arch/powerpc/include/asm/ptrace.h - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0-or-later */
 /*
  * Copyright (C) 2001 PPC64 Team, IBM Corp
  *
  * This struct defines the way the registers are stored on the
  * kernel stack during a system call or other kernel entry.
  *
  * this should only contain volatile regs
  * since we can keep non-volatile in the thread_struct
  * should set this up when only volatiles are saved
  * by intr code.
  *
  * Since this is going on the stack, *CARE MUST BE TAKEN* to insure
  * that the overall structure is a multiple of 16 bytes in length.
  *
  * Note that the offsets of the fields in this struct correspond with
  * the PT_* values below.  This simplifies arch/powerpc/kernel/ptrace.c.
  */
 #ifndef _ASM_POWERPC_PTRACE_H
 #define _ASM_POWERPC_PTRACE_H

 #include <linux/err.h>
 #include <uapi/asm/ptrace.h>
 #include <asm/asm-const.h>
 #include <asm/reg.h>

 #ifndef __ASSEMBLY__
 struct pt_regs
 {
 	union {
 		struct user_pt_regs user_regs;
 		struct {
 			unsigned long gpr[32];
 			unsigned long nip;
 			unsigned long msr;
 			unsigned long orig_gpr3;
 			unsigned long ctr;
 			unsigned long link;
 			unsigned long xer;
 			unsigned long ccr;
 #ifdef CONFIG_PPC64
 			unsigned long softe;
 #else
 			unsigned long mq;
 #endif
 			unsigned long trap;
 			union {
 				unsigned long dar;
 				unsigned long dear;
 			};
 			union {
 				unsigned long dsisr;
 				unsigned long esr;
 			};
 			unsigned long result;
 		};
 	};
 #if defined(CONFIG_PPC64) || defined(CONFIG_PPC_KUAP)
 	union {
 		struct {
 #ifdef CONFIG_PPC64
 			unsigned long ppr;
 			unsigned long exit_result;
 #endif
 			union {
 #ifdef CONFIG_PPC_KUAP
 				unsigned long kuap;
 #endif
 #ifdef CONFIG_PPC_PKEY
 				unsigned long amr;
 #endif
 			};
 #ifdef CONFIG_PPC_PKEY
 			unsigned long iamr;
 #endif
 		};
 		unsigned long __pad[4];	/* Maintain 16 byte interrupt stack alignment */
 	};
 #endif
 #if defined(CONFIG_PPC32) && defined(CONFIG_BOOKE)
 	struct { /* Must be a multiple of 16 bytes */
 		unsigned long mas0;
 		unsigned long mas1;
 		unsigned long mas2;
 		unsigned long mas3;
 		unsigned long mas6;
 		unsigned long mas7;
 		unsigned long srr0;
 		unsigned long srr1;
 		unsigned long csrr0;
 		unsigned long csrr1;
 		unsigned long dsrr0;
 		unsigned long dsrr1;
 	};
 #endif
 };
 #endif


 #define STACK_FRAME_WITH_PT_REGS (STACK_FRAME_OVERHEAD + sizeof(struct pt_regs))

 #ifdef __powerpc64__

 /*
  * Size of redzone that userspace is allowed to use below the stack
  * pointer.  This is 288 in the 64-bit big-endian ELF ABI, and 512 in
  * the new ELFv2 little-endian ABI, so we allow the larger amount.
  *
  * For kernel code we allow a 288-byte redzone, in order to conserve
  * kernel stack space; gcc currently only uses 288 bytes, and will
  * hopefully allow explicit control of the redzone size in future.
  */
 #define USER_REDZONE_SIZE	512
 #define KERNEL_REDZONE_SIZE	288

 #define STACK_FRAME_OVERHEAD	112	/* size of minimum stack frame */
 #define STACK_FRAME_LR_SAVE	2	/* Location of LR in stack frame */
 #define STACK_FRAME_REGS_MARKER	ASM_CONST(0x7265677368657265)
 #define STACK_INT_FRAME_SIZE	(sizeof(struct pt_regs) + \
 				 STACK_FRAME_OVERHEAD + KERNEL_REDZONE_SIZE)
 #define STACK_FRAME_MARKER	12

 #ifdef PPC64_ELF_ABI_v2
 #define STACK_FRAME_MIN_SIZE	32
 #else
 #define STACK_FRAME_MIN_SIZE	STACK_FRAME_OVERHEAD
 #endif

 /* Size of dummy stack frame allocated when calling signal handler. */
 #define __SIGNAL_FRAMESIZE	128
 #define __SIGNAL_FRAMESIZE32	64

 #else /* __powerpc64__ */

 #define USER_REDZONE_SIZE	0
 #define KERNEL_REDZONE_SIZE	0
 #define STACK_FRAME_OVERHEAD	16	/* size of minimum stack frame */
 #define STACK_FRAME_LR_SAVE	1	/* Location of LR in stack frame */
 #define STACK_FRAME_REGS_MARKER	ASM_CONST(0x72656773)
 #define STACK_INT_FRAME_SIZE	(sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD)
 #define STACK_FRAME_MARKER	2
 #define STACK_FRAME_MIN_SIZE	STACK_FRAME_OVERHEAD

 /* Size of stack frame allocated when calling signal handler. */
 #define __SIGNAL_FRAMESIZE	64

 #endif /* __powerpc64__ */

 #ifndef __ASSEMBLY__
 #include <asm/paca.h>

 #ifdef CONFIG_SMP
 extern unsigned long profile_pc(struct pt_regs *regs);
 #else
 #define profile_pc(regs) instruction_pointer(regs)
 #endif

 long do_syscall_trace_enter(struct pt_regs *regs);
 void do_syscall_trace_leave(struct pt_regs *regs);

 static inline void set_return_regs_changed(void)
 {
 #ifdef CONFIG_PPC_BOOK3S_64
 	local_paca->hsrr_valid = 0;
 	local_paca->srr_valid = 0;
 #endif
 }

 static inline void regs_set_return_ip(struct pt_regs *regs, unsigned long ip)
 {
 	regs->nip = ip;
 	set_return_regs_changed();
 }

 static inline void regs_set_return_msr(struct pt_regs *regs, unsigned long msr)
 {
 	regs->msr = msr;
 	set_return_regs_changed();
 }

 static inline void regs_add_return_ip(struct pt_regs *regs, long offset)
 {
 	regs_set_return_ip(regs, regs->nip + offset);
 }

 static inline unsigned long instruction_pointer(struct pt_regs *regs)
 {
 	return regs->nip;
 }

 static inline void instruction_pointer_set(struct pt_regs *regs,
 		unsigned long val)
 {
 	regs_set_return_ip(regs, val);
 }

 static inline unsigned long user_stack_pointer(struct pt_regs *regs)
 {
 	return regs->gpr[1];
 }

 static inline unsigned long frame_pointer(struct pt_regs *regs)
 {
 	return 0;
 }

 #define user_mode(regs) (((regs)->msr & MSR_PR) != 0)

 #define force_successful_syscall_return()   \
 	do { \
 		set_thread_flag(TIF_NOERROR); \
 	} while(0)

 #define current_pt_regs() \
 	((struct pt_regs *)((unsigned long)task_stack_page(current) + THREAD_SIZE) - 1)

 /*
  * The 4 low bits (0xf) are available as flags to overload the trap word,
  * because interrupt vectors have minimum alignment of 0x10. TRAP_FLAGS_MASK
  * must cover the bits used as flags, including bit 0 which is used as the
  * "norestart" bit.
  */
 #ifdef __powerpc64__
 #define TRAP_FLAGS_MASK		0x1
 #else
 /*
  * On 4xx we use bit 1 in the trap word to indicate whether the exception
  * is a critical exception (1 means it is).
  */
 #define TRAP_FLAGS_MASK		0xf
 #define IS_CRITICAL_EXC(regs)	(((regs)->trap & 2) != 0)
 #define IS_MCHECK_EXC(regs)	(((regs)->trap & 4) != 0)
 #define IS_DEBUG_EXC(regs)	(((regs)->trap & 8) != 0)
 #endif /* __powerpc64__ */
 #define TRAP(regs)		((regs)->trap & ~TRAP_FLAGS_MASK)

 static __always_inline void set_trap(struct pt_regs *regs, unsigned long val)
 {
 	regs->trap = (regs->trap & TRAP_FLAGS_MASK) | (val & ~TRAP_FLAGS_MASK);
 }

 static inline bool trap_is_scv(struct pt_regs *regs)
 {
 	return (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && TRAP(regs) == 0x3000);
 }

 static inline bool trap_is_unsupported_scv(struct pt_regs *regs)
 {
 	return IS_ENABLED(CONFIG_PPC_BOOK3S_64) && TRAP(regs) == 0x7ff0;
 }

 static inline bool trap_is_syscall(struct pt_regs *regs)
 {
 	return (trap_is_scv(regs) || TRAP(regs) == 0xc00);
 }

 static inline bool trap_norestart(struct pt_regs *regs)
 {
 	return regs->trap & 0x1;
 }

 static __always_inline void set_trap_norestart(struct pt_regs *regs)
 {
 	regs->trap |= 0x1;
 }

 #define kernel_stack_pointer(regs) ((regs)->gpr[1])
 static inline int is_syscall_success(struct pt_regs *regs)
 {
 	if (trap_is_scv(regs))
 		return !IS_ERR_VALUE((unsigned long)regs->gpr[3]);
 	else
 		return !(regs->ccr & 0x10000000);
 }

 static inline long regs_return_value(struct pt_regs *regs)
 {
 	if (trap_is_scv(regs))
 		return regs->gpr[3];

 	if (is_syscall_success(regs))
 		return regs->gpr[3];
 	else
 		return -regs->gpr[3];
 }

 static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
 {
 	regs->gpr[3] = rc;
 }

 static inline bool cpu_has_msr_ri(void)
 {
 	return !IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x);
 }

 static inline bool regs_is_unrecoverable(struct pt_regs *regs)
 {
 	return unlikely(cpu_has_msr_ri() && !(regs->msr & MSR_RI));
 }

 static inline void regs_set_recoverable(struct pt_regs *regs)
 {
 	if (cpu_has_msr_ri())
 		regs_set_return_msr(regs, regs->msr | MSR_RI);
 }

 static inline void regs_set_unrecoverable(struct pt_regs *regs)
 {
 	if (cpu_has_msr_ri())
 		regs_set_return_msr(regs, regs->msr & ~MSR_RI);
 }

 #define arch_has_single_step()	(1)
 #define arch_has_block_step()	(true)
 #define ARCH_HAS_USER_SINGLE_STEP_REPORT

 /*
  * kprobe-based event tracer support
  */

 #include <linux/stddef.h>
 #include <linux/thread_info.h>
 extern int regs_query_register_offset(const char *name);
 extern const char *regs_query_register_name(unsigned int offset);
 #define MAX_REG_OFFSET (offsetof(struct pt_regs, dsisr))

 /**
  * regs_get_register() - get register value from its offset
  * @regs:	   pt_regs from which register value is gotten
  * @offset:    offset number of the register.
  *
  * regs_get_register returns the value of a register whose offset from @regs.
  * The @offset is the offset of the register in struct pt_regs.
  * If @offset is bigger than MAX_REG_OFFSET, this returns 0.
  */
 static inline unsigned long regs_get_register(struct pt_regs *regs,
 						unsigned int offset)
 {
 	if (unlikely(offset > MAX_REG_OFFSET))
 		return 0;
 	return *(unsigned long *)((unsigned long)regs + offset);
 }

 /**
  * regs_within_kernel_stack() - check the address in the stack
  * @regs:      pt_regs which contains kernel stack pointer.
  * @addr:      address which is checked.
  *
  * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
  * If @addr is within the kernel stack, it returns true. If not, returns false.
  */

 static inline bool regs_within_kernel_stack(struct pt_regs *regs,
 						unsigned long addr)
 {
 	return ((addr & ~(THREAD_SIZE - 1))  ==
 		(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
 }

 /**
  * regs_get_kernel_stack_nth() - get Nth entry of the stack
  * @regs:	pt_regs which contains kernel stack pointer.
  * @n:		stack entry number.
  *
  * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
  * is specified by @regs. If the @n th entry is NOT in the kernel stack,
  * this returns 0.
  */
 static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
 						      unsigned int n)
 {
 	unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
 	addr += n;
 	if (regs_within_kernel_stack(regs, (unsigned long)addr))
 		return *addr;
 	else
 		return 0;
 }

 #endif /* __ASSEMBLY__ */

 #ifndef __powerpc64__
 /* We need PT_SOFTE defined at all time to avoid #ifdefs */
 #define PT_SOFTE PT_MQ
 #else /* __powerpc64__ */
 #define PT_FPSCR32 (PT_FPR0 + 2*32 + 1)	/* each FP reg occupies 2 32-bit userspace slots */
 #define PT_VR0_32 164	/* each Vector reg occupies 4 slots in 32-bit */
 #define PT_VSCR_32 (PT_VR0 + 32*4 + 3)
 #define PT_VRSAVE_32 (PT_VR0 + 33*4)
 #define PT_VSR0_32 300 	/* each VSR reg occupies 4 slots in 32-bit */
 #endif /* __powerpc64__ */
 #endif /* _ASM_POWERPC_PTRACE_H */
	/* SPDX-License-Identifier: GPL-2.0-or-later */
	/*
	* Copyright (C) 2001 PPC64 Team, IBM Corp
	*
	* This struct defines the way the registers are stored on the
	* kernel stack during a system call or other kernel entry.
	*
	* this should only contain volatile regs
	* since we can keep non-volatile in the thread_struct
	* should set this up when only volatiles are saved
	* by intr code.
	*
	* Since this is going on the stack, CARE MUST BE TAKEN to insure
	* that the overall structure is a multiple of 16 bytes in length.
	*
	* Note that the offsets of the fields in this struct correspond with
	* the PT_* values below. This simplifies arch/powerpc/kernel/ptrace.c.
	*/
	#ifndef _ASM_POWERPC_PTRACE_H
	#define _ASM_POWERPC_PTRACE_H

	#include <linux/err.h>
	#include <uapi/asm/ptrace.h>
	#include <asm/asm-const.h>
	#include <asm/reg.h>

	#ifndef __ASSEMBLY__
	struct pt_regs
	{
	union {
	struct user_pt_regs user_regs;
	struct {
	unsigned long gpr[32];
	unsigned long nip;
	unsigned long msr;
	unsigned long orig_gpr3;
	unsigned long ctr;
	unsigned long link;
	unsigned long xer;
	unsigned long ccr;
	#ifdef CONFIG_PPC64
	unsigned long softe;
	#else
	unsigned long mq;
	#endif
	unsigned long trap;
	union {
	unsigned long dar;
	unsigned long dear;
	};
	union {
	unsigned long dsisr;
	unsigned long esr;
	};
	unsigned long result;
	};
	};
	#if defined(CONFIG_PPC64) \|\| defined(CONFIG_PPC_KUAP)
	union {
	struct {
	#ifdef CONFIG_PPC64
	unsigned long ppr;
	unsigned long exit_result;
	#endif
	union {
	#ifdef CONFIG_PPC_KUAP
	unsigned long kuap;
	#endif
	#ifdef CONFIG_PPC_PKEY
	unsigned long amr;
	#endif
	};
	#ifdef CONFIG_PPC_PKEY
	unsigned long iamr;
	#endif
	};
	unsigned long __pad[4]; /* Maintain 16 byte interrupt stack alignment */
	};
	#endif
	#if defined(CONFIG_PPC32) && defined(CONFIG_BOOKE)
	struct { /* Must be a multiple of 16 bytes */
	unsigned long mas0;
	unsigned long mas1;
	unsigned long mas2;
	unsigned long mas3;
	unsigned long mas6;
	unsigned long mas7;
	unsigned long srr0;
	unsigned long srr1;
	unsigned long csrr0;
	unsigned long csrr1;
	unsigned long dsrr0;
	unsigned long dsrr1;
	};
	#endif
	};
	#endif


	#define STACK_FRAME_WITH_PT_REGS (STACK_FRAME_OVERHEAD + sizeof(struct pt_regs))

	#ifdef __powerpc64__

	/*
	* Size of redzone that userspace is allowed to use below the stack
	* pointer. This is 288 in the 64-bit big-endian ELF ABI, and 512 in
	* the new ELFv2 little-endian ABI, so we allow the larger amount.
	*
	* For kernel code we allow a 288-byte redzone, in order to conserve
	* kernel stack space; gcc currently only uses 288 bytes, and will
	* hopefully allow explicit control of the redzone size in future.
	*/
	#define USER_REDZONE_SIZE 512
	#define KERNEL_REDZONE_SIZE 288

	#define STACK_FRAME_OVERHEAD 112 /* size of minimum stack frame */
	#define STACK_FRAME_LR_SAVE 2 /* Location of LR in stack frame */
	#define STACK_FRAME_REGS_MARKER ASM_CONST(0x7265677368657265)
	#define STACK_INT_FRAME_SIZE (sizeof(struct pt_regs) + \
	STACK_FRAME_OVERHEAD + KERNEL_REDZONE_SIZE)
	#define STACK_FRAME_MARKER 12

	#ifdef PPC64_ELF_ABI_v2
	#define STACK_FRAME_MIN_SIZE 32
	#else
	#define STACK_FRAME_MIN_SIZE STACK_FRAME_OVERHEAD
	#endif

	/* Size of dummy stack frame allocated when calling signal handler. */
	#define __SIGNAL_FRAMESIZE 128
	#define __SIGNAL_FRAMESIZE32 64

	#else /* __powerpc64__ */

	#define USER_REDZONE_SIZE 0
	#define KERNEL_REDZONE_SIZE 0
	#define STACK_FRAME_OVERHEAD 16 /* size of minimum stack frame */
	#define STACK_FRAME_LR_SAVE 1 /* Location of LR in stack frame */
	#define STACK_FRAME_REGS_MARKER ASM_CONST(0x72656773)
	#define STACK_INT_FRAME_SIZE (sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD)
	#define STACK_FRAME_MARKER 2
	#define STACK_FRAME_MIN_SIZE STACK_FRAME_OVERHEAD

	/* Size of stack frame allocated when calling signal handler. */
	#define __SIGNAL_FRAMESIZE 64

	#endif /* __powerpc64__ */

	#ifndef __ASSEMBLY__
	#include <asm/paca.h>

	#ifdef CONFIG_SMP
	extern unsigned long profile_pc(struct pt_regs *regs);
	#else
	#define profile_pc(regs) instruction_pointer(regs)
	#endif

	long do_syscall_trace_enter(struct pt_regs *regs);
	void do_syscall_trace_leave(struct pt_regs *regs);

	static inline void set_return_regs_changed(void)
	{
	#ifdef CONFIG_PPC_BOOK3S_64
	local_paca->hsrr_valid = 0;
	local_paca->srr_valid = 0;
	#endif
	}

	static inline void regs_set_return_ip(struct pt_regs *regs, unsigned long ip)
	{
	regs->nip = ip;
	set_return_regs_changed();
	}

	static inline void regs_set_return_msr(struct pt_regs *regs, unsigned long msr)
	{
	regs->msr = msr;
	set_return_regs_changed();
	}

	static inline void regs_add_return_ip(struct pt_regs *regs, long offset)
	{
	regs_set_return_ip(regs, regs->nip + offset);
	}

	static inline unsigned long instruction_pointer(struct pt_regs *regs)
	{
	return regs->nip;
	}

	static inline void instruction_pointer_set(struct pt_regs *regs,
	unsigned long val)
	{
	regs_set_return_ip(regs, val);
	}

	static inline unsigned long user_stack_pointer(struct pt_regs *regs)
	{
	return regs->gpr[1];
	}

	static inline unsigned long frame_pointer(struct pt_regs *regs)
	{
	return 0;
	}

	#define user_mode(regs) (((regs)->msr & MSR_PR) != 0)

	#define force_successful_syscall_return() \
	do { \
	set_thread_flag(TIF_NOERROR); \
	} while(0)

	#define current_pt_regs() \
	((struct pt_regs *)((unsigned long)task_stack_page(current) + THREAD_SIZE) - 1)

	/*
	* The 4 low bits (0xf) are available as flags to overload the trap word,
	* because interrupt vectors have minimum alignment of 0x10. TRAP_FLAGS_MASK
	* must cover the bits used as flags, including bit 0 which is used as the
	* "norestart" bit.
	*/
	#ifdef __powerpc64__
	#define TRAP_FLAGS_MASK 0x1
	#else
	/*
	* On 4xx we use bit 1 in the trap word to indicate whether the exception
	* is a critical exception (1 means it is).
	*/
	#define TRAP_FLAGS_MASK 0xf
	#define IS_CRITICAL_EXC(regs) (((regs)->trap & 2) != 0)
	#define IS_MCHECK_EXC(regs) (((regs)->trap & 4) != 0)
	#define IS_DEBUG_EXC(regs) (((regs)->trap & 8) != 0)
	#endif /* __powerpc64__ */
	#define TRAP(regs) ((regs)->trap & ~TRAP_FLAGS_MASK)

	static __always_inline void set_trap(struct pt_regs *regs, unsigned long val)
	{
	regs->trap = (regs->trap & TRAP_FLAGS_MASK) \| (val & ~TRAP_FLAGS_MASK);
	}

	static inline bool trap_is_scv(struct pt_regs *regs)
	{
	return (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && TRAP(regs) == 0x3000);
	}

	static inline bool trap_is_unsupported_scv(struct pt_regs *regs)
	{
	return IS_ENABLED(CONFIG_PPC_BOOK3S_64) && TRAP(regs) == 0x7ff0;
	}

	static inline bool trap_is_syscall(struct pt_regs *regs)
	{
	return (trap_is_scv(regs) \|\| TRAP(regs) == 0xc00);
	}

	static inline bool trap_norestart(struct pt_regs *regs)
	{
	return regs->trap & 0x1;
	}

	static __always_inline void set_trap_norestart(struct pt_regs *regs)
	{
	regs->trap \|= 0x1;
	}

	#define kernel_stack_pointer(regs) ((regs)->gpr[1])
	static inline int is_syscall_success(struct pt_regs *regs)
	{
	if (trap_is_scv(regs))
	return !IS_ERR_VALUE((unsigned long)regs->gpr[3]);
	else
	return !(regs->ccr & 0x10000000);
	}

	static inline long regs_return_value(struct pt_regs *regs)
	{
	if (trap_is_scv(regs))
	return regs->gpr[3];

	if (is_syscall_success(regs))
	return regs->gpr[3];
	else
	return -regs->gpr[3];
	}

	static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
	{
	regs->gpr[3] = rc;
	}

	static inline bool cpu_has_msr_ri(void)
	{
	return !IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x);
	}

	static inline bool regs_is_unrecoverable(struct pt_regs *regs)
	{
	return unlikely(cpu_has_msr_ri() && !(regs->msr & MSR_RI));
	}

	static inline void regs_set_recoverable(struct pt_regs *regs)
	{
	if (cpu_has_msr_ri())
	regs_set_return_msr(regs, regs->msr \| MSR_RI);
	}

	static inline void regs_set_unrecoverable(struct pt_regs *regs)
	{
	if (cpu_has_msr_ri())
	regs_set_return_msr(regs, regs->msr & ~MSR_RI);
	}

	#define arch_has_single_step() (1)
	#define arch_has_block_step() (true)
	#define ARCH_HAS_USER_SINGLE_STEP_REPORT

	/*
	* kprobe-based event tracer support
	*/

	#include <linux/stddef.h>
	#include <linux/thread_info.h>
	extern int regs_query_register_offset(const char *name);
	extern const char *regs_query_register_name(unsigned int offset);
	#define MAX_REG_OFFSET (offsetof(struct pt_regs, dsisr))

	/**
	* regs_get_register() - get register value from its offset
	* @regs: pt_regs from which register value is gotten
	* @offset: offset number of the register.
	*
	* regs_get_register returns the value of a register whose offset from @regs.
	* The @offset is the offset of the register in struct pt_regs.
	* If @offset is bigger than MAX_REG_OFFSET, this returns 0.
	*/
	static inline unsigned long regs_get_register(struct pt_regs *regs,
	unsigned int offset)
	{
	if (unlikely(offset > MAX_REG_OFFSET))
	return 0;
	return (unsigned long )((unsigned long)regs + offset);
	}

	/**
	* regs_within_kernel_stack() - check the address in the stack
	* @regs: pt_regs which contains kernel stack pointer.
	* @addr: address which is checked.
	*
	* regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
	* If @addr is within the kernel stack, it returns true. If not, returns false.
	*/

	static inline bool regs_within_kernel_stack(struct pt_regs *regs,
	unsigned long addr)
	{
	return ((addr & ~(THREAD_SIZE - 1)) ==
	(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
	}

	/**
	* regs_get_kernel_stack_nth() - get Nth entry of the stack
	* @regs: pt_regs which contains kernel stack pointer.
	* @n: stack entry number.
	*
	* regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
	* is specified by @regs. If the @n th entry is NOT in the kernel stack,
	* this returns 0.
	*/
	static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
	unsigned int n)
	{
	unsigned long addr = (unsigned long )kernel_stack_pointer(regs);
	addr += n;
	if (regs_within_kernel_stack(regs, (unsigned long)addr))
	return *addr;
	else
	return 0;
	}

	#endif /* __ASSEMBLY__ */

	#ifndef __powerpc64__
	/* We need PT_SOFTE defined at all time to avoid #ifdefs */
	#define PT_SOFTE PT_MQ
	#else /* __powerpc64__ */
	#define PT_FPSCR32 (PT_FPR0 + 232 + 1) / each FP reg occupies 2 32-bit userspace slots */
	#define PT_VR0_32 164 /* each Vector reg occupies 4 slots in 32-bit */
	#define PT_VSCR_32 (PT_VR0 + 32*4 + 3)
	#define PT_VRSAVE_32 (PT_VR0 + 33*4)
	#define PT_VSR0_32 300 /* each VSR reg occupies 4 slots in 32-bit */
	#endif /* __powerpc64__ */
	#endif /* _ASM_POWERPC_PTRACE_H */