On 05/21/15 13:55, Catalin Marinas wrote:
On Wed, May 20, 2015 at 11:29:24PM -0400, David Long wrote:
On 05/20/15 09:39, Catalin Marinas wrote:
On Mon, Apr 20, 2015 at 04:19:42PM -0400, David Long wrote:
diff --git a/arch/arm64/include/uapi/asm/ptrace.h 
b/arch/arm64/include/uapi/asm/ptrace.h
index 6913643..58c0223 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_pstate     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

I replied some time ago on this part. I don't see the point these
macros.

I replied belatedly on April 20 saying what I did matches (more or less) how
it's done on various other platforms, including arm and powerpc.
It looks like this comes from the pt_regs structure defining the
registers as an array instead of a list of structure fields. It looks
to me like that design choice is pretty widely depended upon now and
would be quite disruptive to change.  It also seems to me a relatively
clean way to do it on systems with a uniform register set.

I see why we need to cope with the regs[] array but why do we need these
definitions in a uapi file?


I expect Sandeepa did it that way because it's the way it's done in other architectures. I see your point though, these definitions are only referenced in a macro that's defined and used only in ptrace.c. I can easily move them there.

+
  /*
   * 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 d882b83..a889f79 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -48,6 +48,122 @@
  #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)}

Can you not just use "offsetof(struct pt_regs, r)" here? That would be
the same as x86, powerpc.

The registers (except for pc, pstate, and sp) are not separate structure
fields, they are slots in a single array. To reference them the symbolic
name has to be converted to an index (integer register number) somehow.

Can we not keep them local to this file, say __reg_x0 etc. (something to
make it clear they are for internal use)?


As above we can make it local to the file. Given that I don't think there's a need to chance ARM_x* to __reg_x* though, is there? Either way, no problem.

-dl

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