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u-boot/arch/riscv/cpu/start.S
Bo Gan 28ff3f16c4 riscv: setup per-hart stack earlier 
Harts need to use per-hart stack before any function call, even if that
function is a simple one. When the callee uses stack for register save/
restore, especially RA, if nested call, concurrent access by multiple
harts on the same stack will cause data-race.

This patch sets up SP before `board_init_f_alloc_reserve`. A side effect
of this is that the memory layout has changed as the following:

+----------------+        +----------------+ <----- SPL_STACK/
|  ......        |        |  hart 0 stack  |        SYS_INIT_SP_ADDR
|  malloc_base   |        +----------------+
+----------------+        |  hart 1 stack  |
|  GD            |        +----------------+ If not SMP, N=1
+----------------+        |  ......        |
|  hart 0 stack  |        +----------------+
+----------------+   ==>  |  hart N-1 stack|
|  hart 1 stack  |        +----------------+
+----------------+        |  ......        |
|  ......        |        |  malloc_base   |
+----------------+        +----------------+
|  hart N-1 stack|        |  GD            |
+----------------+        +----------------+
|                |        |                |

Signed-off-by: Bo Gan <ganboing@gmail.com>
Cc: Rick Chen <rick@andestech.com>
Cc: Leo <ycliang@andestech.com>
Cc: Sean Anderson <seanga2@gmail.com>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Rick Chen <rick@andestech.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
2023-07-24 13:17:26 +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:
#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
li t0, CONFIG_SPL_STACK
#else
li t0, SYS_INIT_SP_ADDR
#endif
and t0, t0, -16 /* force 16 byte alignment */
/* setup stack */
#if CONFIG_IS_ENABLED(SMP)
/* tp: hart id */
slli t1, tp, CONFIG_STACK_SIZE_SHIFT
sub sp, t0, t1
#else
mv sp, t0
#endif
/*
* Now sp points to the right stack belonging to current CPU.
* It's essential before any function call, otherwise, we get data-race.
*/
call_board_init_f_0:
/* find top of reserve space */
#if CONFIG_IS_ENABLED(SMP)
li t1, CONFIG_NR_CPUS
#else
li t1, 1
#endif
slli t1, t1, CONFIG_STACK_SIZE_SHIFT
sub a0, t0, t1 /* t1 -> size of all CPU stacks */
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
/* 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
j board_init_r
#endif
#if !defined(CONFIG_SPL_BUILD)
/*
* 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() */
#endif /* !defined(CONFIG_SPL_BUILD) */
#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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