RE: Misaligned read/write of memory by GDB

"Dave Brolley" <[email protected]>
Newsgroups gmane.comp.emulators.sid.devel
Organization Red Hat Canada
Message-ID <[email protected]> 
In response to Frank's comments, I have removed my previous patch and
committed this one in its place.

The cache component now handles misaligned accesses except those which cross
a cache line boundary. For those it returns bus::misaligned

The GDB component reverts to the byte-at-a-time method of access if
bus::misaligned is returned from downstream.

Dave
sid-gdbalign.ChangeLog (application/octet-stream, 640 B) - not displayed
sid-gdbalign.patch.txt (text/plain, 6.5 KB) 
Index: sid/component/gdb/gdb.cxx
===================================================================
RCS file: /cvs/src/src/sid/component/gdb/gdb.cxx,v
retrieving revision 1.11
diff -c -p -r1.11 gdb.cxx
*** sid/component/gdb/gdb.cxx	22 Mar 2004 21:27:23 -0000	1.11
--- sid/component/gdb/gdb.cxx	1 Jul 2004 16:46:54 -0000
*************** gdb::process_get_exp_regs ()
*** 532,538 ****
  // Helper functions
  
  template <class Type>
! void 
  read_bus_word(gdbserv* gdbserv, 
  	      sid::bus* bus,
  	      host_int_4 address,
--- 532,538 ----
  // Helper functions
  
  template <class Type>
! bus::status
  read_bus_word(gdbserv* gdbserv, 
  	      sid::bus* bus,
  	      host_int_4 address,
*************** read_bus_word(gdbserv* gdbserv, 
*** 545,557 ****
        for (unsigned i=0; i < sizeof(typename Type::value_type); i++)
  	gdbserv_output_byte (gdbserv, value.read_byte(i));
      }
!   else
      gdbserv_output_string (gdbserv, "E05");
  }
  
  
  template <class Type>
! void 
  write_bus_word(gdbserv* gdbserv, 
  	       int binary,
  	       sid::bus* bus,
--- 545,559 ----
        for (unsigned i=0; i < sizeof(typename Type::value_type); i++)
  	gdbserv_output_byte (gdbserv, value.read_byte(i));
      }
!   // misaligned will be handled by the caller
!   else if (s != bus::misaligned)
      gdbserv_output_string (gdbserv, "E05");
+   return s;
  }
  
  
  template <class Type>
! bus::status
  write_bus_word(gdbserv* gdbserv, 
  	       int binary,
  	       sid::bus* bus,
*************** write_bus_word(gdbserv* gdbserv, 
*** 572,581 ****
      }
  
    bus::status s = bus->write (address, value);
!   if (s == bus::ok)
!     ; // No response means "OK"
    else
      gdbserv_output_string (gdbserv, "E05");
  }
  
  
--- 574,584 ----
      }
  
    bus::status s = bus->write (address, value);
!   if (s == bus::ok || s == bus::misaligned)
!     ; // No response means "OK" -- misaligned will be handled by the caller
    else
      gdbserv_output_string (gdbserv, "E05");
+   return s;
  }
  
  
*************** gdb::process_get_mem (struct gdbserv_reg
*** 620,642 ****
      }
    host_int_4 addr = addr8; // truncate
  
    if (len==1 && e==endian_big) 
!     read_bus_word (gdbserv, memory, addr, big_int_1());
    else if (len==1 && e==endian_little)
!     read_bus_word (gdbserv, memory, addr, little_int_1());
    else if (len==2 && e==endian_big) 
!     read_bus_word (gdbserv, memory, addr, big_int_2());
    else if (len==2 && e==endian_little)
!     read_bus_word (gdbserv, memory, addr, little_int_2());
    else if (len==4 && e==endian_big) 
!     read_bus_word (gdbserv, memory, addr, big_int_4());
    else if (len==4 && e==endian_little)
!     read_bus_word (gdbserv, memory, addr, little_int_4());
    else if (len==8 && e==endian_big) 
!     read_bus_word (gdbserv, memory, addr, big_int_8());
    else if (len==8 && e==endian_little)
!     read_bus_word (gdbserv, memory, addr, little_int_8());
!   else if (e==endian_little)
      {
        for (unsigned long i=0; i<len; i++)
  	read_bus_word (gdbserv, memory, addr + i, little_int_1());
--- 623,651 ----
      }
    host_int_4 addr = addr8; // truncate
  
+   bus::status b = bus::misaligned;
    if (len==1 && e==endian_big) 
!     b = read_bus_word (gdbserv, memory, addr, big_int_1());
    else if (len==1 && e==endian_little)
!     b = read_bus_word (gdbserv, memory, addr, little_int_1());
    else if (len==2 && e==endian_big) 
!     b = read_bus_word (gdbserv, memory, addr, big_int_2());
    else if (len==2 && e==endian_little)
!     b = read_bus_word (gdbserv, memory, addr, little_int_2());
    else if (len==4 && e==endian_big) 
!     b = read_bus_word (gdbserv, memory, addr, big_int_4());
    else if (len==4 && e==endian_little)
!     b = read_bus_word (gdbserv, memory, addr, little_int_4());
    else if (len==8 && e==endian_big) 
!     b = read_bus_word (gdbserv, memory, addr, big_int_8());
    else if (len==8 && e==endian_little)
!     b = read_bus_word (gdbserv, memory, addr, little_int_8());
! 
!   if (b != bus::misaligned)
!     return;
!   
!   // Unaligned access or unsupported size.
!   if (e==endian_little)
      {
        for (unsigned long i=0; i<len; i++)
  	read_bus_word (gdbserv, memory, addr + i, little_int_1());
*************** gdb::process_set_mem (struct gdbserv_reg
*** 700,722 ****
      }
    host_int_4 addr = addr8; // truncate
  
    if (len==1 && e==endian_big) 
!     write_bus_word (gdbserv, binary, memory, addr, big_int_1());
!   else if (len==1 && e==endian_little)
!     write_bus_word (gdbserv, binary, memory, addr, little_int_1());
!   else if (len==2 && e==endian_big) 
!     write_bus_word (gdbserv, binary, memory, addr, big_int_2());
!   else if (len==2 && e==endian_little)
!     write_bus_word (gdbserv, binary, memory, addr, little_int_2());
!   else if (len==4 && e==endian_big) 
!     write_bus_word (gdbserv, binary, memory, addr, big_int_4());
!   else if (len==4 && e==endian_little)
!     write_bus_word (gdbserv, binary, memory, addr, little_int_4());
!   else if (len==8 && e==endian_big) 
!     write_bus_word (gdbserv, binary, memory, addr, big_int_8());
!   else if (len==8 && e==endian_little)
!     write_bus_word (gdbserv, binary, memory, addr, little_int_8());
!   else if (e==endian_little)
      {
        for (unsigned long i=0; i<len; i++)
  	write_bus_word (gdbserv, binary, memory, addr + i, little_int_1());
--- 709,737 ----
      }
    host_int_4 addr = addr8; // truncate
  
+   bus::status b = bus::misaligned;
    if (len==1 && e==endian_big) 
!     b = write_bus_word (gdbserv, binary, memory, addr, big_int_1());
!   if (len==1 && e==endian_little)
!     b = write_bus_word (gdbserv, binary, memory, addr, little_int_1());
!   if (len==2 && e==endian_big) 
!     b = write_bus_word (gdbserv, binary, memory, addr, big_int_2());
!   if (len==2 && e==endian_little)
!     b = write_bus_word (gdbserv, binary, memory, addr, little_int_2());
!   if (len==4 && e==endian_big) 
!     b = write_bus_word (gdbserv, binary, memory, addr, big_int_4());
!   if (len==4 && e==endian_little)
!     b = write_bus_word (gdbserv, binary, memory, addr, little_int_4());
!   if (len==8 && e==endian_big) 
!     b = write_bus_word (gdbserv, binary, memory, addr, big_int_8());
!   if (len==8 && e==endian_little)
!     b = write_bus_word (gdbserv, binary, memory, addr, little_int_8());
! 
!   if (b != bus::misaligned)
!     return;
! 
!   // Unaligned access or unsupported size.
!   if (e==endian_little)
      {
        for (unsigned long i=0; i<len; i++)
  	write_bus_word (gdbserv, binary, memory, addr + i, little_int_1());
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