arch/arm/include/asm/user.h

#ifndef _ARM_USER_H
#define _ARM_USER_H

#include <asm/page.h>
#include <asm/ptrace.h>
/* Core file format: The core file is written in such a way that gdb
   can understand it and provide useful information to the user (under
   linux we use the 'trad-core' bfd).  There are quite a number of
   obstacles to being able to view the contents of the floating point
   registers, and until these are solved you will not be able to view the
   contents of them.  Actually, you can read in the core file and look at
   the contents of the user struct to find out what the floating point
   registers contain.
   The actual file contents are as follows:
   UPAGE: 1 page consisting of a user struct that tells gdb what is present
   in the file.  Directly after this is a copy of the task_struct, which
   is currently not used by gdb, but it may come in useful at some point.
   All of the registers are stored as part of the upage.  The upage should
   always be only one page.
   DATA: The data area is stored.  We use current->end_text to
   current->brk to pick up all of the user variables, plus any memory
   that may have been malloced.  No attempt is made to determine if a page
   is demand-zero or if a page is totally unused, we just cover the entire
   range.  All of the addresses are rounded in such a way that an integral
   number of pages is written.
   STACK: We need the stack information in order to get a meaningful
   backtrace.  We need to write the data from (esp) to
   current->start_stack, so we round each of these off in order to be able
   to write an integer number of pages.
   The minimum core file size is 3 pages, or 12288 bytes.
*/

struct user_fp {
	struct fp_reg {
		unsigned int sign1:1;
		unsigned int unused:15;
		unsigned int sign2:1;
		unsigned int exponent:14;
		unsigned int j:1;
		unsigned int mantissa1:31;
		unsigned int mantissa0:32;
	} fpregs[8];
	unsigned int fpsr:32;
	unsigned int fpcr:32;
	unsigned char ftype[8];
	unsigned int init_flag;
};

/* When the kernel dumps core, it starts by dumping the user struct -
   this will be used by gdb to figure out where the data and stack segments
   are within the file, and what virtual addresses to use. */
struct user{
/* We start with the registers, to mimic the way that "memory" is returned
   from the ptrace(3,...) function.  */
  struct pt_regs regs;		/* Where the registers are actually stored */
/* ptrace does not yet supply these.  Someday.... */
  int u_fpvalid;		/* True if math co-processor being used. */
                                /* for this mess. Not yet used. */
/* The rest of this junk is to help gdb figure out what goes where */
  unsigned long int u_tsize;	/* Text segment size (pages). */
  unsigned long int u_dsize;	/* Data segment size (pages). */
  unsigned long int u_ssize;	/* Stack segment size (pages). */
  unsigned long start_code;     /* Starting virtual address of text. */
  unsigned long start_stack;	/* Starting virtual address of stack area.
				   This is actually the bottom of the stack,
				   the top of the stack is always found in the
				   esp register.  */
  long int signal;     		/* Signal that caused the core dump. */
  int reserved;			/* No longer used */
  unsigned long u_ar0;		/* Used by gdb to help find the values for */
				/* the registers. */
  unsigned long magic;		/* To uniquely identify a core file */
  char u_comm[32];		/* User command that was responsible */
  int u_debugreg[8];		/* No longer used */
  struct user_fp u_fp;		/* FP state */
  struct user_fp_struct * u_fp0;/* Used by gdb to help find the values for */
  				/* the FP registers. */
};
#define NBPG PAGE_SIZE
#define UPAGES 1
#define HOST_TEXT_START_ADDR (u.start_code)
#define HOST_STACK_END_ADDR (u.start_stack + u.u_ssize * NBPG)

/*
 * User specific VFP registers. If only VFPv2 is present, registers 16 to 31
 * are ignored by the ptrace system call and the signal handler.
 */
struct user_vfp {
	unsigned long long fpregs[32];
	unsigned long fpscr;
};

/*
 * VFP exception registers exposed to user space during signal delivery.
 * Fields not relavant to the current VFP architecture are ignored.
 */
struct user_vfp_exc {
	unsigned long	fpexc;
	unsigned long	fpinst;
	unsigned long	fpinst2;
};

#endif /* _ARM_USER_H */