arch/powerpc/kernel/trace/ftrace.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Code for replacing ftrace calls with jumps.
  *
  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
  *
  * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.
  *
  * Added function graph tracer code, taken from x86 that was written
  * by Frederic Weisbecker, and ported to PPC by Steven Rostedt.
  *
  */

 #define pr_fmt(fmt) "ftrace-powerpc: " fmt

 #include <linux/spinlock.h>
 #include <linux/hardirq.h>
 #include <linux/uaccess.h>
 #include <linux/module.h>
 #include <linux/ftrace.h>
 #include <linux/percpu.h>
 #include <linux/init.h>
 #include <linux/list.h>

 #include <asm/cacheflush.h>
 #include <asm/code-patching.h>
 #include <asm/ftrace.h>
 #include <asm/syscall.h>
 #include <asm/inst.h>

 #define	NUM_FTRACE_TRAMPS	2
 static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];

 static ppc_inst_t ftrace_create_branch_inst(unsigned long ip, unsigned long addr, int link)
 {
 	ppc_inst_t op;

 	WARN_ON(!is_offset_in_branch_range(addr - ip));
 	create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0);

 	return op;
 }

 static inline int ftrace_read_inst(unsigned long ip, ppc_inst_t *op)
 {
 	if (copy_inst_from_kernel_nofault(op, (void *)ip)) {
 		pr_err("0x%lx: fetching instruction failed\n", ip);
 		return -EFAULT;
 	}

 	return 0;
 }

 static inline int ftrace_validate_inst(unsigned long ip, ppc_inst_t inst)
 {
 	ppc_inst_t op;
 	int ret;

 	ret = ftrace_read_inst(ip, &op);
 	if (!ret && !ppc_inst_equal(op, inst)) {
 		pr_err("0x%lx: expected (%08lx) != found (%08lx)\n",
 		       ip, ppc_inst_as_ulong(inst), ppc_inst_as_ulong(op));
 		ret = -EINVAL;
 	}

 	return ret;
 }

 static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
 {
 	int ret = ftrace_validate_inst(ip, old);

 	if (!ret)
 		ret = patch_instruction((u32 *)ip, new);

 	return ret;
 }

 static int is_bl_op(ppc_inst_t op)
 {
 	return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
 }

 static unsigned long find_ftrace_tramp(unsigned long ip)
 {
 	int i;

 	for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
 		if (!ftrace_tramps[i])
 			continue;
 		else if (is_offset_in_branch_range(ftrace_tramps[i] - ip))
 			return ftrace_tramps[i];

 	return 0;
 }

 static int ftrace_get_call_inst(struct dyn_ftrace *rec, unsigned long addr, ppc_inst_t *call_inst)
 {
 	unsigned long ip = rec->ip;
 	unsigned long stub;

 	if (is_offset_in_branch_range(addr - ip)) {
 		/* Within range */
 		stub = addr;
 #ifdef CONFIG_MODULES
 	} else if (rec->arch.mod) {
 		/* Module code would be going to one of the module stubs */
 		stub = (addr == (unsigned long)ftrace_caller ? rec->arch.mod->arch.tramp :
 							       rec->arch.mod->arch.tramp_regs);
 #endif
 	} else if (core_kernel_text(ip)) {
 		/* We would be branching to one of our ftrace stubs */
 		stub = find_ftrace_tramp(ip);
 		if (!stub) {
 			pr_err("0x%lx: No ftrace stubs reachable\n", ip);
 			return -EINVAL;
 		}
 	} else {
 		return -EINVAL;
 	}

 	*call_inst = ftrace_create_branch_inst(ip, stub, 1);
 	return 0;
 }

 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
 {
 	/* This should never be called since we override ftrace_replace_code() */
 	WARN_ON(1);
 	return -EINVAL;
 }
 #endif

 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 {
 	ppc_inst_t old, new;
 	int ret;

 	/* This can only ever be called during module load */
 	if (WARN_ON(!IS_ENABLED(CONFIG_MODULES) || core_kernel_text(rec->ip)))
 		return -EINVAL;

 	old = ppc_inst(PPC_RAW_NOP());
 	ret = ftrace_get_call_inst(rec, addr, &new);
 	if (ret)
 		return ret;

 	return ftrace_modify_code(rec->ip, old, new);
 }

 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
 {
 	/*
 	 * This should never be called since we override ftrace_replace_code(),
 	 * as well as ftrace_init_nop()
 	 */
 	WARN_ON(1);
 	return -EINVAL;
 }

 void ftrace_replace_code(int enable)
 {
 	ppc_inst_t old, new, call_inst, new_call_inst;
 	ppc_inst_t nop_inst = ppc_inst(PPC_RAW_NOP());
 	unsigned long ip, new_addr, addr;
 	struct ftrace_rec_iter *iter;
 	struct dyn_ftrace *rec;
 	int ret = 0, update;

 	for_ftrace_rec_iter(iter) {
 		rec = ftrace_rec_iter_record(iter);
 		ip = rec->ip;

 		if (rec->flags & FTRACE_FL_DISABLED && !(rec->flags & FTRACE_FL_ENABLED))
 			continue;

 		addr = ftrace_get_addr_curr(rec);
 		new_addr = ftrace_get_addr_new(rec);
 		update = ftrace_update_record(rec, enable);

 		switch (update) {
 		case FTRACE_UPDATE_IGNORE:
 		default:
 			continue;
 		case FTRACE_UPDATE_MODIFY_CALL:
 			ret = ftrace_get_call_inst(rec, new_addr, &new_call_inst);
 			ret |= ftrace_get_call_inst(rec, addr, &call_inst);
 			old = call_inst;
 			new = new_call_inst;
 			break;
 		case FTRACE_UPDATE_MAKE_NOP:
 			ret = ftrace_get_call_inst(rec, addr, &call_inst);
 			old = call_inst;
 			new = nop_inst;
 			break;
 		case FTRACE_UPDATE_MAKE_CALL:
 			ret = ftrace_get_call_inst(rec, new_addr, &call_inst);
 			old = nop_inst;
 			new = call_inst;
 			break;
 		}

 		if (!ret)
 			ret = ftrace_modify_code(ip, old, new);
 		if (ret)
 			goto out;
 	}

 out:
 	if (ret)
 		ftrace_bug(ret, rec);
 	return;
 }

 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
 {
 	unsigned long addr, ip = rec->ip;
 	ppc_inst_t old, new;
 	int ret = 0;

 	/* Verify instructions surrounding the ftrace location */
 	if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
 		/* Expect nops */
 		ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_NOP()));
 		if (!ret)
 			ret = ftrace_validate_inst(ip, ppc_inst(PPC_RAW_NOP()));
 	} else if (IS_ENABLED(CONFIG_PPC32)) {
 		/* Expected sequence: 'mflr r0', 'stw r0,4(r1)', 'bl _mcount' */
 		ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
 		if (!ret)
 			ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STW(_R0, _R1, 4)));
 	} else if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
 		/* Expected sequence: 'mflr r0', ['std r0,16(r1)'], 'bl _mcount' */
 		ret = ftrace_read_inst(ip - 4, &old);
 		if (!ret && !ppc_inst_equal(old, ppc_inst(PPC_RAW_MFLR(_R0)))) {
 			ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
 			ret |= ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STD(_R0, _R1, 16)));
 		}
 	} else {
 		return -EINVAL;
 	}

 	if (ret)
 		return ret;

 	if (!core_kernel_text(ip)) {
 		if (!mod) {
 			pr_err("0x%lx: No module provided for non-kernel address\n", ip);
 			return -EFAULT;
 		}
 		rec->arch.mod = mod;
 	}

 	/* Nop-out the ftrace location */
 	new = ppc_inst(PPC_RAW_NOP());
 	addr = MCOUNT_ADDR;
 	if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
 		/* we instead patch-in the 'mflr r0' */
 		old = ppc_inst(PPC_RAW_NOP());
 		new = ppc_inst(PPC_RAW_MFLR(_R0));
 		ret = ftrace_modify_code(ip - 4, old, new);
 	} else if (is_offset_in_branch_range(addr - ip)) {
 		/* Within range */
 		old = ftrace_create_branch_inst(ip, addr, 1);
 		ret = ftrace_modify_code(ip, old, new);
 	} else if (core_kernel_text(ip) || (IS_ENABLED(CONFIG_MODULES) && mod)) {
 		/*
 		 * We would be branching to a linker-generated stub, or to the module _mcount
 		 * stub. Let's just confirm we have a 'bl' here.
 		 */
 		ret = ftrace_read_inst(ip, &old);
 		if (ret)
 			return ret;
 		if (!is_bl_op(old)) {
 			pr_err("0x%lx: expected (bl) != found (%08lx)\n", ip, ppc_inst_as_ulong(old));
 			return -EINVAL;
 		}
 		ret = patch_instruction((u32 *)ip, new);
 	} else {
 		return -EINVAL;
 	}

 	return ret;
 }

 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
 	unsigned long ip = (unsigned long)(&ftrace_call);
 	ppc_inst_t old, new;
 	int ret;

 	old = ppc_inst_read((u32 *)&ftrace_call);
 	new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
 	ret = ftrace_modify_code(ip, old, new);

 	/* Also update the regs callback function */
 	if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) {
 		ip = (unsigned long)(&ftrace_regs_call);
 		old = ppc_inst_read((u32 *)&ftrace_regs_call);
 		new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
 		ret = ftrace_modify_code(ip, old, new);
 	}

 	return ret;
 }

 /*
  * Use the default ftrace_modify_all_code, but without
  * stop_machine().
  */
 void arch_ftrace_update_code(int command)
 {
 	ftrace_modify_all_code(command);
 }

 void ftrace_free_init_tramp(void)
 {
 	int i;

 	for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
 		if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
 			ftrace_tramps[i] = 0;
 			return;
 		}
 }

 static void __init add_ftrace_tramp(unsigned long tramp)
 {
 	int i;

 	for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
 		if (!ftrace_tramps[i]) {
 			ftrace_tramps[i] = tramp;
 			return;
 		}
 }

 int __init ftrace_dyn_arch_init(void)
 {
 	unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
 	unsigned long addr = FTRACE_REGS_ADDR;
 	long reladdr;
 	int i;
 	u32 stub_insns[] = {
 #ifdef CONFIG_PPC_KERNEL_PCREL
 		/* pla r12,addr */
 		PPC_PREFIX_MLS | __PPC_PRFX_R(1),
 		PPC_INST_PADDI | ___PPC_RT(_R12),
 		PPC_RAW_MTCTR(_R12),
 		PPC_RAW_BCTR()
 #elif defined(CONFIG_PPC64)
 		PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernel_toc)),
 		PPC_RAW_ADDIS(_R12, _R12, 0),
 		PPC_RAW_ADDI(_R12, _R12, 0),
 		PPC_RAW_MTCTR(_R12),
 		PPC_RAW_BCTR()
 #else
 		PPC_RAW_LIS(_R12, 0),
 		PPC_RAW_ADDI(_R12, _R12, 0),
 		PPC_RAW_MTCTR(_R12),
 		PPC_RAW_BCTR()
 #endif
 	};

 	if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
 		for (i = 0; i < 2; i++) {
 			reladdr = addr - (unsigned long)tramp[i];

 			if (reladdr >= (long)SZ_8G || reladdr < -(long)SZ_8G) {
 				pr_err("Address of %ps out of range of pcrel address.\n",
 					(void *)addr);
 				return -1;
 			}

 			memcpy(tramp[i], stub_insns, sizeof(stub_insns));
 			tramp[i][0] |= IMM_H18(reladdr);
 			tramp[i][1] |= IMM_L(reladdr);
 			add_ftrace_tramp((unsigned long)tramp[i]);
 		}
 	} else if (IS_ENABLED(CONFIG_PPC64)) {
 		reladdr = addr - kernel_toc_addr();

 		if (reladdr >= (long)SZ_2G || reladdr < -(long long)SZ_2G) {
 			pr_err("Address of %ps out of range of kernel_toc.\n",
 				(void *)addr);
 			return -1;
 		}

 		for (i = 0; i < 2; i++) {
 			memcpy(tramp[i], stub_insns, sizeof(stub_insns));
 			tramp[i][1] |= PPC_HA(reladdr);
 			tramp[i][2] |= PPC_LO(reladdr);
 			add_ftrace_tramp((unsigned long)tramp[i]);
 		}
 	} else {
 		for (i = 0; i < 2; i++) {
 			memcpy(tramp[i], stub_insns, sizeof(stub_insns));
 			tramp[i][0] |= PPC_HA(addr);
 			tramp[i][1] |= PPC_LO(addr);
 			add_ftrace_tramp((unsigned long)tramp[i]);
 		}
 	}

 	return 0;
 }

 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
 		       struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	unsigned long sp = fregs->regs.gpr[1];
 	int bit;

 	if (unlikely(ftrace_graph_is_dead()))
 		goto out;

 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		goto out;

 	bit = ftrace_test_recursion_trylock(ip, parent_ip);
 	if (bit < 0)
 		goto out;

 	if (!function_graph_enter(parent_ip, ip, 0, (unsigned long *)sp))
 		parent_ip = ppc_function_entry(return_to_handler);

 	ftrace_test_recursion_unlock(bit);
 out:
 	fregs->regs.link = parent_ip;
 }
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Code for replacing ftrace calls with jumps.
	*
	* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
	*
	* Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.
	*
	* Added function graph tracer code, taken from x86 that was written
	* by Frederic Weisbecker, and ported to PPC by Steven Rostedt.
	*
	*/

	#define pr_fmt(fmt) "ftrace-powerpc: " fmt

	#include <linux/spinlock.h>
	#include <linux/hardirq.h>
	#include <linux/uaccess.h>
	#include <linux/module.h>
	#include <linux/ftrace.h>
	#include <linux/percpu.h>
	#include <linux/init.h>
	#include <linux/list.h>

	#include <asm/cacheflush.h>
	#include <asm/code-patching.h>
	#include <asm/ftrace.h>
	#include <asm/syscall.h>
	#include <asm/inst.h>

	#define NUM_FTRACE_TRAMPS 2
	static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS];

	static ppc_inst_t ftrace_create_branch_inst(unsigned long ip, unsigned long addr, int link)
	{
	ppc_inst_t op;

	WARN_ON(!is_offset_in_branch_range(addr - ip));
	create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0);

	return op;
	}

	static inline int ftrace_read_inst(unsigned long ip, ppc_inst_t *op)
	{
	if (copy_inst_from_kernel_nofault(op, (void *)ip)) {
	pr_err("0x%lx: fetching instruction failed\n", ip);
	return -EFAULT;
	}

	return 0;
	}

	static inline int ftrace_validate_inst(unsigned long ip, ppc_inst_t inst)
	{
	ppc_inst_t op;
	int ret;

	ret = ftrace_read_inst(ip, &op);
	if (!ret && !ppc_inst_equal(op, inst)) {
	pr_err("0x%lx: expected (%08lx) != found (%08lx)\n",
	ip, ppc_inst_as_ulong(inst), ppc_inst_as_ulong(op));
	ret = -EINVAL;
	}

	return ret;
	}

	static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
	{
	int ret = ftrace_validate_inst(ip, old);

	if (!ret)
	ret = patch_instruction((u32 *)ip, new);

	return ret;
	}

	static int is_bl_op(ppc_inst_t op)
	{
	return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0);
	}

	static unsigned long find_ftrace_tramp(unsigned long ip)
	{
	int i;

	for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
	if (!ftrace_tramps[i])
	continue;
	else if (is_offset_in_branch_range(ftrace_tramps[i] - ip))
	return ftrace_tramps[i];

	return 0;
	}

	static int ftrace_get_call_inst(struct dyn_ftrace rec, unsigned long addr, ppc_inst_t call_inst)
	{
	unsigned long ip = rec->ip;
	unsigned long stub;

	if (is_offset_in_branch_range(addr - ip)) {
	/* Within range */
	stub = addr;
	#ifdef CONFIG_MODULES
	} else if (rec->arch.mod) {
	/* Module code would be going to one of the module stubs */
	stub = (addr == (unsigned long)ftrace_caller ? rec->arch.mod->arch.tramp :
	rec->arch.mod->arch.tramp_regs);
	#endif
	} else if (core_kernel_text(ip)) {
	/* We would be branching to one of our ftrace stubs */
	stub = find_ftrace_tramp(ip);
	if (!stub) {
	pr_err("0x%lx: No ftrace stubs reachable\n", ip);
	return -EINVAL;
	}
	} else {
	return -EINVAL;
	}

	*call_inst = ftrace_create_branch_inst(ip, stub, 1);
	return 0;
	}

	#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
	int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
	{
	/* This should never be called since we override ftrace_replace_code() */
	WARN_ON(1);
	return -EINVAL;
	}
	#endif

	int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
	{
	ppc_inst_t old, new;
	int ret;

	/* This can only ever be called during module load */
	if (WARN_ON(!IS_ENABLED(CONFIG_MODULES) \|\| core_kernel_text(rec->ip)))
	return -EINVAL;

	old = ppc_inst(PPC_RAW_NOP());
	ret = ftrace_get_call_inst(rec, addr, &new);
	if (ret)
	return ret;

	return ftrace_modify_code(rec->ip, old, new);
	}

	int ftrace_make_nop(struct module mod, struct dyn_ftrace rec, unsigned long addr)
	{
	/*
	* This should never be called since we override ftrace_replace_code(),
	* as well as ftrace_init_nop()
	*/
	WARN_ON(1);
	return -EINVAL;
	}

	void ftrace_replace_code(int enable)
	{
	ppc_inst_t old, new, call_inst, new_call_inst;
	ppc_inst_t nop_inst = ppc_inst(PPC_RAW_NOP());
	unsigned long ip, new_addr, addr;
	struct ftrace_rec_iter *iter;
	struct dyn_ftrace *rec;
	int ret = 0, update;

	for_ftrace_rec_iter(iter) {
	rec = ftrace_rec_iter_record(iter);
	ip = rec->ip;

	if (rec->flags & FTRACE_FL_DISABLED && !(rec->flags & FTRACE_FL_ENABLED))
	continue;

	addr = ftrace_get_addr_curr(rec);
	new_addr = ftrace_get_addr_new(rec);
	update = ftrace_update_record(rec, enable);

	switch (update) {
	case FTRACE_UPDATE_IGNORE:
	default:
	continue;
	case FTRACE_UPDATE_MODIFY_CALL:
	ret = ftrace_get_call_inst(rec, new_addr, &new_call_inst);
	ret \|= ftrace_get_call_inst(rec, addr, &call_inst);
	old = call_inst;
	new = new_call_inst;
	break;
	case FTRACE_UPDATE_MAKE_NOP:
	ret = ftrace_get_call_inst(rec, addr, &call_inst);
	old = call_inst;
	new = nop_inst;
	break;
	case FTRACE_UPDATE_MAKE_CALL:
	ret = ftrace_get_call_inst(rec, new_addr, &call_inst);
	old = nop_inst;
	new = call_inst;
	break;
	}

	if (!ret)
	ret = ftrace_modify_code(ip, old, new);
	if (ret)
	goto out;
	}

	out:
	if (ret)
	ftrace_bug(ret, rec);
	return;
	}

	int ftrace_init_nop(struct module mod, struct dyn_ftrace rec)
	{
	unsigned long addr, ip = rec->ip;
	ppc_inst_t old, new;
	int ret = 0;

	/* Verify instructions surrounding the ftrace location */
	if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
	/* Expect nops */
	ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_NOP()));
	if (!ret)
	ret = ftrace_validate_inst(ip, ppc_inst(PPC_RAW_NOP()));
	} else if (IS_ENABLED(CONFIG_PPC32)) {
	/* Expected sequence: 'mflr r0', 'stw r0,4(r1)', 'bl _mcount' */
	ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
	if (!ret)
	ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STW(_R0, _R1, 4)));
	} else if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) {
	/* Expected sequence: 'mflr r0', ['std r0,16(r1)'], 'bl _mcount' */
	ret = ftrace_read_inst(ip - 4, &old);
	if (!ret && !ppc_inst_equal(old, ppc_inst(PPC_RAW_MFLR(_R0)))) {
	ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0)));
	ret \|= ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STD(_R0, _R1, 16)));
	}
	} else {
	return -EINVAL;
	}

	if (ret)
	return ret;

	if (!core_kernel_text(ip)) {
	if (!mod) {
	pr_err("0x%lx: No module provided for non-kernel address\n", ip);
	return -EFAULT;
	}
	rec->arch.mod = mod;
	}

	/* Nop-out the ftrace location */
	new = ppc_inst(PPC_RAW_NOP());
	addr = MCOUNT_ADDR;
	if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)) {
	/* we instead patch-in the 'mflr r0' */
	old = ppc_inst(PPC_RAW_NOP());
	new = ppc_inst(PPC_RAW_MFLR(_R0));
	ret = ftrace_modify_code(ip - 4, old, new);
	} else if (is_offset_in_branch_range(addr - ip)) {
	/* Within range */
	old = ftrace_create_branch_inst(ip, addr, 1);
	ret = ftrace_modify_code(ip, old, new);
	} else if (core_kernel_text(ip) \|\| (IS_ENABLED(CONFIG_MODULES) && mod)) {
	/*
	* We would be branching to a linker-generated stub, or to the module _mcount
	* stub. Let's just confirm we have a 'bl' here.
	*/
	ret = ftrace_read_inst(ip, &old);
	if (ret)
	return ret;
	if (!is_bl_op(old)) {
	pr_err("0x%lx: expected (bl) != found (%08lx)\n", ip, ppc_inst_as_ulong(old));
	return -EINVAL;
	}
	ret = patch_instruction((u32 *)ip, new);
	} else {
	return -EINVAL;
	}

	return ret;
	}

	int ftrace_update_ftrace_func(ftrace_func_t func)
	{
	unsigned long ip = (unsigned long)(&ftrace_call);
	ppc_inst_t old, new;
	int ret;

	old = ppc_inst_read((u32 *)&ftrace_call);
	new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
	ret = ftrace_modify_code(ip, old, new);

	/* Also update the regs callback function */
	if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) {
	ip = (unsigned long)(&ftrace_regs_call);
	old = ppc_inst_read((u32 *)&ftrace_regs_call);
	new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1);
	ret = ftrace_modify_code(ip, old, new);
	}

	return ret;
	}

	/*
	* Use the default ftrace_modify_all_code, but without
	* stop_machine().
	*/
	void arch_ftrace_update_code(int command)
	{
	ftrace_modify_all_code(command);
	}

	void ftrace_free_init_tramp(void)
	{
	int i;

	for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++)
	if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) {
	ftrace_tramps[i] = 0;
	return;
	}
	}

	static void __init add_ftrace_tramp(unsigned long tramp)
	{
	int i;

	for (i = 0; i < NUM_FTRACE_TRAMPS; i++)
	if (!ftrace_tramps[i]) {
	ftrace_tramps[i] = tramp;
	return;
	}
	}

	int __init ftrace_dyn_arch_init(void)
	{
	unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
	unsigned long addr = FTRACE_REGS_ADDR;
	long reladdr;
	int i;
	u32 stub_insns[] = {
	#ifdef CONFIG_PPC_KERNEL_PCREL
	/* pla r12,addr */
	PPC_PREFIX_MLS \| __PPC_PRFX_R(1),
	PPC_INST_PADDI \| ___PPC_RT(_R12),
	PPC_RAW_MTCTR(_R12),
	PPC_RAW_BCTR()
	#elif defined(CONFIG_PPC64)
	PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernel_toc)),
	PPC_RAW_ADDIS(_R12, _R12, 0),
	PPC_RAW_ADDI(_R12, _R12, 0),
	PPC_RAW_MTCTR(_R12),
	PPC_RAW_BCTR()
	#else
	PPC_RAW_LIS(_R12, 0),
	PPC_RAW_ADDI(_R12, _R12, 0),
	PPC_RAW_MTCTR(_R12),
	PPC_RAW_BCTR()
	#endif
	};

	if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
	for (i = 0; i < 2; i++) {
	reladdr = addr - (unsigned long)tramp[i];

	if (reladdr >= (long)SZ_8G \|\| reladdr < -(long)SZ_8G) {
	pr_err("Address of %ps out of range of pcrel address.\n",
	(void *)addr);
	return -1;
	}

	memcpy(tramp[i], stub_insns, sizeof(stub_insns));
	tramp[i][0] \|= IMM_H18(reladdr);
	tramp[i][1] \|= IMM_L(reladdr);
	add_ftrace_tramp((unsigned long)tramp[i]);
	}
	} else if (IS_ENABLED(CONFIG_PPC64)) {
	reladdr = addr - kernel_toc_addr();

	if (reladdr >= (long)SZ_2G \|\| reladdr < -(long long)SZ_2G) {
	pr_err("Address of %ps out of range of kernel_toc.\n",
	(void *)addr);
	return -1;
	}

	for (i = 0; i < 2; i++) {
	memcpy(tramp[i], stub_insns, sizeof(stub_insns));
	tramp[i][1] \|= PPC_HA(reladdr);
	tramp[i][2] \|= PPC_LO(reladdr);
	add_ftrace_tramp((unsigned long)tramp[i]);
	}
	} else {
	for (i = 0; i < 2; i++) {
	memcpy(tramp[i], stub_insns, sizeof(stub_insns));
	tramp[i][0] \|= PPC_HA(addr);
	tramp[i][1] \|= PPC_LO(addr);
	add_ftrace_tramp((unsigned long)tramp[i]);
	}
	}

	return 0;
	}

	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
	struct ftrace_ops op, struct ftrace_regs fregs)
	{
	unsigned long sp = fregs->regs.gpr[1];
	int bit;

	if (unlikely(ftrace_graph_is_dead()))
	goto out;

	if (unlikely(atomic_read(&current->tracing_graph_pause)))
	goto out;

	bit = ftrace_test_recursion_trylock(ip, parent_ip);
	if (bit < 0)
	goto out;

	if (!function_graph_enter(parent_ip, ip, 0, (unsigned long *)sp))
	parent_ip = ppc_function_entry(return_to_handler);

	ftrace_test_recursion_unlock(bit);
	out:
	fregs->regs.link = parent_ip;
	}
	#endif /* CONFIG_FUNCTION_GRAPH_TRACER */