mirror of
https://github.com/espressif/binutils-gdb.git
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Initial creation of sourceware repository
This commit is contained in:
Stan Shebs
558
gdb/dcache.c
Normal file
558
gdb/dcache.c
Normal file
@ -0,0 +1,558 @@
|
||||
/* Caching code. Typically used by remote back ends for
|
||||
caching remote memory.
|
||||
|
||||
Copyright 1992, 1993, 1995, 1998 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 2 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, write to the Free Software
|
||||
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
|
||||
|
||||
#include "defs.h"
|
||||
#include "dcache.h"
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#include "gdbcmd.h"
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#include "gdb_string.h"
|
||||
#include "gdbcore.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 remotecache 0
|
||||
|
||||
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 32 byte (actually LINE_SIZE) chunks.
|
||||
Reducing the overhead to an eighth of what it was. This is very
|
||||
obvious when displaying a large amount of data,
|
||||
|
||||
eg, x/200x 0
|
||||
|
||||
caching | no yes
|
||||
----------------------------
|
||||
first time | 4 sec 2 sec improvement due to chunking
|
||||
second time | 4 sec 0 sec improvement due to caching
|
||||
|
||||
The cache structure is unusual, we keep a number of cache blocks
|
||||
(DCACHE_SIZE) and each one caches a LINE_SIZEed area of memory.
|
||||
Within each line we remember the address of the line (always a
|
||||
multiple of the LINE_SIZE) and a vector of bytes over the range.
|
||||
There's another vector which contains the state of the bytes.
|
||||
|
||||
ENTRY_BAD means that the byte is just plain wrong, and has no
|
||||
correspondence with anything else (as it would when the cache is
|
||||
turned on, but nothing has been done to it.
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||||
|
||||
ENTRY_DIRTY means that the byte has some data in it which should be
|
||||
written out to the remote target one day, but contains correct
|
||||
data. ENTRY_OK means that the data is the same in the cache as it
|
||||
is in remote memory.
|
||||
|
||||
|
||||
The ENTRY_DIRTY state is necessary because GDB likes to write large
|
||||
lumps of memory in small bits. If the caching mechanism didn't
|
||||
maintain the DIRTY information, then something like a two byte
|
||||
write would mean that the entire cache line would have to be read,
|
||||
the two bytes modified and then written out again. The alternative
|
||||
would be to not read in the cache line in the first place, and just
|
||||
write the two bytes directly into target memory. The trouble with
|
||||
that is that it really nails performance, because of the remote
|
||||
protocol overhead. This way, all those little writes are bundled
|
||||
up into an entire cache line write in one go, without having to
|
||||
read the cache line in the first place.
|
||||
|
||||
|
||||
*/
|
||||
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||||
|
||||
/* This value regulates the number of cache blocks stored.
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||||
Smaller values reduce the time spent searching for a cache
|
||||
line, and reduce memory requirements, but increase the risk
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of a line not being in memory */
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#define DCACHE_SIZE 64
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/* This value regulates the size of a cache line. Smaller values
|
||||
reduce the time taken to read a single byte, but reduce overall
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||||
throughput. */
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|
||||
#define LINE_SIZE_POWER (5)
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#define LINE_SIZE (1 << LINE_SIZE_POWER)
|
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|
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/* 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)
|
||||
|
||||
|
||||
#define ENTRY_BAD 0 /* data at this byte is wrong */
|
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#define ENTRY_DIRTY 1 /* data at this byte needs to be written back */
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||||
#define ENTRY_OK 2 /* data at this byte is same as in memory */
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||||
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||||
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||||
struct dcache_block
|
||||
{
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||||
struct dcache_block *p; /* next in list */
|
||||
CORE_ADDR addr; /* Address for which data is recorded. */
|
||||
char data[LINE_SIZE]; /* bytes at given address */
|
||||
unsigned char state[LINE_SIZE]; /* what state the data is in */
|
||||
|
||||
/* whether anything in state is dirty - used to speed up the
|
||||
dirty scan. */
|
||||
int anydirty;
|
||||
|
||||
int refs;
|
||||
};
|
||||
|
||||
|
||||
struct dcache_struct
|
||||
{
|
||||
/* Function to actually read the target memory. */
|
||||
memxferfunc read_memory;
|
||||
|
||||
/* Function to actually write the target memory */
|
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memxferfunc write_memory;
|
||||
|
||||
/* free list */
|
||||
struct dcache_block *free_head;
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||||
struct dcache_block *free_tail;
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||||
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||||
/* in use list */
|
||||
struct dcache_block *valid_head;
|
||||
struct dcache_block *valid_tail;
|
||||
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||||
/* The cache itself. */
|
||||
struct dcache_block *the_cache;
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||||
|
||||
/* potentially, if the cache was enabled, and then turned off, and
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||||
then turned on again, the stuff in it could be stale, so this is
|
||||
used to mark it */
|
||||
int cache_has_stuff;
|
||||
} ;
|
||||
|
||||
static int dcache_poke_byte PARAMS ((DCACHE *dcache, CORE_ADDR addr,
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||||
char *ptr));
|
||||
|
||||
static int dcache_peek_byte PARAMS ((DCACHE *dcache, CORE_ADDR addr,
|
||||
char *ptr));
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||||
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||||
static struct dcache_block *dcache_hit PARAMS ((DCACHE *dcache,
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CORE_ADDR addr));
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||||
static int dcache_write_line PARAMS ((DCACHE *dcache,struct dcache_block *db));
|
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|
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static struct dcache_block *dcache_alloc PARAMS ((DCACHE *dcache));
|
||||
|
||||
static int dcache_writeback PARAMS ((DCACHE *dcache));
|
||||
|
||||
static void dcache_info PARAMS ((char *exp, int tty));
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||||
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||||
void _initialize_dcache PARAMS ((void));
|
||||
|
||||
int remote_dcache = 0;
|
||||
|
||||
DCACHE *last_cache; /* Used by info dcache */
|
||||
|
||||
|
||||
/* Free all the data cache blocks, thus discarding all cached data. */
|
||||
|
||||
void
|
||||
dcache_flush (dcache)
|
||||
DCACHE *dcache;
|
||||
{
|
||||
int i;
|
||||
dcache->valid_head = 0;
|
||||
dcache->valid_tail = 0;
|
||||
|
||||
dcache->free_head = 0;
|
||||
dcache->free_tail = 0;
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||||
|
||||
for (i = 0; i < DCACHE_SIZE; i++)
|
||||
{
|
||||
struct dcache_block *db = dcache->the_cache + i;
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||||
|
||||
if (!dcache->free_head)
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||||
dcache->free_head = db;
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||||
else
|
||||
dcache->free_tail->p = db;
|
||||
dcache->free_tail = db;
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||||
db->p = 0;
|
||||
}
|
||||
|
||||
dcache->cache_has_stuff = 0;
|
||||
|
||||
return;
|
||||
}
|
||||
|
||||
/* If addr is present in the dcache, return the address of the block
|
||||
containing it. */
|
||||
|
||||
static struct dcache_block *
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||||
dcache_hit (dcache, addr)
|
||||
DCACHE *dcache;
|
||||
CORE_ADDR addr;
|
||||
{
|
||||
register struct dcache_block *db;
|
||||
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||||
/* Search all cache blocks for one that is at this address. */
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||||
db = dcache->valid_head;
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||||
|
||||
while (db)
|
||||
{
|
||||
if (MASK(addr) == db->addr)
|
||||
{
|
||||
db->refs++;
|
||||
return db;
|
||||
}
|
||||
db = db->p;
|
||||
}
|
||||
|
||||
return NULL;
|
||||
}
|
||||
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||||
/* Make sure that anything in this line which needs to
|
||||
be written is. */
|
||||
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||||
static int
|
||||
dcache_write_line (dcache, db)
|
||||
DCACHE *dcache;
|
||||
register struct dcache_block *db;
|
||||
{
|
||||
int s;
|
||||
int e;
|
||||
s = 0;
|
||||
if (db->anydirty)
|
||||
{
|
||||
for (s = 0; s < LINE_SIZE; s++)
|
||||
{
|
||||
if (db->state[s] == ENTRY_DIRTY)
|
||||
{
|
||||
int len = 0;
|
||||
for (e = s ; e < LINE_SIZE; e++, len++)
|
||||
if (db->state[e] != ENTRY_DIRTY)
|
||||
break;
|
||||
{
|
||||
/* all bytes from s..s+len-1 need to
|
||||
be written out */
|
||||
int done = 0;
|
||||
while (done < len) {
|
||||
int t = dcache->write_memory (db->addr + s + done,
|
||||
db->data + s + done,
|
||||
len - done);
|
||||
if (t == 0)
|
||||
return 0;
|
||||
done += t;
|
||||
}
|
||||
memset (db->state + s, ENTRY_OK, len);
|
||||
s = e;
|
||||
}
|
||||
}
|
||||
}
|
||||
db->anydirty = 0;
|
||||
}
|
||||
return 1;
|
||||
}
|
||||
|
||||
|
||||
/* Get a free cache block, put or keep it on the valid list,
|
||||
and return its address. The caller should store into the block
|
||||
the address and data that it describes, then remque it from the
|
||||
free list and insert it into the valid list. This procedure
|
||||
prevents errors from creeping in if a memory retrieval is
|
||||
interrupted (which used to put garbage blocks in the valid
|
||||
list...). */
|
||||
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||||
static struct dcache_block *
|
||||
dcache_alloc (dcache)
|
||||
DCACHE *dcache;
|
||||
{
|
||||
register struct dcache_block *db;
|
||||
|
||||
if (remote_dcache == 0)
|
||||
abort ();
|
||||
|
||||
/* Take something from the free list */
|
||||
db = dcache->free_head;
|
||||
if (db)
|
||||
{
|
||||
dcache->free_head = db->p;
|
||||
}
|
||||
else
|
||||
{
|
||||
/* Nothing left on free list, so grab one from the valid list */
|
||||
db = dcache->valid_head;
|
||||
dcache->valid_head = db->p;
|
||||
|
||||
dcache_write_line (dcache, db);
|
||||
}
|
||||
|
||||
/* append this line to end of valid list */
|
||||
if (!dcache->valid_head)
|
||||
dcache->valid_head = db;
|
||||
else
|
||||
dcache->valid_tail->p = db;
|
||||
dcache->valid_tail = db;
|
||||
db->p = 0;
|
||||
|
||||
return db;
|
||||
}
|
||||
|
||||
/* Using the data cache DCACHE return the contents of the byte at
|
||||
address ADDR in the remote machine.
|
||||
|
||||
Returns 0 on error. */
|
||||
|
||||
static int
|
||||
dcache_peek_byte (dcache, addr, ptr)
|
||||
DCACHE *dcache;
|
||||
CORE_ADDR addr;
|
||||
char *ptr;
|
||||
{
|
||||
register struct dcache_block *db = dcache_hit (dcache, addr);
|
||||
int ok=1;
|
||||
int done = 0;
|
||||
if (db == 0
|
||||
|| db->state[XFORM (addr)] == ENTRY_BAD)
|
||||
{
|
||||
if (db)
|
||||
{
|
||||
dcache_write_line (dcache, db);
|
||||
}
|
||||
else
|
||||
db = dcache_alloc (dcache);
|
||||
immediate_quit++;
|
||||
db->addr = MASK (addr);
|
||||
while (done < LINE_SIZE)
|
||||
{
|
||||
int try =
|
||||
(*dcache->read_memory)
|
||||
(db->addr + done,
|
||||
db->data + done,
|
||||
LINE_SIZE - done);
|
||||
if (try == 0)
|
||||
return 0;
|
||||
done += try;
|
||||
}
|
||||
immediate_quit--;
|
||||
|
||||
memset (db->state, ENTRY_OK, sizeof (db->data));
|
||||
db->anydirty = 0;
|
||||
}
|
||||
*ptr = db->data[XFORM (addr)];
|
||||
return ok;
|
||||
}
|
||||
|
||||
/* Writeback any dirty lines to the remote. */
|
||||
static int
|
||||
dcache_writeback (dcache)
|
||||
DCACHE *dcache;
|
||||
{
|
||||
struct dcache_block *db;
|
||||
|
||||
db = dcache->valid_head;
|
||||
|
||||
while (db)
|
||||
{
|
||||
if (!dcache_write_line (dcache, db))
|
||||
return 0;
|
||||
db = db->p;
|
||||
}
|
||||
return 1;
|
||||
}
|
||||
|
||||
|
||||
/* Using the data cache DCACHE return the contents of the word at
|
||||
address ADDR in the remote machine. */
|
||||
int
|
||||
dcache_fetch (dcache, addr)
|
||||
DCACHE *dcache;
|
||||
CORE_ADDR addr;
|
||||
{
|
||||
int res;
|
||||
|
||||
if (dcache_xfer_memory (dcache, addr, (char *)&res, sizeof res, 0) != sizeof res)
|
||||
memory_error (EIO, addr);
|
||||
|
||||
return res;
|
||||
}
|
||||
|
||||
|
||||
/* Write the byte at PTR into ADDR in the data cache.
|
||||
Return zero on write error.
|
||||
*/
|
||||
|
||||
static int
|
||||
dcache_poke_byte (dcache, addr, ptr)
|
||||
DCACHE *dcache;
|
||||
CORE_ADDR addr;
|
||||
char *ptr;
|
||||
{
|
||||
register struct dcache_block *db = dcache_hit (dcache, addr);
|
||||
|
||||
if (!db)
|
||||
{
|
||||
db = dcache_alloc (dcache);
|
||||
db->addr = MASK (addr);
|
||||
memset (db->state, ENTRY_BAD, sizeof (db->data));
|
||||
}
|
||||
|
||||
db->data[XFORM (addr)] = *ptr;
|
||||
db->state[XFORM (addr)] = ENTRY_DIRTY;
|
||||
db->anydirty = 1;
|
||||
return 1;
|
||||
}
|
||||
|
||||
/* Write the word at ADDR both in the data cache and in the remote machine.
|
||||
Return zero on write error.
|
||||
*/
|
||||
|
||||
int
|
||||
dcache_poke (dcache, addr, data)
|
||||
DCACHE *dcache;
|
||||
CORE_ADDR addr;
|
||||
int data;
|
||||
{
|
||||
if (dcache_xfer_memory (dcache, addr, (char *)&data, sizeof data, 1) != sizeof data)
|
||||
return 0;
|
||||
|
||||
return dcache_writeback (dcache);
|
||||
}
|
||||
|
||||
|
||||
/* Initialize the data cache. */
|
||||
DCACHE *
|
||||
dcache_init (reading, writing)
|
||||
memxferfunc reading;
|
||||
memxferfunc writing;
|
||||
{
|
||||
int csize = sizeof (struct dcache_block) * DCACHE_SIZE;
|
||||
DCACHE *dcache;
|
||||
|
||||
dcache = (DCACHE *) xmalloc (sizeof (*dcache));
|
||||
dcache->read_memory = reading;
|
||||
dcache->write_memory = writing;
|
||||
|
||||
dcache->the_cache = (struct dcache_block *) xmalloc (csize);
|
||||
memset (dcache->the_cache, 0, csize);
|
||||
|
||||
dcache_flush (dcache);
|
||||
|
||||
last_cache = dcache;
|
||||
return 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.
|
||||
|
||||
Returns length of data written or read; 0 for error.
|
||||
|
||||
This routine is indended to be called by remote_xfer_ functions. */
|
||||
|
||||
int
|
||||
dcache_xfer_memory (dcache, memaddr, myaddr, len, should_write)
|
||||
DCACHE *dcache;
|
||||
CORE_ADDR memaddr;
|
||||
char *myaddr;
|
||||
int len;
|
||||
int should_write;
|
||||
{
|
||||
int i;
|
||||
|
||||
if (remote_dcache)
|
||||
{
|
||||
int (*xfunc) PARAMS ((DCACHE *dcache, CORE_ADDR addr, char *ptr));
|
||||
xfunc = should_write ? dcache_poke_byte : dcache_peek_byte;
|
||||
|
||||
for (i = 0; i < len; i++)
|
||||
{
|
||||
if (!xfunc (dcache, memaddr + i, myaddr + i))
|
||||
return 0;
|
||||
}
|
||||
dcache->cache_has_stuff = 1;
|
||||
dcache_writeback (dcache);
|
||||
}
|
||||
else
|
||||
{
|
||||
memxferfunc xfunc;
|
||||
xfunc = should_write ? dcache->write_memory : dcache->read_memory;
|
||||
|
||||
if (dcache->cache_has_stuff)
|
||||
dcache_flush (dcache);
|
||||
|
||||
len = xfunc (memaddr, myaddr, len);
|
||||
}
|
||||
return len;
|
||||
}
|
||||
|
||||
static void
|
||||
dcache_info (exp, tty)
|
||||
char *exp;
|
||||
int tty;
|
||||
{
|
||||
struct dcache_block *p;
|
||||
|
||||
if (!remote_dcache)
|
||||
{
|
||||
printf_filtered ("Dcache not enabled\n");
|
||||
return;
|
||||
}
|
||||
printf_filtered ("Dcache enabled, line width %d, depth %d\n",
|
||||
LINE_SIZE, DCACHE_SIZE);
|
||||
|
||||
printf_filtered ("Cache state:\n");
|
||||
|
||||
for (p = last_cache->valid_head; p; p = p->p)
|
||||
{
|
||||
int j;
|
||||
printf_filtered ("Line at %08xd, referenced %d times\n",
|
||||
p->addr, p->refs);
|
||||
|
||||
for (j = 0; j < LINE_SIZE; j++)
|
||||
printf_filtered ("%02x", p->data[j] & 0xFF);
|
||||
printf_filtered ("\n");
|
||||
|
||||
for (j = 0; j < LINE_SIZE; j++)
|
||||
printf_filtered (" %2x", p->state[j]);
|
||||
printf_filtered ("\n");
|
||||
}
|
||||
}
|
||||
|
||||
void
|
||||
_initialize_dcache ()
|
||||
{
|
||||
add_show_from_set
|
||||
(add_set_cmd ("remotecache", class_support, var_boolean,
|
||||
(char *) &remote_dcache,
|
||||
"\
|
||||
Set cache use for remote targets.\n\
|
||||
When on, use data caching for remote targets. For many remote targets\n\
|
||||
this option can offer better throughput for reading target memory.\n\
|
||||
Unfortunately, gdb does not currently know anything about volatile\n\
|
||||
registers and thus data caching will produce incorrect results with\n\
|
||||
volatile registers are in use. By default, this option is on.",
|
||||
&setlist),
|
||||
&showlist);
|
||||
|
||||
add_info ("dcache", dcache_info,
|
||||
"Print information on the dcache performance.");
|
||||
|
||||
}
|
||||
Reference in New Issue
Block a user