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  1. 12 7月, 2008 4 次提交
    • G
      x86: merge dwarf2 headers · 392a0fc9
      由 Glauber Costa 提交于 
      Merge dwarf2_32.h and dwarf2_64.h into dwarf2.h.
Signed-off-by: NGlauber Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      392a0fc9
    • G
      x86: use AS_CFI instead of UNWIND_INFO · d73a731a
      由 Glauber Costa 提交于 
      In dwarf2_32.h, test for CONFIG_AS_CFI instead of
CONFIG_UNWIND_INFO. Turns out that searching for UNWIND_INFO
returns no match in any Kconfig or Makefile, so we're really
just throwing everything away regarding dwarf frames for i386.

The test that generates CONFIG_AS_CFI does not have anything
x86_64-specific, and right now, checking V=1 builds shows me
that the flags is there anyway, although unused.
Signed-off-by: NGlauber Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      d73a731a
    • G
      x86: use ignore macro instead of hash comment · 70f1bba4
      由 Glauber Costa 提交于 
      In dwarf_64.h header, use the "ignore" macro the way
i386 does.
Signed-off-by: NGlauber Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      70f1bba4
    • I
      x86: fix savesegment() bug causing crashes on 64-bit · d9fc3fd3
      由 Ingo Molnar 提交于 
      i spent a fair amount of time chasing a 64-bit bootup crash that manifested
itself as bootup segfaults:

  S10network[1825]: segfault at 7f3e2b5d16b8 ip 00000031108748c9 sp 00007fffb9c14c70 error 4 in libc-2.7.so[3110800000+14d000]

eventually causing init to die and panic the system:

  Kernel panic - not syncing: Attempted to kill init!
  Pid: 1, comm: init Not tainted 2.6.26-rc9-tip #13878

after a maratonic bisection session, the bad commit turned out to be:

| b7675791859075418199c7af86a116ea34eaf5bd is first bad commit
| commit b7675791859075418199c7af86a116ea34eaf5bd
| Author: Jeremy Fitzhardinge <jeremy@goop.org>
| Date:   Wed Jun 25 00:19:00 2008 -0400
|
|     x86: remove open-coded save/load segment operations
|
|     This removes a pile of buggy open-coded implementations of savesegment
|     and loadsegment.

after some more bisection of this patch itself, it turns out that what
makes the difference are the savesegment() changes to __switch_to().

Taking a look at this portion of arch/x86/kernel/process_64.o revealed
this crutial difference:

| good:    99c:       8c e0                   mov    %fs,%eax
|          99e:       89 45 cc                mov    %eax,-0x34(%rbp)
|
| bad:     99c:       8c 65 cc                mov    %fs,-0x34(%rbp)

which is due to:

|                 unsigned fsindex;
| -               asm volatile("movl %%fs,%0" : "=r" (fsindex));
| +               savesegment(fs, fsindex);

savesegment() is implemented as:

 #define savesegment(seg, value)                                \
          asm("mov %%" #seg ",%0":"=rm" (value) : : "memory")

note the "m" modifier - it allows GCC to generate the segment move
into a memory operand as well.

But regarding segment operands there's a subtle detail in the x86
instruction set: the above 16-bit moves are zero-extend, but only
if it goes to a register.

If it goes to a memory operand, -0x34(%rbp) in the above case, there's
no zero-extend to 32-bit and the instruction will only save 16 bits
instead of the intended 32-bit.

The other 16 bits is random data - which can cause problems when that
value is used later on.

The solution is to only allow segment operands to go to registers.
This fix allows my test-system to boot up without crashing.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      d9fc3fd3
  3. 11 7月, 2008 15 次提交
  5. 10 7月, 2008 3 次提交
  7. 09 7月, 2008 18 次提交