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/*
* Copyright (c) 2018, Linaro Limited
*/
#include <assert.h>
#include <config.h>
#include <kernel/lockdep.h>
#include <kernel/unwind.h>
#include <stdlib.h>
#include <string.h>
#include <sys/queue.h>
#include <util.h>
/* lockdep_node::flags values */
/* Flags used for depth-first topological sorting */
#define LOCKDEP_NODE_TEMP_MARK BIT(0)
#define LOCKDEP_NODE_PERM_MARK BIT(1)
/* Flag used during breadth-first search (print shortest cycle) */
#define LOCKDEP_NODE_BFS_VISITED BIT(2)
/* Find node in graph or add it */
static struct lockdep_node *lockdep_add_to_graph(
struct lockdep_node_head *graph,
uintptr_t lock_id)
{
struct lockdep_node *node = NULL;
assert(graph);
TAILQ_FOREACH(node, graph, link)
if (node->lock_id == lock_id)
return node;
node = calloc(1, sizeof(*node));
if (!node)
return NULL;
node->lock_id = lock_id;
STAILQ_INIT(&node->edges);
TAILQ_INSERT_TAIL(graph, node, link);
return node;
}
static vaddr_t *dup_call_stack(vaddr_t *stack)
{
vaddr_t *nstack = NULL;
int n = 0;
if (!stack)
return NULL;
while (stack[n])
n++;
nstack = malloc((n + 1) * sizeof(vaddr_t));
if (!nstack)
return NULL;
memcpy(nstack, stack, (n + 1) * sizeof(vaddr_t));
return nstack;
}
static void lockdep_print_call_stack(vaddr_t *stack)
{
vaddr_t *p = NULL;
if (!IS_ENABLED(CFG_LOCKDEP_RECORD_STACK))
return;
EMSG_RAW("Call stack:");
for (p = stack; p && *p; p++)
EMSG_RAW(" %#" PRIxPTR, *p);
}
static TEE_Result lockdep_add_edge(struct lockdep_node *from,
struct lockdep_node *to,
vaddr_t *call_stack_from,
vaddr_t *call_stack_to,
uintptr_t thread_id)
{
struct lockdep_edge *edge = NULL;
STAILQ_FOREACH(edge, &from->edges, link)
if (edge->to == to)
return TEE_SUCCESS;
edge = calloc(1, sizeof(*edge));
if (!edge)
return TEE_ERROR_OUT_OF_MEMORY;
edge->to = to;
edge->call_stack_from = dup_call_stack(call_stack_from);
edge->call_stack_to = dup_call_stack(call_stack_to);
edge->thread_id = thread_id;
STAILQ_INSERT_TAIL(&from->edges, edge, link);
return TEE_SUCCESS;
}
struct lockdep_bfs {
struct lockdep_node *node;
uintptr_t *path;
int pathlen;
TAILQ_ENTRY(lockdep_bfs) link;
};
TAILQ_HEAD(lockdep_bfs_head, lockdep_bfs);
static void lockdep_bfs_queue_delete(struct lockdep_bfs_head *queue)
{
struct lockdep_bfs *cur = NULL;
struct lockdep_bfs *next = NULL;
TAILQ_FOREACH_SAFE(cur, queue, link, next) {
TAILQ_REMOVE(queue, cur, link);
free(cur->path);
free(cur);
}
}
/*
* Print shortest cycle in @graph that contains @node.
* This function performs an iterative breadth-first search starting from @node,
* and stops when it reaches @node again. In each node we're tracking the path
* from the start node.
*/
static uintptr_t *lockdep_graph_get_shortest_cycle(struct lockdep_node *node)
{
struct lockdep_bfs_head queue;
struct lockdep_bfs *qe = NULL;
uintptr_t *ret = NULL;
TAILQ_INIT(&queue);
node->flags |= LOCKDEP_NODE_BFS_VISITED;
qe = calloc(1, sizeof(*qe));
if (!qe)
goto out;
qe->node = node;
qe->path = malloc(sizeof(uintptr_t));
if (!qe->path)
goto out;
qe->path[0] = node->lock_id;
qe->pathlen = 1;
TAILQ_INSERT_TAIL(&queue, qe, link);
while (!TAILQ_EMPTY(&queue)) {
qe = TAILQ_FIRST(&queue);
struct lockdep_node *n = qe->node;
TAILQ_REMOVE(&queue, qe, link);
struct lockdep_edge *e = NULL;
STAILQ_FOREACH(e, &n->edges, link) {
if (e->to->lock_id == node->lock_id) {
uintptr_t *tmp = NULL;
size_t nlen = qe->pathlen + 1;
/*
* Cycle found. Terminate cycle path with NULL
* and return it.
*/
tmp = realloc(qe->path,
nlen * sizeof(uintptr_t));
if (!tmp) {
EMSG("Out of memory");
free(qe->path);
ret = NULL;
goto out;
}
qe->path = tmp;
qe->path[nlen - 1] = 0;
ret = qe->path;
goto out;
}
if (!(e->to->flags & LOCKDEP_NODE_BFS_VISITED)) {
e->to->flags |= LOCKDEP_NODE_BFS_VISITED;
size_t nlen = qe->pathlen + 1;
struct lockdep_bfs *nqe = calloc(1,
sizeof(*nqe));
if (!nqe)
goto out;
nqe->node = e->to;
nqe->path = malloc(nlen * sizeof(uintptr_t));
if (!nqe->path)
goto out;
nqe->pathlen = nlen;
memcpy(nqe->path, qe->path,
qe->pathlen * sizeof(uintptr_t));
nqe->path[nlen - 1] = e->to->lock_id;
TAILQ_INSERT_TAIL(&queue, nqe, link);
}
}
free(qe->path);
free(qe);
qe = NULL;
}
out:
free(qe);
lockdep_bfs_queue_delete(&queue);
return ret;
}
static TEE_Result lockdep_visit(struct lockdep_node *node)
{
if (node->flags & LOCKDEP_NODE_PERM_MARK)
return TEE_SUCCESS;
if (node->flags & LOCKDEP_NODE_TEMP_MARK)
return TEE_ERROR_BAD_STATE; /* Not a DAG! */
node->flags |= LOCKDEP_NODE_TEMP_MARK;
struct lockdep_edge *e;
STAILQ_FOREACH(e, &node->edges, link) {
TEE_Result res = lockdep_visit(e->to);
if (res)
return res;
}
node->flags |= LOCKDEP_NODE_PERM_MARK;
return TEE_SUCCESS;
}
static TEE_Result lockdep_graph_sort(struct lockdep_node_head *graph)
{
struct lockdep_node *node = NULL;
TAILQ_FOREACH(node, graph, link) {
if (!node->flags) {
/* Unmarked node */
TEE_Result res = lockdep_visit(node);
if (res)
return res;
}
}
TAILQ_FOREACH(node, graph, link)
node->flags = 0;
return TEE_SUCCESS;
}
static struct lockdep_edge *lockdep_find_edge(struct lockdep_node_head *graph,
uintptr_t from, uintptr_t to)
{
struct lockdep_node *node = NULL;
struct lockdep_edge *edge = NULL;
TAILQ_FOREACH(node, graph, link)
if (node->lock_id == from)
STAILQ_FOREACH(edge, &node->edges, link)
if (edge->to->lock_id == to)
return edge;
return NULL;
}
static void lockdep_print_edge_info(uintptr_t from __maybe_unused,
struct lockdep_edge *edge)
{
uintptr_t __maybe_unused to = edge->to->lock_id;
const char __maybe_unused *at_msg = "";
const char __maybe_unused *acq_msg = "";
if (IS_ENABLED(CFG_LOCKDEP_RECORD_STACK)) {
at_msg = " at:";
acq_msg = " acquired at:";
}
EMSG_RAW("-> Thread %#" PRIxPTR " acquired lock %#" PRIxPTR "%s",
edge->thread_id, to, at_msg);
lockdep_print_call_stack(edge->call_stack_to);
EMSG_RAW("...while holding lock %#" PRIxPTR "%s",
from, acq_msg);
lockdep_print_call_stack(edge->call_stack_from);
}
/*
* Find cycle containing @node in the lock graph, then print full debug
* information about each edge (thread that acquired the locks and call stacks)
*/
static void lockdep_print_cycle_info(struct lockdep_node_head *graph,
struct lockdep_node *node)
{
struct lockdep_edge *edge = NULL;
uintptr_t *cycle = NULL;
uintptr_t *p = NULL;
uintptr_t from = 0;
uintptr_t to = 0;
cycle = lockdep_graph_get_shortest_cycle(node);
assert(cycle && cycle[0]);
EMSG_RAW("-> Shortest cycle:");
for (p = cycle; *p; p++)
EMSG_RAW(" Lock %#" PRIxPTR, *p);
for (p = cycle; ; p++) {
if (!*p) {
assert(p != cycle);
from = to;
to = cycle[0];
edge = lockdep_find_edge(graph, from, to);
lockdep_print_edge_info(from, edge);
break;
}
if (p != cycle)
from = to;
to = *p;
if (p != cycle) {
edge = lockdep_find_edge(graph, from, to);
lockdep_print_edge_info(from, edge);
}
}
free(cycle);
}
static vaddr_t *lockdep_get_kernel_stack(void)
{
if (IS_ENABLED(CFG_LOCKDEP_RECORD_STACK))
return unw_get_kernel_stack();
return NULL;
}
TEE_Result __lockdep_lock_acquire(struct lockdep_node_head *graph,
struct lockdep_lock_head *owned,
uintptr_t id)
{
struct lockdep_node *node = lockdep_add_to_graph(graph, id);
if (!node)
return TEE_ERROR_OUT_OF_MEMORY;
struct lockdep_lock *lock = NULL;
vaddr_t *acq_stack = lockdep_get_kernel_stack();
TAILQ_FOREACH(lock, owned, link) {
TEE_Result res = lockdep_add_edge(lock->node, node,
lock->call_stack,
acq_stack,
(uintptr_t)owned);
if (res)
return res;
}
TEE_Result res = lockdep_graph_sort(graph);
if (res) {
EMSG_RAW("Potential deadlock detected!");
EMSG_RAW("When trying to acquire lock %#" PRIxPTR, id);
lockdep_print_cycle_info(graph, node);
return res;
}
lock = calloc(1, sizeof(*lock));
if (!lock)
return TEE_ERROR_OUT_OF_MEMORY;
lock->node = node;
lock->call_stack = acq_stack;
TAILQ_INSERT_TAIL(owned, lock, link);
return TEE_SUCCESS;
}
/*
* Call this when it is known that the thread has been able to acquire the lock.
* Similar to __lockdep_lock_acquire(), but since the operation is non-blocking,
* no dependency to currently owned locks are created.
*/
TEE_Result __lockdep_lock_tryacquire(struct lockdep_node_head *graph,
struct lockdep_lock_head *owned,
uintptr_t id)
{
struct lockdep_node *node = lockdep_add_to_graph(graph, id);
if (!node)
return TEE_ERROR_OUT_OF_MEMORY;
struct lockdep_lock *lock = NULL;
vaddr_t *acq_stack = lockdep_get_kernel_stack();
lock = calloc(1, sizeof(*lock));
if (!lock)
return TEE_ERROR_OUT_OF_MEMORY;
lock->node = node;
lock->call_stack = acq_stack;
TAILQ_INSERT_TAIL(owned, lock, link);
return TEE_SUCCESS;
}
TEE_Result __lockdep_lock_release(struct lockdep_lock_head *owned, uintptr_t id)
{
struct lockdep_lock *lock = NULL;
TAILQ_FOREACH_REVERSE(lock, owned, lockdep_lock_head, link) {
if (lock->node->lock_id == id) {
TAILQ_REMOVE(owned, lock, link);
free(lock->call_stack);
free(lock);
return TEE_SUCCESS;
}
}
EMSG_RAW("Thread %p does not own lock %#" PRIxPTR, (void *)owned, id);
return TEE_ERROR_ITEM_NOT_FOUND;
}
static void lockdep_free_edge(struct lockdep_edge *edge)
{
free(edge->call_stack_from);
free(edge->call_stack_to);
free(edge);
}
static void lockdep_node_delete(struct lockdep_node *node)
{
struct lockdep_edge *edge = NULL;
struct lockdep_edge *next = NULL;
STAILQ_FOREACH_SAFE(edge, &node->edges, link, next)
lockdep_free_edge(edge);
free(node);
}
void lockdep_graph_delete(struct lockdep_node_head *graph)
{
struct lockdep_node *node = NULL;
struct lockdep_node *next = NULL;
TAILQ_FOREACH_SAFE(node, graph, link, next) {
TAILQ_REMOVE(graph, node, link);
lockdep_node_delete(node);
}
}
void lockdep_queue_delete(struct lockdep_lock_head *owned)
{
struct lockdep_lock *lock = NULL;
struct lockdep_lock *next = NULL;
TAILQ_FOREACH_SAFE(lock, owned, link, next) {
TAILQ_REMOVE(owned, lock, link);
free(lock);
}
}
static void lockdep_node_destroy(struct lockdep_node_head *graph,
struct lockdep_node *node)
{
struct lockdep_edge *edge = NULL;
struct lockdep_edge *next = NULL;
struct lockdep_node *from = NULL;
TAILQ_REMOVE(graph, node, link);
/*
* Loop over all nodes in the graph to remove all edges with the
* node to remove in the "to" field.
*/
TAILQ_FOREACH(from, graph, link) {
edge = STAILQ_FIRST(&from->edges);
while (edge && edge->to == node) {
STAILQ_REMOVE_HEAD(&from->edges, link);
lockdep_free_edge(edge);
edge = STAILQ_FIRST(&from->edges);
}
if (!edge)
continue;
next = STAILQ_NEXT(edge, link);
while (next) {
if (next->to == node) {
STAILQ_REMOVE_AFTER(&from->edges, edge, link);
lockdep_free_edge(next);
} else {
edge = next;
}
next = STAILQ_NEXT(edge, link);
}
}
STAILQ_FOREACH_SAFE(edge, &node->edges, link, next)
lockdep_free_edge(edge);
free(node);
}
void lockdep_lock_destroy(struct lockdep_node_head *graph, uintptr_t lock_id)
{
struct lockdep_node *node = NULL;
assert(graph);
TAILQ_FOREACH(node, graph, link) {
if (node->lock_id == lock_id) {
lockdep_node_destroy(graph, node);
break;
}
}
}
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