Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit cceb55aa authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes: Introduce copy_opcode(), kill read_opcode() 



No functional changes, preparations.

1. Extract the kmap-and-memcpy code from read_opcode() into the
   new trivial helper, copy_opcode(). The next patch will add
   another user.

2. read_opcode() becomes really trivial, fold it into its single
   caller, is_swbp_at_addr().

3. Remove "auprobe" argument from write_opcode(), it is not used
   since f403072c.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
parent e97f65a1

kernel/events/uprobes.c

+19 −44
Original line number Original line Diff line number Diff line
@@ -183,19 +183,25 @@ bool __weak is_swbp_insn(uprobe_opcode_t *insn) 
	return *insn == UPROBE_SWBP_INSN;

	return *insn == UPROBE_SWBP_INSN;

}

}





static void copy_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *opcode)

{

	void *kaddr = kmap_atomic(page);

	memcpy(opcode, kaddr + (vaddr & ~PAGE_MASK), UPROBE_SWBP_INSN_SIZE);

	kunmap_atomic(kaddr);

}



/*

/*

 * NOTE:

 * NOTE:

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

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

 * the architecture. If an arch has variable length instruction and the

 * the architecture. If an arch has variable length instruction and the

 * breakpoint instruction is not of the smallest length instruction

 * breakpoint instruction is not of the smallest length instruction

 * supported by that architecture then we need to modify read_opcode /

 * supported by that architecture then we need to modify is_swbp_at_addr and

 * write_opcode accordingly. This would never be a problem for archs that

 * write_opcode accordingly. This would never be a problem for archs that

 * have fixed length instructions.

 * have fixed length instructions.

 */

 */





/*

/*

 * write_opcode - write the opcode at a given virtual address.

 * write_opcode - write the opcode at a given virtual address.

 * @auprobe: arch breakpointing information.

 * @mm: the probed process address space.

 * @mm: the probed process address space.

 * @vaddr: the virtual address to store the opcode.

 * @vaddr: the virtual address to store the opcode.

 * @opcode: opcode to be written at @vaddr.

 * @opcode: opcode to be written at @vaddr.
@@ -206,8 +212,8 @@ bool __weak is_swbp_insn(uprobe_opcode_t *insn) 
 * For mm @mm, write the opcode at @vaddr.

 * For mm @mm, write the opcode at @vaddr.

 * Return 0 (success) or a negative errno.

 * Return 0 (success) or a negative errno.

 */

 */

static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,

static int write_opcode(struct mm_struct *mm, unsigned long vaddr,

			unsigned long vaddr, uprobe_opcode_t opcode)

			uprobe_opcode_t opcode)

{

{

	struct page *old_page, *new_page;

	struct page *old_page, *new_page;

	void *vaddr_old, *vaddr_new;

	void *vaddr_old, *vaddr_new;
@@ -253,40 +259,9 @@ put_old: 
	return ret;

	return ret;

}

}





/**

 * read_opcode - read the opcode at a given virtual address.

 * @mm: the probed process address space.

 * @vaddr: the virtual address to read the opcode.

 * @opcode: location to store the read opcode.

 *

 * Called with mm->mmap_sem held (for read and with a reference to

 * mm.

 *

 * For mm @mm, read the opcode at @vaddr and store it in @opcode.

 * Return 0 (success) or a negative errno.

 */

static int read_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t *opcode)

{

	struct page *page;

	void *vaddr_new;

	int ret;



	ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);

	if (ret <= 0)

		return ret;



	vaddr_new = kmap_atomic(page);

	vaddr &= ~PAGE_MASK;

	memcpy(opcode, vaddr_new + vaddr, UPROBE_SWBP_INSN_SIZE);

	kunmap_atomic(vaddr_new);



	put_page(page);



	return 0;

}



static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr)

static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr)

{

{

	struct page *page;

	uprobe_opcode_t opcode;

	uprobe_opcode_t opcode;

	int result;

	int result;
@@ -300,14 +275,14 @@ static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr) 
			goto out;

			goto out;

	}

	}





	result = read_opcode(mm, vaddr, &opcode);

	result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);

	if (result)

	if (result < 0)

		return result;

		return result;

out:

	if (is_swbp_insn(&opcode))

		return 1;





	return 0;

	copy_opcode(page, vaddr, &opcode);

	put_page(page);

 out:

	return is_swbp_insn(&opcode);

}

}





/**

/**
@@ -321,7 +296,7 @@ out: 
 */

 */

int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)

int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)

{

{

	return write_opcode(auprobe, mm, vaddr, UPROBE_SWBP_INSN);

	return write_opcode(mm, vaddr, UPROBE_SWBP_INSN);

}

}





/**

/**
@@ -345,7 +320,7 @@ set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long v 
	if (result != 1)

	if (result != 1)

		return result;

		return result;





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

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

}

}





static int match_uprobe(struct uprobe *l, struct uprobe *r)

static int match_uprobe(struct uprobe *l, struct uprobe *r)