Ptrace support for Aarch64 SVEusers/simark/regcache-for-alan

Add support for reading and writing registers for Aarch64 SVE.
I've made this functionality common as it will be required for
gdbserver when gdbsever sve support is added.

Given that gdbserver does not yet call this function, I am
happy to remove the regcache commonise functions from the
previous patch. However, this would result in code in nat/
that does not compile for gdbserver. I wanted to avoid that.

We need to support the cases where the kernel only gives us a
fpsimd structure. This occurs when there is no active SVE state
in the kernel (for example, after starting a new process).

As per the covering email description, I've included large chunks
of linux kernel headers within an ifdef. Formatting of these macros
remains identical to the Kernel versions (ie not adapted to GNU style).

Added checks to make sure the vector length has not changed whilst
the process is running.

2018-05-11  Alan Hayward  <alan.hayward@arm.com>

gdb/
	* aarch64-linux-nat.c (fetch_sveregs_from_thread): New function.
	(store_sveregs_to_thread): Likewise.
	(aarch64_linux_fetch_inferior_registers): Check for SVE.
	(aarch64_linux_store_inferior_registers): Likewise.
	* nat/aarch64-sve-linux-ptrace.c (aarch64_sve_get_sveregs): New
	function.
	(aarch64_sve_regs_copy_to_regcache): Likewise.
	(aarch64_sve_regs_copy_from_regcache): Likewise.
	* nat/aarch64-sve-linux-ptrace.h (aarch64_sve_get_sveregs): New
	declaration.
	(aarch64_sve_regs_copy_to_regcache): Likewise.
	(aarch64_sve_regs_copy_from_regcache): Likewise.
	(sve_context): Structure from Linux headers.
	(SVE_SIG_ZREGS_SIZE): Define from Linux headers.
	(SVE_SIG_ZREG_SIZE): Likewise.
	(SVE_SIG_PREG_SIZE): Likewise.
	(SVE_SIG_FFR_SIZE): Likewise.
	(SVE_SIG_REGS_OFFSET): Likewise.
	(SVE_SIG_ZREGS_OFFSET): Likewise.
	(SVE_SIG_ZREG_OFFSET): Likewise.
	(SVE_SIG_ZREGS_SIZE): Likewise.
	(SVE_SIG_PREGS_OFFSET): Likewise.
	(SVE_SIG_PREG_OFFSET): Likewise.
	(SVE_SIG_PREGS_SIZE): Likewise.
	(SVE_SIG_FFR_OFFSET): Likewise.
	(SVE_SIG_REGS_SIZE): Likewise.
	(SVE_SIG_CONTEXT_SIZE): Likewise.
	(SVE_PT_REGS_MASK): Likewise.
	(SVE_PT_REGS_FPSIMD): Likewise.
	(SVE_PT_REGS_SVE): Likewise.
	(SVE_PT_VL_INHERIT): Likewise.
	(SVE_PT_VL_ONEXEC): Likewise.
	(SVE_PT_REGS_OFFSET): Likewise.
	(SVE_PT_FPSIMD_OFFSET): Likewise.
	(SVE_PT_FPSIMD_SIZE): Likewise.
	(SVE_PT_SVE_ZREG_SIZE): Likewise.
	(SVE_PT_SVE_PREG_SIZE): Likewise.
	(SVE_PT_SVE_FFR_SIZE): Likewise.
	(SVE_PT_SVE_FPSR_SIZE): Likewise.
	(SVE_PT_SVE_FPCR_SIZE): Likewise.
	(__SVE_SIG_TO_PT): Likewise.
	(SVE_PT_SVE_OFFSET): Likewise.
	(SVE_PT_SVE_ZREGS_OFFSET): Likewise.
	(SVE_PT_SVE_ZREG_OFFSET): Likewise.
	(SVE_PT_SVE_ZREGS_SIZE): Likewise.
	(SVE_PT_SVE_PREGS_OFFSET): Likewise.
	(SVE_PT_SVE_PREG_OFFSET): Likewise.
	(SVE_PT_SVE_PREGS_SIZE): Likewise.
	(SVE_PT_SVE_FFR_OFFSET): Likewise.
	(SVE_PT_SVE_FPSR_OFFSET): Likewise.
	(SVE_PT_SVE_FPCR_OFFSET): Likewise.
	(SVE_PT_SVE_SIZE): Likewise.
	(SVE_PT_SIZE): Likewise.
	(HAS_SVE_STATE): New define.

gdbserver
	* Makefile.in: Add aarch64-sve-linux-ptrace.c.

1 files changed, 10 insertions, 10 deletions

diff --git a/gdb/gdbserver/regcache.h b/gdb/gdbserver/regcache.h
index b3631bebd27..ad199a9ef19 100644
--- a/gdb/gdbserver/regcache.h
+++ b/gdb/gdbserver/regcache.h
@@ -28,31 +28,31 @@ struct target_desc;
    inferior; this is primarily for simplicity, as the performance
    benefit is minimal.  */
 
-struct regcache
+struct regcache : public reg_buffer_common
 {
   /* The regcache's target description.  */
-  const struct target_desc *tdesc;
+  const struct target_desc *tdesc = nullptr;
 
   /* Whether the REGISTERS buffer's contents are valid.  If false, we
      haven't fetched the registers from the target yet.  Not that this
      register cache is _not_ pass-through, unlike GDB's.  Note that
      "valid" here is unrelated to whether the registers are available
      in a traceframe.  For that, check REGISTER_STATUS below.  */
-  int registers_valid;
-  int registers_owned;
-  unsigned char *registers;
+  int registers_valid = 0;
+  int registers_owned = 0;
+  unsigned char *registers = nullptr;
 #ifndef IN_PROCESS_AGENT
   /* One of REG_UNAVAILBLE or REG_VALID.  */
-  unsigned char *register_status;
+  unsigned char *register_status = nullptr;
 #endif
 
-  void raw_supply (int regnum, const void *buf);
+  void raw_supply (int regnum, const void *buf) override;
 
-  void raw_collect (int regnum, void *buf) const;
+  void raw_collect (int regnum, void *buf) const override;
 
-  int raw_compare (int regnum, const void *buf, int offset) const;
+  bool raw_compare (int regnum, const void *buf, int offset) const override;
 
-  enum register_status get_register_status (int regnum) const;
+  enum register_status get_register_status (int regnum) const override;
 };
 
 struct regcache *init_register_cache (struct regcache *regcache,