Commit ba640a59 authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Martin Schwidefsky
Browse files

[S390] kprobes: instruction fixup 



Determine instruction fixup details in resume_execution, no need to do
it beforehand. Remove fixup, ilen and reg from arch_specific_insn.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 5a8b589f

arch/s390/include/asm/kprobes.h

+0 −5
Original line number Diff line number Diff line
@@ -59,9 +59,6 @@ typedef u16 kprobe_opcode_t; 
struct arch_specific_insn {

	/* copy of original instruction */

	kprobe_opcode_t *insn;

	int fixup;

	int ilen;

	int reg;

};



struct prev_kprobe {
@@ -83,8 +80,6 @@ struct kprobe_ctlblk { 


void arch_remove_kprobe(struct kprobe *p);

void kretprobe_trampoline(void);

int  is_prohibited_opcode(kprobe_opcode_t *instruction);

void get_instruction_type(struct arch_specific_insn *ainsn);



int kprobe_fault_handler(struct pt_regs *regs, int trapnr);

int kprobe_exceptions_notify(struct notifier_block *self,

arch/s390/kernel/kprobes.c

+57 −73
Original line number Diff line number Diff line
@@ -37,29 +37,9 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); 


struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};



int __kprobes arch_prepare_kprobe(struct kprobe *p)

{

	/* Make sure the probe isn't going on a difficult instruction */

	if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))

		return -EINVAL;



	if ((unsigned long)p->addr & 0x01)

		return -EINVAL;



	/* Use the get_insn_slot() facility for correctness */

	if (!(p->ainsn.insn = get_insn_slot()))

		return -ENOMEM;



	memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));



	get_instruction_type(&p->ainsn);

	p->opcode = *p->addr;

	return 0;

}



int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)

static int __kprobes is_prohibited_opcode(kprobe_opcode_t *insn)

{

	switch (*(__u8 *) instruction) {

	switch (insn[0] >> 8) {

	case 0x0c:	/* bassm */

	case 0x0b:	/* bsm	 */

	case 0x83:	/* diag  */
@@ -68,7 +48,7 @@ int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction) 
	case 0xad:	/* stosm */

		return -EINVAL;

	}

	switch (*(__u16 *) instruction) {

	switch (insn[0]) {

	case 0x0101:	/* pr	 */

	case 0xb25a:	/* bsa	 */

	case 0xb240:	/* bakr  */
@@ -81,80 +61,79 @@ int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction) 
	return 0;

}



void __kprobes get_instruction_type(struct arch_specific_insn *ainsn)

static int __kprobes get_fixup_type(kprobe_opcode_t *insn)

{

	/* default fixup method */

	ainsn->fixup = FIXUP_PSW_NORMAL;



	/* save r1 operand */

	ainsn->reg = (*ainsn->insn & 0xf0) >> 4;



	/* save the instruction length (pop 5-5) in bytes */

	switch (*(__u8 *) (ainsn->insn) >> 6) {

	case 0:

		ainsn->ilen = 2;

		break;

	case 1:

	case 2:

		ainsn->ilen = 4;

		break;

	case 3:

		ainsn->ilen = 6;

		break;

	}

	int fixup = FIXUP_PSW_NORMAL;



	switch (*(__u8 *) ainsn->insn) {

	switch (insn[0] >> 8) {

	case 0x05:	/* balr	*/

	case 0x0d:	/* basr */

		ainsn->fixup = FIXUP_RETURN_REGISTER;

		fixup = FIXUP_RETURN_REGISTER;

		/* if r2 = 0, no branch will be taken */

		if ((*ainsn->insn & 0x0f) == 0)

			ainsn->fixup |= FIXUP_BRANCH_NOT_TAKEN;

		if ((insn[0] & 0x0f) == 0)

			fixup |= FIXUP_BRANCH_NOT_TAKEN;

		break;

	case 0x06:	/* bctr	*/

	case 0x07:	/* bcr	*/

		ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;

		fixup = FIXUP_BRANCH_NOT_TAKEN;

		break;

	case 0x45:	/* bal	*/

	case 0x4d:	/* bas	*/

		ainsn->fixup = FIXUP_RETURN_REGISTER;

		fixup = FIXUP_RETURN_REGISTER;

		break;

	case 0x47:	/* bc	*/

	case 0x46:	/* bct	*/

	case 0x86:	/* bxh	*/

	case 0x87:	/* bxle	*/

		ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;

		fixup = FIXUP_BRANCH_NOT_TAKEN;

		break;

	case 0x82:	/* lpsw	*/

		ainsn->fixup = FIXUP_NOT_REQUIRED;

		fixup = FIXUP_NOT_REQUIRED;

		break;

	case 0xb2:	/* lpswe */

		if (*(((__u8 *) ainsn->insn) + 1) == 0xb2) {

			ainsn->fixup = FIXUP_NOT_REQUIRED;

		}

		if ((insn[0] & 0xff) == 0xb2)

			fixup = FIXUP_NOT_REQUIRED;

		break;

	case 0xa7:	/* bras	*/

		if ((*ainsn->insn & 0x0f) == 0x05) {

			ainsn->fixup |= FIXUP_RETURN_REGISTER;

		}

		if ((insn[0] & 0x0f) == 0x05)

			fixup |= FIXUP_RETURN_REGISTER;

		break;

	case 0xc0:

		if ((*ainsn->insn & 0x0f) == 0x00  /* larl  */

			|| (*ainsn->insn & 0x0f) == 0x05) /* brasl */

		ainsn->fixup |= FIXUP_RETURN_REGISTER;

		if ((insn[0] & 0x0f) == 0x00 ||	/* larl  */

		    (insn[0] & 0x0f) == 0x05)	/* brasl */

		fixup |= FIXUP_RETURN_REGISTER;

		break;

	case 0xeb:

		if (*(((__u8 *) ainsn->insn) + 5 ) == 0x44 ||	/* bxhg  */

			*(((__u8 *) ainsn->insn) + 5) == 0x45) {/* bxleg */

			ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;

		}

		if ((insn[2] & 0xff) == 0x44 ||	/* bxhg  */

		    (insn[2] & 0xff) == 0x45)	/* bxleg */

			fixup = FIXUP_BRANCH_NOT_TAKEN;

		break;

	case 0xe3:	/* bctg	*/

		if (*(((__u8 *) ainsn->insn) + 5) == 0x46) {

			ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;

		}

		if ((insn[2] & 0xff) == 0x46)

			fixup = FIXUP_BRANCH_NOT_TAKEN;

		break;

	}

	return fixup;

}



int __kprobes arch_prepare_kprobe(struct kprobe *p)

{

	if ((unsigned long) p->addr & 0x01)

		return -EINVAL;



	/* Make sure the probe isn't going on a difficult instruction */

	if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))

		return -EINVAL;



	/* Use the get_insn_slot() facility for correctness */

	if (!(p->ainsn.insn = get_insn_slot()))

		return -ENOMEM;



	p->opcode = *p->addr;

	memcpy(p->ainsn.insn, p->addr, ((p->opcode >> 14) + 3) & -2);



	return 0;

}



struct ins_replace_args {
@@ -444,17 +423,22 @@ static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs) 
{

	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

	unsigned long ip = regs->psw.addr & PSW_ADDR_INSN;

	int fixup = get_fixup_type(p->ainsn.insn);



	if (p->ainsn.fixup & FIXUP_PSW_NORMAL)

	if (fixup & FIXUP_PSW_NORMAL)

		ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn;



	if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)

		if (ip - (unsigned long) p->ainsn.insn == p->ainsn.ilen)

			ip = (unsigned long) p->addr + p->ainsn.ilen;

	if (fixup & FIXUP_BRANCH_NOT_TAKEN) {

		int ilen = ((p->ainsn.insn[0] >> 14) + 3) & -2;

		if (ip - (unsigned long) p->ainsn.insn == ilen)

			ip = (unsigned long) p->addr + ilen;

	}



	if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)

		regs->gprs[p->ainsn.reg] += (unsigned long) p->addr -

	if (fixup & FIXUP_RETURN_REGISTER) {

		int reg = (p->ainsn.insn[0] & 0xf0) >> 4;

		regs->gprs[reg] += (unsigned long) p->addr -

				   (unsigned long) p->ainsn.insn;

	}



	disable_singlestep(kcb, regs, ip);

}

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