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Commit ed6f6a50 authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes: Kill set_orig_insn()->is_swbp_at_addr() 



Unlike set_swbp(), set_orig_insn()->is_swbp_at_addr() makes sense,
although it can't prevent all confusions.

But the usage of is_swbp_at_addr() is equally confusing, and it adds
the extra get_user_pages() we can avoid.

This patch removes set_orig_insn()->is_swbp_at_addr() but changes
write_opcode() to do the necessary checks before replace_page().

Perhaps it also makes sense to ensure PAGE_MAPPING_ANON in unregister
case.

find_active_uprobe() becomes the only user of is_swbp_at_addr(),
we can change its semantics.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
parent cceb55aa

kernel/events/uprobes.c

+23 −9
Original line number Original line Diff line number Diff line
@@ -190,6 +190,25 @@ static void copy_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t 
	kunmap_atomic(kaddr);

	kunmap_atomic(kaddr);

}

}





static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode)

{

	uprobe_opcode_t old_opcode;

	bool is_swbp;



	copy_opcode(page, vaddr, &old_opcode);

	is_swbp = is_swbp_insn(&old_opcode);



	if (is_swbp_insn(new_opcode)) {

		if (is_swbp)		/* register: already installed? */

			return 0;

	} else {

		if (!is_swbp)		/* unregister: was it changed by us? */

			return -EINVAL;

	}



	return 1;

}



/*

/*

 * NOTE:

 * NOTE:

 * Expect the breakpoint instruction to be the smallest size instruction for

 * Expect the breakpoint instruction to be the smallest size instruction for
@@ -226,6 +245,10 @@ retry: 
	if (ret <= 0)

	if (ret <= 0)

		return ret;

		return ret;





	ret = verify_opcode(old_page, vaddr, &opcode);

	if (ret <= 0)

		goto put_old;



	ret = -ENOMEM;

	ret = -ENOMEM;

	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);

	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);

	if (!new_page)

	if (!new_page)
@@ -311,15 +334,6 @@ int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned 
int __weak

int __weak

set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)

set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)

{

{

	int result;



	result = is_swbp_at_addr(mm, vaddr);

	if (!result)

		return -EINVAL;



	if (result != 1)

		return result;



	return write_opcode(mm, vaddr, *(uprobe_opcode_t *)auprobe->insn);

	return write_opcode(mm, vaddr, *(uprobe_opcode_t *)auprobe->insn);

}

}