[PATCH 1/3] fdt: common API to populate kaslr seed

[Simon Glass]

Hi,

On Fri, 4 Aug 2023 at 17:34, <seanedmond at linux.microsoft.com> wrote:
>
> From: Dhananjay Phadke <dphadke at linux.microsoft.com>
>
> fdt_fixup_kaslr_seed() will update given FDT with random seed value.
> Source for random seed can be TPM or RNG driver in u-boot or sec
> firmware (ARM).
>
> Signed-off-by: Dhananjay Phadke <dphadke at linux.microsoft.com>
> ---
>  arch/arm/cpu/armv8/sec_firmware.c | 32 +++++++------------------------
>  common/fdt_support.c              | 31 ++++++++++++++++++++++++++++++
>  include/fdt_support.h             |  3 +++
>  3 files changed, 41 insertions(+), 25 deletions(-)

We need to find a way to use the ofnode API here.

>
> diff --git a/arch/arm/cpu/armv8/sec_firmware.c b/arch/arm/cpu/armv8/sec_firmware.c
> index c0e8726346..84ba49924e 100644
> --- a/arch/arm/cpu/armv8/sec_firmware.c
> +++ b/arch/arm/cpu/armv8/sec_firmware.c
> @@ -411,46 +411,28 @@ int sec_firmware_init(const void *sec_firmware_img,
>  /*
>   * fdt_fix_kaslr - Add kalsr-seed node in Device tree
>   * @fdt:               Device tree
> - * @eret:              0 in case of error, 1 for success
> + * @eret:              0 for success
>   */
>  int fdt_fixup_kaslr(void *fdt)

You could pass an oftree to this function, e.g. obtained with:

oftree_from_fdt(fdt)

>  {
> -       int nodeoffset;
> -       int err, ret = 0;
> -       u8 rand[8];
> +       int ret = 0;
>
>  #if defined(CONFIG_ARMV8_SEC_FIRMWARE_SUPPORT)
> +       u8 rand[8];
> +
>         /* Check if random seed generation is  supported */
>         if (sec_firmware_support_hwrng() == false) {
>                 printf("WARNING: SEC firmware not running, no kaslr-seed\n");
> -               return 0;
> +               return -EOPNOTSUPP;
>         }
>
>         err = sec_firmware_get_random(rand, 8);
>         if (err < 0) {
>                 printf("WARNING: No random number to set kaslr-seed\n");
> -               return 0;
> -       }
> -
> -       err = fdt_check_header(fdt);
> -       if (err < 0) {
> -               printf("fdt_chosen: %s\n", fdt_strerror(err));
> -               return 0;
> +               return ret;
>         }
>
> -       /* find or create "/chosen" node. */
> -       nodeoffset = fdt_find_or_add_subnode(fdt, 0, "chosen");
> -       if (nodeoffset < 0)
> -               return 0;
> -
> -       err = fdt_setprop(fdt, nodeoffset, "kaslr-seed", rand,
> -                                 sizeof(rand));
> -       if (err < 0) {
> -               printf("WARNING: can't set kaslr-seed %s.\n",
> -                      fdt_strerror(err));
> -               return 0;
> -       }
> -       ret = 1;
> +       ret = fdt_fixup_kaslr_seed(fdt, rand, sizeof(rand));
>  #endif
>
>         return ret;
> diff --git a/common/fdt_support.c b/common/fdt_support.c
> index 5e49078f8c..35d4f26dbd 100644
> --- a/common/fdt_support.c
> +++ b/common/fdt_support.c
> @@ -631,6 +631,37 @@ void fdt_fixup_ethernet(void *fdt)
>         }
>  }
>
> +/*
> + * fdt_fix_kaslr_seed - Add kalsr-seed node in Device tree
> + * @fdt:               Device tree
> + * @eret:              0 for success
> + */
> +int fdt_fixup_kaslr_seed(void *fdt, const u8 *seed, int len)
> +{
> +       int nodeoffset;
> +       int err;
> +
> +       err = fdt_check_header(fdt);
> +       if (err < 0) {
> +               printf("fdt_chosen: %s\n", fdt_strerror(err));
> +               return err;
> +       }
> +
> +       /* find or create "/chosen" node. */
> +       nodeoffset = fdt_find_or_add_subnode(fdt, 0, "chosen");
> +       if (nodeoffset < 0)
> +               return -ENOENT;
> +
> +       err = fdt_setprop(fdt, nodeoffset, "kaslr-seed", seed, len);
> +       if (err < 0) {
> +               printf("WARNING: can't set kaslr-seed %s.\n",
> +                      fdt_strerror(err));
> +               return err;
> +       }
> +
> +       return 0;
> +}
> +
>  int fdt_record_loadable(void *blob, u32 index, const char *name,
>                         uintptr_t load_addr, u32 size, uintptr_t entry_point,
>                         const char *type, const char *os, const char *arch)
> diff --git a/include/fdt_support.h b/include/fdt_support.h
> index 2cd8366898..d74ef4e0a7 100644
> --- a/include/fdt_support.h
> +++ b/include/fdt_support.h
> @@ -121,6 +121,9 @@ static inline int fdt_fixup_memory_banks(void *blob, u64 start[], u64 size[],
>  #endif
>
>  void fdt_fixup_ethernet(void *fdt);
> +
> +int fdt_fixup_kaslr_seed(void *fdt, const u8 *seed, int len);

Please get in the habit of adding full comments to exported functions.

> +
>  int fdt_find_and_setprop(void *fdt, const char *node, const char *prop,
>                          const void *val, int len, int create);
>  void fdt_fixup_qe_firmware(void *fdt);
> --
> 2.40.0
>

Regards,
Simon