gdb/gdbserver/i386-low.h

   1 /* Misc. low level support for i386.
   2
   3    Copyright (C) 2009-2012 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 /* Support for hardware watchpoints and breakpoints using the i386
  21    debug registers.
  22
  23    This provides several functions for inserting and removing
  24    hardware-assisted breakpoints and watchpoints, testing if one or
  25    more of the watchpoints triggered and at what address, checking
  26    whether a given region can be watched, etc.
  27
  28    The functions below implement debug registers sharing by reference
  29    counts, and allow to watch regions up to 16 bytes long
  30    (32 bytes on 64 bit hosts).  */
  31
  32
  33 /* Debug registers' indices.  */
  34 #define DR_FIRSTADDR 0
  35 #define DR_LASTADDR  3
  36 #define DR_NADDR     4 /* The number of debug address registers.  */
  37 #define DR_STATUS    6
  38 #define DR_CONTROL   7
  39
  40 /* Global state needed to track h/w watchpoints.  */
  41
  42 struct i386_debug_reg_state
  43 {
  44   /* Mirror the inferior's DRi registers.  We keep the status and
  45      control registers separated because they don't hold addresses.
  46      Note that since we can change these mirrors while threads are
  47      running, we never trust them to explain a cause of a trap.
  48      For that, we need to peek directly in the inferior registers.  */
  49   CORE_ADDR dr_mirror[DR_NADDR];
  50   unsigned dr_status_mirror, dr_control_mirror;
  51
  52   /* Reference counts for each debug register.  */
  53   int dr_ref_count[DR_NADDR];
  54 };
  55
  56 /* Initialize STATE.  */
  57 extern void i386_low_init_dregs (struct i386_debug_reg_state *state);
  58
  59 /* Insert a watchpoint to watch a memory region which starts at
  60    address ADDR and whose length is LEN bytes.  Watch memory accesses
  61    of the type TYPE_FROM_PACKET.  Return 0 on success, -1 on failure.  */
  62 extern int i386_low_insert_watchpoint (struct i386_debug_reg_state *state,
  63                                        char type_from_packet, CORE_ADDR addr,
  64                                        int len);
  65
  66 /* Remove a watchpoint that watched the memory region which starts at
  67    address ADDR, whose length is LEN bytes, and for accesses of the
  68    type TYPE_FROM_PACKET.  Return 0 on success, -1 on failure.  */
  69 extern int i386_low_remove_watchpoint (struct i386_debug_reg_state *state,
  70                                        char type_from_packet, CORE_ADDR addr,
  71                                        int len);
  72
  73 /* Return non-zero if we can watch a memory region that starts at
  74    address ADDR and whose length is LEN bytes.  */
  75 extern int i386_low_region_ok_for_watchpoint (struct i386_debug_reg_state *state,
  76                                               CORE_ADDR addr, int len);
  77
  78 /* If the inferior has some break/watchpoint that triggered, set the
  79    address associated with that break/watchpoint and return true.
  80    Otherwise, return false.  */
  81 extern int i386_low_stopped_data_address (struct i386_debug_reg_state *state,
  82                                           CORE_ADDR *addr_p);
  83
  84 /* Return true if the inferior has some watchpoint that triggered.
  85    Otherwise return false.  */
  86 extern int i386_low_stopped_by_watchpoint (struct i386_debug_reg_state *state);
  87 \f
  88 /* Each target needs to provide several low-level functions
  89    that will be called to insert watchpoints and hardware breakpoints
  90    into the inferior, remove them, and check their status.  These
  91    functions are:
  92
  93       i386_dr_low_set_control  -- set the debug control (DR7)
  94                                   register to a given value
  95
  96       i386_dr_low_set_addr     -- put an address into one debug register
  97
  98       i386_dr_low_get_status   -- return the value of the debug
  99                                   status (DR6) register.
 100 */
 101
 102 /* Update the inferior's debug register REGNUM from STATE.  */
 103 extern void i386_dr_low_set_addr (const struct i386_debug_reg_state *state,
 104                                   int regnum);
 105
 106 /* Return the inferior's debug register REGNUM.  */
 107 extern CORE_ADDR i386_dr_low_get_addr (int regnum);
 108
 109 /* Update the inferior's DR7 debug control register from STATE.  */
 110 extern void i386_dr_low_set_control (const struct i386_debug_reg_state *state);
 111
 112 /* Return the value of the inferior's DR7 debug control register.  */
 113 extern unsigned i386_dr_low_get_control (void);
 114
 115 /* Return the value of the inferior's DR6 debug status register.  */
 116 extern unsigned i386_dr_low_get_status (void);