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Fix arm_addr_bits_remove: 26-bit Thumb doesn't exist
- To: <gdb-patches at sourceware dot cygnus dot com>
- Subject: Fix arm_addr_bits_remove: 26-bit Thumb doesn't exist
- From: Ben Harris <bjh21 at netbsd dot org>
- Date: Sat, 20 Oct 2001 18:23:51 +0100 (BST)
I haven't actually encountered this bug in reality yet, but it looks to me
as if arm_addr_bits_remove() is bogus. Specifically, it has a case for
Thumb state in a 26-bit mode. According to the ARM ARM (2nd Edition,
section A8.1), no processor will support both 26-bit mode and thumb state
at all, let alone at the same time. I suspect this might be a noticable
problem when debugging SVC mode code, since then R15 will have its bottom
bit set, which arm_pc_is_thumb() is likely to interpret as meaning the CPU
is in Thumb state.
ChangeLog entry:
2001-10-20 Ben Harris <bjh21@netbsd.org>
* arm-tdep.c (arm_addr_bits_remove): Don't believe in 26-bit
Thumb.
Patch:
*** arm-tdep.c 2000/07/26 00:32:33
--- arm-tdep.c 2001/10/20 17:14:36
*************** arm_pc_is_thumb_dummy (bfd_vma memaddr)
*** 270,279 ****
CORE_ADDR
arm_addr_bits_remove (CORE_ADDR val)
{
! if (arm_pc_is_thumb (val))
! return (val & (arm_apcs_32 ? 0xfffffffe : 0x03fffffe));
else
! return (val & (arm_apcs_32 ? 0xfffffffc : 0x03fffffc));
}
CORE_ADDR
--- 270,281 ----
CORE_ADDR
arm_addr_bits_remove (CORE_ADDR val)
{
! if (!arm_apcs_32)
! return (val & 0x03fffffc);
! else if (arm_pc_is_thumb (val))
! return (val & 0xfffffffe);
else
! return (val & 0xfffffffc);
}
--
Ben Harris <bjh21@netbsd.org>
Portmaster, NetBSD/arm26 <URL:http://www.netbsd.org/Ports/arm26/>