x32: Add ptrace for x32

X32 ptrace is a hybrid of 64bit ptrace and compat ptrace with 32bit
address and longs.  It use 64bit ptrace to access the full 64bit
registers.  PTRACE_PEEKUSR and PTRACE_POKEUSR are only allowed to access
segment and debug registers.  PTRACE_PEEKUSR returns the lower 32bits
and PTRACE_POKEUSR zero-extends 32bit value to 64bit.   It works since
the upper 32bits of segment and debug registers of x32 process are always
zero.  GDB only uses PTRACE_PEEKUSR and PTRACE_POKEUSR to access
segment and debug registers.

[ hpa: changed TIF_X32 test to use !is_ia32_task() instead, and moved
  the system call number to the now-unused 521 slot. ]

Signed-off-by: "H.J. Lu" <[email protected]>
Signed-off-by: H. Peter Anvin <[email protected]>
Cc: Roland McGrath <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]

0 files changed, 0 insertions, 0 deletions