linux/arch/xtensa/include/asm/traps.h
Max Filippov 77d6273e79 xtensa: fix kernel register spilling
call12 can't be safely used as the first call in the inline function,
because the compiler does not extend the stack frame of the bounding
function accordingly, which may result in corruption of local variables.

If a call needs to be done, do call8 first followed by call12.

For pure assembly code in _switch_to increase stack frame size of the
bounding function.

Cc: stable@vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2015-08-17 07:33:35 +03:00

69 lines
1.4 KiB
C

/*
* arch/xtensa/include/asm/traps.h
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2012 Tensilica Inc.
*/
#ifndef _XTENSA_TRAPS_H
#define _XTENSA_TRAPS_H
#include <asm/ptrace.h>
/*
* handler must be either of the following:
* void (*)(struct pt_regs *regs);
* void (*)(struct pt_regs *regs, unsigned long exccause);
*/
extern void * __init trap_set_handler(int cause, void *handler);
extern void do_unhandled(struct pt_regs *regs, unsigned long exccause);
void secondary_trap_init(void);
static inline void spill_registers(void)
{
#if XCHAL_NUM_AREGS > 16
__asm__ __volatile__ (
" call8 1f\n"
" _j 2f\n"
" retw\n"
" .align 4\n"
"1:\n"
#if XCHAL_NUM_AREGS == 32
" _entry a1, 32\n"
" addi a8, a0, 3\n"
" _entry a1, 16\n"
" mov a12, a12\n"
" retw\n"
#else
" _entry a1, 48\n"
" call12 1f\n"
" retw\n"
" .align 4\n"
"1:\n"
" .rept (" __stringify(XCHAL_NUM_AREGS) " - 16) / 12\n"
" _entry a1, 48\n"
" mov a12, a0\n"
" .endr\n"
" _entry a1, 16\n"
#if XCHAL_NUM_AREGS % 12 == 0
" mov a12, a12\n"
#elif XCHAL_NUM_AREGS % 12 == 4
" mov a4, a4\n"
#elif XCHAL_NUM_AREGS % 12 == 8
" mov a8, a8\n"
#endif
" retw\n"
#endif
"2:\n"
: : : "a8", "a9", "memory");
#else
__asm__ __volatile__ (
" mov a12, a12\n"
: : : "memory");
#endif
}
#endif /* _XTENSA_TRAPS_H */