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/*
* 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", (void *)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;
STATIC void GC_add_block(struct hblk *h, word dummy GC_ATTR_UNUSED)
{
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 */
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