Commit 6105c5d4 authored by Mark Rutland's avatar Mark Rutland Committed by Catalin Marinas
Browse files

arm64: probes: Move kprobes-specific fields 



We share struct arch_probe_insn between krpboes and uprobes, but most of
its fields aren't necessary for uprobes:

* The 'insn' field is only used by kprobes as a pointer to the XOL slot.

* The 'restore' field is only used by probes as the PC to restore after
  stepping an instruction in the XOL slot.

* The 'pstate_cc' field isn't used by kprobes or uprobes, and seems to
  only exist as a result of copy-pasting the 32-bit arm implementation
  of kprobes.

As these fields live in struct arch_probe_insn they cannot use
definitions that only exist when CONFIG_KPROBES=y, such as the
kprobe_opcode_t typedef, which we'd like to use in subsequent patches.

Clean this up by removing the 'pstate_cc' field, and moving the
kprobes-specific fields into the kprobes-specific struct
arch_specific_insn. To make it clear that the fields are related to
stepping instructions in the XOL slot, 'insn' is renamed to 'xol_insn'
and 'restore' is renamed to 'xol_restore'

At the same time, remove the misleading and useless comment above struct
arch_probe_insn.

The should be no functional change as a result of this patch.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20241008155851.801546-5-mark.rutland@arm.com


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 13f8f1e0

arch/arm64/include/asm/probes.h

+3 −5
Original line number Diff line number Diff line
@@ -12,18 +12,16 @@ 
typedef u32 probe_opcode_t;

typedef void (probes_handler_t) (u32 opcode, long addr, struct pt_regs *);



/* architecture specific copy of original instruction */

struct arch_probe_insn {

	probe_opcode_t *insn;

	pstate_check_t *pstate_cc;

	probes_handler_t *handler;

	/* restore address after step xol */

	unsigned long restore;

};

#ifdef CONFIG_KPROBES

typedef u32 kprobe_opcode_t;

struct arch_specific_insn {

	struct arch_probe_insn api;

	probe_opcode_t *xol_insn;

	/* restore address after step xol */

	unsigned long xol_restore;

};

#endif

arch/arm64/kernel/probes/kprobes.c

+15 −15
Original line number Diff line number Diff line
@@ -43,7 +43,7 @@ post_kprobe_handler(struct kprobe *, struct kprobe_ctlblk *, struct pt_regs *); 


static void __kprobes arch_prepare_ss_slot(struct kprobe *p)

{

	kprobe_opcode_t *addr = p->ainsn.api.insn;

	kprobe_opcode_t *addr = p->ainsn.xol_insn;



	/*

	 * Prepare insn slot, Mark Rutland points out it depends on a coupe of
@@ -70,14 +70,14 @@ static void __kprobes arch_prepare_ss_slot(struct kprobe *p) 
	/*

	 * Needs restoring of return address after stepping xol.

	 */

	p->ainsn.api.restore = (unsigned long) p->addr +

	p->ainsn.xol_restore = (unsigned long) p->addr +

	  sizeof(kprobe_opcode_t);

}



static void __kprobes arch_prepare_simulate(struct kprobe *p)

{

	/* This instructions is not executed xol. No need to adjust the PC */

	p->ainsn.api.restore = 0;

	p->ainsn.xol_restore = 0;

}



static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs)
@@ -110,18 +110,18 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) 
		return -EINVAL;



	case INSN_GOOD_NO_SLOT:	/* insn need simulation */

		p->ainsn.api.insn = NULL;

		p->ainsn.xol_insn = NULL;

		break;



	case INSN_GOOD:	/* instruction uses slot */

		p->ainsn.api.insn = get_insn_slot();

		if (!p->ainsn.api.insn)

		p->ainsn.xol_insn = get_insn_slot();

		if (!p->ainsn.xol_insn)

			return -ENOMEM;

		break;

	}



	/* prepare the instruction */

	if (p->ainsn.api.insn)

	if (p->ainsn.xol_insn)

		arch_prepare_ss_slot(p);

	else

		arch_prepare_simulate(p);
@@ -148,9 +148,9 @@ void __kprobes arch_disarm_kprobe(struct kprobe *p) 


void __kprobes arch_remove_kprobe(struct kprobe *p)

{

	if (p->ainsn.api.insn) {

		free_insn_slot(p->ainsn.api.insn, 0);

		p->ainsn.api.insn = NULL;

	if (p->ainsn.xol_insn) {

		free_insn_slot(p->ainsn.xol_insn, 0);

		p->ainsn.xol_insn = NULL;

	}

}
@@ -205,9 +205,9 @@ static void __kprobes setup_singlestep(struct kprobe *p, 
	}





	if (p->ainsn.api.insn) {

	if (p->ainsn.xol_insn) {

		/* prepare for single stepping */

		slot = (unsigned long)p->ainsn.api.insn;

		slot = (unsigned long)p->ainsn.xol_insn;



		kprobes_save_local_irqflag(kcb, regs);

		instruction_pointer_set(regs, slot);
@@ -245,8 +245,8 @@ static void __kprobes 
post_kprobe_handler(struct kprobe *cur, struct kprobe_ctlblk *kcb, struct pt_regs *regs)

{

	/* return addr restore if non-branching insn */

	if (cur->ainsn.api.restore != 0)

		instruction_pointer_set(regs, cur->ainsn.api.restore);

	if (cur->ainsn.xol_restore != 0)

		instruction_pointer_set(regs, cur->ainsn.xol_restore);



	/* restore back original saved kprobe variables and continue */

	if (kcb->kprobe_status == KPROBE_REENTER) {
@@ -348,7 +348,7 @@ kprobe_breakpoint_ss_handler(struct pt_regs *regs, unsigned long esr) 
	struct kprobe *cur = kprobe_running();



	if (cur && (kcb->kprobe_status & (KPROBE_HIT_SS | KPROBE_REENTER)) &&

	    ((unsigned long)&cur->ainsn.api.insn[1] == addr)) {

	    ((unsigned long)&cur->ainsn.xol_insn[1] == addr)) {

		kprobes_restore_local_irqflag(kcb, regs);

		post_kprobe_handler(cur, kcb, regs);