[PATCH 3/4 v2] bsp/riscv: work area size based on stack pointer
Hesham Almatary
hesham.almatary at cl.cam.ac.uk
Fri Feb 12 09:11:26 UTC 2021
On Fri, 12 Feb 2021 at 10:50, Daniel Hellstrom <daniel at gaisler.com> wrote:
>
> From: Martin Aberg <maberg at gaisler.com>
>
> Remember the initial stack pointer in start.S. It can later be used to
> determine top of RAM.
> ---
> bsps/riscv/include/bsp/start.h | 65 ++++++++++++++++++++++
> bsps/riscv/shared/start/bspgetworkarea-fromstack.c | 53 ++++++++++++++++++
> bsps/riscv/shared/start/start.S | 25 +++++++++
> 3 files changed, 143 insertions(+)
> create mode 100644 bsps/riscv/include/bsp/start.h
> create mode 100644 bsps/riscv/shared/start/bspgetworkarea-fromstack.c
>
> diff --git a/bsps/riscv/include/bsp/start.h b/bsps/riscv/include/bsp/start.h
> new file mode 100644
> index 0000000..6c9d57d
> --- /dev/null
> +++ b/bsps/riscv/include/bsp/start.h
> @@ -0,0 +1,65 @@
> +/**
> + * @file
> + *
> + * @ingroup RTEMSBSPsRISCVSharedStart
> + *
> + * @brief RISC-V start definitions.
> + */
> +
> +/*
> + * Copyright (c) 2021 Cobham Gaisler AB.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * 1. Redistributions of source code must retain the above copyright
> + * notice, this list of conditions and the following disclaimer.
> + * 2. 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.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
> + */
> +
> +#ifndef LIBBSP_RISCV_SHARED_START_H
> +#define LIBBSP_RISCV_SHARED_START_H
> +
> +/**
> + * @defgroup RTEMSBSPsRISCVSharedStart Start Support
> + *
> + * @ingroup RTEMSBSPsRISCVShared
> + *
> + * @brief Start support.
> + *
> + * @{
> + */
> +
> +#include <stdint.h>
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +/*
> + * This variable is initialized by the first CPU entering the BSP start code.
> + * The value is the stack pointer at entry.
> + */
> +extern uintptr_t riscv_start_stack_pointer;
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +/** @} */
> +
> +#endif /* LIBBSP_RISCV_SHARED_START_H */
> diff --git a/bsps/riscv/shared/start/bspgetworkarea-fromstack.c b/bsps/riscv/shared/start/bspgetworkarea-fromstack.c
> new file mode 100644
> index 0000000..6885a77
> --- /dev/null
> +++ b/bsps/riscv/shared/start/bspgetworkarea-fromstack.c
> @@ -0,0 +1,53 @@
> +/*
> + * This set of routines are the BSP specific initialization
> + * support routines.
> + *
> + * COPYRIGHT (c) 1989-2020.
> + * On-Line Applications Research Corporation (OAR),
> + * Cobham Gaisler AB.
> + *
> + * The license and distribution terms for this file may be
> + * found in the file LICENSE in this distribution or at
> + * http://www.rtems.org/license/LICENSE.
> + */
> +
> +#include <bsp.h>
> +#include <bsp/start.h>
> +#include <bsp/bootcard.h>
> +
> +#include <rtems/sysinit.h>
> +
> +/*
> + * These are provided by the linkcmds for ALL of the BSPs which use this file.
> + */
> +extern char WorkAreaBase[];
> +extern char RamEnd[];
> +
> +static Memory_Area _Memory_Areas[ 1 ];
> +
> +static void bsp_memory_initialize( void )
> +{
> + char *end;
> +
> + /* top of RAM inidicated by initial stack pointer */
> + end = (char *) riscv_start_stack_pointer;
> + if (end == 0) {
> + /* fall back to linker symbol if not set */
> + end = RamEnd;
> + }
> + _Memory_Initialize( &_Memory_Areas[ 0 ], WorkAreaBase, end );
> +}
> +
> +RTEMS_SYSINIT_ITEM(
> + bsp_memory_initialize,
> + RTEMS_SYSINIT_MEMORY,
> + RTEMS_SYSINIT_ORDER_MIDDLE
> +);
> +
> +static const Memory_Information _Memory_Information =
> + MEMORY_INFORMATION_INITIALIZER( _Memory_Areas );
> +
> +const Memory_Information *_Memory_Get( void )
> +{
> + return &_Memory_Information;
> +}
> diff --git a/bsps/riscv/shared/start/start.S b/bsps/riscv/shared/start/start.S
> index 04a62a2..6f40279 100644
> --- a/bsps/riscv/shared/start/start.S
> +++ b/bsps/riscv/shared/start/start.S
> @@ -35,6 +35,16 @@
> #include <bsp/linker-symbols.h>
> #include <bspopts.h>
>
> +#if __riscv_xlen == 32
> +#define PTR_ALIGN 2
> +#define PTR_SIZE 4
> +#define PTR_VALUE .word
> +#elif __riscv_xlen == 64
> +#define PTR_ALIGN 3
> +#define PTR_SIZE 8
> +#define PTR_VALUE .dword
> +#endif
> +
Since that's an architecture thing, I wonder if we can just include
cpu.h that already does have macros for pointer sizes and stack
alignments https://github.com/RTEMS/rtems/blob/master/cpukit/score/cpu/riscv/include/rtems/score/cpu.h#L70
Similarly, can we define something like "define ASM_CPU_POINTER
[d]word" in asm.h (the same file where SREG, LADDR, etc are defined).
> PUBLIC(_start)
>
> .section .bsp_start_text, "wax", @progbits
> @@ -59,6 +69,9 @@ SYM(_start):
> LADDR t0, _RISCV_Exception_handler
> csrw mtvec, t0
>
> + /* Save stack pointer so it can mark end of work area later on */
> + mv t3, sp
> +
> /* Load stack pointer and branch to secondary processor start if necessary */
> #ifdef RTEMS_SMP
> LADDR sp, _ISR_Stack_area_begin
> @@ -74,6 +87,9 @@ SYM(_start):
> LADDR sp, _ISR_Stack_area_end
> #endif
>
> + LADDR t0, riscv_start_stack_pointer
> + SREG t3, 0(t0)
> +
> #ifdef BSP_START_COPY_FDT_FROM_U_BOOT
> mv a0, a1
> call bsp_fdt_copy
> @@ -145,3 +161,12 @@ SYM(_start):
> #endif
>
> #endif /* RTEMS_SMP */
> +
> + .section .data, "aw"
> + .align PTR_ALIGN
> +
> + .globl riscv_start_stack_pointer
> + .type riscv_start_stack_pointer, @object
> + .size riscv_start_stack_pointer, PTR_SIZE
> +riscv_start_stack_pointer:
> + PTR_VALUE 0
> --
> 2.7.4
>
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