[GDB] Zero-extend 16-bit segment registers
authorStefan Hajnoczi <stefanha@gmail.com>
Fri, 13 Jun 2008 09:26:49 +0000 (10:26 +0100)
committerMichael Brown <mcb30@etherboot.org>
Mon, 30 Jun 2008 18:19:48 +0000 (19:19 +0100)
When the 16-bit segment registers are accessed using 32-bit instructions
the high order bytes are undefined on older CPUs.  We now explicitly
zero the high order bytes when snapshotting the CPU state.  This ensures
that the GDB stub reports consistent values for the segment registers.

src/arch/i386/core/gdbidt.S
src/tests/gdbstub_test.gdb

index a494923..860f7b0 100644 (file)
@@ -163,12 +163,18 @@ int_page_fault:
 #define IH_OFFSET_FLUX_END ( IH_OFFSET_END - 20 )
 do_interrupt:
        /* Store CPU state in GDB register snapshot */
-       pushl   %gs
-       pushl   %fs
-       pushl   %es
-       pushl   %ds
-       pushl   %ss
-       pushl   IH_OFFSET_FLUX_OLD_CS(%esp)
+       pushw   $0
+       pushw   %gs
+       pushw   $0
+       pushw   %fs
+       pushw   $0
+       pushw   %es
+       pushw   $0
+       pushw   %ds
+       pushw   $0
+       pushw   %ss
+       pushw   $0
+       pushw   IH_OFFSET_FLUX_OLD_CS + 2(%esp)
        pushl   IH_OFFSET_FLUX_OLD_EFLAGS(%esp)
        pushl   IH_OFFSET_FLUX_OLD_EIP(%esp)
        pushl   %edi
index 191799a..52aa693 100755 (executable)
@@ -81,13 +81,13 @@ define gpxe_test_awatch
        awatch watch_me
 
        c
-       gpxe_assert $ecx 0x600d0000 "gpxe_test_awatch"
+       gpxe_assert $ecx 0x600d0000 "gpxe_test_awatch read"
        if $ecx == 0x600d0000
                c
        end
 
        c
-       gpxe_assert $ecx 0x600d0001 "gpxe_test_awatch"
+       gpxe_assert $ecx 0x600d0001 "gpxe_test_awatch write"
        if $ecx == 0x600d0001
                c
        end