| /* |
| * Copyright (c) 2013-2014, ARM Limited and Contributors. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are met: |
| * |
| * Redistributions of source code must retain the above copyright notice, this |
| * list of conditions and the following disclaimer. |
| * |
| * Redistributions in binary form must reproduce the above copyright notice, |
| * this list of conditions and the following disclaimer in the documentation |
| * and/or other materials provided with the distribution. |
| * |
| * Neither the name of ARM nor the names of its contributors may be used |
| * to endorse or promote products derived from this software without specific |
| * prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE |
| * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| * POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| .globl bl21_entrypoint |
| |
| .func |
| bl21_entrypoint: |
| /* --------------------------------------------- |
| * Zero out NOBITS sections. There are 2 of them: |
| * - the .bss section; |
| * - the coherent memory section. |
| * --------------------------------------------- |
| */ |
| ldr r0, =__BSS_START__ |
| ldr r1, =__BSS_SIZE__ |
| /* |
| * Readable names for registers |
| * |
| * Registers r0, r1 and r2 are also set by zeromem which |
| * branches into the fallback path directly, so cursor, length and |
| * stop_address should not be retargeted to other registers. |
| */ |
| cursor .req r0 /* Start address and then current address */ |
| length .req r1 /* Length in bytes of the region to zero out */ |
| /* |
| * Reusing the r1 register as length is only used at the beginning of |
| * the function. |
| */ |
| stop_address .req r1 /* Address past the last zeroed byte */ |
| zeroreg1 .req r2 /* Source register filled with 0 */ |
| zeroreg2 .req r3 /* Source register filled with 0 */ |
| tmp .req r12 /* Temporary scratch register */ |
| |
| mov zeroreg1, #0 |
| |
| /* stop_address is the address past the last to zero */ |
| add stop_address, cursor, length |
| |
| /* |
| * Length cannot be used anymore as it shares the same register with |
| * stop_address. |
| */ |
| .unreq length |
| |
| /* |
| * If the start address is already aligned to 8 bytes, skip this loop. |
| */ |
| tst cursor, #(8-1) |
| beq .Lzeromem_8bytes_aligned |
| |
| /* Calculate the next address aligned to 8 bytes */ |
| orr tmp, cursor, #(8-1) |
| adds tmp, tmp, #1 |
| /* If it overflows, fallback to byte per byte zeroing */ |
| beq .Lzeromem_1byte_aligned |
| /* If the next aligned address is after the stop address, fall back */ |
| cmp tmp, stop_address |
| bhs .Lzeromem_1byte_aligned |
| |
| /* zero byte per byte */ |
| 1: |
| strb zeroreg1, [cursor], #1 |
| cmp cursor, tmp |
| bne 1b |
| |
| /* zero 8 bytes at a time */ |
| .Lzeromem_8bytes_aligned: |
| |
| /* Calculate the last 8 bytes aligned address. */ |
| bic tmp, stop_address, #(8-1) |
| |
| cmp cursor, tmp |
| bhs 2f |
| |
| mov zeroreg2, #0 |
| 1: |
| stmia cursor!, {zeroreg1, zeroreg2} |
| cmp cursor, tmp |
| blo 1b |
| 2: |
| |
| /* zero byte per byte */ |
| .Lzeromem_1byte_aligned: |
| cmp cursor, stop_address |
| beq 2f |
| 1: |
| strb zeroreg1, [cursor], #1 |
| cmp cursor, stop_address |
| bne 1b |
| 2: |
| |
| /* --------------------------------------------- |
| * Jump to main function. |
| * --------------------------------------------- |
| */ |
| b bl21_main |
| .endfunc |
| |
| #if 0 |
| /* ----------------------------------------------------------------------- |
| * void zeromem(void *mem, unsigned int length) |
| * |
| * Initialise a region in normal memory to 0. This functions complies with the |
| * AAPCS and can be called from C code. |
| * |
| * ----------------------------------------------------------------------- |
| */ |
| func zeromem |
| /* |
| * Readable names for registers |
| * |
| * Registers r0, r1 and r2 are also set by zeromem which |
| * branches into the fallback path directly, so cursor, length and |
| * stop_address should not be retargeted to other registers. |
| */ |
| cursor .req r0 /* Start address and then current address */ |
| length .req r1 /* Length in bytes of the region to zero out */ |
| /* |
| * Reusing the r1 register as length is only used at the beginning of |
| * the function. |
| */ |
| stop_address .req r1 /* Address past the last zeroed byte */ |
| zeroreg1 .req r2 /* Source register filled with 0 */ |
| zeroreg2 .req r3 /* Source register filled with 0 */ |
| tmp .req r12 /* Temporary scratch register */ |
| |
| mov zeroreg1, #0 |
| |
| /* stop_address is the address past the last to zero */ |
| add stop_address, cursor, length |
| |
| /* |
| * Length cannot be used anymore as it shares the same register with |
| * stop_address. |
| */ |
| .unreq length |
| |
| /* |
| * If the start address is already aligned to 8 bytes, skip this loop. |
| */ |
| tst cursor, #(8-1) |
| beq .Lzeromem_8bytes_aligned |
| |
| /* Calculate the next address aligned to 8 bytes */ |
| orr tmp, cursor, #(8-1) |
| adds tmp, tmp, #1 |
| /* If it overflows, fallback to byte per byte zeroing */ |
| beq .Lzeromem_1byte_aligned |
| /* If the next aligned address is after the stop address, fall back */ |
| cmp tmp, stop_address |
| bhs .Lzeromem_1byte_aligned |
| |
| /* zero byte per byte */ |
| 1: |
| strb zeroreg1, [cursor], #1 |
| cmp cursor, tmp |
| bne 1b |
| |
| /* zero 8 bytes at a time */ |
| .Lzeromem_8bytes_aligned: |
| |
| /* Calculate the last 8 bytes aligned address. */ |
| bic tmp, stop_address, #(8-1) |
| |
| cmp cursor, tmp |
| bhs 2f |
| |
| mov zeroreg2, #0 |
| 1: |
| stmia cursor!, {zeroreg1, zeroreg2} |
| cmp cursor, tmp |
| blo 1b |
| 2: |
| |
| /* zero byte per byte */ |
| .Lzeromem_1byte_aligned: |
| cmp cursor, stop_address |
| beq 2f |
| 1: |
| strb zeroreg1, [cursor], #1 |
| cmp cursor, stop_address |
| bne 1b |
| 2: |
| bx lr |
| |
| .unreq cursor |
| /* |
| * length is already unreq'ed to reuse the register for another |
| * variable. |
| */ |
| .unreq stop_address |
| .unreq zeroreg1 |
| .unreq zeroreg2 |
| .unreq tmp |
| endfunc zeromem |
| |
| #endif |
