
  98          * This is only valid when the page is allocated. */
  99         large_object :1,
 100         /* Cleared if the page is known to contain only zeroes. */
 101         need_to_zero :1;
 102
 103     /* If a page has a conservative pointer to it it will have
 104        an associated map of words that are in use, for wiping.
 105        This bit can differ from dont_move because not all pages
 106        that are pinned are going through word-wise wiping,
 107        at this time those are multi-page object's pages. */
 108     /* I am starting a new 8-bit word here because 32 bit overflew the old
 109        one.  Might be worth reviting by somebody with lots of platforms
 110        at hand.
 111      */
 112     signed char has_pin_map;
 113     /* the generation that this page belongs to. This should be valid
 114      * for all pages that may have objects allocated, even current
 115      * allocation region pages - this allows the space of an object to
 116      * be easily determined. */
 117     generation_index_t gen;
 118 };
 119
 120
 121 /* values for the page.allocated field */
 122
 123 \f
 124 extern page_index_t page_table_pages;
 125 extern struct page *page_table;
 126
 127 \f
 128 /* forward declarations */
 129 #ifdef LISP_FEATURE_X86
 130 void sniff_code_object(struct code *code, os_vm_size_t displacement);
 131 void gencgc_apply_code_fixups(struct code *old_code, struct code *new_code);
 132 #endif
 133
 134 sword_t update_dynamic_space_free_pointer(void);
 135 void gc_alloc_update_page_tables(int page_type_flag, struct alloc_region *alloc_region);
 136 void gc_alloc_update_all_page_tables(void);
 137 void gc_set_region_empty(struct alloc_region *region);
 138
 139 /*
 140  * predicates
 141  */
 142
 143 static inline boolean
 144 space_matches_p(lispobj obj, generation_index_t space,
 145                 page_index_t *store_page_index_here)
 146 {
 147     if (obj >= DYNAMIC_SPACE_START) {
 148         page_index_t page_index=((pointer_sized_uint_t)obj
 149                                  - DYNAMIC_SPACE_START) / GENCGC_CARD_BYTES;
 150         if (store_page_index_here) {
 151             *store_page_index_here = page_index;
 152         }
 153         return ((page_index < page_table_pages) &&
 154                 (page_table[page_index].gen == space));
 155     } else {
 156         return 0;
 157     }
 158 }
 159
 160 static boolean __attribute__((unused))
 161 from_space_p(lispobj obj)
 162 {
 163     extern boolean in_dontmove_nativeptr_p(page_index_t, lispobj*);
 164     page_index_t page_index;
 165
 166     if (space_matches_p(obj, from_space, &page_index)) {
 167         lispobj *native = native_pointer(obj);
 168         if (in_dontmove_nativeptr_p(page_index, native)) {
 169             // pretend it is not in oldspace to protect it from being moved
 170             return 0;
 171         } else {
 172             return 1;
 173         }
 174     } else {
 175         return 0;
 176     }
 177 }
 178 static inline boolean
 179 new_space_p(lispobj obj)
 180 {
 181     return space_matches_p(obj, new_space, NULL);
 182 }
 183
 184 boolean in_dontmove_nativeptr_p(page_index_t page_index, lispobj *native_ptr);
 185
 186 extern page_index_t last_free_page;
 187 extern boolean gencgc_partial_pickup;
 188
 189 #endif