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u-boot/arch/riscv/cpu/start.S
Lukas Auer e043240252 riscv: do not rely on hart ID passed by previous boot stage 
RISC-V U-Boot expects the hart ID to be passed to it via register a0 by
the previous boot stage. Machine mode firmware such as BBL and OpenSBI
do this when starting their payload (U-Boot) in supervisor mode. If
U-Boot is running in machine mode, this task must be handled by the boot
ROM. Explicitly populate register a0 with the hart ID from the mhartid
CSR to avoid possible problems on RISC-V processors with a boot ROM that
does not handle this task.

Suggested-by: Rick Chen <rick@andestech.com>
Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>
Tested-by: Rick Chen <rick@andestech.com>
2019-04-08 09:44:26 +08:00

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6.7 KiB
ArmAsm
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/* SPDX-License-Identifier: GPL-2.0+ */
/*
* Startup Code for RISC-V Core
*
* Copyright (c) 2017 Microsemi Corporation.
* Copyright (c) 2017 Padmarao Begari <Padmarao.Begari@microsemi.com>
*
* Copyright (C) 2017 Andes Technology Corporation
* Rick Chen, Andes Technology Corporation <rick@andestech.com>
*/
#include <asm-offsets.h>
#include <config.h>
#include <common.h>
#include <elf.h>
#include <asm/csr.h>
#include <asm/encoding.h>
#include <generated/asm-offsets.h>
#ifdef CONFIG_32BIT
#define LREG lw
#define SREG sw
#define REGBYTES 4
#define RELOC_TYPE R_RISCV_32
#define SYM_INDEX 0x8
#define SYM_SIZE 0x10
#else
#define LREG ld
#define SREG sd
#define REGBYTES 8
#define RELOC_TYPE R_RISCV_64
#define SYM_INDEX 0x20
#define SYM_SIZE 0x18
#endif
.section .text
.globl _start
_start:
#ifdef CONFIG_RISCV_MMODE
csrr a0, mhartid
#endif
/* save hart id and dtb pointer */
mv tp, a0
mv s1, a1
la t0, trap_entry
csrw MODE_PREFIX(tvec), t0
/* mask all interrupts */
csrw MODE_PREFIX(ie), zero
#ifdef CONFIG_SMP
/* check if hart is within range */
/* tp: hart id */
li t0, CONFIG_NR_CPUS
bge tp, t0, hart_out_of_bounds_loop
#endif
#ifdef CONFIG_SMP
/* set xSIE bit to receive IPIs */
#ifdef CONFIG_RISCV_MMODE
li t0, MIE_MSIE
#else
li t0, SIE_SSIE
#endif
csrs MODE_PREFIX(ie), t0
#endif
/*
* Set stackpointer in internal/ex RAM to call board_init_f
*/
call_board_init_f:
li t0, -16
li t1, CONFIG_SYS_INIT_SP_ADDR
and sp, t1, t0 /* force 16 byte alignment */
call_board_init_f_0:
mv a0, sp
jal board_init_f_alloc_reserve
/*
* Set global data pointer here for all harts, uninitialized at this
* point.
*/
mv gp, a0
/* setup stack */
#ifdef CONFIG_SMP
/* tp: hart id */
slli t0, tp, CONFIG_STACK_SIZE_SHIFT
sub sp, a0, t0
#else
mv sp, a0
#endif
/*
* Pick hart to initialize global data and run U-Boot. The other harts
* wait for initialization to complete.
*/
la t0, hart_lottery
li s2, 1
amoswap.w s2, t1, 0(t0)
bnez s2, wait_for_gd_init
la t0, prior_stage_fdt_address
SREG s1, 0(t0)
jal board_init_f_init_reserve
/* save the boot hart id to global_data */
SREG tp, GD_BOOT_HART(gp)
la t0, available_harts_lock
fence rw, w
amoswap.w zero, zero, 0(t0)
wait_for_gd_init:
la t0, available_harts_lock
li t1, 1
1: amoswap.w t1, t1, 0(t0)
fence r, rw
bnez t1, 1b
/* register available harts in the available_harts mask */
li t1, 1
sll t1, t1, tp
LREG t2, GD_AVAILABLE_HARTS(gp)
or t2, t2, t1
SREG t2, GD_AVAILABLE_HARTS(gp)
fence rw, w
amoswap.w zero, zero, 0(t0)
/*
* Continue on hart lottery winner, others branch to
* secondary_hart_loop.
*/
bnez s2, secondary_hart_loop
/* Enable cache */
jal icache_enable
jal dcache_enable
#ifdef CONFIG_DEBUG_UART
jal debug_uart_init
#endif
mv a0, zero /* a0 <-- boot_flags = 0 */
la t5, board_init_f
jr t5 /* jump to board_init_f() */
/*
* void relocate_code (addr_sp, gd, addr_moni)
*
* This "function" does not return, instead it continues in RAM
* after relocating the monitor code.
*
*/
.globl relocate_code
relocate_code:
mv s2, a0 /* save addr_sp */
mv s3, a1 /* save addr of gd */
mv s4, a2 /* save addr of destination */
/*
*Set up the stack
*/
stack_setup:
#ifdef CONFIG_SMP
/* tp: hart id */
slli t0, tp, CONFIG_STACK_SIZE_SHIFT
sub sp, s2, t0
#else
mv sp, s2
#endif
la t0, _start
sub t6, s4, t0 /* t6 <- relocation offset */
beq t0, s4, clear_bss /* skip relocation */
mv t1, s4 /* t1 <- scratch for copy_loop */
la t3, __bss_start
sub t3, t3, t0 /* t3 <- __bss_start_ofs */
add t2, t0, t3 /* t2 <- source end address */
copy_loop:
LREG t5, 0(t0)
addi t0, t0, REGBYTES
SREG t5, 0(t1)
addi t1, t1, REGBYTES
blt t0, t2, copy_loop
/*
* Update dynamic relocations after board_init_f
*/
fix_rela_dyn:
la t1, __rel_dyn_start
la t2, __rel_dyn_end
beq t1, t2, clear_bss
add t1, t1, t6 /* t1 <- rela_dyn_start in RAM */
add t2, t2, t6 /* t2 <- rela_dyn_end in RAM */
/*
* skip first reserved entry: address, type, addend
*/
bne t1, t2, 7f
6:
LREG t5, -(REGBYTES*2)(t1) /* t5 <-- relocation info:type */
li t3, R_RISCV_RELATIVE /* reloc type R_RISCV_RELATIVE */
bne t5, t3, 8f /* skip non-RISCV_RELOC entries */
LREG t3, -(REGBYTES*3)(t1)
LREG t5, -(REGBYTES)(t1) /* t5 <-- addend */
add t5, t5, t6 /* t5 <-- location to fix up in RAM */
add t3, t3, t6 /* t3 <-- location to fix up in RAM */
SREG t5, 0(t3)
7:
addi t1, t1, (REGBYTES*3)
ble t1, t2, 6b
8:
la t4, __dyn_sym_start
add t4, t4, t6
9:
LREG t5, -(REGBYTES*2)(t1) /* t5 <-- relocation info:type */
srli t0, t5, SYM_INDEX /* t0 <--- sym table index */
andi t5, t5, 0xFF /* t5 <--- relocation type */
li t3, RELOC_TYPE
bne t5, t3, 10f /* skip non-addned entries */
LREG t3, -(REGBYTES*3)(t1)
li t5, SYM_SIZE
mul t0, t0, t5
add s5, t4, t0
LREG t5, REGBYTES(s5)
add t5, t5, t6 /* t5 <-- location to fix up in RAM */
add t3, t3, t6 /* t3 <-- location to fix up in RAM */
SREG t5, 0(t3)
10:
addi t1, t1, (REGBYTES*3)
ble t1, t2, 9b
/*
* trap update
*/
la t0, trap_entry
add t0, t0, t6
csrw MODE_PREFIX(tvec), t0
clear_bss:
la t0, __bss_start /* t0 <- rel __bss_start in FLASH */
add t0, t0, t6 /* t0 <- rel __bss_start in RAM */
la t1, __bss_end /* t1 <- rel __bss_end in FLASH */
add t1, t1, t6 /* t1 <- rel __bss_end in RAM */
beq t0, t1, relocate_secondary_harts
clbss_l:
SREG zero, 0(t0) /* clear loop... */
addi t0, t0, REGBYTES
bne t0, t1, clbss_l
relocate_secondary_harts:
#ifdef CONFIG_SMP
/* send relocation IPI */
la t0, secondary_hart_relocate
add a0, t0, t6
/* store relocation offset */
mv s5, t6
mv a1, s2
mv a2, s3
jal smp_call_function
/* restore relocation offset */
mv t6, s5
#endif
/*
* We are done. Do not return, instead branch to second part of board
* initialization, now running from RAM.
*/
call_board_init_r:
jal invalidate_icache_all
jal flush_dcache_all
la t0, board_init_r
mv t4, t0 /* offset of board_init_r() */
add t4, t4, t6 /* real address of board_init_r() */
/*
* setup parameters for board_init_r
*/
mv a0, s3 /* gd_t */
mv a1, s4 /* dest_addr */
/*
* jump to it ...
*/
jr t4 /* jump to board_init_r() */
#ifdef CONFIG_SMP
hart_out_of_bounds_loop:
/* Harts in this loop are out of bounds, increase CONFIG_NR_CPUS. */
wfi
j hart_out_of_bounds_loop
#endif
#ifdef CONFIG_SMP
/* SMP relocation entry */
secondary_hart_relocate:
/* a1: new sp */
/* a2: new gd */
/* tp: hart id */
/* setup stack */
slli t0, tp, CONFIG_STACK_SIZE_SHIFT
sub sp, a1, t0
/* update global data pointer */
mv gp, a2
#endif
secondary_hart_loop:
wfi
#ifdef CONFIG_SMP
csrr t0, MODE_PREFIX(ip)
#ifdef CONFIG_RISCV_MMODE
andi t0, t0, MIE_MSIE
#else
andi t0, t0, SIE_SSIE
#endif
beqz t0, secondary_hart_loop
mv a0, tp
jal handle_ipi
#endif
j secondary_hart_loop
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