[PATCH 1/1] sandbox: correct determination of the text base

[Simon Glass]

Hi Heinrich,

On Sat, 15 May 2021 at 11:29, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
> os_find_text_base() assumes that first line of /proc/self/maps holds
> information about the text. Hence we must call the function before calling
> os_malloc() which calls mmap(0x10000000,).
>
> Failure to do so has led to incorrect values for pc_reloc when an
> exception was reported
>
>     => exception undefined
>
>     Illegal instruction
>     pc = 0x5628d82e9d3c, pc_reloc = 0x5628c82e9d3c
>
> as well as incorrect output of the bdinfo command
>
>     => bdinfo
>     relocaddr   = 0x0000000007858000
>     reloc off   = 0x0000000010000000
>
> Fixes: b308d9fd18fa ("sandbox: Avoid using malloc() for system state")
> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> ---
> This patch must be applied after
> [PATCH 1/1] sandbox: ensure that state->ram_buf is in low memory
> ---
>  arch/sandbox/cpu/start.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>

Reviewed-by: Simon Glass <sjg at chromium.org>

> diff --git a/arch/sandbox/cpu/start.c b/arch/sandbox/cpu/start.c
> index 1388dba895..4000bcc4f1 100644
> --- a/arch/sandbox/cpu/start.c
> +++ b/arch/sandbox/cpu/start.c
> @@ -435,10 +435,13 @@ void sandbox_reset(void)
>  int main(int argc, char *argv[])
>  {
>         struct sandbox_state *state;
> +       void * text_base;
>         gd_t data;
>         int size;
>         int ret;
>

I think you should have a comment about this needing to be first.

> +       text_base = os_find_text_base();
> +
>         /*
>          * This must be the first invocation of os_malloc() to have
>          * state->ram_buf in the low 4 GiB.
> @@ -459,7 +462,7 @@ int main(int argc, char *argv[])
>
>         memset(&data, '\0', sizeof(data));
>         gd = &data;
> -       gd->arch.text_base = os_find_text_base();
> +       gd->arch.text_base = text_base;
>
>         state = state_get_current();
>         if (os_parse_args(state, argc, argv))
> --
> 2.30.2
>

Regards,
Simon