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u-boot/arch/riscv/cpu/start.S
Bin Meng 485f593079 riscv: Change to use positive offset to access relocation entries 
The codes currently skip the very first relocation entry, and have
an inaccurate comment "skip first reserved entry" indicating that
the first entry is reserved, but later it references the elements
in the first relocation entry using a minus offset.

Change to use a positive offset so that there is no need to skip
the first relocation entry.

Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
2023-04-20 20:45:08 +08:00

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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 <system-constants.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 .data
secondary_harts_relocation_error:
.ascii "Relocation of secondary harts has failed, error %d\n"
.section .text
.globl _start
_start:
#if CONFIG_IS_ENABLED(RISCV_MMODE)
csrr a0, CSR_MHARTID
#endif
/*
* Save hart id and dtb pointer. The thread pointer register is not
* modified by C code. It is used by secondary_hart_loop.
*/
mv tp, a0
mv s1, a1
/*
* Set the global data pointer to a known value in case we get a very
* early trap. The global data pointer will be set its actual value only
* after it has been initialized.
*/
mv gp, zero
/*
* Set the trap handler. This must happen after initializing gp because
* the handler may use it.
*/
la t0, trap_entry
csrw MODE_PREFIX(tvec), t0
/*
* Mask all interrupts. Interrupts are disabled globally (in m/sstatus)
* for U-Boot, but we will need to read m/sip to determine if we get an
* IPI
*/
csrw MODE_PREFIX(ie), zero
#if CONFIG_IS_ENABLED(SMP)
/* check if hart is within range */
/* tp: hart id */
li t0, CONFIG_NR_CPUS
bge tp, t0, hart_out_of_bounds_loop
/* set xSIE bit to receive IPIs */
#if CONFIG_IS_ENABLED(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
#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
li t1, CONFIG_SPL_STACK
#else
li t1, SYS_INIT_SP_ADDR
#endif
and sp, t1, t0 /* force 16 byte alignment */
call_board_init_f_0:
mv a0, sp
jal board_init_f_alloc_reserve
/*
* Save global data pointer for later. We don't set it here because it
* is not initialized yet.
*/
mv s0, a0
/* setup stack */
#if CONFIG_IS_ENABLED(SMP)
/* tp: hart id */
slli t0, tp, CONFIG_STACK_SIZE_SHIFT
sub sp, a0, t0
#else
mv sp, a0
#endif
/* Configure proprietary settings and customized CSRs of harts */
call_harts_early_init:
jal harts_early_init
#if !CONFIG_IS_ENABLED(XIP)
/*
* Pick hart to initialize global data and run U-Boot. The other harts
* wait for initialization to complete.
*/
la t0, hart_lottery
li t1, 1
amoswap.w s2, t1, 0(t0)
bnez s2, wait_for_gd_init
#else
/*
* FIXME: gp is set before it is initialized. If an XIP U-Boot ever
* encounters a pending IPI on boot it is liable to jump to whatever
* memory happens to be in ipi_data.addr on boot. It may also run into
* problems if it encounters an exception too early (because printf/puts
* accesses gd).
*/
mv gp, s0
#if CONFIG_IS_ENABLED(RISCV_MMODE)
bnez tp, secondary_hart_loop
#endif
#endif
mv a0, s0
jal board_init_f_init_reserve
SREG s1, GD_FIRMWARE_FDT_ADDR(gp)
/* save the boot hart id to global_data */
SREG tp, GD_BOOT_HART(gp)
#if !CONFIG_IS_ENABLED(XIP)
#ifdef CONFIG_AVAILABLE_HARTS
la t0, available_harts_lock
amoswap.w.rl zero, zero, 0(t0)
#endif
wait_for_gd_init:
/*
* Set the global data pointer only when gd_t has been initialized.
* This was already set by arch_setup_gd on the boot hart, but all other
* harts' global data pointers gets set here.
*/
mv gp, s0
#ifdef CONFIG_AVAILABLE_HARTS
la t0, available_harts_lock
li t1, 1
1: amoswap.w.aq t1, t1, 0(t0)
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)
amoswap.w.rl zero, zero, 0(t0)
#endif
/*
* Continue on hart lottery winner, others branch to
* secondary_hart_loop.
*/
bnez s2, secondary_hart_loop
#endif
/* 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
jalr t5 /* jump to board_init_f() */
#ifdef CONFIG_SPL_BUILD
spl_clear_bss:
la t0, __bss_start
la t1, __bss_end
beq t0, t1, spl_stack_gd_setup
spl_clear_bss_loop:
SREG zero, 0(t0)
addi t0, t0, REGBYTES
blt t0, t1, spl_clear_bss_loop
spl_stack_gd_setup:
jal spl_relocate_stack_gd
/* skip setup if we did not relocate */
beqz a0, spl_call_board_init_r
mv s0, a0
/* setup stack on main hart */
#if CONFIG_IS_ENABLED(SMP)
/* tp: hart id */
slli t0, tp, CONFIG_STACK_SIZE_SHIFT
sub sp, s0, t0
#else
mv sp, s0
#endif
#if CONFIG_IS_ENABLED(SMP)
/* set new stack and global data pointer on secondary harts */
spl_secondary_hart_stack_gd_setup:
la a0, secondary_hart_relocate
mv a1, s0
mv a2, s0
mv a3, zero
jal smp_call_function
/* hang if relocation of secondary harts has failed */
beqz a0, 1f
mv a1, a0
la a0, secondary_harts_relocation_error
jal printf
jal hang
#endif
/* set new global data pointer on main hart */
1: mv gp, s0
spl_call_board_init_r:
mv a0, zero
mv a1, zero
jal board_init_r
#endif
/*
* 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:
#if CONFIG_IS_ENABLED(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 t2, __bss_start /* 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 */
6:
LREG t5, REGBYTES(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, 0(t1)
LREG t5, (REGBYTES * 2)(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)
j 10f
8:
la t4, __dyn_sym_start
add t4, t4, t6
9:
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, 0(t1)
li t5, SYM_SIZE
mul t0, t0, t5
add s5, t4, t0
LREG t0, (REGBYTES * 2)(t1) /* t0 <-- addend */
LREG t5, REGBYTES(s5)
add t5, t5, t0
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)
blt t1, t2, 6b
/*
* 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
blt t0, t1, clbss_l
relocate_secondary_harts:
#if CONFIG_IS_ENABLED(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
mv a3, zero
jal smp_call_function
/* hang if relocation of secondary harts has failed */
beqz a0, 1f
mv a1, a0
la a0, secondary_harts_relocation_error
jal printf
jal hang
/* restore relocation offset */
1: 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 /* offset of board_init_r() */
add t4, t0, 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() */
#if CONFIG_IS_ENABLED(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
/* 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
/*
* Interrupts are disabled globally, but they can still be read from m/sip. The
* wfi function will wake us up if we get an IPI, even if we do not trap.
*/
secondary_hart_loop:
wfi
#if CONFIG_IS_ENABLED(SMP)
csrr t0, MODE_PREFIX(ip)
#if CONFIG_IS_ENABLED(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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