[PATCH] Kprobes/IA64: support kprobe on branch/call instructions (cd2675bf) · Commits · e / devices / android_kernel_xiaomi_markw

arch/ia64/kernel/kprobes.c

+116 −15

Original line number	Diff line number	Diff line
		@@ -120,25 +120,75 @@ void arch_arm_kprobe(struct kprobe *p)
		unsigned long arm_addr = addr & ~0xFULL;
		unsigned long slot = addr & 0xf;
		unsigned long template;
		unsigned long major_opcode = 0;
		unsigned long lx_type_inst = 0;
		unsigned long kprobe_inst = 0;
		bundle_t bundle;

		memcpy(&bundle, &p->ainsn.insn.bundle, sizeof(bundle_t));
		p->ainsn.inst_flag = 0;
		p->ainsn.target_br_reg = 0;

		memcpy(&bundle, &p->ainsn.insn.bundle, sizeof(bundle_t));
		template = bundle.quad0.template;
		if (slot == 1 && bundle_encoding[template][1] == L)
		if (slot == 1 && bundle_encoding[template][1] == L) {
		lx_type_inst = 1;
		slot = 2;
		}


		switch (slot) {
		case 0:
		major_opcode = (bundle.quad0.slot0 >> SLOT0_OPCODE_SHIFT);
		kprobe_inst = bundle.quad0.slot0;
		bundle.quad0.slot0 = BREAK_INST;
		break;
		case 1:
		major_opcode = (bundle.quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
		kprobe_inst = (bundle.quad0.slot1_p0 \|
		(bundle.quad1.slot1_p1 << (64-46)));
		bundle.quad0.slot1_p0 = BREAK_INST;
		bundle.quad1.slot1_p1 = (BREAK_INST >> (64-46));
		break;
		case 2:
		major_opcode = (bundle.quad1.slot2 >> SLOT2_OPCODE_SHIFT);
		kprobe_inst = bundle.quad1.slot2;
		bundle.quad1.slot2 = BREAK_INST;
		break;
		}
		/*
		* Look for IP relative Branches, IP relative call or
		* IP relative predicate instructions
		*/
		if (bundle_encoding[template][slot] == B) {
		switch (major_opcode) {
		case INDIRECT_CALL_OPCODE:
		p->ainsn.inst_flag \|= INST_FLAG_FIX_BRANCH_REG;
		p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
		break;
		case IP_RELATIVE_PREDICT_OPCODE:
		case IP_RELATIVE_BRANCH_OPCODE:
		p->ainsn.inst_flag \|= INST_FLAG_FIX_RELATIVE_IP_ADDR;
		break;
		case IP_RELATIVE_CALL_OPCODE:
		p->ainsn.inst_flag \|= INST_FLAG_FIX_RELATIVE_IP_ADDR;
		p->ainsn.inst_flag \|= INST_FLAG_FIX_BRANCH_REG;
		p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
		break;
		default:
		/* Do nothing */
		break;
		}
		} else if (lx_type_inst) {
		switch (major_opcode) {
		case LONG_CALL_OPCODE:
		p->ainsn.inst_flag \|= INST_FLAG_FIX_BRANCH_REG;
		p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
		break;
		default:
		/* Do nothing */
		break;
		}
		}

		/* Flush icache for the instruction at the emulated address */
		flush_icache_range((unsigned long)&p->ainsn.insn.bundle,
		@@ -170,23 +220,74 @@ void arch_remove_kprobe(struct kprobe *p)
		* We are resuming execution after a single step fault, so the pt_regs
		* structure reflects the register state after we executed the instruction
		* located in the kprobe (p->ainsn.insn.bundle). We still need to adjust
		* the ip to point back to the original stack address, and if we see that
		* the slot has incremented back to zero, then we need to point to the next
		* slot location.
		* the ip to point back to the original stack address. To set the IP address
		* to original stack address, handle the case where we need to fixup the
		* relative IP address and/or fixup branch register.
		*/
		static void resume_execution(struct kprobe p, struct pt_regs regs)
		{
		unsigned long bundle = (unsigned long)p->addr & ~0xFULL;
		unsigned long bundle_addr = ((unsigned long) (&p->ainsn.insn.bundle)) & ~0xFULL;
		unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
		unsigned long template;
		int slot = ((unsigned long)p->addr & 0xf);

		template = p->opcode.bundle.quad0.template;

		if (slot == 1 && bundle_encoding[template][1] == L)
		slot = 2;

		if (p->ainsn.inst_flag) {

		if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
		/* Fix relative IP address */
		regs->cr_iip = (regs->cr_iip - bundle_addr) + resume_addr;
		}

		if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
		/*
		* TODO: Handle cases where kprobe was inserted on a branch instruction
		* Fix target branch register, software convention is
		* to use either b0 or b6 or b7, so just checking
		* only those registers
		*/
		switch (p->ainsn.target_br_reg) {
		case 0:
		if ((regs->b0 == bundle_addr) \|\|
		(regs->b0 == bundle_addr + 0x10)) {
		regs->b0 = (regs->b0 - bundle_addr) +
		resume_addr;
		}
		break;
		case 6:
		if ((regs->b6 == bundle_addr) \|\|
		(regs->b6 == bundle_addr + 0x10)) {
		regs->b6 = (regs->b6 - bundle_addr) +
		resume_addr;
		}
		break;
		case 7:
		if ((regs->b7 == bundle_addr) \|\|
		(regs->b7 == bundle_addr + 0x10)) {
		regs->b7 = (regs->b7 - bundle_addr) +
		resume_addr;
		}
		break;
		} /* end switch */
		}
		goto turn_ss_off;
		}

		if (!ia64_psr(regs)->ri)
		regs->cr_iip = bundle + 0x10;
		else
		regs->cr_iip = bundle;
		if (slot == 2) {
		if (regs->cr_iip == bundle_addr + 0x10) {
		regs->cr_iip = resume_addr + 0x10;
		}
		} else {
		if (regs->cr_iip == bundle_addr) {
		regs->cr_iip = resume_addr;
		}
		}

		turn_ss_off:
		/* Turn off Single Step bit */
		ia64_psr(regs)->ss = 0;
		}

include/asm-ia64/kprobes.h

+16 −1

Original line number	Diff line number	Diff line
		@@ -44,6 +44,17 @@ typedef struct _bundle {

		#define JPROBE_ENTRY(pentry) (kprobe_opcode_t *)pentry

		#define SLOT0_OPCODE_SHIFT (37)
		#define SLOT1_p1_OPCODE_SHIFT (37 - (64-46))
		#define SLOT2_OPCODE_SHIFT (37)

		#define INDIRECT_CALL_OPCODE (1)
		#define IP_RELATIVE_CALL_OPCODE (5)
		#define IP_RELATIVE_BRANCH_OPCODE (4)
		#define IP_RELATIVE_PREDICT_OPCODE (7)
		#define LONG_BRANCH_OPCODE (0xC)
		#define LONG_CALL_OPCODE (0xD)

		typedef struct kprobe_opcode {
		bundle_t bundle;
		} kprobe_opcode_t;
		@@ -55,8 +66,12 @@ struct fnptr {

		/* Architecture specific copy of original instruction*/
		struct arch_specific_insn {
		/* copy of the original instruction */
		/* copy of the instruction to be emulated */
		kprobe_opcode_t insn;
		#define INST_FLAG_FIX_RELATIVE_IP_ADDR 1
		#define INST_FLAG_FIX_BRANCH_REG 2
		unsigned long inst_flag;
		unsigned short target_br_reg;
		};

		/* ia64 does not need this */