Message-Id: <1434386579-6045-3-git-send-email-dave.long@linaro.org>
Date:	Mon, 15 Jun 2015 12:42:59 -0400
From:	David Long <dave.long@...aro.org>
To:	"H. Peter Anvin" <hpa@...or.com>,
	Andy Lutomirski <luto@...capital.net>,
	Anton Blanchard <anton@...ba.org>,
	Behan Webster <behanw@...verseincode.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Eric Paris <eparis@...hat.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Ingo Molnar <mingo@...hat.com>,
	Jan Willeke <willeke@...ibm.com>,
	Kees Cook <keescook@...omium.org>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Nikolay Borisov <Nikolay.Borisov@....com>,
	Oleg Nesterov <oleg@...hat.com>,
	Paul Mackerras <paulus@...ba.org>,
	Richard Kuo <rkuo@...eaurora.org>,
	Robert Richter <rric@...nel.org>,
	Roland McGrath <roland@...k.frob.com>,
	Russell King <linux@....linux.org.uk>,
	Tejun Heo <tj@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Will Deacon <will.deacon@....com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-hexagon@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
	linux390@...ibm.com, linuxppc-dev@...ts.ozlabs.org, x86@...nel.org
Subject: [PATCH 2/2] Consolidate redundant register/stack access code

From: "David A. Long" <dave.long@...aro.org>

Several architectures have identical or functionally equivalent code
implementing parts of the HAVE_REGS_AND_STACK_ACCESS_API feature.  Move
that code out of the architecture directories.

Signed-off-by: David A. Long <dave.long@...aro.org>
---
 arch/arm/include/asm/ptrace.h          |  6 ---
 arch/arm/kernel/ptrace.c               | 67 +-------------------------------
 arch/hexagon/include/uapi/asm/ptrace.h |  3 --
 arch/powerpc/include/asm/ptrace.h      | 38 ------------------
 arch/powerpc/kernel/ptrace.c           | 34 +----------------
 arch/s390/include/asm/ptrace.h         |  3 --
 arch/s390/kernel/ptrace.c              | 70 ++++++++++------------------------
 arch/sh/include/asm/ptrace.h           | 39 -------------------
 arch/sh/kernel/Makefile                |  2 +-
 arch/sh/kernel/ptrace.c                | 33 ----------------
 arch/sh/kernel/ptrace_32.c             |  2 +-
 arch/sh/kernel/ptrace_64.c             |  2 +-
 arch/x86/include/asm/ptrace.h          | 37 ------------------
 arch/x86/kernel/ptrace.c               | 34 +----------------
 include/linux/ptrace.h                 | 42 ++++++++++++++++++++
 kernel/ptrace.c                        | 38 ++++++++++++++++++
 16 files changed, 107 insertions(+), 343 deletions(-)
 delete mode 100644 arch/sh/kernel/ptrace.c

diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 51622ba..84a0ea4 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -120,12 +120,6 @@ extern unsigned long profile_pc(struct pt_regs *regs);
 #include <linux/types.h>
 #define MAX_REG_OFFSET (offsetof(struct pt_regs, ARM_ORIG_r0))
 
-extern int regs_query_register_offset(const char *name);
-extern const char *regs_query_register_name(unsigned int offset);
-extern bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr);
-extern unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
-					       unsigned int n);
-
 /**
  * regs_get_register() - get register value from its offset
  * @regs:	   pt_regs from which register value is gotten
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index fb45cf1..d63ad99 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -63,7 +63,7 @@
 	{.name = #r, .offset = offsetof(struct pt_regs, ARM_##r)}
 #define REG_OFFSET_END {.name = NULL, .offset = 0}
 
-static const struct pt_regs_offset regoffset_table[] = {
+const struct pt_regs_offset regs_offset_table[] = {
 	REG_OFFSET_NAME(r0),
 	REG_OFFSET_NAME(r1),
 	REG_OFFSET_NAME(r2),
@@ -85,71 +85,6 @@ static const struct pt_regs_offset regoffset_table[] = {
 	REG_OFFSET_END,
 };
 
-/**
- * regs_query_register_offset() - query register offset from its name
- * @name:	the name of a register
- *
- * regs_query_register_offset() returns the offset of a register in struct
- * pt_regs from its name. If the name is invalid, this returns -EINVAL;
- */
-int regs_query_register_offset(const char *name)
-{
-	const struct pt_regs_offset *roff;
-	for (roff = regoffset_table; roff->name != NULL; roff++)
-		if (!strcmp(roff->name, name))
-			return roff->offset;
-	return -EINVAL;
-}
-
-/**
- * regs_query_register_name() - query register name from its offset
- * @offset:	the offset of a register in struct pt_regs.
- *
- * regs_query_register_name() returns the name of a register from its
- * offset in struct pt_regs. If the @offset is invalid, this returns NULL;
- */
-const char *regs_query_register_name(unsigned int offset)
-{
-	const struct pt_regs_offset *roff;
-	for (roff = regoffset_table; roff->name != NULL; roff++)
-		if (roff->offset == offset)
-			return roff->name;
-	return NULL;
-}
-
-/**
- * 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.
- */
-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.
- */
-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;
-}
-
 /*
  * this routine will get a word off of the processes privileged stack.
  * the offset is how far from the base addr as stored in the THREAD.
diff --git a/arch/hexagon/include/uapi/asm/ptrace.h b/arch/hexagon/include/uapi/asm/ptrace.h
index 065e5b3..0afb664 100644
--- a/arch/hexagon/include/uapi/asm/ptrace.h
+++ b/arch/hexagon/include/uapi/asm/ptrace.h
@@ -29,9 +29,6 @@
 #define profile_pc(regs) instruction_pointer(regs)
 
 /* kprobe-based event tracer support */
-extern int regs_query_register_offset(const char *name);
-extern const char *regs_query_register_name(unsigned int offset);
-
 #define current_pt_regs() \
 	((struct pt_regs *) \
 	 ((unsigned long)current_thread_info() + THREAD_SIZE) - 1)
diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index c0c61fa..64b9b3d 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -156,8 +156,6 @@ do {									      \
 
 #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))
 
 /**
@@ -177,42 +175,6 @@ static inline unsigned long regs_get_register(struct pt_regs *regs,
 	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__
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index ab81733..e35c731 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -58,7 +58,7 @@
 	{.name = STR(gpr##num), .offset = offsetof(struct pt_regs, gpr[num])}
 #define REG_OFFSET_END {.name = NULL, .offset = 0}
 
-static const struct pt_regs_offset regoffset_table[] = {
+const struct pt_regs_offset regs_offset_table[] = {
 	GPR_OFFSET_NAME(0),
 	GPR_OFFSET_NAME(1),
 	GPR_OFFSET_NAME(2),
@@ -108,38 +108,6 @@ static const struct pt_regs_offset regoffset_table[] = {
 	REG_OFFSET_END,
 };
 
-/**
- * regs_query_register_offset() - query register offset from its name
- * @name:	the name of a register
- *
- * regs_query_register_offset() returns the offset of a register in struct
- * pt_regs from its name. If the name is invalid, this returns -EINVAL;
- */
-int regs_query_register_offset(const char *name)
-{
-	const struct pt_regs_offset *roff;
-	for (roff = regoffset_table; roff->name != NULL; roff++)
-		if (!strcmp(roff->name, name))
-			return roff->offset;
-	return -EINVAL;
-}
-
-/**
- * regs_query_register_name() - query register name from its offset
- * @offset:	the offset of a register in struct pt_regs.
- *
- * regs_query_register_name() returns the name of a register from its
- * offset in struct pt_regs. If the @offset is invalid, this returns NULL;
- */
-const char *regs_query_register_name(unsigned int offset)
-{
-	const struct pt_regs_offset *roff;
-	for (roff = regoffset_table; roff->name != NULL; roff++)
-		if (roff->offset == offset)
-			return roff->name;
-	return NULL;
-}
-
 /*
  * does not yet catch signals sent when the child dies.
  * in exit.c or in signal.c.
diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h
index 6feda25..d4f9ad3 100644
--- a/arch/s390/include/asm/ptrace.h
+++ b/arch/s390/include/asm/ptrace.h
@@ -163,10 +163,7 @@ static inline void instruction_pointer_set(struct pt_regs *regs,
 	regs->psw.addr = val | PSW_ADDR_AMODE;
 }
 
-int regs_query_register_offset(const char *name);
-const char *regs_query_register_name(unsigned int offset);
 unsigned long regs_get_register(struct pt_regs *regs, unsigned int offset);
-unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n);
 
 static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
 {
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index d363c9c..a7eb15f 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -1474,9 +1474,27 @@ const struct user_regset_view *task_user_regset_view(struct task_struct *task)
 	return &user_s390_view;
 }
 
-static const char *gpr_names[NUM_GPRS] = {
-	"r0", "r1",  "r2",  "r3",  "r4",  "r5",  "r6",  "r7",
-	"r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
+#define REG_OFFSET_NAME(r) {.name = "r" #r, .offset = r}
+#define REG_OFFSET_END {.name = NULL, .offset = 0}
+
+const struct pt_regs_offset regs_offset_table[NUM_GPRS+1] = {
+	REG_OFFSET_NAME(0),
+	REG_OFFSET_NAME(1),
+	REG_OFFSET_NAME(2),
+	REG_OFFSET_NAME(3),
+	REG_OFFSET_NAME(4),
+	REG_OFFSET_NAME(5),
+	REG_OFFSET_NAME(6),
+	REG_OFFSET_NAME(7),
+	REG_OFFSET_NAME(8),
+	REG_OFFSET_NAME(9),
+	REG_OFFSET_NAME(10),
+	REG_OFFSET_NAME(11),
+	REG_OFFSET_NAME(12),
+	REG_OFFSET_NAME(13),
+	REG_OFFSET_NAME(14),
+	REG_OFFSET_NAME(15),
+	REG_OFFSET_END
 };
 
 unsigned long regs_get_register(struct pt_regs *regs, unsigned int offset)
@@ -1485,49 +1503,3 @@ unsigned long regs_get_register(struct pt_regs *regs, unsigned int offset)
 		return 0;
 	return regs->gprs[offset];
 }
-
-int regs_query_register_offset(const char *name)
-{
-	unsigned long offset;
-
-	if (!name || *name != 'r')
-		return -EINVAL;
-	if (kstrtoul(name + 1, 10, &offset))
-		return -EINVAL;
-	if (offset >= NUM_GPRS)
-		return -EINVAL;
-	return offset;
-}
-
-const char *regs_query_register_name(unsigned int offset)
-{
-	if (offset >= NUM_GPRS)
-		return NULL;
-	return gpr_names[offset];
-}
-
-static int regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
-{
-	unsigned long ksp = kernel_stack_pointer(regs);
-
-	return (addr & ~(THREAD_SIZE - 1)) == (ksp & ~(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 specifined by @regs. If the @n th entry is NOT in the kernel stack,
- * this returns 0.
- */
-unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
-{
-	unsigned long addr;
-
-	addr = kernel_stack_pointer(regs) + n * sizeof(long);
-	if (!regs_within_kernel_stack(regs, addr))
-		return 0;
-	return *(unsigned long *)addr;
-}
diff --git a/arch/sh/include/asm/ptrace.h b/arch/sh/include/asm/ptrace.h
index 677c72b..acfdc81 100644
--- a/arch/sh/include/asm/ptrace.h
+++ b/arch/sh/include/asm/ptrace.h
@@ -31,10 +31,6 @@
 #define REG_OFFSET_END {.name = NULL, .offset = 0}
 
 /* Query offset/name of register from its name/offset */
-extern int regs_query_register_offset(const char *name);
-extern const char *regs_query_register_name(unsigned int offset);
-
-extern const struct pt_regs_offset regoffset_table[];
 
 /**
  * regs_get_register() - get register value from its offset
@@ -53,41 +49,6 @@ static inline unsigned long regs_get_register(struct pt_regs *regs,
 	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 int 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;
-}
-
 struct perf_event;
 struct perf_sample_data;
 
diff --git a/arch/sh/kernel/Makefile b/arch/sh/kernel/Makefile
index 2ccf36c..4ae9a11 100644
--- a/arch/sh/kernel/Makefile
+++ b/arch/sh/kernel/Makefile
@@ -14,7 +14,7 @@ CFLAGS_REMOVE_return_address.o = -pg
 obj-y	:= debugtraps.o dma-nommu.o dumpstack.o 		\
 	   idle.o io.o irq.o irq_$(BITS).o kdebugfs.o			\
 	   machvec.o nmi_debug.o process.o				\
-	   process_$(BITS).o ptrace.o ptrace_$(BITS).o			\
+	   process_$(BITS).o ptrace_$(BITS).o				\
 	   reboot.o return_address.o					\
 	   setup.o signal_$(BITS).o sys_sh.o 				\
 	   syscalls_$(BITS).o time.o topology.o traps.o			\
diff --git a/arch/sh/kernel/ptrace.c b/arch/sh/kernel/ptrace.c
deleted file mode 100644
index 0a05983..0000000
--- a/arch/sh/kernel/ptrace.c
+++ /dev/null
@@ -1,33 +0,0 @@
-#include <linux/ptrace.h>
-
-/**
- * regs_query_register_offset() - query register offset from its name
- * @name:	the name of a register
- *
- * regs_query_register_offset() returns the offset of a register in struct
- * pt_regs from its name. If the name is invalid, this returns -EINVAL;
- */
-int regs_query_register_offset(const char *name)
-{
-	const struct pt_regs_offset *roff;
-	for (roff = regoffset_table; roff->name != NULL; roff++)
-		if (!strcmp(roff->name, name))
-			return roff->offset;
-	return -EINVAL;
-}
-
-/**
- * regs_query_register_name() - query register name from its offset
- * @offset:	the offset of a register in struct pt_regs.
- *
- * regs_query_register_name() returns the name of a register from its
- * offset in struct pt_regs. If the @offset is invalid, this returns NULL;
- */
-const char *regs_query_register_name(unsigned int offset)
-{
-	const struct pt_regs_offset *roff;
-	for (roff = regoffset_table; roff->name != NULL; roff++)
-		if (roff->offset == offset)
-			return roff->name;
-	return NULL;
-}
diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c
index c1a6b89..839f4e7 100644
--- a/arch/sh/kernel/ptrace_32.c
+++ b/arch/sh/kernel/ptrace_32.c
@@ -276,7 +276,7 @@ static int dspregs_active(struct task_struct *target,
 }
 #endif
 
-const struct pt_regs_offset regoffset_table[] = {
+const struct pt_regs_offset regs_offset_table[] = {
 	REGS_OFFSET_NAME(0),
 	REGS_OFFSET_NAME(1),
 	REGS_OFFSET_NAME(2),
diff --git a/arch/sh/kernel/ptrace_64.c b/arch/sh/kernel/ptrace_64.c
index 5cea973..68faa1f 100644
--- a/arch/sh/kernel/ptrace_64.c
+++ b/arch/sh/kernel/ptrace_64.c
@@ -252,7 +252,7 @@ static int fpregs_active(struct task_struct *target,
 }
 #endif
 
-const struct pt_regs_offset regoffset_table[] = {
+const struct pt_regs_offset regs_offset_table[] = {
 	REG_OFFSET_NAME(pc),
 	REG_OFFSET_NAME(sr),
 	REG_OFFSET_NAME(syscall_nr),
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 5fabf13..c01247c 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -157,8 +157,6 @@ static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
 #include <asm-generic/ptrace.h>
 
 /* Query offset/name of register from its name/offset */
-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, ss))
 
 /**
@@ -187,41 +185,6 @@ static inline unsigned long regs_get_register(struct pt_regs *regs,
 	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 int 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;
-}
-
 #define arch_has_single_step()	(1)
 #ifdef CONFIG_X86_DEBUGCTLMSR
 #define arch_has_block_step()	(1)
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index f135d35..9daab75 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -56,7 +56,7 @@ enum x86_regset {
 #define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)}
 #define REG_OFFSET_END {.name = NULL, .offset = 0}
 
-static const struct pt_regs_offset regoffset_table[] = {
+const struct pt_regs_offset regs_offset_table[] = {
 #ifdef CONFIG_X86_64
 	REG_OFFSET_NAME(r15),
 	REG_OFFSET_NAME(r14),
@@ -89,38 +89,6 @@ static const struct pt_regs_offset regoffset_table[] = {
 	REG_OFFSET_END,
 };
 
-/**
- * regs_query_register_offset() - query register offset from its name
- * @name:	the name of a register
- *
- * regs_query_register_offset() returns the offset of a register in struct
- * pt_regs from its name. If the name is invalid, this returns -EINVAL;
- */
-int regs_query_register_offset(const char *name)
-{
-	const struct pt_regs_offset *roff;
-	for (roff = regoffset_table; roff->name != NULL; roff++)
-		if (!strcmp(roff->name, name))
-			return roff->offset;
-	return -EINVAL;
-}
-
-/**
- * regs_query_register_name() - query register name from its offset
- * @offset:	the offset of a register in struct pt_regs.
- *
- * regs_query_register_name() returns the name of a register from its
- * offset in struct pt_regs. If the @offset is invalid, this returns NULL;
- */
-const char *regs_query_register_name(unsigned int offset)
-{
-	const struct pt_regs_offset *roff;
-	for (roff = regoffset_table; roff->name != NULL; roff++)
-		if (roff->offset == offset)
-			return roff->name;
-	return NULL;
-}
-
 static const int arg_offs_table[] = {
 #ifdef CONFIG_X86_32
 	[0] = offsetof(struct pt_regs, ax),
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index b0b1ee6..055d9ac 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -390,6 +390,48 @@ struct pt_regs_offset {
 	int offset;
 };
 
+extern const struct pt_regs_offset regs_offset_table[];
+
+extern int regs_query_register_offset(const char *name);
+extern const char *regs_query_register_name(unsigned int 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	/* CONFIG_HAVE_REGS_AND_STACK_ACCESS_API */
 
 #endif
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index c8e0e05..20c08d9 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -1217,3 +1217,41 @@ COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid,
 	return ret;
 }
 #endif	/* CONFIG_COMPAT */
+
+#ifdef CONFIG_HAVE_REGS_AND_STACK_ACCESS_API
+
+/**
+ * regs_query_register_offset() - query register offset from its name
+ * @name:	the name of a register
+ *
+ * regs_query_register_offset() returns the offset of a register in struct
+ * pt_regs from its name. If the name is invalid, this returns -EINVAL;
+ */
+int regs_query_register_offset(const char *name)
+{
+	const struct pt_regs_offset *roff;
+
+	for (roff = regs_offset_table; roff->name != NULL; roff++)
+		if (!strcmp(roff->name, name))
+			return roff->offset;
+	return -EINVAL;
+}
+
+/**
+ * regs_query_register_name() - query register name from its offset
+ * @offset:	the offset of a register in struct pt_regs.
+ *
+ * regs_query_register_name() returns the name of a register from its
+ * offset in struct pt_regs. If the @offset is invalid, this returns NULL;
+ */
+const char *regs_query_register_name(unsigned int offset)
+{
+	const struct pt_regs_offset *roff;
+
+	for (roff = regs_offset_table; roff->name != NULL; roff++)
+		if (roff->offset == offset)
+			return roff->name;
+	return NULL;
+}
+
+#endif /* CONFIG_HAVE_REGS_AND_STACK_ACCESS_API */
-- 
1.8.1.2

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