linux/arch/blackfin/kernel/entry.S
Robin Getz aa770aa790 Blackfin arch: Fix random crash issue found by Michael.
This is fixes a problem where we could jump to the wrong address. By
doing a "p0 = reti; jump (p0)". If a different, higher level interrupt
came in, just before, rather than returning to the calling function, we
would return to a random place in the kernel.

This very elegant fix from Bernd grabs the return location off the
stack, and places it into P0, so when we do a return, it goes to the
correct place.

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
2007-10-29 18:14:15 +08:00

101 lines
2.1 KiB
ArmAsm

/*
* File: arch/blackfin/kernel/entry.S
* Based on:
* Author:
*
* Created:
* Description:
*
* Modified:
* Copyright 2004-2006 Analog Devices Inc.
*
* Bugs: Enter bugs at http://blackfin.uclinux.org/
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see the file COPYING, or write
* to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <linux/linkage.h>
#include <asm/thread_info.h>
#include <asm/errno.h>
#include <asm/asm-offsets.h>
#include <asm/mach-common/context.S>
#ifdef CONFIG_EXCPT_IRQ_SYSC_L1
.section .l1.text
#else
.text
#endif
ENTRY(_ret_from_fork)
SP += -12;
call _schedule_tail;
SP += 12;
r0 = [sp + PT_IPEND];
cc = bittst(r0,1);
if cc jump .Lin_kernel;
RESTORE_CONTEXT
rti;
.Lin_kernel:
bitclr(r0,1);
[sp + PT_IPEND] = r0;
/* do a 'fake' RTI by jumping to [RETI]
* to avoid clearing supervisor mode in child
*/
r0 = [sp + PT_PC];
[sp + PT_P0] = r0;
RESTORE_ALL_SYS
jump (p0);
ENDPROC(_ret_from_fork)
ENTRY(_sys_fork)
r0 = -EINVAL;
rts;
ENDPROC(_sys_fork)
ENTRY(_sys_vfork)
r0 = sp;
r0 += 24;
[--sp] = rets;
SP += -12;
call _bfin_vfork;
SP += 12;
rets = [sp++];
rts;
ENDPROC(_sys_vfork)
ENTRY(_sys_clone)
r0 = sp;
r0 += 24;
[--sp] = rets;
SP += -12;
call _bfin_clone;
SP += 12;
rets = [sp++];
rts;
ENDPROC(_sys_clone)
ENTRY(_sys_rt_sigreturn)
r0 = sp;
r0 += 24;
[--sp] = rets;
SP += -12;
call _do_rt_sigreturn;
SP += 12;
rets = [sp++];
rts;
ENDPROC(_sys_rt_sigreturn)