powerpc/kprobes: Implement Optprobes

	select HAVE_IOREMAP_PROT

	select HAVE_EFFICIENT_UNALIGNED_ACCESS if !(CPU_LITTLE_ENDIAN && POWER7_CPU)

	select HAVE_KPROBES

	select HAVE_OPTPROBES if PPC64

	select HAVE_ARCH_KGDB

	select HAVE_KRETPROBES

	select HAVE_ARCH_TRACEHOOK

unsigned long branch_target(const unsigned int *instr);

unsigned int translate_branch(const unsigned int *dest,

			      const unsigned int *src);

extern bool is_conditional_branch(unsigned int instr);

#ifdef CONFIG_PPC_BOOK3E_64

void __patch_exception(int exc, unsigned long addr);

#define patch_exception(exc, name) do { \

struct kprobe;

typedef ppc_opcode_t kprobe_opcode_t;

extern kprobe_opcode_t optinsn_slot;

/* Optinsn template address */

extern kprobe_opcode_t optprobe_template_entry[];

extern kprobe_opcode_t optprobe_template_op_address[];

extern kprobe_opcode_t optprobe_template_call_handler[];

extern kprobe_opcode_t optprobe_template_insn[];

extern kprobe_opcode_t optprobe_template_call_emulate[];

extern kprobe_opcode_t optprobe_template_ret[];

extern kprobe_opcode_t optprobe_template_end[];

/* Fixed instruction size for powerpc */

#define MAX_INSN_SIZE		1

#define MAX_OPTIMIZED_LENGTH	sizeof(kprobe_opcode_t)	/* 4 bytes */

#define MAX_OPTINSN_SIZE	(optprobe_template_end - optprobe_template_entry)

#define RELATIVEJUMP_SIZE	sizeof(kprobe_opcode_t)	/* 4 bytes */

#ifdef PPC64_ELF_ABI_v2

/* PPC64 ABIv2 needs local entry point */

	struct prev_kprobe prev_kprobe;

};

struct arch_optimized_insn {

	kprobe_opcode_t copied_insn[1];

	/* detour buffer */

	kprobe_opcode_t *insn;

};

extern int kprobe_exceptions_notify(struct notifier_block *self,

					unsigned long val, void *data);

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

obj-$(CONFIG_BOOTX_TEXT)	+= btext.o

obj-$(CONFIG_SMP)		+= smp.o

obj-$(CONFIG_KPROBES)		+= kprobes.o

obj-$(CONFIG_OPTPROBES)		+= optprobes.o optprobes_head.o

obj-$(CONFIG_UPROBES)		+= uprobes.o

obj-$(CONFIG_PPC_UDBG_16550)	+= legacy_serial.o udbg_16550.o

obj-$(CONFIG_STACKTRACE)	+= stacktrace.o

/*

 * Code for Kernel probes Jump optimization.

 *

 * Copyright 2017, Anju T, IBM Corp.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version

 * 2 of the License, or (at your option) any later version.

 */

#include <linux/kprobes.h>

#include <linux/jump_label.h>

#include <linux/types.h>

#include <linux/slab.h>

#include <linux/list.h>

#include <asm/kprobes.h>

#include <asm/ptrace.h>

#include <asm/cacheflush.h>

#include <asm/code-patching.h>

#include <asm/sstep.h>

#include <asm/ppc-opcode.h>

#define TMPL_CALL_HDLR_IDX	\

	(optprobe_template_call_handler - optprobe_template_entry)

#define TMPL_EMULATE_IDX	\

	(optprobe_template_call_emulate - optprobe_template_entry)

#define TMPL_RET_IDX		\

	(optprobe_template_ret - optprobe_template_entry)

#define TMPL_OP_IDX		\

	(optprobe_template_op_address - optprobe_template_entry)

#define TMPL_INSN_IDX		\

	(optprobe_template_insn - optprobe_template_entry)

#define TMPL_END_IDX		\

	(optprobe_template_end - optprobe_template_entry)

DEFINE_INSN_CACHE_OPS(ppc_optinsn);

static bool insn_page_in_use;

static void *__ppc_alloc_insn_page(void)

{

	if (insn_page_in_use)

		return NULL;

	insn_page_in_use = true;

	return &optinsn_slot;

}

static void __ppc_free_insn_page(void *page __maybe_unused)

{

	insn_page_in_use = false;

}

struct kprobe_insn_cache kprobe_ppc_optinsn_slots = {

	.mutex = __MUTEX_INITIALIZER(kprobe_ppc_optinsn_slots.mutex),

	.pages = LIST_HEAD_INIT(kprobe_ppc_optinsn_slots.pages),

	/* insn_size initialized later */

	.alloc = __ppc_alloc_insn_page,

	.free = __ppc_free_insn_page,

	.nr_garbage = 0,

};

/*

 * Check if we can optimize this probe. Returns NIP post-emulation if this can

 * be optimized and 0 otherwise.

 */

static unsigned long can_optimize(struct kprobe *p)

{

	struct pt_regs regs;

	struct instruction_op op;

	unsigned long nip = 0;

	/*

	 * kprobe placed for kretprobe during boot time

	 * is not optimizing now.

	 *

	 * TODO: Optimize kprobe in kretprobe_trampoline

	 */

	if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)

		return 0;

	/*

	 * We only support optimizing kernel addresses, but not

	 * module addresses.

	 *

	 * FIXME: Optimize kprobes placed in module addresses.

	 */

	if (!is_kernel_addr((unsigned long)p->addr))

		return 0;

	memset(&regs, 0, sizeof(struct pt_regs));

	regs.nip = (unsigned long)p->addr;

	regs.trap = 0x0;

	regs.msr = MSR_KERNEL;

	/*

	 * Kprobe placed in conditional branch instructions are

	 * not optimized, as we can't predict the nip prior with

	 * dummy pt_regs and can not ensure that the return branch

	 * from detour buffer falls in the range of address (i.e 32MB).

	 * A branch back from trampoline is set up in the detour buffer

	 * to the nip returned by the analyse_instr() here.

	 *

	 * Ensure that the instruction is not a conditional branch,

	 * and that can be emulated.

	 */

	if (!is_conditional_branch(*p->ainsn.insn) &&

			analyse_instr(&op, &regs, *p->ainsn.insn))

		nip = regs.nip;

	return nip;

}

static void optimized_callback(struct optimized_kprobe *op,

			       struct pt_regs *regs)

{

	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

	unsigned long flags;

	/* This is possible if op is under delayed unoptimizing */

	if (kprobe_disabled(&op->kp))

		return;

	local_irq_save(flags);

	hard_irq_disable();

	if (kprobe_running()) {

		kprobes_inc_nmissed_count(&op->kp);

	} else {

		__this_cpu_write(current_kprobe, &op->kp);

		regs->nip = (unsigned long)op->kp.addr;

		kcb->kprobe_status = KPROBE_HIT_ACTIVE;

		opt_pre_handler(&op->kp, regs);

		__this_cpu_write(current_kprobe, NULL);

	}

	/*

	 * No need for an explicit __hard_irq_enable() here.

	 * local_irq_restore() will re-enable interrupts,

	 * if they were hard disabled.

	 */

	local_irq_restore(flags);

}

NOKPROBE_SYMBOL(optimized_callback);

void arch_remove_optimized_kprobe(struct optimized_kprobe *op)

{

	if (op->optinsn.insn) {

		free_ppc_optinsn_slot(op->optinsn.insn, 1);

		op->optinsn.insn = NULL;

	}

}

/*

 * emulate_step() requires insn to be emulated as

 * second parameter. Load register 'r4' with the

 * instruction.

 */

void patch_imm32_load_insns(unsigned int val, kprobe_opcode_t *addr)

{

	/* addis r4,0,(insn)@h */

	*addr++ = PPC_INST_ADDIS | ___PPC_RT(4) |

		  ((val >> 16) & 0xffff);

	/* ori r4,r4,(insn)@l */

	*addr = PPC_INST_ORI | ___PPC_RA(4) | ___PPC_RS(4) |

		(val & 0xffff);

}

/*

 * Generate instructions to load provided immediate 64-bit value

 * to register 'r3' and patch these instructions at 'addr'.

 */

void patch_imm64_load_insns(unsigned long val, kprobe_opcode_t *addr)

{

	/* lis r3,(op)@highest */

	*addr++ = PPC_INST_ADDIS | ___PPC_RT(3) |

		  ((val >> 48) & 0xffff);

	/* ori r3,r3,(op)@higher */

	*addr++ = PPC_INST_ORI | ___PPC_RA(3) | ___PPC_RS(3) |

		  ((val >> 32) & 0xffff);

	/* rldicr r3,r3,32,31 */

	*addr++ = PPC_INST_RLDICR | ___PPC_RA(3) | ___PPC_RS(3) |

		  __PPC_SH64(32) | __PPC_ME64(31);

	/* oris r3,r3,(op)@h */

	*addr++ = PPC_INST_ORIS | ___PPC_RA(3) | ___PPC_RS(3) |

		  ((val >> 16) & 0xffff);

	/* ori r3,r3,(op)@l */

	*addr = PPC_INST_ORI | ___PPC_RA(3) | ___PPC_RS(3) |

		(val & 0xffff);

}

int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)

{

	kprobe_opcode_t *buff, branch_op_callback, branch_emulate_step;

	kprobe_opcode_t *op_callback_addr, *emulate_step_addr;

	long b_offset;

	unsigned long nip;

	kprobe_ppc_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;

	nip = can_optimize(p);

	if (!nip)

		return -EILSEQ;

	/* Allocate instruction slot for detour buffer */

	buff = get_ppc_optinsn_slot();

	if (!buff)

		return -ENOMEM;

	/*

	 * OPTPROBE uses 'b' instruction to branch to optinsn.insn.

	 *

	 * The target address has to be relatively nearby, to permit use

	 * of branch instruction in powerpc, because the address is specified

	 * in an immediate field in the instruction opcode itself, ie 24 bits

	 * in the opcode specify the address. Therefore the address should

	 * be within 32MB on either side of the current instruction.

	 */

	b_offset = (unsigned long)buff - (unsigned long)p->addr;

	if (!is_offset_in_branch_range(b_offset))

		goto error;

	/* Check if the return address is also within 32MB range */

	b_offset = (unsigned long)(buff + TMPL_RET_IDX) -

			(unsigned long)nip;

	if (!is_offset_in_branch_range(b_offset))

		goto error;

	/* Setup template */

	memcpy(buff, optprobe_template_entry,

			TMPL_END_IDX * sizeof(kprobe_opcode_t));

	/*

	 * Fixup the template with instructions to:

	 * 1. load the address of the actual probepoint

	 */

	patch_imm64_load_insns((unsigned long)op, buff + TMPL_OP_IDX);

	/*

	 * 2. branch to optimized_callback() and emulate_step()

	 */

	kprobe_lookup_name("optimized_callback", op_callback_addr);

	kprobe_lookup_name("emulate_step", emulate_step_addr);

	if (!op_callback_addr || !emulate_step_addr) {

		WARN(1, "kprobe_lookup_name() failed\n");

		goto error;

	}

	branch_op_callback = create_branch((unsigned int *)buff + TMPL_CALL_HDLR_IDX,

				(unsigned long)op_callback_addr,

				BRANCH_SET_LINK);

	branch_emulate_step = create_branch((unsigned int *)buff + TMPL_EMULATE_IDX,

				(unsigned long)emulate_step_addr,

				BRANCH_SET_LINK);

	if (!branch_op_callback || !branch_emulate_step)

		goto error;

	buff[TMPL_CALL_HDLR_IDX] = branch_op_callback;

	buff[TMPL_EMULATE_IDX] = branch_emulate_step;

	/*

	 * 3. load instruction to be emulated into relevant register, and

	 */

	patch_imm32_load_insns(*p->ainsn.insn, buff + TMPL_INSN_IDX);

	/*

	 * 4. branch back from trampoline

	 */

	buff[TMPL_RET_IDX] = create_branch((unsigned int *)buff + TMPL_RET_IDX,

				(unsigned long)nip, 0);

	flush_icache_range((unsigned long)buff,

			   (unsigned long)(&buff[TMPL_END_IDX]));

	op->optinsn.insn = buff;

	return 0;

error:

	free_ppc_optinsn_slot(buff, 0);

	return -ERANGE;

}

int arch_prepared_optinsn(struct arch_optimized_insn *optinsn)

{

	return optinsn->insn != NULL;

}

/*

 * On powerpc, Optprobes always replaces one instruction (4 bytes

 * aligned and 4 bytes long). It is impossible to encounter another

 * kprobe in this address range. So always return 0.

 */

int arch_check_optimized_kprobe(struct optimized_kprobe *op)

{

	return 0;

}

void arch_optimize_kprobes(struct list_head *oplist)

{

	struct optimized_kprobe *op;

	struct optimized_kprobe *tmp;

	list_for_each_entry_safe(op, tmp, oplist, list) {

		/*

		 * Backup instructions which will be replaced

		 * by jump address

		 */

		memcpy(op->optinsn.copied_insn, op->kp.addr,

					       RELATIVEJUMP_SIZE);

		patch_instruction(op->kp.addr,

			create_branch((unsigned int *)op->kp.addr,

				      (unsigned long)op->optinsn.insn, 0));

		list_del_init(&op->list);

	}

}

void arch_unoptimize_kprobe(struct optimized_kprobe *op)

{

	arch_arm_kprobe(&op->kp);

}

void arch_unoptimize_kprobes(struct list_head *oplist,

			     struct list_head *done_list)

{

	struct optimized_kprobe *op;

	struct optimized_kprobe *tmp;

	list_for_each_entry_safe(op, tmp, oplist, list) {

		arch_unoptimize_kprobe(op);

		list_move(&op->list, done_list);

	}

}

int arch_within_optimized_kprobe(struct optimized_kprobe *op,

				 unsigned long addr)

{

	return ((unsigned long)op->kp.addr <= addr &&

		(unsigned long)op->kp.addr + RELATIVEJUMP_SIZE > addr);

}