[PATCH v3 5/5] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature

[David Long <dave.long@linaro.org>]

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

Add HAVE_REGS_AND_STACK_ACCESS_API feature for arm64.

Signed-off-by: David A. Long <dave.long@linaro.org>
---
 arch/arm64/Kconfig                   |   1 +
 arch/arm64/include/asm/ptrace.h      |  29 +++++++++
 arch/arm64/include/uapi/asm/ptrace.h |  36 +++++++++++
 arch/arm64/kernel/ptrace.c           | 119 +++++++++++++++++++++++++++++++++++
 4 files changed, 185 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 02f31b7..bc9b516 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -58,6 +58,7 @@ config ARM64
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
+	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_RCU_TABLE_FREE
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES if !XIP_KERNEL
diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index d3e782a..24cc048 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -111,6 +111,8 @@ struct pt_regs {
 	u64 syscallno;
 };
 
+#define MAX_REG_OFFSET (offsetof(struct pt_regs, orig_x0))
+
 #define arch_has_single_step()	(1)
 
 #ifdef CONFIG_COMPAT
@@ -139,11 +141,38 @@ struct pt_regs {
 #define user_stack_pointer(regs) \
 	(!compat_user_mode(regs) ? (regs)->sp : (regs)->compat_sp)
 
+/**
+ * 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 u64 regs_get_register(struct pt_regs *regs,
+					      unsigned int offset)
+{
+	if (unlikely(offset > MAX_REG_OFFSET))
+		return 0;
+	return *(u64 *)((u64)regs + offset);
+}
+
+/* Valid only for Kernel mode traps. */
+static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
+{
+	return regs->ARM_sp;
+}
+
 static inline unsigned long regs_return_value(struct pt_regs *regs)
 {
 	return regs->regs[0];
 }
 
+extern int regs_query_register_offset(const char *name);
+extern unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
+					       unsigned int n);
+
 /*
  * Are the current registers suitable for user mode? (used to maintain
  * security in signal handlers)
diff --git a/arch/arm64/include/uapi/asm/ptrace.h b/arch/arm64/include/uapi/asm/ptrace.h
index 6913643..700d28b 100644
--- a/arch/arm64/include/uapi/asm/ptrace.h
+++ b/arch/arm64/include/uapi/asm/ptrace.h
@@ -61,6 +61,42 @@
 
 #ifndef __ASSEMBLY__
 
+#define ARM_cpsr	pstate
+#define ARM_pc		pc
+#define ARM_sp		sp
+#define ARM_lr		regs[30]
+#define ARM_fp		regs[29]
+#define ARM_x28		regs[28]
+#define ARM_x27		regs[27]
+#define ARM_x26		regs[26]
+#define ARM_x25		regs[25]
+#define ARM_x24		regs[24]
+#define ARM_x23		regs[23]
+#define ARM_x22		regs[22]
+#define ARM_x21		regs[21]
+#define ARM_x20		regs[20]
+#define ARM_x19		regs[19]
+#define ARM_x18		regs[18]
+#define ARM_ip1		regs[17]
+#define ARM_ip0		regs[16]
+#define ARM_x15		regs[15]
+#define ARM_x14		regs[14]
+#define ARM_x13		regs[13]
+#define ARM_x12		regs[12]
+#define ARM_x11		regs[11]
+#define ARM_x10		regs[10]
+#define ARM_x9		regs[9]
+#define ARM_x8		regs[8]
+#define ARM_x7		regs[7]
+#define ARM_x6		regs[6]
+#define ARM_x5		regs[5]
+#define ARM_x4		regs[4]
+#define ARM_x3		regs[3]
+#define ARM_x2		regs[2]
+#define ARM_x1		regs[1]
+#define ARM_x0		regs[0]
+#define ARM_ORIG_x0	orig_x0
+
 /*
  * User structures for general purpose, floating point and debug registers.
  */
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 8a4ae8e..36a94c8 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -47,6 +47,125 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/syscalls.h>
 
+struct pt_regs_offset {
+	const char *name;
+	int offset;
+};
+
+#define REG_OFFSET_NAME(r) \
+	{.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[] = {
+	REG_OFFSET_NAME(x0),
+	REG_OFFSET_NAME(x1),
+	REG_OFFSET_NAME(x2),
+	REG_OFFSET_NAME(x3),
+	REG_OFFSET_NAME(x4),
+	REG_OFFSET_NAME(x5),
+	REG_OFFSET_NAME(x6),
+	REG_OFFSET_NAME(x7),
+	REG_OFFSET_NAME(x8),
+	REG_OFFSET_NAME(x9),
+	REG_OFFSET_NAME(x10),
+	REG_OFFSET_NAME(x11),
+	REG_OFFSET_NAME(x12),
+	REG_OFFSET_NAME(x13),
+	REG_OFFSET_NAME(x14),
+	REG_OFFSET_NAME(x15),
+	REG_OFFSET_NAME(ip0),
+	REG_OFFSET_NAME(ip1),
+	REG_OFFSET_NAME(x18),
+	REG_OFFSET_NAME(x19),
+	REG_OFFSET_NAME(x20),
+	REG_OFFSET_NAME(x21),
+	REG_OFFSET_NAME(x22),
+	REG_OFFSET_NAME(x23),
+	REG_OFFSET_NAME(x24),
+	REG_OFFSET_NAME(x25),
+	REG_OFFSET_NAME(x26),
+	REG_OFFSET_NAME(x27),
+	REG_OFFSET_NAME(x28),
+	REG_OFFSET_NAME(fp),
+	REG_OFFSET_NAME(lr),
+/*
+	REG_OFFSET_NAME(ip),
+*/
+	REG_OFFSET_NAME(sp),
+	REG_OFFSET_NAME(pc),
+	REG_OFFSET_NAME(cpsr),
+	REG_OFFSET_NAME(ORIG_x0),
+	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;
+}
+
 /*
  * TODO: does not yet catch signals sent when the child dies.
  * in exit.c or in signal.c.
-- 
1.8.1.2