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Commit d20737c0 authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes/x86: Gather "riprel" functions together 



Cosmetic. Move pre_xol_rip_insn() and handle_riprel_post_xol() up to
the closely related handle_riprel_insn(). This way it is simpler to
read and understand this code, and this lessens the number of ifdef's.

While at it, update the comment in handle_riprel_post_xol() as Jim
suggested.

TODO: rename them somehow to make the naming consistent.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: default avatarJim Keniston <jkenisto@us.ibm.com>
parent 59078d4b

arch/x86/kernel/uprobes.c

+53 −65
Original line number Diff line number Diff line
@@ -313,6 +313,48 @@ handle_riprel_insn(struct arch_uprobe *auprobe, struct insn *insn) 
	}

}



/*

 * If we're emulating a rip-relative instruction, save the contents

 * of the scratch register and store the target address in that register.

 */

static void

pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,

				struct arch_uprobe_task *autask)

{

	if (auprobe->fixups & UPROBE_FIX_RIP_AX) {

		autask->saved_scratch_register = regs->ax;

		regs->ax = current->utask->vaddr;

		regs->ax += auprobe->rip_rela_target_address;

	} else if (auprobe->fixups & UPROBE_FIX_RIP_CX) {

		autask->saved_scratch_register = regs->cx;

		regs->cx = current->utask->vaddr;

		regs->cx += auprobe->rip_rela_target_address;

	}

}



static void

handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction)

{

	if (auprobe->fixups & (UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX)) {

		struct arch_uprobe_task *autask;



		autask = &current->utask->autask;

		if (auprobe->fixups & UPROBE_FIX_RIP_AX)

			regs->ax = autask->saved_scratch_register;

		else

			regs->cx = autask->saved_scratch_register;



		/*

		 * The original instruction includes a displacement, and so

		 * is 4 bytes longer than what we've just single-stepped.

		 * Caller may need to apply other fixups to handle stuff

		 * like "jmpq *...(%rip)" and "callq *...(%rip)".

		 */

		if (correction)

			*correction += 4;

	}

}



static int validate_insn_64bits(struct arch_uprobe *auprobe, struct insn *insn)

{

	insn_init(insn, auprobe->insn, true);
@@ -339,9 +381,19 @@ static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm, 
	return validate_insn_64bits(auprobe, insn);

}

#else /* 32-bit: */

/*

 * No RIP-relative addressing on 32-bit

 */

static void handle_riprel_insn(struct arch_uprobe *auprobe, struct insn *insn)

{

	/* No RIP-relative addressing on 32-bit */

}

static void pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,

				struct arch_uprobe_task *autask)

{

}

static void handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs,

					long *correction)

{

}



static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm,  struct insn *insn)
@@ -415,34 +467,6 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, 
	return 0;

}



#ifdef CONFIG_X86_64

/*

 * If we're emulating a rip-relative instruction, save the contents

 * of the scratch register and store the target address in that register.

 */

static void

pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,

				struct arch_uprobe_task *autask)

{

	if (auprobe->fixups & UPROBE_FIX_RIP_AX) {

		autask->saved_scratch_register = regs->ax;

		regs->ax = current->utask->vaddr;

		regs->ax += auprobe->rip_rela_target_address;

	} else if (auprobe->fixups & UPROBE_FIX_RIP_CX) {

		autask->saved_scratch_register = regs->cx;

		regs->cx = current->utask->vaddr;

		regs->cx += auprobe->rip_rela_target_address;

	}

}

#else

static void

pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,

				struct arch_uprobe_task *autask)

{

	/* No RIP-relative addressing on 32-bit */

}

#endif



/*

 * arch_uprobe_pre_xol - prepare to execute out of line.

 * @auprobe: the probepoint information.
@@ -492,42 +516,6 @@ static int adjust_ret_addr(unsigned long sp, long correction) 
	return 0;

}



#ifdef CONFIG_X86_64

static bool is_riprel_insn(struct arch_uprobe *auprobe)

{

	return ((auprobe->fixups & (UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX)) != 0);

}



static void

handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction)

{

	if (is_riprel_insn(auprobe)) {

		struct arch_uprobe_task *autask;



		autask = &current->utask->autask;

		if (auprobe->fixups & UPROBE_FIX_RIP_AX)

			regs->ax = autask->saved_scratch_register;

		else

			regs->cx = autask->saved_scratch_register;



		/*

		 * The original instruction includes a displacement, and so

		 * is 4 bytes longer than what we've just single-stepped.

		 * Fall through to handle stuff like "jmpq *...(%rip)" and

		 * "callq *...(%rip)".

		 */

		if (correction)

			*correction += 4;

	}

}

#else

static void

handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction)

{

	/* No RIP-relative addressing on 32-bit */

}

#endif



/*

 * If xol insn itself traps and generates a signal(Say,

 * SIGILL/SIGSEGV/etc), then detect the case where a singlestepped