On Thu, Dec 21, 2006 at 11:22:05AM -0800, Jeremy Fitzhardinge wrote: > Frederik Deweerdt wrote: > > Following the i386 pda patches, it's not possible to set gs or fs value > > from gdb anymore. The following patch restores the old behaviour of > > getting and setting thread.gs of thread.fs respectively. > > Here's a gdb session *before* the patch: > > (gdb) info reg > > [...] > > fs 0x33 51 > > gs 0x33 51 > > (gdb) set $fs=0xffff > > (gdb) info reg > > [...] > > fs 0x33 51 > > gs 0x33 51 > > (gdb) set $gs=0xffffffff > > (gdb) info reg > > [...] > > fs 0xffff 65535 > > gs 0x33 51 > > > > Another one *after* the patch: > > (gdb) info reg > > [...] > > fs 0xd8 216 > > > > This doesn't look right. This is the kernel's %fs, not usermode's > (which should be 0). > Right, I missed that. > > gs 0x33 51 > > (gdb) set $fs=0xffff > > (gdb) info reg > > [...] > > fs 0xffff 65535 > > gs 0x33 51 > > (gdb) set $gs=0xffff > > (gdb) info reg > > [...] > > fs 0xffff 65535 > > gs 0xffff 65535 > > > Hm. This shouldn't be possible since this is a bad selector, but I > guess ptrace/gdb doesn't really know that. If you run the target (even > single step it), these should revert to 0. I does, my point there is just that in that case gdb would stick the 0xffff value in the right place, which it doesn't without the patch. > > > Andrew, this goes on top of > > ptrace-fix-efl_offset-value-according-to-i386-pda-changes.patch > > sent by Jeremy yesterday. > > > > Don't think this is quite right yet. Assuming the %gs->%fs patch has > been applied, then the target %fs should be on its stack, and target %gs > will be in thread.gs. I'm not sure that thread.fs has any use, but I'd > want to double check vm86 to be sure. I'm not sure what you mean by the '%gs->%fs patch'. Do you refer to convert-i386-pda-code-to-use-%fs-fixes.patch which is in -mm1? Or is there another one I might have missed? For the record, I'm running -mm1 + the efl_offset patch.
Regards, Frederik > > J > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [EMAIL PROTECTED] > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
