/* 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.
+ Copyright (C) 1992-2020 Free Software Foundation, Inc.
This file is part of GDB.
#include "defs.h"
#include "dcache.h"
#include "gdbcmd.h"
-#include "gdb_string.h"
#include "gdbcore.h"
-#include "target.h"
+#include "target-dcache.h"
+#include "inferior.h"
#include "splay-tree.h"
+#include "gdbarch.h"
+
+/* Commands with a prefix of `{set,show} dcache'. */
+static struct cmd_list_element *dcache_set_list = NULL;
+static struct cmd_list_element *dcache_show_list = NULL;
/* The data cache could lead to incorrect results because it doesn't
know about volatile variables, thus making it impossible to debug
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.
+ Each block caches a LINE_SIZE area of memory. Within 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.
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
+ This doesn't occur very often. The most common occurrence 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
/* The maximum number of lines stored. The total size of the cache is
equal to DCACHE_SIZE times LINE_SIZE. */
-#define DCACHE_SIZE 4096
+#define DCACHE_DEFAULT_SIZE 4096
+static unsigned dcache_size = DCACHE_DEFAULT_SIZE;
-/* The size of a cache line. Smaller values reduce the time taken to
+/* The default 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)
+#define DCACHE_DEFAULT_LINE_SIZE 64
+static unsigned dcache_line_size = DCACHE_DEFAULT_LINE_SIZE;
/* 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 LINE_SIZE_MASK(dcache) ((dcache->line_size - 1))
+#define XFORM(dcache, x) ((x) & LINE_SIZE_MASK (dcache))
+#define MASK(dcache, x) ((x) & ~LINE_SIZE_MASK (dcache))
struct dcache_block
{
- struct dcache_block *newer; /* for LRU and free list */
+ /* For least-recently-allocated and free lists. */
+ struct dcache_block *prev;
+ struct dcache_block *next;
+
CORE_ADDR addr; /* address of data */
- gdb_byte data[LINE_SIZE]; /* bytes at given address */
int refs; /* # hits */
+ gdb_byte data[1]; /* line_size bytes at given address */
};
struct dcache_struct
{
splay_tree tree;
- struct dcache_block *oldest;
- struct dcache_block *newest;
+ struct dcache_block *oldest; /* least-recently-allocated list. */
+ /* The free list is maintained identically to OLDEST to simplify
+ the code: we only need one set of accessors. */
struct dcache_block *freelist;
/* The number of in-use lines in the cache. */
int size;
+ CORE_ADDR line_size; /* current line_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);
+typedef void (block_func) (struct dcache_block *block, void *param);
-static int dcache_write_line (DCACHE *dcache, struct dcache_block *db);
+static struct dcache_block *dcache_hit (DCACHE *dcache, CORE_ADDR addr);
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;
+static bool dcache_enabled_p = false; /* 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, _("Cache use for remote targets is %s.\n"), value);
+ fprintf_filtered (file, _("Deprecated remotecache flag is %s.\n"), value);
+}
+
+/* Add BLOCK to circular block list BLIST, behind the block at *BLIST.
+ *BLIST is not updated (unless it was previously NULL of course).
+ This is for the least-recently-allocated list's sake:
+ BLIST points to the oldest block.
+ ??? This makes for poor cache usage of the free list,
+ but is it measurable? */
+
+static void
+append_block (struct dcache_block **blist, struct dcache_block *block)
+{
+ if (*blist)
+ {
+ block->next = *blist;
+ block->prev = (*blist)->prev;
+ block->prev->next = block;
+ (*blist)->prev = block;
+ /* We don't update *BLIST here to maintain the invariant that for the
+ least-recently-allocated list *BLIST points to the oldest block. */
+ }
+ else
+ {
+ block->next = block;
+ block->prev = block;
+ *blist = block;
+ }
}
+/* Remove BLOCK from circular block list BLIST. */
-static DCACHE *last_cache; /* Used by info dcache */
+static void
+remove_block (struct dcache_block **blist, struct dcache_block *block)
+{
+ if (block->next == block)
+ {
+ *blist = NULL;
+ }
+ else
+ {
+ block->next->prev = block->prev;
+ block->prev->next = block->next;
+ /* If we removed the block *BLIST points to, shift it to the next block
+ to maintain the invariant that for the least-recently-allocated list
+ *BLIST points to the oldest block. */
+ if (*blist == block)
+ *blist = block->next;
+ }
+}
+
+/* Iterate over all elements in BLIST, calling FUNC.
+ PARAM is passed to FUNC.
+ FUNC may remove the block it's passed, but only that block. */
+
+static void
+for_each_block (struct dcache_block **blist, block_func *func, void *param)
+{
+ struct dcache_block *db;
+
+ if (*blist == NULL)
+ return;
+
+ db = *blist;
+ do
+ {
+ struct dcache_block *next = db->next;
+
+ func (db, param);
+ db = next;
+ }
+ while (*blist && db != *blist);
+}
+
+/* BLOCK_FUNC routine for dcache_free. */
+
+static void
+free_block (struct dcache_block *block, void *param)
+{
+ xfree (block);
+}
+
+/* Free a data cache. */
+
+void
+dcache_free (DCACHE *dcache)
+{
+ splay_tree_delete (dcache->tree);
+ for_each_block (&dcache->oldest, free_block, NULL);
+ for_each_block (&dcache->freelist, free_block, NULL);
+ xfree (dcache);
+}
+
+
+/* BLOCK_FUNC function for dcache_invalidate.
+ This doesn't remove the block from the oldest list on purpose.
+ dcache_invalidate will do it later. */
+
+static void
+invalidate_block (struct dcache_block *block, void *param)
+{
+ DCACHE *dcache = (DCACHE *) param;
+
+ splay_tree_remove (dcache->tree, (splay_tree_key) block->addr);
+ append_block (&dcache->freelist, block);
+}
/* Free all the data cache blocks, thus discarding all cached data. */
void
dcache_invalidate (DCACHE *dcache)
{
- struct dcache_block *block, *next;
+ for_each_block (&dcache->oldest, invalidate_block, dcache);
- block = dcache->oldest;
+ dcache->oldest = NULL;
+ dcache->size = 0;
+ dcache->ptid = null_ptid;
- while (block)
+ if (dcache->line_size != dcache_line_size)
{
- splay_tree_remove (dcache->tree, (splay_tree_key) block->addr);
- next = block->newer;
+ /* We've been asked to use a different line size.
+ All of our freelist blocks are now the wrong size, so free them. */
- block->newer = dcache->freelist;
- dcache->freelist = block;
-
- block = next;
+ for_each_block (&dcache->freelist, free_block, dcache);
+ dcache->freelist = NULL;
+ dcache->line_size = dcache_line_size;
}
+}
- dcache->oldest = NULL;
- dcache->newest = NULL;
- dcache->size = 0;
+/* 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);
+ remove_block (&dcache->oldest, db);
+ append_block (&dcache->freelist, db);
+ --dcache->size;
+ }
}
/* If addr is present in the dcache, return the address of the block
- containing it. */
+ containing it. Otherwise return NULL. */
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));
+ (splay_tree_key) MASK (dcache, addr));
if (!node)
return NULL;
return db;
}
-/* Fill a cache line from target memory. */
+/* Fill a cache line from target memory.
+ The result is 1 for success, 0 if the (entire) cache line
+ wasn't readable. */
static int
dcache_read_line (DCACHE *dcache, struct dcache_block *db)
int reg_len;
struct mem_region *region;
- len = LINE_SIZE;
+ len = dcache->line_size;
memaddr = db->addr;
myaddr = db->data;
else
reg_len = region->hi - memaddr;
- /* Skip non-cacheable/non-readable regions. */
- if (!region->attrib.cache || region->attrib.mode == MEM_WO)
+ /* 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)
+
+ res = target_read_raw_memory (memaddr, myaddr, reg_len);
+ if (res != 0)
return 0;
- memaddr += res;
- myaddr += res;
- len -= res;
+ memaddr += reg_len;
+ myaddr += reg_len;
+ len -= reg_len;
}
return 1;
{
struct dcache_block *db;
- if (dcache->size >= DCACHE_SIZE)
+ if (dcache->size >= dcache_size)
{
- /* Evict the least recently used line. */
+ /* Evict the least recently allocated line. */
db = dcache->oldest;
- dcache->oldest = db->newer;
+ remove_block (&dcache->oldest, db);
splay_tree_remove (dcache->tree, (splay_tree_key) db->addr);
}
{
db = dcache->freelist;
if (db)
- dcache->freelist = db->newer;
+ remove_block (&dcache->freelist, db);
else
- db = xmalloc (sizeof (struct dcache_block));
+ db = ((struct dcache_block *)
+ xmalloc (offsetof (struct dcache_block, data)
+ + dcache->line_size));
dcache->size++;
}
- db->addr = MASK (addr);
- db->newer = NULL;
+ db->addr = MASK (dcache, addr);
db->refs = 0;
- if (dcache->newest)
- dcache->newest->newer = db;
-
- dcache->newest = db;
-
- if (!dcache->oldest)
- dcache->oldest = db;
+ /* Put DB at the end of the list, it's the newest. */
+ append_block (&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
+/* Using the data cache DCACHE, store in *PTR the contents of the byte at
address ADDR in the remote machine.
Returns 1 for success, 0 for error. */
return 0;
}
- *ptr = db->data[XFORM (addr)];
+ *ptr = db->data[XFORM (dcache, 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.
+ The caller should have written the data through to target memory
+ already.
- Always return 1 to simplify dcache_xfer_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. */
-static int
-dcache_poke_byte (DCACHE *dcache, CORE_ADDR addr, gdb_byte *ptr)
+static void
+dcache_poke_byte (DCACHE *dcache, CORE_ADDR addr, const gdb_byte *ptr)
{
struct dcache_block *db = dcache_hit (dcache, addr);
if (db)
- db->data[XFORM (addr)] = *ptr;
-
- return 1;
+ db->data[XFORM (dcache, addr)] = *ptr;
}
static int
return -1;
}
-/* Initialize the data cache. */
+/* Allocate and initialize a data cache. */
DCACHE *
dcache_init (void)
{
- DCACHE *dcache;
- int i;
-
- dcache = (DCACHE *) xmalloc (sizeof (*dcache));
+ DCACHE *dcache = XNEW (DCACHE);
dcache->tree = splay_tree_new (dcache_splay_tree_compare,
NULL,
NULL);
dcache->oldest = NULL;
- dcache->newest = NULL;
dcache->freelist = NULL;
dcache->size = 0;
- last_cache = dcache;
+ dcache->line_size = dcache_line_size;
+ dcache->ptid = null_ptid;
return dcache;
}
-/* Free a data cache. */
-void
-dcache_free (DCACHE *dcache)
+/* Read LEN bytes from dcache memory at MEMADDR, transferring to
+ debugger address MYADDR. If the data is presently cached, this
+ fills the cache. Arguments/return are like the target_xfer_partial
+ interface. */
+
+enum target_xfer_status
+dcache_read_memory_partial (struct target_ops *ops, DCACHE *dcache,
+ CORE_ADDR memaddr, gdb_byte *myaddr,
+ ULONGEST len, ULONGEST *xfered_len)
{
- struct dcache_block *db, *next;
+ ULONGEST i;
- if (last_cache == dcache)
- last_cache = NULL;
+ /* If this is a different inferior from what we've recorded,
+ flush the cache. */
- splay_tree_delete (dcache->tree);
- for (db = dcache->freelist; db != NULL; db = next)
+ if (inferior_ptid != dcache->ptid)
{
- next = db->newer;
- xfree (db);
+ dcache_invalidate (dcache);
+ dcache->ptid = inferior_ptid;
}
- 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.
-
- Returns length of data written or read; 0 for error. */
-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;
-
- /* Do write-through first, so that if it fails, we don't write to
- the cache at all. */
+ for (i = 0; i < len; i++)
+ {
+ if (!dcache_peek_byte (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);
+ break;
+ }
+ }
- if (should_write)
+ if (i == 0)
{
- res = target_write (ops, TARGET_OBJECT_RAW_MEMORY,
- NULL, myaddr, memaddr, len);
- if (res < len)
- return 0;
+ /* Even though reading the whole line failed, we may be able to
+ read a piece starting where the caller wanted. */
+ return raw_memory_xfer_partial (ops, myaddr, NULL, memaddr, len,
+ xfered_len);
}
-
- for (i = 0; i < len; i++)
+ else
{
- if (!xfunc (dcache, memaddr + i, myaddr + i))
- return 0;
+ *xfered_len = i;
+ return TARGET_XFER_OK;
}
-
- return len;
}
/* FIXME: There would be some benefit to making the cache write-back and
"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 the target_xfer_partial machinery when writing raw
+ memory. */
+
+void
+dcache_update (DCACHE *dcache, enum target_xfer_status status,
+ CORE_ADDR memaddr, const gdb_byte *myaddr,
+ ULONGEST len)
+{
+ ULONGEST i;
+
+ for (i = 0; i < len; i++)
+ if (status == TARGET_XFER_OK)
+ dcache_poke_byte (dcache, memaddr + i, myaddr + i);
+ else
+ {
+ /* Discard the whole cache line so we don't have a partially
+ valid line. */
+ dcache_invalidate_line (dcache, memaddr + i);
+ }
+}
+
+/* Print DCACHE line INDEX. */
+
static void
-dcache_print_line (int index)
+dcache_print_line (DCACHE *dcache, int index)
{
splay_tree_node n;
struct dcache_block *db;
int i, j;
- if (!last_cache)
+ if (dcache == NULL)
{
printf_filtered (_("No data cache available.\n"));
return;
}
- n = splay_tree_min (last_cache->tree);
+ n = splay_tree_min (dcache->tree);
for (i = index; i > 0; --i)
{
if (!n)
break;
- n = splay_tree_successor (last_cache->tree, n->key);
+ n = splay_tree_successor (dcache->tree, n->key);
}
if (!n)
db = (struct dcache_block *) n->value;
- printf_filtered (_("Line %d: address %lx [%d hits]\n"),
- index, db->addr, db->refs);
+ printf_filtered (_("Line %d: address %s [%d hits]\n"),
+ index, paddress (target_gdbarch (), db->addr), db->refs);
- for (j = 0; j < LINE_SIZE; j++)
+ for (j = 0; j < dcache->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))
+ /* Print a newline every 16 bytes (48 characters). */
+ if ((j % 16 == 15) && (j != dcache->line_size - 1))
printf_filtered ("\n");
}
printf_filtered ("\n");
}
+/* Parse EXP and show the info about DCACHE. */
+
static void
-dcache_info (char *exp, int tty)
+dcache_info_1 (DCACHE *dcache, const char *exp)
{
splay_tree_node n;
- int i, refcount, lineno;
+ int i, refcount;
if (exp)
{
char *linestart;
+
i = strtol (exp, &linestart, 10);
if (linestart == exp || i < 0)
{
- printf_filtered (_("Usage: info dcache [linenumber]\n"));
+ printf_filtered (_("Usage: info dcache [LINENUMBER]\n"));
return;
}
- dcache_print_line (i);
+ dcache_print_line (dcache, i);
return;
}
- printf_filtered (_("Dcache line width %d, maximum size %d\n"),
- LINE_SIZE, DCACHE_SIZE);
+ printf_filtered (_("Dcache %u lines of %u bytes each.\n"),
+ dcache_size,
+ dcache ? (unsigned) dcache->line_size
+ : dcache_line_size);
- if (!last_cache)
+ if (dcache == NULL || dcache->ptid == null_ptid)
{
printf_filtered (_("No data cache available.\n"));
return;
}
+ printf_filtered (_("Contains data for %s\n"),
+ target_pid_to_str (dcache->ptid).c_str ());
+
refcount = 0;
- n = splay_tree_min (last_cache->tree);
+ n = splay_tree_min (dcache->tree);
i = 0;
while (n)
{
struct dcache_block *db = (struct dcache_block *) n->value;
- printf_filtered (_("Line %d: address %lx [%d hits]\n"),
- i, db->addr, db->refs);
+ 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);
+ n = splay_tree_successor (dcache->tree, n->key);
}
printf_filtered (_("Cache state: %d active lines, %d hits\n"), i, refcount);
}
+static void
+info_dcache_command (const char *exp, int tty)
+{
+ dcache_info_1 (target_dcache_get (), exp);
+}
+
+static void
+set_dcache_size (const char *args, int from_tty,
+ struct cmd_list_element *c)
+{
+ if (dcache_size == 0)
+ {
+ dcache_size = DCACHE_DEFAULT_SIZE;
+ error (_("Dcache size must be greater than 0."));
+ }
+ target_dcache_invalidate ();
+}
+
+static void
+set_dcache_line_size (const char *args, int from_tty,
+ struct cmd_list_element *c)
+{
+ if (dcache_line_size < 2
+ || (dcache_line_size & (dcache_line_size - 1)) != 0)
+ {
+ unsigned d = dcache_line_size;
+ dcache_line_size = DCACHE_DEFAULT_LINE_SIZE;
+ error (_("Invalid dcache line size: %u (must be power of 2)."), d);
+ }
+ target_dcache_invalidate ();
+}
+
+void _initialize_dcache ();
void
-_initialize_dcache (void)
+_initialize_dcache ()
{
add_setshow_boolean_cmd ("remotecache", class_support,
&dcache_enabled_p, _("\
Set cache use for remote targets."), _("\
Show cache use for remote targets."), _("\
-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 off."),
+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,
+ add_info ("dcache", info_dcache_command,
_("\
Print information on the dcache performance.\n\
+Usage: info dcache [LINENUMBER]\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."));
+summary of each line in the cache. With an argument, dump\"\n\
+the contents of the given line."));
+
+ add_basic_prefix_cmd ("dcache", class_obscure, _("\
+Use this command to set number of lines in dcache and line-size."),
+ &dcache_set_list, "set dcache ", /*allow_unknown*/0,
+ &setlist);
+ add_show_prefix_cmd ("dcache", class_obscure, _("\
+Show dcachesettings."),
+ &dcache_show_list, "show dcache ", /*allow_unknown*/0,
+ &showlist);
+
+ add_setshow_zuinteger_cmd ("line-size", class_obscure,
+ &dcache_line_size, _("\
+Set dcache line size in bytes (must be power of 2)."), _("\
+Show dcache line size."),
+ NULL,
+ set_dcache_line_size,
+ NULL,
+ &dcache_set_list, &dcache_show_list);
+ add_setshow_zuinteger_cmd ("size", class_obscure,
+ &dcache_size, _("\
+Set number of dcache lines."), _("\
+Show number of dcache lines."),
+ NULL,
+ set_dcache_size,
+ NULL,
+ &dcache_set_list, &dcache_show_list);
}
projects / thirdparty / binutils-gdb.git / blobdiff