metag: ptrace

The ptrace interface for metag provides access to some core register
sets using the PTRACE_GETREGSET and PTRACE_SETREGSET operations. The
details of the internal context structures is abstracted into user API
structures to both ease use and allow flexibility to change the internal
context layouts. Copyin and copyout functions for these register sets
are exposed to allow signal handling code to use them to copy to and
from the signal context.

struct user_gp_regs (NT_PRSTATUS) provides access to the core general
purpose register context.

struct user_cb_regs (NT_METAG_CBUF) provides access to the TXCATCH*
registers which contains information abuot a memory fault, unaligned
access error or watchpoint. This can be modified to alter the way the
fault is replayed on resume ("catch replay"), or to prevent the replay
taking place.

struct user_rp_state (NT_METAG_RPIPE) provides access to the state of
the Meta read pipeline which can be used to hide memory latencies in
hand optimised data loops.

Extended DSP register state, DSP RAM, and hardware breakpoint registers
aren't yet exposed through ptrace.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Tony Lindgren <tony@atomide.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
index 126a8175e3e2..eb164a298b98 100644
--- a/include/uapi/linux/elf.h
+++ b/include/uapi/linux/elf.h
@@ -395,6 +395,8 @@ typedef struct elf64_shdr {
 #define NT_ARM_TLS	0x401		/* ARM TLS register */
 #define NT_ARM_HW_BREAK	0x402		/* ARM hardware breakpoint registers */
 #define NT_ARM_HW_WATCH	0x403		/* ARM hardware watchpoint registers */
+#define NT_METAG_CBUF	0x500		/* Metag catch buffer registers */
+#define NT_METAG_RPIPE	0x501		/* Metag read pipeline state */
 
 
 /* Note header in a PT_NOTE section */