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rbtree: Add generic add and find helpers

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I've always been bothered by the endless (fragile) boilerplate for
rbtree, and I recently wrote some rbtree helpers for objtool and
figured I should lift them into the kernel and use them more widely.

Provide:

partial-order; less() based:
 - rb_add(): add a new entry to the rbtree
 - rb_add_cached(): like rb_add(), but for a rb_root_cached

total-order; cmp() based:
 - rb_find(): find an entry in an rbtree
 - rb_find_add(): find an entry, and add if not found

 - rb_find_first(): find the first (leftmost) matching entry
 - rb_next_match(): continue from rb_find_first()
 - rb_for_each(): iterate a sub-tree using the previous two

Inlining and constant propagation should see the compiler inline the
whole thing, including the various compare functions.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Michel Lespinasse <walken@google.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
This commit is contained in:
Peter Zijlstra 2020-04-29 17:03:22 +02:00 • committed by Ingo Molnar
parent 9fe1f127b9
commit 2d24dd5798
3 changed files with 392 additions and 63 deletions
Download patch file Download diff file Expand all files Collapse all files

73
tools/objtool/elf.c
View file

@ -43,75 +43,24 @@ static void elf_hash_init(struct hlist_head *table)
#define elf_hash_for_each_possible(name, obj, member, key) \
hlist_for_each_entry(obj, &name[hash_min(key, elf_hash_bits())], member)
static void rb_add(struct rb_root *tree, struct rb_node *node,
int (*cmp)(struct rb_node *, const struct rb_node *))
{
struct rb_node **link = &tree->rb_node;
struct rb_node *parent = NULL;
while (*link) {
parent = *link;
if (cmp(node, parent) < 0)
link = &parent->rb_left;
else
link = &parent->rb_right;
}
rb_link_node(node, parent, link);
rb_insert_color(node, tree);
}
static struct rb_node *rb_find_first(const struct rb_root *tree, const void *key,
int (*cmp)(const void *key, const struct rb_node *))
{
struct rb_node *node = tree->rb_node;
struct rb_node *match = NULL;
while (node) {
int c = cmp(key, node);
if (c <= 0) {
if (!c)
match = node;
node = node->rb_left;
} else if (c > 0) {
node = node->rb_right;
}
}
return match;
}
static struct rb_node *rb_next_match(struct rb_node *node, const void *key,
int (*cmp)(const void *key, const struct rb_node *))
{
node = rb_next(node);
if (node && cmp(key, node))
node = NULL;
return node;
}
#define rb_for_each(tree, node, key, cmp) \
for ((node) = rb_find_first((tree), (key), (cmp)); \
(node); (node) = rb_next_match((node), (key), (cmp)))
static int symbol_to_offset(struct rb_node *a, const struct rb_node *b)
static bool symbol_to_offset(struct rb_node *a, const struct rb_node *b)
{
struct symbol *sa = rb_entry(a, struct symbol, node);
struct symbol *sb = rb_entry(b, struct symbol, node);
if (sa->offset < sb->offset)
return -1;
return true;
if (sa->offset > sb->offset)
return 1;
return false;
if (sa->len < sb->len)
return -1;
return true;
if (sa->len > sb->len)
return 1;
return false;
sa->alias = sb;
return 0;
return false;
}
static int symbol_by_offset(const void *key, const struct rb_node *node)
@ -165,7 +114,7 @@ struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
{
struct rb_node *node;
rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
struct symbol *s = rb_entry(node, struct symbol, node);
if (s->offset == offset && s->type != STT_SECTION)
@ -179,7 +128,7 @@ struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
{
struct rb_node *node;
rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
struct symbol *s = rb_entry(node, struct symbol, node);
if (s->offset == offset && s->type == STT_FUNC)
@ -193,7 +142,7 @@ struct symbol *find_symbol_containing(const struct section *sec, unsigned long o
{
struct rb_node *node;
rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
struct symbol *s = rb_entry(node, struct symbol, node);
if (s->type != STT_SECTION)
@ -207,7 +156,7 @@ struct symbol *find_func_containing(struct section *sec, unsigned long offset)
{
struct rb_node *node;
rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
rb_for_each(node, &offset, &sec->symbol_tree, symbol_by_offset) {
struct symbol *s = rb_entry(node, struct symbol, node);
if (s->type == STT_FUNC)
@ -442,7 +391,7 @@ static int read_symbols(struct elf *elf)
sym->offset = sym->sym.st_value;
sym->len = sym->sym.st_size;
rb_add(&sym->sec->symbol_tree, &sym->node, symbol_to_offset);
rb_add(&sym->node, &sym->sec->symbol_tree, symbol_to_offset);
pnode = rb_prev(&sym->node);
if (pnode)
entry = &rb_entry(pnode, struct symbol, node)->list;