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objtool: Fix find_{symbol,func}_containing() 

The current find_{symbol,func}_containing() functions are broken in
the face of overlapping symbols, exactly the case that is needed for a
new ibt/endbr supression.

Import interval_tree_generic.h into the tools tree and convert the
symbol tree to an interval tree to support proper range stabs.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111146.330203761@infradead.org
This commit is contained in:
Peter Zijlstra 2022-09-15 13:11:12 +02:00
parent 0c0a6d8934
commit 5da6aea375
3 changed files with 230 additions and 55 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

187
tools/include/linux/interval_tree_generic.h Normal file
View File

@ -0,0 +1,187 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
Interval Trees
(C) 2012 Michel Lespinasse <walken@google.com>
include/linux/interval_tree_generic.h
*/
#include <linux/rbtree_augmented.h>
/*
* Template for implementing interval trees
*
* ITSTRUCT: struct type of the interval tree nodes
* ITRB: name of struct rb_node field within ITSTRUCT
* ITTYPE: type of the interval endpoints
* ITSUBTREE: name of ITTYPE field within ITSTRUCT holding last-in-subtree
* ITSTART(n): start endpoint of ITSTRUCT node n
* ITLAST(n): last endpoint of ITSTRUCT node n
* ITSTATIC: 'static' or empty
* ITPREFIX: prefix to use for the inline tree definitions
*
* Note - before using this, please consider if generic version
* (interval_tree.h) would work for you...
*/
#define INTERVAL_TREE_DEFINE(ITSTRUCT, ITRB, ITTYPE, ITSUBTREE, \
ITSTART, ITLAST, ITSTATIC, ITPREFIX) \
\
/* Callbacks for augmented rbtree insert and remove */ \
\
RB_DECLARE_CALLBACKS_MAX(static, ITPREFIX ## _augment, \
ITSTRUCT, ITRB, ITTYPE, ITSUBTREE, ITLAST) \
\
/* Insert / remove interval nodes from the tree */ \
\
ITSTATIC void ITPREFIX ## _insert(ITSTRUCT *node, \
struct rb_root_cached *root) \
{ \
struct rb_node **link = &root->rb_root.rb_node, *rb_parent = NULL; \
ITTYPE start = ITSTART(node), last = ITLAST(node); \
ITSTRUCT *parent; \
bool leftmost = true; \
\
while (*link) { \
rb_parent = *link; \
parent = rb_entry(rb_parent, ITSTRUCT, ITRB); \
if (parent->ITSUBTREE < last) \
parent->ITSUBTREE = last; \
if (start < ITSTART(parent)) \
link = &parent->ITRB.rb_left; \
else { \
link = &parent->ITRB.rb_right; \
leftmost = false; \
} \
} \
\
node->ITSUBTREE = last; \
rb_link_node(&node->ITRB, rb_parent, link); \
rb_insert_augmented_cached(&node->ITRB, root, \
leftmost, &ITPREFIX ## _augment); \
} \
\
ITSTATIC void ITPREFIX ## _remove(ITSTRUCT *node, \
struct rb_root_cached *root) \
{ \
rb_erase_augmented_cached(&node->ITRB, root, &ITPREFIX ## _augment); \
} \
\
/* \
* Iterate over intervals intersecting [start;last] \
* \
* Note that a node's interval intersects [start;last] iff: \
* Cond1: ITSTART(node) <= last \
* and \
* Cond2: start <= ITLAST(node) \
*/ \
\
static ITSTRUCT * \
ITPREFIX ## _subtree_search(ITSTRUCT *node, ITTYPE start, ITTYPE last) \
{ \
while (true) { \
/* \
* Loop invariant: start <= node->ITSUBTREE \
* (Cond2 is satisfied by one of the subtree nodes) \
*/ \
if (node->ITRB.rb_left) { \
ITSTRUCT *left = rb_entry(node->ITRB.rb_left, \
ITSTRUCT, ITRB); \
if (start <= left->ITSUBTREE) { \
/* \
* Some nodes in left subtree satisfy Cond2. \
* Iterate to find the leftmost such node N. \
* If it also satisfies Cond1, that's the \
* match we are looking for. Otherwise, there \
* is no matching interval as nodes to the \
* right of N can't satisfy Cond1 either. \
*/ \
node = left; \
continue; \
} \
} \
if (ITSTART(node) <= last) { /* Cond1 */ \
if (start <= ITLAST(node)) /* Cond2 */ \
return node; /* node is leftmost match */ \
if (node->ITRB.rb_right) { \
node = rb_entry(node->ITRB.rb_right, \
ITSTRUCT, ITRB); \
if (start <= node->ITSUBTREE) \
continue; \
} \
} \
return NULL; /* No match */ \
} \
} \
\
ITSTATIC ITSTRUCT * \
ITPREFIX ## _iter_first(struct rb_root_cached *root, \
ITTYPE start, ITTYPE last) \
{ \
ITSTRUCT *node, *leftmost; \
\
if (!root->rb_root.rb_node) \
return NULL; \
\
/* \
* Fastpath range intersection/overlap between A: [a0, a1] and \
* B: [b0, b1] is given by: \
* \
* a0 <= b1 && b0 <= a1 \
* \
* ... where A holds the lock range and B holds the smallest \
* 'start' and largest 'last' in the tree. For the later, we \
* rely on the root node, which by augmented interval tree \
* property, holds the largest value in its last-in-subtree. \
* This allows mitigating some of the tree walk overhead for \
* for non-intersecting ranges, maintained and consulted in O(1). \
*/ \
node = rb_entry(root->rb_root.rb_node, ITSTRUCT, ITRB); \
if (node->ITSUBTREE < start) \
return NULL; \
\
leftmost = rb_entry(root->rb_leftmost, ITSTRUCT, ITRB); \
if (ITSTART(leftmost) > last) \
return NULL; \
\
return ITPREFIX ## _subtree_search(node, start, last); \
} \
\
ITSTATIC ITSTRUCT * \
ITPREFIX ## _iter_next(ITSTRUCT *node, ITTYPE start, ITTYPE last) \
{ \
struct rb_node *rb = node->ITRB.rb_right, *prev; \
\
while (true) { \
/* \
* Loop invariants: \
* Cond1: ITSTART(node) <= last \
* rb == node->ITRB.rb_right \
* \
* First, search right subtree if suitable \
*/ \
if (rb) { \
ITSTRUCT *right = rb_entry(rb, ITSTRUCT, ITRB); \
if (start <= right->ITSUBTREE) \
return ITPREFIX ## _subtree_search(right, \
start, last); \
} \
\
/* Move up the tree until we come from a node's left child */ \
do { \
rb = rb_parent(&node->ITRB); \
if (!rb) \
return NULL; \
prev = &node->ITRB; \
node = rb_entry(rb, ITSTRUCT, ITRB); \
rb = node->ITRB.rb_right; \
} while (prev == rb); \
\
/* Check if the node intersects [start;last] */ \
if (last < ITSTART(node)) /* !Cond1 */ \
return NULL; \
else if (start <= ITLAST(node)) /* Cond2 */ \
return node; \
} \
}

95
tools/objtool/elf.c
View File

@ -16,6 +16,7 @@
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <linux/interval_tree_generic.h>
#include <objtool/builtin.h>
#include <objtool/elf.h>
@ -50,39 +51,23 @@ static inline u32 str_hash(const char *str)
__elf_table(name); \
})
static bool symbol_to_offset(struct rb_node *a, const struct rb_node *b)
static inline unsigned long __sym_start(struct symbol *s)
{
struct symbol *sa = rb_entry(a, struct symbol, node);
struct symbol *sb = rb_entry(b, struct symbol, node);
if (sa->offset < sb->offset)
return true;
if (sa->offset > sb->offset)
return false;
if (sa->len < sb->len)
return true;
if (sa->len > sb->len)
return false;
sa->alias = sb;
return false;
return s->offset;
}
static int symbol_by_offset(const void *key, const struct rb_node *node)
static inline unsigned long __sym_last(struct symbol *s)
{
const struct symbol *s = rb_entry(node, struct symbol, node);
const unsigned long *o = key;
if (*o < s->offset)
return -1;
if (*o >= s->offset + s->len)
return 1;
return 0;
return s->offset + s->len - 1;
}
INTERVAL_TREE_DEFINE(struct symbol, node, unsigned long, __subtree_last,
__sym_start, __sym_last, static, __sym)
#define __sym_for_each(_iter, _tree, _start, _end) \
for (_iter = __sym_iter_first((_tree), (_start), (_end)); \
_iter; _iter = __sym_iter_next(_iter, (_start), (_end)))
struct symbol_hole {
unsigned long key;
const struct symbol *sym;
@ -147,13 +132,12 @@ static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
{
struct rb_node *node;
struct rb_root_cached *tree = (struct rb_root_cached *)&sec->symbol_tree;
struct symbol *iter;
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)
return s;
__sym_for_each(iter, tree, offset, offset) {
if (iter->offset == offset && iter->type != STT_SECTION)
return iter;
}
return NULL;
@ -161,13 +145,12 @@ struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
{
struct rb_node *node;
struct rb_root_cached *tree = (struct rb_root_cached *)&sec->symbol_tree;
struct symbol *iter;
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)
return s;
__sym_for_each(iter, tree, offset, offset) {
if (iter->offset == offset && iter->type == STT_FUNC)
return iter;
}
return NULL;
@ -175,13 +158,12 @@ struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset)
{
struct rb_node *node;
struct rb_root_cached *tree = (struct rb_root_cached *)&sec->symbol_tree;
struct symbol *iter;
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)
return s;
__sym_for_each(iter, tree, offset, offset) {
if (iter->type != STT_SECTION)
return iter;
}
return NULL;
@ -202,7 +184,7 @@ int find_symbol_hole_containing(const struct section *sec, unsigned long offset)
/*
* Find the rightmost symbol for which @offset is after it.
*/
n = rb_find(&hole, &sec->symbol_tree, symbol_hole_by_offset);
n = rb_find(&hole, &sec->symbol_tree.rb_root, symbol_hole_by_offset);
/* found a symbol that contains @offset */
if (n)
@ -224,13 +206,12 @@ int find_symbol_hole_containing(const struct section *sec, unsigned long offset)
struct symbol *find_func_containing(struct section *sec, unsigned long offset)
{
struct rb_node *node;
struct rb_root_cached *tree = (struct rb_root_cached *)&sec->symbol_tree;
struct symbol *iter;
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)
return s;
__sym_for_each(iter, tree, offset, offset) {
if (iter->type == STT_FUNC)
return iter;
}
return NULL;
@ -373,6 +354,7 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
{
struct list_head *entry;
struct rb_node *pnode;
struct symbol *iter;
INIT_LIST_HEAD(&sym->pv_target);
sym->alias = sym;
@ -386,7 +368,12 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
sym->offset = sym->sym.st_value;
sym->len = sym->sym.st_size;
rb_add(&sym->node, &sym->sec->symbol_tree, symbol_to_offset);
__sym_for_each(iter, &sym->sec->symbol_tree, sym->offset, sym->offset) {
if (iter->offset == sym->offset && iter->type == sym->type)
iter->alias = sym;
}
__sym_insert(sym, &sym->sec->symbol_tree);
pnode = rb_prev(&sym->node);
if (pnode)
entry = &rb_entry(pnode, struct symbol, node)->list;
@ -401,7 +388,7 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
* can exist within a function, confusing the sorting.
*/
if (!sym->len)
rb_erase(&sym->node, &sym->sec->symbol_tree);
__sym_remove(sym, &sym->sec->symbol_tree);
}
static int read_symbols(struct elf *elf)

3
tools/objtool/include/objtool/elf.h
View File

@ -30,7 +30,7 @@ struct section {
struct hlist_node hash;
struct hlist_node name_hash;
GElf_Shdr sh;
struct rb_root symbol_tree;
struct rb_root_cached symbol_tree;
struct list_head symbol_list;
struct list_head reloc_list;
struct section *base, *reloc;
@ -53,6 +53,7 @@ struct symbol {
unsigned char bind, type;
unsigned long offset;
unsigned int len;
unsigned long __subtree_last;
struct symbol *pfunc, *cfunc, *alias;
u8 uaccess_safe : 1;
u8 static_call_tramp : 1;