Re: [RFA 3/5] Prec: x86 segment register support: target

Mark Kettenis
2010-03-22T15:05:02Z

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> Date: Mon, 22 Mar 2010 07:35:00 -0700
> From: "H.J. Lu" <hjl.tools@gmail.com>
>
> On Mon, Mar 22, 2010 at 7:02 AM, Hui Zhu <teawater@gmail.com> wrote:
> > Thanks Michael and Daniel.
> >
> > I make a patch to add base of segments registers to x86-32:
> > (gdb) info reg
> > eax            0xffffd514       -10988
> > ecx            0x1eda96c5       517641925
> > edx            0x1      1
> > ebx            0xf7fb1ff4       -134537228
> > esp            0xffffd488       0xffffd488
> > ebp            0xffffd488       0xffffd488
> > esi            0x8048510        134513936
> > edi            0x80483d0        134513616
> > eip            0x8048487        0x8048487 <main+3>
> > eflags         0x246    [ PF ZF IF ]
> > cs             0x23     35
> > ss             0x2b     43
> > ds             0x2b     43
> > es             0x2b     43
> > fs             0x0      0
> > gs             0x63     99
> > cs_base        0x0      0
> > ss_base        0x0      0
> > ds_base        0x0      0
> > es_base        0x0      0
> > fs_base        0x0      0
> > gs_base        0xf7e528d0       -135976752
> >
> > I try it in x86-32 pc and 32bit code in x86-64.  It works OK.
> >
> > Please help me review it.
> >
> > Best regards,
> > Hui
> >
> > 2010-03-22  Hui Zhu  <teawater@gmail.com>
> >
> >        * features/i386/32bit-linux.xml (org.gnu.gdb.i386.linux): Add
> >        cs_base, ss_base, ds_base, es_base, fs_base and gs_base.
> >        * i386-tdep.h (i386_segment_base_regnum): New enum.
> >        * amd64-linux-nat.c (GDT_ENTRY_TLS_MIN,
> >        GDT_ENTRY_TLS_MAX): New marco.
> >        (ps_get_thread_area): New extern.
> >        (amd64_linux_fetch_inferior_registers): Add
> >        code to get 32 bits segment registers base.
> >        * i386-linux-nat.c (GDT_ENTRY_TLS_ENTRIES,
> >        GDT_ENTRY_TLS_MIN,
> >        GDT_ENTRY_TLS_MAX): New marco.
> >        (ps_get_thread_area): New extern.
> >        (i386_linux_fetch_inferior_registers): Add
> >        code to get segment registers base.
>
> Are we going to support them on other OSes? If not,
> the contents of i386_segment_base_regnum should be
> moved to i386-linux-tdep.h and those values should
> be after
>
> /* Register number for the "orig_eax" pseudo-register. If this
> pseudo-register contains a value >= 0 it is interpreted as the
> system call number that the kernel is supposed to restart. */
> #define I386_LINUX_ORIG_EAX_REGNUM I386_SSE_NUM_REGS
>
> In any cases, they shouldn't be hard-coded to any values.
> Otherwise, it won't work with AVX, which will add more registers.

In any case; this stuff will have to wait until we're done withe the
AVX stuff, which I'll be looking at again tonight.