/* Assembly functions for libgcc2. Copyright (C) 2001-2014 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 . */ #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 */ 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 /* __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: 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 #endif isync retw .size __xtensa_sync_caches, .-__xtensa_sync_caches