Commit bdf8647c authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes: Introduce uprobe_apply() 



Currently it is not possible to change the filtering constraints after
uprobe_register(), so a consumer can not, say, start to trace a task/mm
which was previously filtered out, or remove the no longer needed bp's.

Introduce uprobe_apply() which simply does register_for_each_vma() again
to consult uprobe_consumer->filter() and install/remove the breakpoints.
The only complication is that register_for_each_vma() can no longer
assume that uprobe->consumers should be consulter if is_register == T,
so we change it to accept "struct uprobe_consumer *new" instead.

Unlike uprobe_register(), uprobe_apply(true) doesn't do "unregister" if
register_for_each_vma() fails, it is up to caller to handle the error.

Note: we probably need to cleanup the current interface, it is strange
that uprobe_apply/unregister need inode/offset. We should either change
uprobe_register() to return "struct uprobe *", or add a private ->uprobe
member in uprobe_consumer. And in the long term uprobe_apply() should
take a single argument, uprobe or consumer, even "bool add" should go
away.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
parent f22c1bb6

include/linux/uprobes.h

+6 −0
Original line number Diff line number Diff line
@@ -101,6 +101,7 @@ extern int __weak set_swbp(struct arch_uprobe *aup, struct mm_struct *mm, unsign 
extern int __weak set_orig_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr);

extern bool __weak is_swbp_insn(uprobe_opcode_t *insn);

extern int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc);

extern int uprobe_apply(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool);

extern void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc);

extern int uprobe_mmap(struct vm_area_struct *vma);

extern void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end);
@@ -124,6 +125,11 @@ uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 
{

	return -ENOSYS;

}

static inline int

uprobe_apply(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool add)

{

	return -ENOSYS;

}

static inline void

uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)

{

kernel/events/uprobes.c

+35 −4
Original line number Diff line number Diff line
@@ -733,8 +733,10 @@ build_map_info(struct address_space *mapping, loff_t offset, bool is_register) 
	return curr;

}



static int register_for_each_vma(struct uprobe *uprobe, bool is_register)

static int

register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new)

{

	bool is_register = !!new;

	struct map_info *info;

	int err = 0;
@@ -765,7 +767,7 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) 


		if (is_register) {

			/* consult only the "caller", new consumer. */

			if (consumer_filter(uprobe->consumers,

			if (consumer_filter(new,

					UPROBE_FILTER_REGISTER, mm))

				err = install_breakpoint(uprobe, mm, vma, info->vaddr);

		} else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) {
@@ -788,7 +790,7 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) 
static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc)

{

	consumer_add(uprobe, uc);

	return register_for_each_vma(uprobe, true);

	return register_for_each_vma(uprobe, uc);

}



static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
@@ -798,7 +800,7 @@ static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *u 
	if (!consumer_del(uprobe, uc))	/* WARN? */

		return;



	err = register_for_each_vma(uprobe, false);

	err = register_for_each_vma(uprobe, NULL);

	/* TODO : cant unregister? schedule a worker thread */

	if (!uprobe->consumers && !err)

		delete_uprobe(uprobe);
@@ -854,6 +856,35 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer * 
}

EXPORT_SYMBOL_GPL(uprobe_register);



/*

 * uprobe_apply - unregister a already registered probe.

 * @inode: the file in which the probe has to be removed.

 * @offset: offset from the start of the file.

 * @uc: consumer which wants to add more or remove some breakpoints

 * @add: add or remove the breakpoints

 */

int uprobe_apply(struct inode *inode, loff_t offset,

			struct uprobe_consumer *uc, bool add)

{

	struct uprobe *uprobe;

	struct uprobe_consumer *con;

	int ret = -ENOENT;



	uprobe = find_uprobe(inode, offset);

	if (!uprobe)

		return ret;



	down_write(&uprobe->register_rwsem);

	for (con = uprobe->consumers; con && con != uc ; con = con->next)

		;

	if (con)

		ret = register_for_each_vma(uprobe, add ? uc : NULL);

	up_write(&uprobe->register_rwsem);

	put_uprobe(uprobe);



	return ret;

}



/*

 * uprobe_unregister - unregister a already registered probe.

 * @inode: the file in which the probe has to be removed.

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