/* Assembly functions for libgcc2.
Copyright (C) 2001-2020 Free Software Foundation, Inc.
Contributed by Bob Wilson (bwilson@tensilica.com) at Tensilica.
This file is part of GCC.
GCC 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 3, or (at your option) any later
version.
GCC 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.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
#include "xtensa-config.h"
/* __xtensa_libgcc_window_spill: This function flushes out all but the
current register window. This is used to set up the stack so that
arbitrary frames can be accessed. */
#if XCHAL_HAVE_WINDOWED && !__XTENSA_CALL0_ABI__
.align 4
.global __xtensa_libgcc_window_spill
.type __xtensa_libgcc_window_spill,@function
__xtensa_libgcc_window_spill:
entry sp, 48
#if XCHAL_NUM_AREGS > 16
call12 1f
retw
.align 4
1:
.rept (XCHAL_NUM_AREGS - 24) / 12
_entry sp, 48
mov a12, a0
.endr
_entry sp, 16
#if XCHAL_NUM_AREGS % 12 == 0
mov a4, a4
#elif XCHAL_NUM_AREGS % 12 == 4
mov a8, a8
#elif XCHAL_NUM_AREGS % 12 == 8
mov a12, a12
#endif
retw
#else
mov a8, a8
retw
#endif
.size __xtensa_libgcc_window_spill, .-__xtensa_libgcc_window_spill
#endif
/* __xtensa_nonlocal_goto: This code does all the hard work of a
nonlocal goto on Xtensa. It is here in the library to avoid the
code size bloat of generating it in-line. There are two
arguments:
a2 = frame pointer for the procedure containing the label
a3 = goto handler address
This function never returns to its caller but instead goes directly
to the address of the specified goto handler. */
#if XCHAL_HAVE_WINDOWED && !__XTENSA_CALL0_ABI__
.align 4
.global __xtensa_nonlocal_goto
.type __xtensa_nonlocal_goto,@function
__xtensa_nonlocal_goto:
entry sp, 32
/* Flush registers. */
call8 __xtensa_libgcc_window_spill
/* Because the save area for a0-a3 is stored one frame below
the one identified by a2, the only way to restore those
registers is to unwind the stack. If alloca() were never
called, we could just unwind until finding the sp value
matching a2. However, a2 is a frame pointer, not a stack
pointer, and may not be encountered during the unwinding.
The solution is to unwind until going _past_ the value
given by a2. This involves keeping three stack pointer
values during the unwinding:
next = sp of frame N-1
cur = sp of frame N
prev = sp of frame N+1
When next > a2, the desired save area is stored relative
to prev. At this point, cur will be the same as a2
except in the alloca() case.
Besides finding the values to be restored to a0-a3, we also
need to find the current window size for the target
function. This can be extracted from the high bits of the
return address, initially in a0. As the unwinding
proceeds, the window size is taken from the value of a0
saved _two_ frames below the current frame. */
addi a5, sp, -16 /* a5 = prev - save area */
l32i a6, a5, 4
addi a6, a6, -16 /* a6 = cur - save area */
mov a8, a0 /* a8 = return address (for window size) */
j .Lfirstframe
.Lnextframe:
l32i a8, a5, 0 /* next return address (for window size) */
mov a5, a6 /* advance prev */
addi a6, a7, -16 /* advance cur */
.Lfirstframe:
l32i a7, a6, 4 /* a7 = next */
bgeu a2, a7, .Lnextframe
/* At this point, prev (a5) points to the save area with the saved
values of a0-a3. Copy those values into the save area at the
current sp so they will be reloaded when the return from this
function underflows. We don't have to worry about exceptions
while updating the current save area, because the windows have
already been flushed. */
addi a4, sp, -16 /* a4 = save area of this function */
l32i a6, a5, 0
l32i a7, a5, 4
s32i a6, a4, 0
s32i a7, a4, 4
l32i a6, a5, 8
l32i a7, a5, 12
s32i a6, a4, 8
s32i a7, a4, 12
/* Set return address to goto handler. Use the window size bits
from the return address two frames below the target. */
extui a8, a8, 30, 2 /* get window size from return addr. */
slli a3, a3, 2 /* get goto handler addr. << 2 */
ssai 2
src a0, a8, a3 /* combine them with a funnel shift */
retw
.size __xtensa_nonlocal_goto, .-__xtensa_nonlocal_goto
#endif
/* __xtensa_sync_caches: This function is called after writing a trampoline
on the stack to force all the data writes to memory and invalidate the
instruction cache. a2 is the address of the new trampoline.
After the trampoline data is written out, it must be flushed out of
the data cache into memory. We use DHWB in case we have a writeback
cache. At least one DHWB instruction is needed for each data cache
line which may be touched by the trampoline. An ISYNC instruction
must follow the DHWBs.
We have to flush the i-cache to make sure that the new values get used.
At least one IHI instruction is needed for each i-cache line which may
be touched by the trampoline. An ISYNC instruction is also needed to
make sure that the modified instructions are loaded into the instruction
fetch buffer. */
/* Use the maximum trampoline size. Flushing a bit extra is OK. */
#define TRAMPOLINE_SIZE 60
.text
.align 4
.global __xtensa_sync_caches
.type __xtensa_sync_caches,@function
__xtensa_sync_caches:
#if XCHAL_HAVE_WINDOWED && !__XTENSA_CALL0_ABI__
entry sp, 32
#endif
#if XCHAL_DCACHE_SIZE > 0
/* Flush the trampoline from the data cache. */
extui a4, a2, 0, XCHAL_DCACHE_LINEWIDTH
addi a4, a4, TRAMPOLINE_SIZE
addi a4, a4, (1 << XCHAL_DCACHE_LINEWIDTH) - 1
srli a4, a4, XCHAL_DCACHE_LINEWIDTH
mov a3, a2
.Ldcache_loop:
dhwb a3, 0
addi a3, a3, (1 << XCHAL_DCACHE_LINEWIDTH)
addi a4, a4, -1
bnez a4, .Ldcache_loop
isync
#endif
#if XCHAL_ICACHE_SIZE > 0
/* Invalidate the corresponding lines in the instruction cache. */
extui a4, a2, 0, XCHAL_ICACHE_LINEWIDTH
addi a4, a4, TRAMPOLINE_SIZE
addi a4, a4, (1 << XCHAL_ICACHE_LINEWIDTH) - 1
srli a4, a4, XCHAL_ICACHE_LINEWIDTH
.Licache_loop:
ihi a2, 0
addi a2, a2, (1 << XCHAL_ICACHE_LINEWIDTH)
addi a4, a4, -1
bnez a4, .Licache_loop
#endif
isync
#if XCHAL_HAVE_WINDOWED && !__XTENSA_CALL0_ABI__
retw
#else
ret
#endif
.size __xtensa_sync_caches, .-__xtensa_sync_caches