582 lines
15 KiB
C
582 lines
15 KiB
C
/* Caching code for GDB, the GNU debugger.
|
|
|
|
Copyright (C) 1992, 1993, 1995, 1996, 1998, 1999, 2000, 2001, 2003, 2007,
|
|
2008, 2009 Free Software Foundation, Inc.
|
|
|
|
This file is part of GDB.
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program. If not, see <http://www.gnu.org/licenses/>. */
|
|
|
|
#include "defs.h"
|
|
#include "dcache.h"
|
|
#include "gdbcmd.h"
|
|
#include "gdb_string.h"
|
|
#include "gdbcore.h"
|
|
#include "target.h"
|
|
#include "inferior.h"
|
|
#include "splay-tree.h"
|
|
|
|
/* The data cache could lead to incorrect results because it doesn't
|
|
know about volatile variables, thus making it impossible to debug
|
|
functions which use memory mapped I/O devices. Set the nocache
|
|
memory region attribute in those cases.
|
|
|
|
In general the dcache speeds up performance. Some speed improvement
|
|
comes from the actual caching mechanism, but the major gain is in
|
|
the reduction of the remote protocol overhead; instead of reading
|
|
or writing a large area of memory in 4 byte requests, the cache
|
|
bundles up the requests into LINE_SIZE chunks, reducing overhead
|
|
significantly. This is most useful when accessing a large amount
|
|
of data, such as when performing a backtrace.
|
|
|
|
The cache is a splay tree along with a linked list for replacement.
|
|
Each block caches a LINE_SIZE area of memory. Wtihin each line we remember
|
|
the address of the line (which must be a multiple of LINE_SIZE) and the
|
|
actual data block.
|
|
|
|
Lines are only allocated as needed, so DCACHE_SIZE really specifies the
|
|
*maximum* number of lines in the cache.
|
|
|
|
At present, the cache is write-through rather than writeback: as soon
|
|
as data is written to the cache, it is also immediately written to
|
|
the target. Therefore, cache lines are never "dirty". Whether a given
|
|
line is valid or not depends on where it is stored in the dcache_struct;
|
|
there is no per-block valid flag. */
|
|
|
|
/* NOTE: Interaction of dcache and memory region attributes
|
|
|
|
As there is no requirement that memory region attributes be aligned
|
|
to or be a multiple of the dcache page size, dcache_read_line() and
|
|
dcache_write_line() must break up the page by memory region. If a
|
|
chunk does not have the cache attribute set, an invalid memory type
|
|
is set, etc., then the chunk is skipped. Those chunks are handled
|
|
in target_xfer_memory() (or target_xfer_memory_partial()).
|
|
|
|
This doesn't occur very often. The most common occurance is when
|
|
the last bit of the .text segment and the first bit of the .data
|
|
segment fall within the same dcache page with a ro/cacheable memory
|
|
region defined for the .text segment and a rw/non-cacheable memory
|
|
region defined for the .data segment. */
|
|
|
|
/* The maximum number of lines stored. The total size of the cache is
|
|
equal to DCACHE_SIZE times LINE_SIZE. */
|
|
#define DCACHE_SIZE 4096
|
|
|
|
/* The size of a cache line. Smaller values reduce the time taken to
|
|
read a single byte and make the cache more granular, but increase
|
|
overhead and reduce the effectiveness of the cache as a prefetcher. */
|
|
#define LINE_SIZE_POWER 6
|
|
#define LINE_SIZE (1 << LINE_SIZE_POWER)
|
|
|
|
/* Each cache block holds LINE_SIZE bytes of data
|
|
starting at a multiple-of-LINE_SIZE address. */
|
|
|
|
#define LINE_SIZE_MASK ((LINE_SIZE - 1))
|
|
#define XFORM(x) ((x) & LINE_SIZE_MASK)
|
|
#define MASK(x) ((x) & ~LINE_SIZE_MASK)
|
|
|
|
struct dcache_block
|
|
{
|
|
struct dcache_block *newer; /* for LRU and free list */
|
|
CORE_ADDR addr; /* address of data */
|
|
gdb_byte data[LINE_SIZE]; /* bytes at given address */
|
|
int refs; /* # hits */
|
|
};
|
|
|
|
struct dcache_struct
|
|
{
|
|
splay_tree tree;
|
|
struct dcache_block *oldest;
|
|
struct dcache_block *newest;
|
|
|
|
struct dcache_block *freelist;
|
|
|
|
/* The number of in-use lines in the cache. */
|
|
int size;
|
|
|
|
/* The ptid of last inferior to use cache or null_ptid. */
|
|
ptid_t ptid;
|
|
};
|
|
|
|
static struct dcache_block *dcache_hit (DCACHE *dcache, CORE_ADDR addr);
|
|
|
|
static int dcache_write_line (DCACHE *dcache, struct dcache_block *db);
|
|
|
|
static int dcache_read_line (DCACHE *dcache, struct dcache_block *db);
|
|
|
|
static struct dcache_block *dcache_alloc (DCACHE *dcache, CORE_ADDR addr);
|
|
|
|
static void dcache_info (char *exp, int tty);
|
|
|
|
void _initialize_dcache (void);
|
|
|
|
static int dcache_enabled_p = 0; /* OBSOLETE */
|
|
|
|
static void
|
|
show_dcache_enabled_p (struct ui_file *file, int from_tty,
|
|
struct cmd_list_element *c, const char *value)
|
|
{
|
|
fprintf_filtered (file, _("Deprecated remotecache flag is %s.\n"), value);
|
|
}
|
|
|
|
static DCACHE *last_cache; /* Used by info dcache */
|
|
|
|
/* Free all the data cache blocks, thus discarding all cached data. */
|
|
|
|
void
|
|
dcache_invalidate (DCACHE *dcache)
|
|
{
|
|
struct dcache_block *block, *next;
|
|
|
|
block = dcache->oldest;
|
|
|
|
while (block)
|
|
{
|
|
splay_tree_remove (dcache->tree, (splay_tree_key) block->addr);
|
|
next = block->newer;
|
|
|
|
block->newer = dcache->freelist;
|
|
dcache->freelist = block;
|
|
|
|
block = next;
|
|
}
|
|
|
|
dcache->oldest = NULL;
|
|
dcache->newest = NULL;
|
|
dcache->size = 0;
|
|
dcache->ptid = null_ptid;
|
|
}
|
|
|
|
/* Invalidate the line associated with ADDR. */
|
|
|
|
static void
|
|
dcache_invalidate_line (DCACHE *dcache, CORE_ADDR addr)
|
|
{
|
|
struct dcache_block *db = dcache_hit (dcache, addr);
|
|
|
|
if (db)
|
|
{
|
|
splay_tree_remove (dcache->tree, (splay_tree_key) db->addr);
|
|
db->newer = dcache->freelist;
|
|
dcache->freelist = db;
|
|
--dcache->size;
|
|
}
|
|
}
|
|
|
|
/* If addr is present in the dcache, return the address of the block
|
|
containing it. */
|
|
|
|
static struct dcache_block *
|
|
dcache_hit (DCACHE *dcache, CORE_ADDR addr)
|
|
{
|
|
struct dcache_block *db;
|
|
|
|
splay_tree_node node = splay_tree_lookup (dcache->tree,
|
|
(splay_tree_key) MASK (addr));
|
|
|
|
if (!node)
|
|
return NULL;
|
|
|
|
db = (struct dcache_block *) node->value;
|
|
db->refs++;
|
|
return db;
|
|
}
|
|
|
|
/* Fill a cache line from target memory. */
|
|
|
|
static int
|
|
dcache_read_line (DCACHE *dcache, struct dcache_block *db)
|
|
{
|
|
CORE_ADDR memaddr;
|
|
gdb_byte *myaddr;
|
|
int len;
|
|
int res;
|
|
int reg_len;
|
|
struct mem_region *region;
|
|
|
|
len = LINE_SIZE;
|
|
memaddr = db->addr;
|
|
myaddr = db->data;
|
|
|
|
while (len > 0)
|
|
{
|
|
/* Don't overrun if this block is right at the end of the region. */
|
|
region = lookup_mem_region (memaddr);
|
|
if (region->hi == 0 || memaddr + len < region->hi)
|
|
reg_len = len;
|
|
else
|
|
reg_len = region->hi - memaddr;
|
|
|
|
/* Skip non-readable regions. The cache attribute can be ignored,
|
|
since we may be loading this for a stack access. */
|
|
if (region->attrib.mode == MEM_WO)
|
|
{
|
|
memaddr += reg_len;
|
|
myaddr += reg_len;
|
|
len -= reg_len;
|
|
continue;
|
|
}
|
|
|
|
res = target_read (¤t_target, TARGET_OBJECT_RAW_MEMORY,
|
|
NULL, myaddr, memaddr, reg_len);
|
|
if (res < reg_len)
|
|
return 0;
|
|
|
|
memaddr += res;
|
|
myaddr += res;
|
|
len -= res;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/* Get a free cache block, put or keep it on the valid list,
|
|
and return its address. */
|
|
|
|
static struct dcache_block *
|
|
dcache_alloc (DCACHE *dcache, CORE_ADDR addr)
|
|
{
|
|
struct dcache_block *db;
|
|
|
|
if (dcache->size >= DCACHE_SIZE)
|
|
{
|
|
/* Evict the least recently used line. */
|
|
db = dcache->oldest;
|
|
dcache->oldest = db->newer;
|
|
|
|
splay_tree_remove (dcache->tree, (splay_tree_key) db->addr);
|
|
}
|
|
else
|
|
{
|
|
db = dcache->freelist;
|
|
if (db)
|
|
dcache->freelist = db->newer;
|
|
else
|
|
db = xmalloc (sizeof (struct dcache_block));
|
|
|
|
dcache->size++;
|
|
}
|
|
|
|
db->addr = MASK (addr);
|
|
db->newer = NULL;
|
|
db->refs = 0;
|
|
|
|
if (dcache->newest)
|
|
dcache->newest->newer = db;
|
|
|
|
dcache->newest = db;
|
|
|
|
if (!dcache->oldest)
|
|
dcache->oldest = db;
|
|
|
|
splay_tree_insert (dcache->tree, (splay_tree_key) db->addr,
|
|
(splay_tree_value) db);
|
|
|
|
return db;
|
|
}
|
|
|
|
/* Using the data cache DCACHE return the contents of the byte at
|
|
address ADDR in the remote machine.
|
|
|
|
Returns 1 for success, 0 for error. */
|
|
|
|
static int
|
|
dcache_peek_byte (DCACHE *dcache, CORE_ADDR addr, gdb_byte *ptr)
|
|
{
|
|
struct dcache_block *db = dcache_hit (dcache, addr);
|
|
|
|
if (!db)
|
|
{
|
|
db = dcache_alloc (dcache, addr);
|
|
|
|
if (!dcache_read_line (dcache, db))
|
|
return 0;
|
|
}
|
|
|
|
*ptr = db->data[XFORM (addr)];
|
|
return 1;
|
|
}
|
|
|
|
/* Write the byte at PTR into ADDR in the data cache.
|
|
|
|
The caller is responsible for also promptly writing the data
|
|
through to target memory.
|
|
|
|
If addr is not in cache, this function does nothing; writing to
|
|
an area of memory which wasn't present in the cache doesn't cause
|
|
it to be loaded in.
|
|
|
|
Always return 1 (meaning success) to simplify dcache_xfer_memory. */
|
|
|
|
static int
|
|
dcache_poke_byte (DCACHE *dcache, CORE_ADDR addr, gdb_byte *ptr)
|
|
{
|
|
struct dcache_block *db = dcache_hit (dcache, addr);
|
|
|
|
if (db)
|
|
db->data[XFORM (addr)] = *ptr;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int
|
|
dcache_splay_tree_compare (splay_tree_key a, splay_tree_key b)
|
|
{
|
|
if (a > b)
|
|
return 1;
|
|
else if (a == b)
|
|
return 0;
|
|
else
|
|
return -1;
|
|
}
|
|
|
|
/* Initialize the data cache. */
|
|
|
|
DCACHE *
|
|
dcache_init (void)
|
|
{
|
|
DCACHE *dcache;
|
|
int i;
|
|
|
|
dcache = (DCACHE *) xmalloc (sizeof (*dcache));
|
|
|
|
dcache->tree = splay_tree_new (dcache_splay_tree_compare,
|
|
NULL,
|
|
NULL);
|
|
|
|
dcache->oldest = NULL;
|
|
dcache->newest = NULL;
|
|
dcache->freelist = NULL;
|
|
dcache->size = 0;
|
|
dcache->ptid = null_ptid;
|
|
last_cache = dcache;
|
|
|
|
return dcache;
|
|
}
|
|
|
|
/* Free a data cache. */
|
|
|
|
void
|
|
dcache_free (DCACHE *dcache)
|
|
{
|
|
struct dcache_block *db, *next;
|
|
|
|
if (last_cache == dcache)
|
|
last_cache = NULL;
|
|
|
|
splay_tree_delete (dcache->tree);
|
|
for (db = dcache->freelist; db != NULL; db = next)
|
|
{
|
|
next = db->newer;
|
|
xfree (db);
|
|
}
|
|
xfree (dcache);
|
|
}
|
|
|
|
/* Read or write LEN bytes from inferior memory at MEMADDR, transferring
|
|
to or from debugger address MYADDR. Write to inferior if SHOULD_WRITE is
|
|
nonzero.
|
|
|
|
The meaning of the result is the same as for target_write. */
|
|
|
|
int
|
|
dcache_xfer_memory (struct target_ops *ops, DCACHE *dcache,
|
|
CORE_ADDR memaddr, gdb_byte *myaddr,
|
|
int len, int should_write)
|
|
{
|
|
int i;
|
|
int res;
|
|
int (*xfunc) (DCACHE *dcache, CORE_ADDR addr, gdb_byte *ptr);
|
|
xfunc = should_write ? dcache_poke_byte : dcache_peek_byte;
|
|
|
|
/* If this is a different inferior from what we've recorded,
|
|
flush the cache. */
|
|
|
|
if (! ptid_equal (inferior_ptid, dcache->ptid))
|
|
{
|
|
dcache_invalidate (dcache);
|
|
dcache->ptid = inferior_ptid;
|
|
}
|
|
|
|
/* Do write-through first, so that if it fails, we don't write to
|
|
the cache at all. */
|
|
|
|
if (should_write)
|
|
{
|
|
res = target_write (ops, TARGET_OBJECT_RAW_MEMORY,
|
|
NULL, myaddr, memaddr, len);
|
|
if (res <= 0)
|
|
return res;
|
|
/* Update LEN to what was actually written. */
|
|
len = res;
|
|
}
|
|
|
|
for (i = 0; i < len; i++)
|
|
{
|
|
if (!xfunc (dcache, memaddr + i, myaddr + i))
|
|
{
|
|
/* That failed. Discard its cache line so we don't have a
|
|
partially read line. */
|
|
dcache_invalidate_line (dcache, memaddr + i);
|
|
/* If we're writing, we still wrote LEN bytes. */
|
|
if (should_write)
|
|
return len;
|
|
else
|
|
return i;
|
|
}
|
|
}
|
|
|
|
return len;
|
|
}
|
|
|
|
/* FIXME: There would be some benefit to making the cache write-back and
|
|
moving the writeback operation to a higher layer, as it could occur
|
|
after a sequence of smaller writes have been completed (as when a stack
|
|
frame is constructed for an inferior function call). Note that only
|
|
moving it up one level to target_xfer_memory[_partial]() is not
|
|
sufficient since we want to coalesce memory transfers that are
|
|
"logically" connected but not actually a single call to one of the
|
|
memory transfer functions. */
|
|
|
|
/* Just update any cache lines which are already present. This is called
|
|
by memory_xfer_partial in cases where the access would otherwise not go
|
|
through the cache. */
|
|
|
|
void
|
|
dcache_update (DCACHE *dcache, CORE_ADDR memaddr, gdb_byte *myaddr, int len)
|
|
{
|
|
int i;
|
|
for (i = 0; i < len; i++)
|
|
dcache_poke_byte (dcache, memaddr + i, myaddr + i);
|
|
}
|
|
|
|
static void
|
|
dcache_print_line (int index)
|
|
{
|
|
splay_tree_node n;
|
|
struct dcache_block *db;
|
|
int i, j;
|
|
|
|
if (!last_cache)
|
|
{
|
|
printf_filtered (_("No data cache available.\n"));
|
|
return;
|
|
}
|
|
|
|
n = splay_tree_min (last_cache->tree);
|
|
|
|
for (i = index; i > 0; --i)
|
|
{
|
|
if (!n)
|
|
break;
|
|
n = splay_tree_successor (last_cache->tree, n->key);
|
|
}
|
|
|
|
if (!n)
|
|
{
|
|
printf_filtered (_("No such cache line exists.\n"));
|
|
return;
|
|
}
|
|
|
|
db = (struct dcache_block *) n->value;
|
|
|
|
printf_filtered (_("Line %d: address %s [%d hits]\n"),
|
|
index, paddress (target_gdbarch, db->addr), db->refs);
|
|
|
|
for (j = 0; j < LINE_SIZE; j++)
|
|
{
|
|
printf_filtered ("%02x ", db->data[j]);
|
|
|
|
/* Print a newline every 16 bytes (48 characters) */
|
|
if ((j % 16 == 15) && (j != LINE_SIZE - 1))
|
|
printf_filtered ("\n");
|
|
}
|
|
printf_filtered ("\n");
|
|
}
|
|
|
|
static void
|
|
dcache_info (char *exp, int tty)
|
|
{
|
|
splay_tree_node n;
|
|
int i, refcount, lineno;
|
|
|
|
if (exp)
|
|
{
|
|
char *linestart;
|
|
i = strtol (exp, &linestart, 10);
|
|
if (linestart == exp || i < 0)
|
|
{
|
|
printf_filtered (_("Usage: info dcache [linenumber]\n"));
|
|
return;
|
|
}
|
|
|
|
dcache_print_line (i);
|
|
return;
|
|
}
|
|
|
|
printf_filtered (_("Dcache line width %d, maximum size %d\n"),
|
|
LINE_SIZE, DCACHE_SIZE);
|
|
|
|
if (!last_cache || ptid_equal (last_cache->ptid, null_ptid))
|
|
{
|
|
printf_filtered (_("No data cache available.\n"));
|
|
return;
|
|
}
|
|
|
|
printf_filtered (_("Contains data for %s\n"),
|
|
target_pid_to_str (last_cache->ptid));
|
|
|
|
refcount = 0;
|
|
|
|
n = splay_tree_min (last_cache->tree);
|
|
i = 0;
|
|
|
|
while (n)
|
|
{
|
|
struct dcache_block *db = (struct dcache_block *) n->value;
|
|
|
|
printf_filtered (_("Line %d: address %s [%d hits]\n"),
|
|
i, paddress (target_gdbarch, db->addr), db->refs);
|
|
i++;
|
|
refcount += db->refs;
|
|
|
|
n = splay_tree_successor (last_cache->tree, n->key);
|
|
}
|
|
|
|
printf_filtered (_("Cache state: %d active lines, %d hits\n"), i, refcount);
|
|
}
|
|
|
|
void
|
|
_initialize_dcache (void)
|
|
{
|
|
add_setshow_boolean_cmd ("remotecache", class_support,
|
|
&dcache_enabled_p, _("\
|
|
Set cache use for remote targets."), _("\
|
|
Show cache use for remote targets."), _("\
|
|
This used to enable the data cache for remote targets. The cache\n\
|
|
functionality is now controlled by the memory region system and the\n\
|
|
\"stack-cache\" flag; \"remotecache\" now does nothing and\n\
|
|
exists only for compatibility reasons."),
|
|
NULL,
|
|
show_dcache_enabled_p,
|
|
&setlist, &showlist);
|
|
|
|
add_info ("dcache", dcache_info,
|
|
_("\
|
|
Print information on the dcache performance.\n\
|
|
With no arguments, this command prints the cache configuration and a\n\
|
|
summary of each line in the cache. Use \"info dcache <lineno> to dump\"\n\
|
|
the contents of a given line."));
|
|
}
|