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/* Assembly functions for libgcc2.
Copyright (C) 2001 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 2, or (at your option) any later
version.
In addition to the permissions in the GNU General Public License, the
Free Software Foundation gives you unlimited permission to link the
compiled version of this file into combinations with other programs,
and to distribute those combinations without any restriction coming
from the use of this file. (The General Public License restrictions
do apply in other respects; for example, they cover modification of
the file, and distribution when not linked into a combine
executable.)
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.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING. If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA. */
#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. */
.align 4
.global __xtensa_libgcc_window_spill
.type __xtensa_libgcc_window_spill,@function
__xtensa_libgcc_window_spill:
entry sp, 32
movi a2, 0
syscall
retw
.size __xtensa_libgcc_window_spill,.-__xtensa_libgcc_window_spill
/* __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. */
.align 4
.global __xtensa_nonlocal_goto
.type __xtensa_nonlocal_goto,@function
__xtensa_nonlocal_goto:
entry sp, 32
/* flush registers */
mov a5, a2
movi a2, 0
syscall
mov a2, a5
/* 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
bge 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
/* __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. */
#define TRAMPOLINE_SIZE 60
.text
.align 4
.global __xtensa_sync_caches
.type __xtensa_sync_caches,@function
__xtensa_sync_caches:
entry sp, 32
#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
isync
#endif
retw
.size __xtensa_sync_caches,.-__xtensa_sync_caches
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