coregrind/m_gdbserver/valgrind-low.c

/* Low level interface to valgrind, for the remote server for GDB integrated
   in valgrind.
   Copyright (C) 2011
   Free Software Foundation, Inc.

   This file is part of VALGRIND.
   It has been inspired from a file from gdbserver in gdb 6.6.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.  */

#include "server.h"
#include "target.h"
#include "regdef.h"
#include "regcache.h"
#include "valgrind_low.h"
#include "gdb/signals.h"
#include "pub_core_aspacemgr.h"
#include "pub_tool_machine.h"
#include "pub_core_threadstate.h"
#include "pub_core_transtab.h"
#include "pub_core_gdbserver.h"
#include "pub_tool_debuginfo.h"

/* the_low_target defines the architecture specific aspects depending
   on the cpu */
static struct valgrind_target_ops the_low_target;

/* builds an image of bin according to byte order of the architecture
   Useful for register and int image */
char* heximage (char *buf, char *bin, int count)
{
#if defined(VGA_x86) || defined(VGA_amd64)
   char rev[count];
   /* note: no need for trailing \0, length is known with count */
  int i;
  for (i = 0; i < count; i++)
    rev[i] = bin[count - i - 1];
  hexify (buf, rev, count);
#else
  hexify (buf, bin, count);
#endif
  return buf;
}

void* C2v(CORE_ADDR addr)
{
   return (void*) addr;
}

static
char *image_ptid(unsigned long ptid)
{
  static char result[100];
  VG_(sprintf) (result, "id %ld", ptid);
  return result;
}
#define get_thread(inf) ((struct thread_info *)(inf))
static
void remove_thread_if_not_in_vg_threads (struct inferior_list_entry *inf)
{
  struct thread_info *thread = get_thread (inf);
  if (!VG_(lwpid_to_vgtid)(thread_to_gdb_id(thread))) {
     dlog(1, "removing gdb ptid %s\n",
          image_ptid(thread_to_gdb_id(thread)));
     remove_thread (thread);
  }
}

/* synchronize threads known by valgrind and threads known by gdbserver */
static
void valgrind_update_threads (int pid)
{
  ThreadId tid;
  ThreadState *ts;
  unsigned long ptid;
  struct thread_info *ti;

  /* call remove_thread for all gdb threads not in valgrind threads */
  for_each_inferior (&all_threads, remove_thread_if_not_in_vg_threads);

  /* call add_thread for all valgrind threads not known in gdb all_threads */
  for (tid = 1; tid < VG_N_THREADS; tid++) {

#define LOCAL_THREAD_TRACE " ti* %p vgtid %d status %s as gdb ptid %s lwpid %d\n", \
        ti, tid, VG_(name_of_ThreadStatus) (ts->status), \
        image_ptid (ptid), ts->os_state.lwpid

     if (VG_(is_valid_tid) (tid)) {
        ts = VG_(get_ThreadState) (tid);
        ptid = ts->os_state.lwpid;
        ti = gdb_id_to_thread (ptid);
        if (!ti) {
           /* we do not report the threads which are not yet fully
              initialized otherwise this creates duplicated threads
              in gdb: once with pid xxx lwpid 0, then after that
              with pid xxx lwpid yyy. */
           if (ts->status != VgTs_Init) {
              dlog(1, "adding_thread" LOCAL_THREAD_TRACE);
              add_thread (ptid, ts, ptid);
           }
        } else {
           dlog(2, "(known thread)" LOCAL_THREAD_TRACE);
        }
     }
#undef LOCAL_THREAD_TRACE
  }
}

/* Return nonzero if the given thread is still alive.  */
static
int valgrind_thread_alive (unsigned long tid)
{
  struct thread_info *ti =  gdb_id_to_thread(tid);
  ThreadState *tst;

  if (ti != NULL) {
     tst = (ThreadState *) inferior_target_data (ti);
     return tst->status != VgTs_Zombie;
  }
  else {
    return 0;
  }
}

/* allocate and build a register structure containing the shadow registers.
   reg_defs is the normal registers, n is their numbers */
static
struct reg* build_shadow_arch (struct reg *reg_defs, int n) {
   int i, r;
   static char *postfix[3] = { "", "s1", "s2" };
   struct reg *new_regs = malloc(3 * n * sizeof(reg_defs[0]));
   int reg_set_len = reg_defs[n-1].offset + reg_defs[n-1].size;

   for (i = 0; i < 3; i++) {
      for (r = 0; r < n; r++) {
         new_regs[i*n + r].name = malloc(strlen(reg_defs[r].name)
                                         + strlen (postfix[i]) + 1);
         strcpy (new_regs[i*n + r].name, reg_defs[r].name);
         strcat (new_regs[i*n + r].name, postfix[i]);
         new_regs[i*n + r].offset = i*reg_set_len + reg_defs[r].offset;
         new_regs[i*n + r].size = reg_defs[r].size;
         dlog(1,
              "%10s Nr %d offset(bit) %d offset(byte) %d  size(bit) %d\n",
              new_regs[i*n + r].name, i*n + r, new_regs[i*n + r].offset,
              (new_regs[i*n + r].offset) / 8, new_regs[i*n + r].size);
      }
   }

   return new_regs;
}

/* Fetch one register from valgrind VEX guest state.  */
static
void fetch_register (int regno)
{
   int size;
   ThreadState *tst = (ThreadState *) inferior_target_data (current_inferior);
   ThreadId tid = tst->tid;

   if (regno >= the_low_target.num_regs) {
      dlog(0, "error fetch_register regno %d max %d\n",
           regno, the_low_target.num_regs);
      return;
   }
   size = register_size (regno);
   if (size > 0) {
      Bool mod;
      char buf [size];
      VG_(memset) (buf, 0, size); // registers not fetched will be seen as 0.
      (*the_low_target.transfer_register) (tid, regno, buf,
                                           valgrind_to_gdbserver, size, &mod);
      // Note: the *mod received from transfer_register is not interesting.
      // We are interested to see if the register data in the register cache is modified.
      supply_register (regno, buf, &mod);
      if (mod && VG_(debugLog_getLevel)() > 1) {
         char bufimage [2*size + 1];
         heximage (bufimage, buf, size);
         dlog(2, "fetched register %d size %d name %s value %s tid %d status %s\n",
              regno, size, the_low_target.reg_defs[regno].name, bufimage,
              tid, VG_(name_of_ThreadStatus) (tst->status));
      }
   }
}

/* Fetch all registers, or just one, from the child process.  */
static
void usr_fetch_inferior_registers (int regno)
{
   if (regno == -1 || regno == 0)
      for (regno = 0; regno < the_low_target.num_regs; regno++)
         fetch_register (regno);
   else
      fetch_register (regno);
}

/* Store our register values back into the inferior.
   If REGNO is -1, do this for all registers.
   Otherwise, REGNO specifies which register (so we can save time).  */
static
void usr_store_inferior_registers (int regno)
{
   int size;
   ThreadState *tst = (ThreadState *) inferior_target_data (current_inferior);
   ThreadId tid = tst->tid;

   if (regno >= 0) {

      if (regno >= the_low_target.num_regs) {
         dlog(0, "error store_register regno %d max %d\n",
              regno, the_low_target.num_regs);
         return;
      }

      size = register_size (regno);
      if (size > 0) {
         Bool mod;
         Addr old_SP, new_SP;
         char buf[size];

         if (regno == the_low_target.stack_pointer_regno) {
            /* When the stack pointer register is changed such that
               the stack is extended, we better inform the tool of the
               stack increase.  This is needed in particular to avoid
               spurious Memcheck errors during Inferior calls. So, we
               save in old_SP the SP before the change. A change of
               stack pointer is also assumed to have initialised this
               new stack space. For the typical example of an inferior
               call, gdb writes arguments on the stack, and then
               changes the stack pointer. As the stack increase tool
               function might mark it as undefined, we have to call it
               at the good moment. */
            VG_(memset) ((void *) &old_SP, 0, size);
            (*the_low_target.transfer_register) (tid, regno, (void *) &old_SP,
                                                 valgrind_to_gdbserver, size, &mod);
         }

         VG_(memset) (buf, 0, size);
         collect_register (regno, buf);
         (*the_low_target.transfer_register) (tid, regno, buf,
                                              gdbserver_to_valgrind, size, &mod);
         if (mod && VG_(debugLog_getLevel)() > 1) {
            char bufimage [2*size + 1];
            heximage (bufimage, buf, size);
            dlog(2,
                 "stored register %d size %d name %s value %s "
                 "tid %d status %s\n",
                 regno, size, the_low_target.reg_defs[regno].name, bufimage,
                 tid, VG_(name_of_ThreadStatus) (tst->status));
         }
         if (regno == the_low_target.stack_pointer_regno) {
            VG_(memcpy) (&new_SP, buf, size);
            if (old_SP > new_SP) {
               Word delta  = (Word)new_SP - (Word)old_SP;
               dlog(1,
                    "   stack increase by stack pointer changed from %p to %p "
                    "delta %ld\n",
                    (void*) old_SP, (void *) new_SP,
                    delta);
               VG_TRACK( new_mem_stack_w_ECU, new_SP, -delta, 0 );
               VG_TRACK( new_mem_stack,       new_SP, -delta );
               if (VG_(tdict).track_post_mem_write) {
                  VG_(tdict).track_post_mem_write( Vg_CoreClientReq, tid,
                                                   new_SP, -delta);
               }
            }
         }
      }
   }
   else {
      for (regno = 0; regno < the_low_target.num_regs; regno++)
         usr_store_inferior_registers (regno);
   }
}

static
void valgrind_fetch_registers (int regno)
{
   usr_fetch_inferior_registers (regno);
}

static
void valgrind_store_registers (int regno)
{
   usr_store_inferior_registers (regno);
}

/* Copy LEN bytes from inferior's memory starting at MEMADDR
   to debugger memory starting at MYADDR.  */

static
int valgrind_read_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
{
   const void *sourceaddr = C2v (memaddr);
   dlog(2, "reading memory %p size %d\n", sourceaddr, len);
   if (!VG_(am_is_valid_for_client_or_free_or_resvn) ((Addr) sourceaddr,
                                                      len, VKI_PROT_READ)) {
      dlog(1, "error reading memory %p size %d\n", sourceaddr, len);
      return -1;
   }
   VG_(memcpy) (myaddr, sourceaddr, len);
   return 0;
}

/* Copy LEN bytes of data from debugger memory at MYADDR
   to inferior's memory at MEMADDR.
   On failure (cannot write the inferior)
   returns the value of errno.  */

static
int valgrind_write_memory (CORE_ADDR memaddr, const unsigned char *myaddr, int len)
{
   void *targetaddr = C2v (memaddr);
   dlog(2, "writing memory %p size %d\n", targetaddr, len);
   if (!VG_(am_is_valid_for_client_or_free_or_resvn) ((Addr)targetaddr,
                                                      len, VKI_PROT_WRITE)) {
      dlog(1, "error writing memory %p size %d\n", targetaddr, len);
      return -1;
   }
   if (len > 0) {
      VG_(memcpy) (targetaddr, myaddr, len);
      if (VG_(tdict).track_post_mem_write) {
         /* Inform the tool of the post memwrite.  Note that we do the
            minimum necessary to avoid complains from e.g.
            memcheck. The idea is that the debugger is as least
            intrusive as possible.  So, we do not inform of the pre
            mem write (and in any case, this would cause problems with
            memcheck that does not like our CorePart in
            pre_mem_write. */
         ThreadState *tst = (ThreadState *) inferior_target_data (current_inferior);
         ThreadId tid = tst->tid;
         VG_(tdict).track_post_mem_write( Vg_CoreClientReq, tid, (Addr) targetaddr, len );
      }
   }
   return 0;
}

/* insert or remove a breakpoint */
static
int valgrind_point (Bool insert, char type, CORE_ADDR addr, int len)
{
   PointKind kind;
   switch (type) {
   case '0': /* implemented by inserting checks at each instruction in sb */
      kind = software_breakpoint;
      break;
   case '1': /* hw breakpoint, same implementation as sw breakpoint */
      kind = hardware_breakpoint;
      break;
   case '2':
      kind = write_watchpoint;
      break;
   case '3':
      kind = read_watchpoint;
      break;
   case '4':
      kind = access_watchpoint;
      break;
   default:
      vg_assert (0);
   }

   /* Attention: gdbserver convention differs: 0 means ok; 1 means not ok */
   if (VG_(gdbserver_point) (kind, insert, addr, len))
      return 0;
   else
      return 1; /* error or unsupported */
}

static
void valgrind_send_signal (int sig)
{
   dlog(1, "valgrind_send_signal %d called ????\n", sig);
}

static
char* valgrind_target_xml (void)
{
   return (char *) the_low_target.target_xml;
}

static
char* valgrind_shadow_target_xml (void)
{
   return (char *) the_low_target.shadow_target_xml;
}

static
int valgrind_insert_point (char type, CORE_ADDR addr, int len)
{
   return valgrind_point (/* insert */ True, type, addr, len);
}

static
int valgrind_remove_point (char type, CORE_ADDR addr, int len)
{
   return valgrind_point (/* insert*/ False, type, addr, len);
}

static CORE_ADDR stopped_data_address = 0;
void VG_(set_watchpoint_stop_address) (Addr addr)
{
   stopped_data_address = addr;
}

static
int valgrind_stopped_by_watchpoint (void)
{
   return stopped_data_address != 0;
}

static
CORE_ADDR valgrind_stopped_data_address (void)
{
   return stopped_data_address;
}

/* pc at which we last stopped */
static CORE_ADDR stop_pc;

/* pc at which we resume.
   If stop_pc != resume_pc, it means
      gdb/gdbserver has changed the pc so as to have either
      a    "continue by jumping at that address"
      or a "continue at that address to call some code from gdb".
*/
static CORE_ADDR resume_pc;

static int signal_to_report;

void gdbserver_signal_encountered (Int sigNo)
{
   signal_to_report = sigNo;
}

static int signal_to_deliver;
Bool gdbserver_deliver_signal (Int sigNo)
{
   return sigNo == signal_to_deliver;
}

static
char* sym (Addr addr)
{
   static char buf[200];
   VG_(describe_IP) (addr, buf, 200);
   return buf;
}

ThreadId vgdb_interrupted_tid = 0;
/* called to wait for the process to stop */
static
unsigned char valgrind_wait (char *ourstatus)
{
   int pid;
   unsigned long wptid;
   ThreadState *tst;
   enum target_signal sig;

   pid = VG_(getpid) ();
   dlog(1, "enter valgrind_wait pid %d\n", pid);

   regcache_invalidate();
   valgrind_update_threads(pid);

   /* in valgrind, we consider that a wait always succeeds with STOPPED 'T'
      and with a signal TRAP (i.e. a breakpoint), unless there is
      a signal to report. */
   *ourstatus = 'T';
   if (signal_to_report == 0)
      sig = TARGET_SIGNAL_TRAP;
   else
      sig = target_signal_from_host(signal_to_report);

   if (vgdb_interrupted_tid != 0)
      tst = VG_(get_ThreadState) (vgdb_interrupted_tid);
   else
      tst = VG_(get_ThreadState) (VG_(running_tid));
   wptid = tst->os_state.lwpid;
   /* we can only change the current_inferior when the wptid references
      an existing thread. Otherwise, we are still in the init phase.
      (hack similar to main thread hack in valgrind_update_threads) */
   if (tst->os_state.lwpid)
      current_inferior = gdb_id_to_thread (wptid);
   stop_pc = (*the_low_target.get_pc) ();

   dlog(1,
        "exit valgrind_wait returns ptid %s stop_pc %s signal %d\n",
        image_ptid (wptid), sym (stop_pc), sig);
   return sig;
}

/* 0 => not single stepping.
   1 => single stepping asked by gdb
   2 => single stepping asked by valgrind (watchpoint) */
static int stepping = 0;

/* called when the process is to be resumed */
static
void valgrind_resume (struct thread_resume *resume_info)
{
   dlog(1,
        "resume_info thread %ld leave_stopped %d step %d sig %d stepping %d\n",
        resume_info->thread,
        resume_info->leave_stopped,
        resume_info->step,
        resume_info->sig,
        stepping);
   if (valgrind_stopped_by_watchpoint()) {
      dlog(1, "clearing watchpoint stopped_data_address %p\n",
           C2v(stopped_data_address));
      VG_(set_watchpoint_stop_address) ((Addr) 0);
   }
   signal_to_deliver = resume_info->sig;

   stepping = resume_info->step;
   resume_pc = (*the_low_target.get_pc) ();
   if (resume_pc != stop_pc) {
      dlog(1,
           "stop_pc %p changed to be resume_pc %s\n",
           C2v(stop_pc), sym(resume_pc));
   }
   regcache_invalidate();
}

Addr valgrind_get_ignore_break_once(void)
{
   if (valgrind_single_stepping())
      return resume_pc;
   else
      return 0;
}


void valgrind_set_single_stepping(Bool set)
{
   if (set)
      stepping = 2;
   else
      stepping = 0;
}

Bool valgrind_single_stepping(void)
{
   if (stepping)
      return True;
   else
      return False;
}

static struct target_ops valgrind_target_ops = {
   valgrind_thread_alive,
   valgrind_resume,
   valgrind_wait,
   valgrind_fetch_registers,
   valgrind_store_registers,
   valgrind_read_memory,
   valgrind_write_memory,
   valgrind_send_signal,
   valgrind_target_xml,
   valgrind_shadow_target_xml,
   valgrind_insert_point,
   valgrind_remove_point,
   valgrind_stopped_by_watchpoint,
   valgrind_stopped_data_address,
};


/* returns a pointer to the architecture state corresponding to
   the provided register set: 0 => normal guest registers,
                              1 => shadow1
                              2 => shadow2
*/
VexGuestArchState* get_arch (int set, ThreadState* tst)
{
  switch (set) {
  case 0: return &tst->arch.vex;
  case 1: return &tst->arch.vex_shadow1;
  case 2: return &tst->arch.vex_shadow2;
  default: vg_assert(0);
  }
}

static int non_shadow_num_regs = 0;
static struct reg *non_shadow_reg_defs = NULL;
void initialize_shadow_low(Bool shadow_mode)
{
  if (non_shadow_reg_defs == NULL) {
    non_shadow_reg_defs = the_low_target.reg_defs;
    non_shadow_num_regs = the_low_target.num_regs;
  }

  regcache_invalidate();
  if (the_low_target.reg_defs != non_shadow_reg_defs) {
     free (the_low_target.reg_defs);
  }
  if (shadow_mode) {
    the_low_target.num_regs = 3 * non_shadow_num_regs;
    the_low_target.reg_defs = build_shadow_arch (non_shadow_reg_defs, non_shadow_num_regs);
  } else {
    the_low_target.num_regs = non_shadow_num_regs;
    the_low_target.reg_defs = non_shadow_reg_defs;
  }
  set_register_cache (the_low_target.reg_defs, the_low_target.num_regs);
}

void initialize_low(void)
{
   set_target_ops (&valgrind_target_ops);

#if defined(VGA_x86)
   x86_init_architecture(&the_low_target);
#elif defined(VGA_amd64)
   amd64_init_architecture(&the_low_target);
#elif defined(VGA_arm)
   arm_init_architecture(&the_low_target);
#elif defined(VGA_ppc32)
   ppc32_init_architecture(&the_low_target);
#elif defined(VGA_ppc64)
   ppc64_init_architecture(&the_low_target);
#elif defined(VGA_s390x)
   s390x_init_architecture(&the_low_target);
#else
   architecture missing in valgrind-low.c
#endif

}