Jack Ren cb08204053 libc/x86: ensure the stack 16-byte aligned when tasks created
Currently Renderscript sample code RsBalls crashed on x86 when SSE2
enabled. The root cause is that the stack was not 16-byte aligned
from the beginning when the processes/threads were created, so the
RsBalls crashed when SSE2 instructions tried to access the variables
on the stack.

- For the thread created by fork():
Its stack alignment is determined by crtbegin_{dynamic, static}.S

- For the thread created by pthread_create():
Its stack alignment is determined by clone.S. __thread_entry( ) is
a standard C function. In order to have its stack be aligned with
16 byte properly, __thread_entry() needs the stack with following
layout when it is called:
layout #1 (correct)
--------------
|            |
-------------- <--ESP (ECX - 20)
| ret EIP    |
-------------- <--ECX - 16
| arg0       |
-------------- <--ECX - 12
| arg1       |
-------------- <--ECX - 8
| arg2       |
-------------- <--ECX - 4
| unused     |
-------------- <--ECX (16-byte boundary)

But it has following layout for now:
layout #2: (incorrect)
--------------
|            |
-------------- <--ESP (ECX - 16)
| unused     |
-------------- <--ECX - 12
| arg0       |
-------------- <--ECX - 8
| arg1       |
-------------- <--ECX - 4
| arg2       |
-------------- <--ECX (16-byte boundary)

Fixed in this patch.

Change-Id: Ibe01f64db14be14033c505d854c73033556ddaa8
Signed-off-by: Michael Liao <michael.liao@intel.com>
Signed-off-by: H.J. Lu <hongjiu.lu@intel.com>
Signed-off-by: Jack Ren <jack.ren@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
2012-03-23 20:04:04 +08:00
2011-09-28 12:17:34 -07:00
2010-03-08 18:04:02 -08:00
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