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Commit 8ad8e9d3 authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes/x86: Introduce uprobe_xol_ops and arch_uprobe->ops 



Introduce arch_uprobe->ops pointing to the "struct uprobe_xol_ops",
move the current UPROBE_FIX_{RIP*,IP,CALL} code into the default
set of methods and change arch_uprobe_pre/post_xol() accordingly.

This way we can add the new uprobe_xol_ops's to handle the insns
which need the special processing (rip-relative jmp/call at least).

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarJim Keniston <jkenisto@us.ibm.com>
Reviewed-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
parent 34e7317d

arch/x86/include/asm/uprobes.h

+6 −1
Original line number Diff line number Diff line
@@ -33,12 +33,17 @@ typedef u8 uprobe_opcode_t; 
#define UPROBE_SWBP_INSN		0xcc

#define UPROBE_SWBP_INSN_SIZE		   1



struct uprobe_xol_ops;



struct arch_uprobe {

	u16				fixups;

	union {

		u8			insn[MAX_UINSN_BYTES];

		u8			ixol[MAX_UINSN_BYTES];

	};



	u16				fixups;

	const struct uprobe_xol_ops	*ops;



#ifdef CONFIG_X86_64

	unsigned long			rip_rela_target_address;

#endif

arch/x86/kernel/uprobes.c

+68 −39
Original line number Diff line number Diff line
@@ -402,6 +402,64 @@ static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm, 
}

#endif /* CONFIG_X86_64 */



struct uprobe_xol_ops {

	bool	(*emulate)(struct arch_uprobe *, struct pt_regs *);

	int	(*pre_xol)(struct arch_uprobe *, struct pt_regs *);

	int	(*post_xol)(struct arch_uprobe *, struct pt_regs *);

};



static int default_pre_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs)

{

	pre_xol_rip_insn(auprobe, regs, &current->utask->autask);

	return 0;

}



/*

 * Adjust the return address pushed by a call insn executed out of line.

 */

static int adjust_ret_addr(unsigned long sp, long correction)

{

	int rasize, ncopied;

	long ra = 0;



	if (is_ia32_task())

		rasize = 4;

	else

		rasize = 8;



	ncopied = copy_from_user(&ra, (void __user *)sp, rasize);

	if (unlikely(ncopied))

		return -EFAULT;



	ra += correction;

	ncopied = copy_to_user((void __user *)sp, &ra, rasize);

	if (unlikely(ncopied))

		return -EFAULT;



	return 0;

}



static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs)

{

	struct uprobe_task *utask = current->utask;

	long correction = (long)(utask->vaddr - utask->xol_vaddr);

	int ret = 0;



	handle_riprel_post_xol(auprobe, regs, &correction);

	if (auprobe->fixups & UPROBE_FIX_IP)

		regs->ip += correction;



	if (auprobe->fixups & UPROBE_FIX_CALL)

		ret = adjust_ret_addr(regs->sp, correction);



	return ret;

}



static struct uprobe_xol_ops default_xol_ops = {

	.pre_xol  = default_pre_xol_op,

	.post_xol = default_post_xol_op,

};



/**

 * arch_uprobe_analyze_insn - instruction analysis including validity and fixups.

 * @mm: the probed address space.
@@ -464,6 +522,7 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, 
	if (fix_call)

		auprobe->fixups |= UPROBE_FIX_CALL;



	auprobe->ops = &default_xol_ops;

	return 0;

}
@@ -485,33 +544,8 @@ int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) 
	if (test_tsk_thread_flag(current, TIF_BLOCKSTEP))

		set_task_blockstep(current, false);



	pre_xol_rip_insn(auprobe, regs, &utask->autask);

	return 0;

}



/*

 * This function is called by arch_uprobe_post_xol() to adjust the return

 * address pushed by a call instruction executed out of line.

 */

static int adjust_ret_addr(unsigned long sp, long correction)

{

	int rasize, ncopied;

	long ra = 0;



	if (is_ia32_task())

		rasize = 4;

	else

		rasize = 8;



	ncopied = copy_from_user(&ra, (void __user *)sp, rasize);

	if (unlikely(ncopied))

		return -EFAULT;



	ra += correction;

	ncopied = copy_to_user((void __user *)sp, &ra, rasize);

	if (unlikely(ncopied))

		return -EFAULT;



	if (auprobe->ops->pre_xol)

		return auprobe->ops->pre_xol(auprobe, regs);

	return 0;

}
@@ -560,11 +594,8 @@ bool arch_uprobe_xol_was_trapped(struct task_struct *t) 
int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)

{

	struct uprobe_task *utask = current->utask;

	long correction;

	int result = 0;



	WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);



	current->thread.trap_nr = utask->autask.saved_trap_nr;

	/*

	 * arch_uprobe_pre_xol() doesn't save the state of TIF_BLOCKSTEP
@@ -576,15 +607,9 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) 
	else if (!(auprobe->fixups & UPROBE_FIX_SETF))

		regs->flags &= ~X86_EFLAGS_TF;



	correction = (long)(utask->vaddr - utask->xol_vaddr);

	handle_riprel_post_xol(auprobe, regs, &correction);

	if (auprobe->fixups & UPROBE_FIX_IP)

		regs->ip += correction;



	if (auprobe->fixups & UPROBE_FIX_CALL)

		result = adjust_ret_addr(regs->sp, correction);



	return result;

	if (auprobe->ops->post_xol)

		return auprobe->ops->post_xol(auprobe, regs);

	return 0;

}



/* callback routine for handling exceptions. */
@@ -642,6 +667,10 @@ static bool __skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) 
{

	int i;



	if (auprobe->ops->emulate)

		return auprobe->ops->emulate(auprobe, regs);



	/* TODO: move this code into ->emulate() hook */

	for (i = 0; i < MAX_UINSN_BYTES; i++) {

		if (auprobe->insn[i] == 0x66)

			continue;