/* Have a copy of original instruction */
#define UPROBE_COPY_INSN 0
-/* Dont run handlers when first register/ last unregister in progress*/
-#define UPROBE_RUN_HANDLER 1
/* Can skip singlestep */
-#define UPROBE_SKIP_SSTEP 2
+#define UPROBE_SKIP_SSTEP 1
struct uprobe {
struct rb_node rb_node; /* node in the rb tree */
atomic_t ref;
+ struct rw_semaphore register_rwsem;
struct rw_semaphore consumer_rwsem;
- struct mutex copy_mutex; /* TODO: kill me and UPROBE_COPY_INSN */
struct list_head pending_list;
struct uprobe_consumer *consumers;
struct inode *inode; /* Also hold a ref to inode */
u = __insert_uprobe(uprobe);
spin_unlock(&uprobes_treelock);
- /* For now assume that the instruction need not be single-stepped */
- __set_bit(UPROBE_SKIP_SSTEP, &uprobe->flags);
-
return u;
}
uprobe->inode = igrab(inode);
uprobe->offset = offset;
+ init_rwsem(&uprobe->register_rwsem);
init_rwsem(&uprobe->consumer_rwsem);
- mutex_init(&uprobe->copy_mutex);
+ /* For now assume that the instruction need not be single-stepped */
+ __set_bit(UPROBE_SKIP_SSTEP, &uprobe->flags);
/* add to uprobes_tree, sorted on inode:offset */
cur_uprobe = insert_uprobe(uprobe);
{
struct uprobe_consumer *uc;
- if (!test_bit(UPROBE_RUN_HANDLER, &uprobe->flags))
- return;
-
- down_read(&uprobe->consumer_rwsem);
- for (uc = uprobe->consumers; uc; uc = uc->next) {
- if (!uc->filter || uc->filter(uc, current))
- uc->handler(uc, regs);
- }
- up_read(&uprobe->consumer_rwsem);
+ down_read(&uprobe->register_rwsem);
+ for (uc = uprobe->consumers; uc; uc = uc->next)
+ uc->handler(uc, regs);
+ up_read(&uprobe->register_rwsem);
}
-/* Returns the previous consumer */
-static struct uprobe_consumer *
-consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc)
+static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc)
{
down_write(&uprobe->consumer_rwsem);
uc->next = uprobe->consumers;
uprobe->consumers = uc;
up_write(&uprobe->consumer_rwsem);
-
- return uc->next;
}
/*
if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
return ret;
- mutex_lock(&uprobe->copy_mutex);
+ /* TODO: move this into _register, until then we abuse this sem. */
+ down_write(&uprobe->consumer_rwsem);
if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
goto out;
set_bit(UPROBE_COPY_INSN, &uprobe->flags);
out:
- mutex_unlock(&uprobe->copy_mutex);
+ up_write(&uprobe->consumer_rwsem);
+
+ return ret;
+}
+
+static bool filter_chain(struct uprobe *uprobe)
+{
+ struct uprobe_consumer *uc;
+ bool ret = false;
+
+ down_read(&uprobe->consumer_rwsem);
+ for (uc = uprobe->consumers; uc; uc = uc->next) {
+ /* TODO: ret = uc->filter(...) */
+ ret = true;
+ if (ret)
+ break;
+ }
+ up_read(&uprobe->consumer_rwsem);
return ret;
}
/*
* If probe is being deleted, unregister thread could be done with
* the vma-rmap-walk through. Adding a probe now can be fatal since
- * nobody will be able to cleanup. Also we could be from fork or
- * mremap path, where the probe might have already been inserted.
- * Hence behave as if probe already existed.
+ * nobody will be able to cleanup. But in this case filter_chain()
+ * must return false, all consumers have gone away.
*/
- if (!uprobe->consumers)
+ if (!filter_chain(uprobe))
return 0;
ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr);
static int
remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr)
{
- /* can happen if uprobe_register() fails */
if (!test_bit(MMF_HAS_UPROBES, &mm->flags))
return 0;
+ if (filter_chain(uprobe))
+ return 0;
+
set_bit(MMF_RECALC_UPROBES, &mm->flags);
return set_orig_insn(&uprobe->arch, mm, vaddr);
}
return err;
}
-static int __uprobe_register(struct uprobe *uprobe)
+static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc)
{
+ consumer_add(uprobe, uc);
return register_for_each_vma(uprobe, true);
}
-static void __uprobe_unregister(struct uprobe *uprobe)
+static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
{
- if (!register_for_each_vma(uprobe, false))
- delete_uprobe(uprobe);
+ int err;
+
+ if (!consumer_del(uprobe, uc)) /* WARN? */
+ return;
+ err = register_for_each_vma(uprobe, false);
/* TODO : cant unregister? schedule a worker thread */
+ if (!uprobe->consumers && !err)
+ delete_uprobe(uprobe);
}
/*
struct uprobe *uprobe;
int ret;
- if (!inode || !uc || uc->next)
- return -EINVAL;
-
+ /* Racy, just to catch the obvious mistakes */
if (offset > i_size_read(inode))
return -EINVAL;
- ret = 0;
+ ret = -ENOMEM;
mutex_lock(uprobes_hash(inode));
uprobe = alloc_uprobe(inode, offset);
-
- if (!uprobe) {
- ret = -ENOMEM;
- } else if (!consumer_add(uprobe, uc)) {
- ret = __uprobe_register(uprobe);
- if (ret) {
- uprobe->consumers = NULL;
- __uprobe_unregister(uprobe);
- } else {
- set_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
- }
+ if (uprobe) {
+ down_write(&uprobe->register_rwsem);
+ ret = __uprobe_register(uprobe, uc);
+ if (ret)
+ __uprobe_unregister(uprobe, uc);
+ up_write(&uprobe->register_rwsem);
}
-
mutex_unlock(uprobes_hash(inode));
if (uprobe)
put_uprobe(uprobe);
{
struct uprobe *uprobe;
- if (!inode || !uc)
- return;
-
uprobe = find_uprobe(inode, offset);
if (!uprobe)
return;
mutex_lock(uprobes_hash(inode));
-
- if (consumer_del(uprobe, uc)) {
- if (!uprobe->consumers) {
- __uprobe_unregister(uprobe);
- clear_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
- }
- }
-
+ down_write(&uprobe->register_rwsem);
+ __uprobe_unregister(uprobe, uc);
+ up_write(&uprobe->register_rwsem);
mutex_unlock(uprobes_hash(inode));
- if (uprobe)
- put_uprobe(uprobe);
+ put_uprobe(uprobe);
}
static struct rb_node *
* This is not strictly accurate, we can race with
* uprobe_unregister() and see the already removed
* uprobe if delete_uprobe() was not yet called.
+ * Or this uprobe can be filtered out.
*/
if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end))
return;
projects / karo-tx-linux.git / blobdiff