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Subject[PATCH v3 2/2] Consolidate redundant register/stack access code
Date
From: "David A. Long" <dave.long@linaro.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@linaro.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 | 69 ++++++++++------------------------
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, 106 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 3b5a2ba..f26e23b 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -63,7 +63,7 @@
#define REG_OFFSET_NAME(r) \
{.name = #r, .offset = offsetof(struct pt_regs, ARM_##r)}

-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[] = {
REGS_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 77bd4c4..1f8310a 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -57,7 +57,7 @@
{.name = STR(r##num), .offset = offsetof(struct pt_regs, gpr[num])}, \
{.name = STR(gpr##num), .offset = offsetof(struct pt_regs, gpr[num])}

-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),
@@ -107,38 +107,6 @@ static const struct pt_regs_offset regoffset_table[] = {
REGS_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 99bc456..890bc54 100644
--- a/arch/s390/include/asm/ptrace.h
+++ b/arch/s390/include/asm/ptrace.h
@@ -164,10 +164,7 @@ static inline void instruction_pointer_set(struct pt_regs *regs,
regs->psw.addr = val;
}

-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 49b1c13..8e75a93 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -1430,9 +1430,26 @@ 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}
+
+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),
+ REGS_OFFSET_END
};

unsigned long regs_get_register(struct pt_regs *regs, unsigned int offset)
@@ -1441,49 +1458,3 @@ 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 523955f..8045eb4 100644
--- a/arch/sh/include/asm/ptrace.h
+++ b/arch/sh/include/asm/ptrace.h
@@ -29,10 +29,6 @@
{.name = __stringify(tr##num), .offset = offsetof(struct pt_regs, tregs[num])}

/* 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
@@ -51,41 +47,6 @@ 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 e6fe4f4..c5c385c 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[] = {
REG_OFFSET_NAME(0),
REG_OFFSET_NAME(1),
REG_OFFSET_NAME(2),
diff --git a/arch/sh/kernel/ptrace_64.c b/arch/sh/kernel/ptrace_64.c
index af55bb6..565227ef 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[] = {
REGS_OFFSET_NAME(pc),
REGS_OFFSET_NAME(sr),
REGS_OFFSET_NAME(syscall_nr),
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 6271281..0f498ff 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -156,8 +156,6 @@ 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))

/**
@@ -186,41 +184,6 @@ 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 ff3314f..e380e3d 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -52,7 +52,7 @@ enum x86_regset {
};


-static const struct pt_regs_offset regoffset_table[] = {
+const struct pt_regs_offset regs_offset_table[] = {
#ifdef CONFIG_X86_64
REGS_OFFSET_NAME(r15),
REGS_OFFSET_NAME(r14),
@@ -85,38 +85,6 @@ static const struct pt_regs_offset regoffset_table[] = {
REGS_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/include/linux/ptrace.h b/include/linux/ptrace.h
index 4e1c6fd..08423b0 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -416,6 +416,48 @@ 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 2341efe..f657018 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -1264,3 +1264,41 @@ 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 */
--
2.5.0
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