[PATCH master 1/3] RISC-V: cpu: request stack memory region

[Antony Pavlov]

On Wed, 24 Mar 2021 09:23:02 +0100
Ahmad Fatoum <a.fatoum at pengutronix.de> wrote:

Current RISC-V erizo barebox master succesfully runs on QEMU
but hangs on FPGA.

git bisection shows this:

    barebox$ git bisect good 809e66d4ef
    ...
    barebox$ git bisect bad
    fef19e17f651a7f4b6063a76c506a67cabfe4a69 is the first bad commit
    commit fef19e17f651a7f4b6063a76c506a67cabfe4a69
    Author: Ahmad Fatoum <a.fatoum at pengutronix.de>
    Date:   Wed Mar 24 09:23:02 2021 +0100

        RISC-V: cpu: request stack memory region

I see that request_sdram_region("stack", ...) hangs in input_data_len().

On FPGA I load barebox image at 0x80000000 (erizo RAM start)
not at 0x0 (link address).
The problem is that input_data_end in input_data_len()
contains link-time address, not actual run-time address.

I have added this hack

--- a/arch/riscv/boot/uncompress.c
+++ b/arch/riscv/boot/uncompress.c
@@ -46,7 +46,7 @@ void __noreturn barebox_pbl_start(unsigned long membase, unsigned long memsize,
                relocate_to_adr(membase);
 
        pg_len = pg_end - pg_start;
-       uncompressed_len = input_data_len();
+       uncompressed_len = get_unaligned((const u32 *)(input_data_end - 4 + get_runtime_offset()));
 
        barebox_base = riscv_mem_barebox_image(membase, endmem,
                                               uncompressed_len + MAX_BSS_SIZE);

Alas, this hack does not fix the problem completely.


> Now that the stack base region is determined dynamically,
> mem_malloc_resource can no longer reserve the stack space.
> Do as ARM does and add a RISC-V specific initcall to reserve
> the main thread's stack space.
> 
> Reported-by: Antony Pavlov <antonynpavlov at gmail.com>
> Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
> ---
> Fix for master as otherwise stack could be overwritten at runtime
> ---
>  arch/riscv/cpu/core.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/arch/riscv/cpu/core.c b/arch/riscv/cpu/core.c
> index bdcd500ed748..982d378eddec 100644
> --- a/arch/riscv/cpu/core.c
> +++ b/arch/riscv/cpu/core.c
> @@ -2,6 +2,9 @@
>  /*
>   * Copyright (C) 2012 Regents of the University of California
>   * Copyright (C) 2017 SiFive
> + * Copyright (C) 2021 Ahmad Fatoum, Pengutronix
> + *
> + * Common RISC-V core initcalls.
>   *
>   * All RISC-V systems have a timer attached to every hart.  These timers can
>   * either be read from the "time" and "timeh" CSRs, and can use the SBI to
> @@ -14,8 +17,17 @@
>  #include <of.h>
>  #include <linux/clk.h>
>  #include <linux/err.h>
> +#include <memory.h>
> +#include <asm-generic/memory_layout.h>
>  #include <io.h>
>  
> +static int riscv_request_stack(void)
> +{
> +	extern unsigned long riscv_stack_top;
> +	return PTR_ERR_OR_ZERO(request_sdram_region("stack", riscv_stack_top - STACK_SIZE, STACK_SIZE));
> +}
> +coredevice_initcall(riscv_request_stack);
> +
>  static struct device_d timer_dev;
>  
>  static int riscv_probe(struct device_d *parent)
> -- 
> 2.29.2
> 


-- 
Best regards,
  Antony Pavlov