Re: [PATCH v7 1/7] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature

[David Long]

On 06/29/15 13:23, Steve Capper wrote:
On 15 June 2015 at 20:07, David Long <dave.l...@linaro.org> wrote:
From: "David A. Long" <dave.l...@linaro.org>
Add HAVE_REGS_AND_STACK_ACCESS_API feature for arm64.

Signed-off-by: David A. Long <dave.l...@linaro.org>
---
  arch/arm64/Kconfig              |  1 +
  arch/arm64/include/asm/ptrace.h | 25 +++++++++++++
  arch/arm64/kernel/ptrace.c      | 77 +++++++++++++++++++++++++++++++++++++++++
  3 files changed, 103 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7796af4..966091f 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -68,6 +68,7 @@ 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 IRQ_DOMAIN
diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index d6dd9fd..8f440e9 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -118,6 +118,8 @@ struct pt_regs {
         u64 syscallno;
  };

+#define MAX_REG_OFFSET (sizeof(struct user_pt_regs) - sizeof(u64))
+
  #define arch_has_single_step() (1)

  #ifdef CONFIG_COMPAT
@@ -146,6 +148,29 @@ 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);

Why not:
return regs->regs[offset];


This would not be correct.  The offset is a byte offset and your code 
would index eight times that amount into the structure.  The offset 
needs to remain a byte offset so architecture-independent code does not 
need to know the architecture-specific layout of the structure.

+}
+
+/* Valid only for Kernel mode traps. */
+static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
+{
+       return regs->sp;
+}
+
  static inline unsigned long regs_return_value(struct pt_regs *regs)
  {
         return regs->regs[0];
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index d882b83..f6199a5 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -48,6 +48,83 @@
  #define CREATE_TRACE_POINTS
  #include <trace/events/syscalls.h>

+#define ARM_pstate     pstate
+#define ARM_pc         pc
+#define ARM_sp         sp
+#define ARM_x30                regs[30]
+#define ARM_x29                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_x17                regs[17]
+#define ARM_x16                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 REG_OFFSET_NAME(r) \
+       {.name = #r, .offset = offsetof(struct pt_regs, ARM_##r)}
+#define REG_OFFSET_END {.name = NULL, .offset = 0}
+
+const struct pt_regs_offset regs_offset_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(x16),
+       REG_OFFSET_NAME(x17),
+       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(x29),
+       REG_OFFSET_NAME(x30),
+       REG_OFFSET_NAME(sp),
+       REG_OFFSET_NAME(pc),
+       REG_OFFSET_NAME(pstate),
+       REG_OFFSET_END,
+};
+
  /*
   * TODO: does not yet catch signals sent when the child dies.
   * in exit.c or in signal.c.
--
1.8.1.2


Thanks,
-dl

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