arm/lib/crt0_64.S

2  * crt0 - C-runtime startup Code for AArch64 U-Boot
10  * SPDX-License-Identifier:	GPL-2.0+
14 #include <asm-offsets.h>
20  * This file handles the target-independent stages of the U-Boot
21  * start-up where a C runtime environment is needed. Its entry point
29  *    available RAM (SRAM, locked cache...). In this context, VARIABLE
35  *    execution from system RAM (DRAM, DDR...) As system RAM may not
42  *    ones allocated by board_init_f() in system RAM, but BSS and
43  *    initialized non-const data are still not available.
45  * 4a.For U-Boot proper (not SPL), call relocate_code(). This function
46  *    relocates U-Boot from its current location into the relocation
50  *    code relocation in SPL.
53  *    environment has BSS (initialized to 0), initialized non-const
55  *    RAM (for SPL moving the stack and GD into RAM is optional - see
60  * 6. For U-Boot proper (not SPL), some CPUs have some work left to do
80 	bic	sp, x0, #0xf	/* 16-byte alignment for ABI compliance */
84 	/* set up gd here, outside any C code */
98 	ldr	x0, [x18, #GD_START_ADDR_SP]	/* x0 <- gd->start_addr_sp */
99 	bic	sp, x0, #0xf	/* 16-byte alignment for ABI compliance */
100 	ldr	x18, [x18, #GD_NEW_GD]		/* x18 <- gd->new_gd */
105 	/* Add in link-vs-runtime offset */
106 	adr	x0, _start		/* x0 <- Runtime value of _start */
107 	ldr	x9, _TEXT_BASE		/* x9 <- Linked value of _start */
108 	sub	x9, x9, x0		/* x9 <- Run-vs-link offset */
111 	/* Add in link-vs-relocation offset */
112 	ldr	x9, [x18, #GD_RELOC_OFF]	/* x9 <- gd->reloc_off */
114 	ldr	x0, [x18, #GD_RELOCADDR]	/* x0 <- gd->relocaddr */
127 	/* set up gd here, outside any C code, if new stack is returned */
144 	ldr	x0, =__bss_start		/* this is auto-relocated! */
145 	ldr	x1, =__bss_end			/* this is auto-relocated! */
156 	/* NOTREACHED - board_init_r() does not return */