/* addrmap.c --- implementation of address map data structure. Copyright (C) 2007-2021 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 . */ #include "defs.h" #include "splay-tree.h" #include "gdb_obstack.h" #include "addrmap.h" #include "gdbsupport/selftest.h" /* Make sure splay trees can actually hold the values we want to store in them. */ gdb_static_assert (sizeof (splay_tree_key) >= sizeof (CORE_ADDR *)); gdb_static_assert (sizeof (splay_tree_value) >= sizeof (void *)); /* The "abstract class". */ /* Functions implementing the addrmap functions for a particular implementation. */ struct addrmap_funcs { void (*set_empty) (struct addrmap *self, CORE_ADDR start, CORE_ADDR end_inclusive, void *obj); void *(*find) (struct addrmap *self, CORE_ADDR addr); struct addrmap *(*create_fixed) (struct addrmap *self, struct obstack *obstack); void (*relocate) (struct addrmap *self, CORE_ADDR offset); int (*foreach) (struct addrmap *self, addrmap_foreach_fn fn); }; struct addrmap { const struct addrmap_funcs *funcs; }; void addrmap_set_empty (struct addrmap *map, CORE_ADDR start, CORE_ADDR end_inclusive, void *obj) { map->funcs->set_empty (map, start, end_inclusive, obj); } void * addrmap_find (struct addrmap *map, CORE_ADDR addr) { return map->funcs->find (map, addr); } struct addrmap * addrmap_create_fixed (struct addrmap *original, struct obstack *obstack) { return original->funcs->create_fixed (original, obstack); } /* Relocate all the addresses in MAP by OFFSET. (This can be applied to either mutable or immutable maps.) */ void addrmap_relocate (struct addrmap *map, CORE_ADDR offset) { map->funcs->relocate (map, offset); } int addrmap_foreach (struct addrmap *map, addrmap_foreach_fn fn) { return map->funcs->foreach (map, fn); } /* Fixed address maps. */ /* A transition: a point in an address map where the value changes. The map maps ADDR to VALUE, but if ADDR > 0, it maps ADDR-1 to something else. */ struct addrmap_transition { CORE_ADDR addr; void *value; }; struct addrmap_fixed { struct addrmap addrmap; /* The number of transitions in TRANSITIONS. */ size_t num_transitions; /* An array of transitions, sorted by address. For every point in the map where either ADDR == 0 or ADDR is mapped to one value and ADDR - 1 is mapped to something different, we have an entry here containing ADDR and VALUE. (Note that this means we always have an entry for address 0). */ struct addrmap_transition transitions[1]; }; static void addrmap_fixed_set_empty (struct addrmap *self, CORE_ADDR start, CORE_ADDR end_inclusive, void *obj) { internal_error (__FILE__, __LINE__, "addrmap_fixed_set_empty: " "fixed addrmaps can't be changed\n"); } static void * addrmap_fixed_find (struct addrmap *self, CORE_ADDR addr) { struct addrmap_fixed *map = (struct addrmap_fixed *) self; struct addrmap_transition *bottom = &map->transitions[0]; struct addrmap_transition *top = &map->transitions[map->num_transitions - 1]; while (bottom < top) { /* This needs to round towards top, or else when top = bottom + 1 (i.e., two entries are under consideration), then mid == bottom, and then we may not narrow the range when (mid->addr < addr). */ struct addrmap_transition *mid = top - (top - bottom) / 2; if (mid->addr == addr) { bottom = mid; break; } else if (mid->addr < addr) /* We don't eliminate mid itself here, since each transition covers all subsequent addresses until the next. This is why we must round up in computing the midpoint. */ bottom = mid; else top = mid - 1; } return bottom->value; } static struct addrmap * addrmap_fixed_create_fixed (struct addrmap *self, struct obstack *obstack) { internal_error (__FILE__, __LINE__, _("addrmap_create_fixed is not implemented yet " "for fixed addrmaps")); } static void addrmap_fixed_relocate (struct addrmap *self, CORE_ADDR offset) { struct addrmap_fixed *map = (struct addrmap_fixed *) self; size_t i; for (i = 0; i < map->num_transitions; i++) map->transitions[i].addr += offset; } static int addrmap_fixed_foreach (struct addrmap *self, addrmap_foreach_fn fn) { struct addrmap_fixed *map = (struct addrmap_fixed *) self; size_t i; for (i = 0; i < map->num_transitions; i++) { int res = fn (map->transitions[i].addr, map->transitions[i].value); if (res != 0) return res; } return 0; } static const struct addrmap_funcs addrmap_fixed_funcs = { addrmap_fixed_set_empty, addrmap_fixed_find, addrmap_fixed_create_fixed, addrmap_fixed_relocate, addrmap_fixed_foreach }; /* Mutable address maps. */ struct addrmap_mutable { struct addrmap addrmap; /* The obstack to use for allocations for this map. */ struct obstack *obstack; /* A splay tree, with a node for each transition; there is a transition at address T if T-1 and T map to different objects. Any addresses below the first node map to NULL. (Unlike fixed maps, we have no entry at (CORE_ADDR) 0; it doesn't simplify enough.) The last region is assumed to end at CORE_ADDR_MAX. Since we can't know whether CORE_ADDR is larger or smaller than splay_tree_key (unsigned long) --- I think both are possible, given all combinations of 32- and 64-bit hosts and targets --- our keys are pointers to CORE_ADDR values. Since the splay tree library doesn't pass any closure pointer to the key free function, we can't keep a freelist for keys. Since mutable addrmaps are only used temporarily right now, we just leak keys from deleted nodes; they'll be freed when the obstack is freed. */ splay_tree tree; /* A freelist for splay tree nodes, allocated on obstack, and chained together by their 'right' pointers. */ splay_tree_node free_nodes; }; /* Allocate a copy of CORE_ADDR in MAP's obstack. */ static splay_tree_key allocate_key (struct addrmap_mutable *map, CORE_ADDR addr) { CORE_ADDR *key = XOBNEW (map->obstack, CORE_ADDR); *key = addr; return (splay_tree_key) key; } /* Type-correct wrappers for splay tree access. */ static splay_tree_node addrmap_splay_tree_lookup (struct addrmap_mutable *map, CORE_ADDR addr) { return splay_tree_lookup (map->tree, (splay_tree_key) &addr); } static splay_tree_node addrmap_splay_tree_predecessor (struct addrmap_mutable *map, CORE_ADDR addr) { return splay_tree_predecessor (map->tree, (splay_tree_key) &addr); } static splay_tree_node addrmap_splay_tree_successor (struct addrmap_mutable *map, CORE_ADDR addr) { return splay_tree_successor (map->tree, (splay_tree_key) &addr); } static void addrmap_splay_tree_remove (struct addrmap_mutable *map, CORE_ADDR addr) { splay_tree_remove (map->tree, (splay_tree_key) &addr); } static CORE_ADDR addrmap_node_key (splay_tree_node node) { return * (CORE_ADDR *) node->key; } static void * addrmap_node_value (splay_tree_node node) { return (void *) node->value; } static void addrmap_node_set_value (splay_tree_node node, void *value) { node->value = (splay_tree_value) value; } static void addrmap_splay_tree_insert (struct addrmap_mutable *map, CORE_ADDR key, void *value) { splay_tree_insert (map->tree, allocate_key (map, key), (splay_tree_value) value); } /* Without changing the mapping of any address, ensure that there is a tree node at ADDR, even if it would represent a "transition" from one value to the same value. */ static void force_transition (struct addrmap_mutable *self, CORE_ADDR addr) { splay_tree_node n = addrmap_splay_tree_lookup (self, addr); if (! n) { n = addrmap_splay_tree_predecessor (self, addr); addrmap_splay_tree_insert (self, addr, n ? addrmap_node_value (n) : NULL); } } static void addrmap_mutable_set_empty (struct addrmap *self, CORE_ADDR start, CORE_ADDR end_inclusive, void *obj) { struct addrmap_mutable *map = (struct addrmap_mutable *) self; splay_tree_node n, next; void *prior_value; /* If we're being asked to set all empty portions of the given address range to empty, then probably the caller is confused. (If that turns out to be useful in some cases, then we can change this to simply return, since overriding NULL with NULL is a no-op.) */ gdb_assert (obj); /* We take a two-pass approach, for simplicity. - Establish transitions where we think we might need them. - First pass: change all NULL regions to OBJ. - Second pass: remove any unnecessary transitions. */ /* Establish transitions at the start and end. */ force_transition (map, start); if (end_inclusive < CORE_ADDR_MAX) force_transition (map, end_inclusive + 1); /* Walk the area, changing all NULL regions to OBJ. */ for (n = addrmap_splay_tree_lookup (map, start), gdb_assert (n); n && addrmap_node_key (n) <= end_inclusive; n = addrmap_splay_tree_successor (map, addrmap_node_key (n))) { if (! addrmap_node_value (n)) addrmap_node_set_value (n, obj); } /* Walk the area again, removing transitions from any value to itself. Be sure to visit both the transitions we forced above. */ n = addrmap_splay_tree_predecessor (map, start); prior_value = n ? addrmap_node_value (n) : NULL; for (n = addrmap_splay_tree_lookup (map, start), gdb_assert (n); n && (end_inclusive == CORE_ADDR_MAX || addrmap_node_key (n) <= end_inclusive + 1); n = next) { next = addrmap_splay_tree_successor (map, addrmap_node_key (n)); if (addrmap_node_value (n) == prior_value) addrmap_splay_tree_remove (map, addrmap_node_key (n)); else prior_value = addrmap_node_value (n); } } static void * addrmap_mutable_find (struct addrmap *self, CORE_ADDR addr) { struct addrmap_mutable *map = (struct addrmap_mutable *) self; splay_tree_node n = addrmap_splay_tree_lookup (map, addr); if (n != nullptr) { gdb_assert (addrmap_node_key (n) == addr); return addrmap_node_value (n); } n = addrmap_splay_tree_predecessor (map, addr); if (n != nullptr) { gdb_assert (addrmap_node_key (n) < addr); return addrmap_node_value (n); } return nullptr; } /* A function to pass to splay_tree_foreach to count the number of nodes in the tree. */ static int splay_foreach_count (splay_tree_node n, void *closure) { size_t *count = (size_t *) closure; (*count)++; return 0; } /* A function to pass to splay_tree_foreach to copy entries into a fixed address map. */ static int splay_foreach_copy (splay_tree_node n, void *closure) { struct addrmap_fixed *fixed = (struct addrmap_fixed *) closure; struct addrmap_transition *t = &fixed->transitions[fixed->num_transitions]; t->addr = addrmap_node_key (n); t->value = addrmap_node_value (n); fixed->num_transitions++; return 0; } static struct addrmap * addrmap_mutable_create_fixed (struct addrmap *self, struct obstack *obstack) { struct addrmap_mutable *mutable_obj = (struct addrmap_mutable *) self; struct addrmap_fixed *fixed; size_t num_transitions; size_t alloc_len; /* Count the number of transitions in the tree. */ num_transitions = 0; splay_tree_foreach (mutable_obj->tree, splay_foreach_count, &num_transitions); /* Include an extra entry for the transition at zero (which fixed maps have, but mutable maps do not.) */ num_transitions++; alloc_len = sizeof (*fixed) + (num_transitions * sizeof (fixed->transitions[0])); fixed = (struct addrmap_fixed *) obstack_alloc (obstack, alloc_len); fixed->addrmap.funcs = &addrmap_fixed_funcs; fixed->num_transitions = 1; fixed->transitions[0].addr = 0; fixed->transitions[0].value = NULL; /* Copy all entries from the splay tree to the array, in order of increasing address. */ splay_tree_foreach (mutable_obj->tree, splay_foreach_copy, fixed); /* We should have filled the array. */ gdb_assert (fixed->num_transitions == num_transitions); return (struct addrmap *) fixed; } static void addrmap_mutable_relocate (struct addrmap *self, CORE_ADDR offset) { /* Not needed yet. */ internal_error (__FILE__, __LINE__, _("addrmap_relocate is not implemented yet " "for mutable addrmaps")); } /* This is a splay_tree_foreach_fn. */ static int addrmap_mutable_foreach_worker (splay_tree_node node, void *data) { addrmap_foreach_fn *fn = (addrmap_foreach_fn *) data; return (*fn) (addrmap_node_key (node), addrmap_node_value (node)); } static int addrmap_mutable_foreach (struct addrmap *self, addrmap_foreach_fn fn) { struct addrmap_mutable *mutable_obj = (struct addrmap_mutable *) self; return splay_tree_foreach (mutable_obj->tree, addrmap_mutable_foreach_worker, &fn); } static const struct addrmap_funcs addrmap_mutable_funcs = { addrmap_mutable_set_empty, addrmap_mutable_find, addrmap_mutable_create_fixed, addrmap_mutable_relocate, addrmap_mutable_foreach }; static void * splay_obstack_alloc (int size, void *closure) { struct addrmap_mutable *map = (struct addrmap_mutable *) closure; splay_tree_node n; /* We should only be asked to allocate nodes and larger things. (If, at some point in the future, this is no longer true, we can just round up the size to sizeof (*n).) */ gdb_assert (size >= sizeof (*n)); if (map->free_nodes) { n = map->free_nodes; map->free_nodes = n->right; return n; } else return obstack_alloc (map->obstack, size); } static void splay_obstack_free (void *obj, void *closure) { struct addrmap_mutable *map = (struct addrmap_mutable *) closure; splay_tree_node n = (splay_tree_node) obj; /* We've asserted in the allocation function that we only allocate nodes or larger things, so it should be safe to put whatever we get passed back on the free list. */ n->right = map->free_nodes; map->free_nodes = n; } /* Compare keys as CORE_ADDR * values. */ static int splay_compare_CORE_ADDR_ptr (splay_tree_key ak, splay_tree_key bk) { CORE_ADDR a = * (CORE_ADDR *) ak; CORE_ADDR b = * (CORE_ADDR *) bk; /* We can't just return a-b here, because of over/underflow. */ if (a < b) return -1; else if (a == b) return 0; else return 1; } struct addrmap * addrmap_create_mutable (struct obstack *obstack) { struct addrmap_mutable *map = XOBNEW (obstack, struct addrmap_mutable); map->addrmap.funcs = &addrmap_mutable_funcs; map->obstack = obstack; /* splay_tree_new_with_allocator uses the provided allocation function to allocate the main splay_tree structure itself, so our free list has to be initialized before we create the tree. */ map->free_nodes = NULL; map->tree = splay_tree_new_with_allocator (splay_compare_CORE_ADDR_ptr, NULL, /* no delete key */ NULL, /* no delete value */ splay_obstack_alloc, splay_obstack_free, map); return (struct addrmap *) map; } #if GDB_SELF_TEST namespace selftests { /* Convert P to CORE_ADDR. */ static CORE_ADDR core_addr (void *p) { return (CORE_ADDR)(uintptr_t)p; } /* Check that &ARRAY[LOW]..&ARRAY[HIGH] has VAL in MAP. */ #define CHECK_ADDRMAP_FIND(MAP, ARRAY, LOW, HIGH, VAL) \ do \ { \ for (unsigned i = LOW; i <= HIGH; ++i) \ SELF_CHECK (addrmap_find (MAP, core_addr (&ARRAY[i])) == VAL); \ } \ while (0) /* Entry point for addrmap unit tests. */ static void test_addrmap () { /* We'll verify using the addresses of the elements of this array. */ char array[20]; /* We'll verify using these values stored into the map. */ void *val1 = &array[1]; void *val2 = &array[2]; /* Create mutable addrmap. */ struct obstack temp_obstack; obstack_init (&temp_obstack); struct addrmap *map = addrmap_create_mutable (&temp_obstack); SELF_CHECK (map != nullptr); /* Check initial state. */ CHECK_ADDRMAP_FIND (map, array, 0, 19, nullptr); /* Insert address range into mutable addrmap. */ addrmap_set_empty (map, core_addr (&array[10]), core_addr (&array[12]), val1); CHECK_ADDRMAP_FIND (map, array, 0, 9, nullptr); CHECK_ADDRMAP_FIND (map, array, 10, 12, val1); CHECK_ADDRMAP_FIND (map, array, 13, 19, nullptr); /* Create corresponding fixed addrmap. */ struct addrmap *map2 = addrmap_create_fixed (map, &temp_obstack); SELF_CHECK (map2 != nullptr); CHECK_ADDRMAP_FIND (map2, array, 0, 9, nullptr); CHECK_ADDRMAP_FIND (map2, array, 10, 12, val1); CHECK_ADDRMAP_FIND (map2, array, 13, 19, nullptr); /* Iterate over both addrmaps. */ auto callback = [&] (CORE_ADDR start_addr, void *obj) { if (start_addr == core_addr (nullptr)) SELF_CHECK (obj == nullptr); else if (start_addr == core_addr (&array[10])) SELF_CHECK (obj == val1); else if (start_addr == core_addr (&array[13])) SELF_CHECK (obj == nullptr); else SELF_CHECK (false); return 0; }; SELF_CHECK (addrmap_foreach (map, callback) == 0); SELF_CHECK (addrmap_foreach (map2, callback) == 0); /* Relocate fixed addrmap. */ addrmap_relocate (map2, 1); CHECK_ADDRMAP_FIND (map2, array, 0, 10, nullptr); CHECK_ADDRMAP_FIND (map2, array, 11, 13, val1); CHECK_ADDRMAP_FIND (map2, array, 14, 19, nullptr); /* Insert partially overlapping address range into mutable addrmap. */ addrmap_set_empty (map, core_addr (&array[11]), core_addr (&array[13]), val2); CHECK_ADDRMAP_FIND (map, array, 0, 9, nullptr); CHECK_ADDRMAP_FIND (map, array, 10, 12, val1); CHECK_ADDRMAP_FIND (map, array, 13, 13, val2); CHECK_ADDRMAP_FIND (map, array, 14, 19, nullptr); /* Cleanup. */ obstack_free (&temp_obstack, NULL); } } // namespace selftests void _initialize_addrmap (); void _initialize_addrmap () { selftests::register_test ("addrmap", selftests::test_addrmap); } #endif /* GDB_SELF_TEST */