2 * Copyright (c) 1992-1994 by Xerox Corporation. All rights reserved.
4 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
5 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
7 * Permission is hereby granted to use or copy this program
8 * for any purpose, provided the above notices are retained on all copies.
9 * Permission to modify the code and to distribute modified code is granted,
10 * provided the above notices are retained, and a notice that the code was
11 * modified is included with the above copyright notice.
14 #include "private/gc_priv.h"
18 /* This is debugging code intended to verify the results of dirty bit */
19 /* computations. Works only in a single threaded environment. */
20 /* We assume that stubborn objects are changed only when they are */
21 /* enabled for writing. (Certain kinds of writing are actually */
22 /* safe under other conditions.) */
25 #define OFFSET 0x10000
31 struct hblk * block; /* Block to which this refers + OFFSET */
32 /* to hide it from collector. */
35 page_entry GC_sums[NSUMS];
37 STATIC word GC_faulted[NSUMS] = { 0 };
38 /* Record of pages on which we saw a write fault. */
40 STATIC size_t GC_n_faulted = 0;
42 void GC_record_fault(struct hblk * h)
46 page += GC_page_size - 1;
47 page &= ~(GC_page_size - 1);
48 if (GC_n_faulted >= NSUMS) ABORT("write fault log overflowed");
49 GC_faulted[GC_n_faulted++] = page;
52 STATIC GC_bool GC_was_faulted(struct hblk *h)
57 page += GC_page_size - 1;
58 page &= ~(GC_page_size - 1);
59 for (i = 0; i < GC_n_faulted; ++i) {
60 if (GC_faulted[i] == page) return TRUE;
65 STATIC word GC_checksum(struct hblk *h)
68 word *lim = (word *)(h+1);
74 return(result | 0x80000000 /* doesn't look like pointer */);
78 /* Check whether a stubborn object from the given block appears on */
79 /* the appropriate free list. */
80 STATIC GC_bool GC_on_free_list(struct hblk *h)
83 size_t sz = BYTES_TO_WORDS(hhdr -> hb_sz);
86 if (sz > MAXOBJWORDS) return(FALSE);
87 for (p = GC_sobjfreelist[sz]; p != 0; p = obj_link(p)) {
88 if (HBLKPTR(p) == h) return(TRUE);
94 int GC_n_dirty_errors = 0;
95 int GC_n_faulted_dirty_errors = 0;
96 int GC_n_changed_errors = 0;
100 STATIC void GC_update_check_page(struct hblk *h, int index)
102 page_entry *pe = GC_sums + index;
106 if (pe -> block != 0 && pe -> block != h + OFFSET) ABORT("goofed");
107 pe -> old_sum = pe -> new_sum;
108 pe -> new_sum = GC_checksum(h);
109 # if !defined(MSWIN32) && !defined(MSWINCE)
110 if (pe -> new_sum != 0x80000000 && !GC_page_was_ever_dirty(h)) {
111 GC_err_printf("GC_page_was_ever_dirty(%p) is wrong\n", h);
114 if (GC_page_was_dirty(h)) {
120 while (IS_FORWARDING_ADDR_OR_NIL(hhdr) && hhdr != 0) {
125 && hhdr != 0 && hhdr -> hb_descr != 0 /* may contain pointers */
126 && pe -> old_sum != pe -> new_sum) {
127 if (!GC_page_was_dirty(h) || !GC_page_was_ever_dirty(h)) {
128 GC_bool was_faulted = GC_was_faulted(h);
129 /* Set breakpoint here */GC_n_dirty_errors++;
130 if (was_faulted) GC_n_faulted_dirty_errors++;
132 # ifdef STUBBORN_ALLOC
133 if (!HBLK_IS_FREE(hhdr)
134 && hhdr -> hb_obj_kind == STUBBORN
135 && !GC_page_was_changed(h)
136 && !GC_on_free_list(h)) {
137 /* if GC_on_free_list(h) then reclaim may have touched it */
138 /* without any allocations taking place. */
139 /* Set breakpoint here */GC_n_changed_errors++;
143 pe -> new_valid = TRUE;
144 pe -> block = h + OFFSET;
147 word GC_bytes_in_used_blocks = 0;
150 STATIC void GC_add_block(struct hblk *h, word dummy)
153 size_t bytes = hhdr -> hb_sz;
156 bytes &= ~(HBLKSIZE-1);
157 GC_bytes_in_used_blocks += bytes;
160 STATIC void GC_check_blocks(void)
162 word bytes_in_free_blocks = GC_large_free_bytes;
164 GC_bytes_in_used_blocks = 0;
165 GC_apply_to_all_blocks(GC_add_block, (word)0);
167 GC_log_printf("GC_bytes_in_used_blocks = %lu,"
168 " bytes_in_free_blocks = %lu, heapsize = %lu\n",
169 (unsigned long)GC_bytes_in_used_blocks,
170 (unsigned long)bytes_in_free_blocks,
171 (unsigned long)GC_heapsize);
172 if (GC_bytes_in_used_blocks + bytes_in_free_blocks != GC_heapsize) {
173 GC_err_printf("LOST SOME BLOCKS!!\n");
177 /* Should be called immediately after GC_read_dirty and GC_read_changed. */
178 void GC_check_dirty(void)
187 GC_n_dirty_errors = 0;
188 GC_n_faulted_dirty_errors = 0;
189 GC_n_changed_errors = 0;
194 for (i = 0; i < GC_n_heap_sects; i++) {
195 start = GC_heap_sects[i].hs_start;
196 for (h = (struct hblk *)start;
197 h < (struct hblk *)(start + GC_heap_sects[i].hs_bytes);
199 GC_update_check_page(h, index);
201 if (index >= NSUMS) goto out;
206 GC_log_printf("Checked %lu clean and %lu dirty pages\n",
207 (unsigned long)GC_n_clean, (unsigned long)GC_n_dirty);
208 if (GC_n_dirty_errors > 0) {
209 GC_err_printf("Found %d dirty bit errors (%d were faulted)\n",
210 GC_n_dirty_errors, GC_n_faulted_dirty_errors);
212 if (GC_n_changed_errors > 0) {
213 GC_err_printf("Found %lu changed bit errors\n",
214 (unsigned long)GC_n_changed_errors);
216 "These may be benign (provoked by nonpointer changes)\n");
219 "Also expect 1 per thread currently allocating a stubborn obj\n");
222 for (i = 0; i < GC_n_faulted; ++i) {
223 GC_faulted[i] = 0; /* Don't expose block pointers to GC */
228 #endif /* CHECKSUMS */