+/*
+ * Copyright (c) 1992-1994 by Xerox Corporation. All rights reserved.
+ *
+ * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
+ * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
+ *
+ * Permission is hereby granted to use or copy this program
+ * for any purpose, provided the above notices are retained on all copies.
+ * Permission to modify the code and to distribute modified code is granted,
+ * provided the above notices are retained, and a notice that the code was
+ * modified is included with the above copyright notice.
+ */
+
+#include "private/gc_priv.h"
+
+#ifdef CHECKSUMS
+
+/* This is debugging code intended to verify the results of dirty bit */
+/* computations. Works only in a single threaded environment. */
+/* We assume that stubborn objects are changed only when they are */
+/* enabled for writing. (Certain kinds of writing are actually */
+/* safe under other conditions.) */
+#define NSUMS 10000
+
+#define OFFSET 0x10000
+
+typedef struct {
+ GC_bool new_valid;
+ word old_sum;
+ word new_sum;
+ struct hblk * block; /* Block to which this refers + OFFSET */
+ /* to hide it from collector. */
+} page_entry;
+
+page_entry GC_sums[NSUMS];
+
+STATIC word GC_faulted[NSUMS] = { 0 };
+ /* Record of pages on which we saw a write fault. */
+
+STATIC size_t GC_n_faulted = 0;
+
+void GC_record_fault(struct hblk * h)
+{
+ word page = (word)h;
+
+ page += GC_page_size - 1;
+ page &= ~(GC_page_size - 1);
+ if (GC_n_faulted >= NSUMS) ABORT("write fault log overflowed");
+ GC_faulted[GC_n_faulted++] = page;
+}
+
+STATIC GC_bool GC_was_faulted(struct hblk *h)
+{
+ size_t i;
+ word page = (word)h;
+
+ page += GC_page_size - 1;
+ page &= ~(GC_page_size - 1);
+ for (i = 0; i < GC_n_faulted; ++i) {
+ if (GC_faulted[i] == page) return TRUE;
+ }
+ return FALSE;
+}
+
+STATIC word GC_checksum(struct hblk *h)
+{
+ word *p = (word *)h;
+ word *lim = (word *)(h+1);
+ word result = 0;
+
+ while (p < lim) {
+ result += *p++;
+ }
+ return(result | 0x80000000 /* doesn't look like pointer */);
+}
+
+#ifdef STUBBORN_ALLOC
+ /* Check whether a stubborn object from the given block appears on */
+ /* the appropriate free list. */
+ STATIC GC_bool GC_on_free_list(struct hblk *h)
+ {
+ hdr * hhdr = HDR(h);
+ size_t sz = BYTES_TO_WORDS(hhdr -> hb_sz);
+ ptr_t p;
+
+ if (sz > MAXOBJWORDS) return(FALSE);
+ for (p = GC_sobjfreelist[sz]; p != 0; p = obj_link(p)) {
+ if (HBLKPTR(p) == h) return(TRUE);
+ }
+ return(FALSE);
+ }
+#endif
+
+int GC_n_dirty_errors = 0;
+int GC_n_faulted_dirty_errors = 0;
+int GC_n_changed_errors = 0;
+int GC_n_clean = 0;
+int GC_n_dirty = 0;
+
+STATIC void GC_update_check_page(struct hblk *h, int index)
+{
+ page_entry *pe = GC_sums + index;
+ hdr * hhdr = HDR(h);
+ struct hblk *b;
+
+ if (pe -> block != 0 && pe -> block != h + OFFSET) ABORT("goofed");
+ pe -> old_sum = pe -> new_sum;
+ pe -> new_sum = GC_checksum(h);
+# if !defined(MSWIN32) && !defined(MSWINCE)
+ if (pe -> new_sum != 0x80000000 && !GC_page_was_ever_dirty(h)) {
+ GC_err_printf("GC_page_was_ever_dirty(%p) is wrong\n", h);
+ }
+# endif
+ if (GC_page_was_dirty(h)) {
+ GC_n_dirty++;
+ } else {
+ GC_n_clean++;
+ }
+ b = h;
+ while (IS_FORWARDING_ADDR_OR_NIL(hhdr) && hhdr != 0) {
+ b -= (word)hhdr;
+ hhdr = HDR(b);
+ }
+ if (pe -> new_valid
+ && hhdr != 0 && hhdr -> hb_descr != 0 /* may contain pointers */
+ && pe -> old_sum != pe -> new_sum) {
+ if (!GC_page_was_dirty(h) || !GC_page_was_ever_dirty(h)) {
+ GC_bool was_faulted = GC_was_faulted(h);
+ /* Set breakpoint here */GC_n_dirty_errors++;
+ if (was_faulted) GC_n_faulted_dirty_errors++;
+ }
+# ifdef STUBBORN_ALLOC
+ if (!HBLK_IS_FREE(hhdr)
+ && hhdr -> hb_obj_kind == STUBBORN
+ && !GC_page_was_changed(h)
+ && !GC_on_free_list(h)) {
+ /* if GC_on_free_list(h) then reclaim may have touched it */
+ /* without any allocations taking place. */
+ /* Set breakpoint here */GC_n_changed_errors++;
+ }
+# endif
+ }
+ pe -> new_valid = TRUE;
+ pe -> block = h + OFFSET;
+}
+
+word GC_bytes_in_used_blocks = 0;
+
+/*ARGSUSED*/
+STATIC void GC_add_block(struct hblk *h, word dummy)
+{
+ hdr * hhdr = HDR(h);
+ size_t bytes = hhdr -> hb_sz;
+
+ bytes += HBLKSIZE-1;
+ bytes &= ~(HBLKSIZE-1);
+ GC_bytes_in_used_blocks += bytes;
+}
+
+STATIC void GC_check_blocks(void)
+{
+ word bytes_in_free_blocks = GC_large_free_bytes;
+
+ GC_bytes_in_used_blocks = 0;
+ GC_apply_to_all_blocks(GC_add_block, (word)0);
+ if (GC_print_stats)
+ GC_log_printf("GC_bytes_in_used_blocks = %lu,"
+ " bytes_in_free_blocks = %lu, heapsize = %lu\n",
+ (unsigned long)GC_bytes_in_used_blocks,
+ (unsigned long)bytes_in_free_blocks,
+ (unsigned long)GC_heapsize);
+ if (GC_bytes_in_used_blocks + bytes_in_free_blocks != GC_heapsize) {
+ GC_err_printf("LOST SOME BLOCKS!!\n");
+ }
+}
+
+/* Should be called immediately after GC_read_dirty and GC_read_changed. */
+void GC_check_dirty(void)
+{
+ int index;
+ unsigned i;
+ struct hblk *h;
+ ptr_t start;
+
+ GC_check_blocks();
+
+ GC_n_dirty_errors = 0;
+ GC_n_faulted_dirty_errors = 0;
+ GC_n_changed_errors = 0;
+ GC_n_clean = 0;
+ GC_n_dirty = 0;
+
+ index = 0;
+ for (i = 0; i < GC_n_heap_sects; i++) {
+ start = GC_heap_sects[i].hs_start;
+ for (h = (struct hblk *)start;
+ h < (struct hblk *)(start + GC_heap_sects[i].hs_bytes);
+ h++) {
+ GC_update_check_page(h, index);
+ index++;
+ if (index >= NSUMS) goto out;
+ }
+ }
+out:
+ if (GC_print_stats)
+ GC_log_printf("Checked %lu clean and %lu dirty pages\n",
+ (unsigned long)GC_n_clean, (unsigned long)GC_n_dirty);
+ if (GC_n_dirty_errors > 0) {
+ GC_err_printf("Found %d dirty bit errors (%d were faulted)\n",
+ GC_n_dirty_errors, GC_n_faulted_dirty_errors);
+ }
+ if (GC_n_changed_errors > 0) {
+ GC_err_printf("Found %lu changed bit errors\n",
+ (unsigned long)GC_n_changed_errors);
+ GC_err_printf(
+ "These may be benign (provoked by nonpointer changes)\n");
+# ifdef THREADS
+ GC_err_printf(
+ "Also expect 1 per thread currently allocating a stubborn obj\n");
+# endif
+ }
+ for (i = 0; i < GC_n_faulted; ++i) {
+ GC_faulted[i] = 0; /* Don't expose block pointers to GC */
+ }
+ GC_n_faulted = 0;
+}
+
+#endif /* CHECKSUMS */
projects / hs-boehmgc.git / blobdiff