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Re: Misaligned read/write of memory by GDB
- From: Dave Brolley <brolley at redhat dot com>
- To: Dave Brolley <brolley at redhat dot com>
- Cc: sid at sources dot redhat dot com
- Date: Mon, 28 Jun 2004 18:50:24 -0400
- Subject: Re: Misaligned read/write of memory by GDB
- Organization: Red Hat Canada, Ltd
- References: <40E08B13.7000404@redhat.com>
Ooops, sent the wrong patch......
Dave Brolley wrote:
Hi,
Some sid components don't support misaligned reads/writes. The current
cache components are the example which caused my particular problem.
They punt on misaligned reads/writes, presumably so that they don't
have to worry about accesses which cross cache line boundaries. This
causes a problem when GDB attempts to read memory at unaligned addresses.
This patch to gdb::process_get_mem and gdb::process_set_mem forces any
unaligned requests to use the existing byte-at-a-time method.
I've committed this patch. Let me know if there are any problems.
Dave
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 28 Jun 2004 21:10:43 -0000
*************** 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());
--- 620,647 ----
}
host_int_4 addr = addr8; // truncate
! if (addr % len == 0)
! {
! if (len==1 && e==endian_big)
! { read_bus_word (gdbserv, memory, addr, big_int_1()); return; }
! if (len==1 && e==endian_little)
! { read_bus_word (gdbserv, memory, addr, little_int_1()); return; }
! if (len==2 && e==endian_big)
! { read_bus_word (gdbserv, memory, addr, big_int_2()); return; }
! if (len==2 && e==endian_little)
! { read_bus_word (gdbserv, memory, addr, little_int_2()); return; }
! if (len==4 && e==endian_big)
! { read_bus_word (gdbserv, memory, addr, big_int_4()); return; }
! if (len==4 && e==endian_little)
! { read_bus_word (gdbserv, memory, addr, little_int_4()); return; }
! if (len==8 && e==endian_big)
! { read_bus_word (gdbserv, memory, addr, big_int_8()); return; }
! if (len==8 && e==endian_little)
! { read_bus_word (gdbserv, memory, addr, little_int_8()); 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());
--- 705,732 ----
}
host_int_4 addr = addr8; // truncate
! if (addr % len == 0)
! {
! if (len==1 && e==endian_big)
! { write_bus_word (gdbserv, binary, memory, addr, big_int_1()); return; }
! if (len==1 && e==endian_little)
! { write_bus_word (gdbserv, binary, memory, addr, little_int_1()); return; }
! if (len==2 && e==endian_big)
! { write_bus_word (gdbserv, binary, memory, addr, big_int_2()); return; }
! if (len==2 && e==endian_little)
! { write_bus_word (gdbserv, binary, memory, addr, little_int_2()); return; }
! if (len==4 && e==endian_big)
! { write_bus_word (gdbserv, binary, memory, addr, big_int_4()); return; }
! if (len==4 && e==endian_little)
! { write_bus_word (gdbserv, binary, memory, addr, little_int_4()); return; }
! if (len==8 && e==endian_big)
! { write_bus_word (gdbserv, binary, memory, addr, big_int_8()); return; }
! if (len==8 && e==endian_little)
! { write_bus_word (gdbserv, binary, memory, addr, little_int_8()); 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());