Hello Marco,
On 11/10/25 9:35 PM, Marco Felsch wrote:
> Add helpers to disable the /secure-chosen/stdout-path property from a
> FDT to keep the secure-OS silent. This is useful to keep the console on
> for development purpose and off for the release case. For the later
> case, the board code also needs to ensure that no /chosen/stdout-path
> exsits, else the secure-OS may fallback to this node.
>
> The API is very specific to make clear that only the
> /secure-chosen/stdout-path is patched on demand.
>
> Signed-off-by: Marco Felsch <[email protected]>
> ---
> include/pbl.h | 4 ++++
> pbl/console.c | 18 ++++++++++++++++++
> pbl/fdt.c | 26 ++++++++++++++++++++++++++
> 3 files changed, 48 insertions(+)
>
> diff --git a/include/pbl.h b/include/pbl.h
> index
> 0961b6b91e585a59a3e8facb1af261857cb6f57e..7e64a9d200ade522ebeb6394c730b608abc6d2bf
> 100644
> --- a/include/pbl.h
> +++ b/include/pbl.h
> @@ -17,6 +17,9 @@ extern unsigned long free_mem_end_ptr;
> void pbl_barebox_uncompress(void *dest, void *compressed_start, unsigned int
> len);
> int pbl_dtbz_uncompress(void *dest, void *compressed_start, unsigned long
> len);
>
> +void pbl_set_disable_secure_chosen_stdout(void);
> +int pbl_disable_secure_chosen_stdout(void);
> +
> void fdt_find_mem(const void *fdt, unsigned long *membase, unsigned long
> *memsize);
> int fdt_fixup_mem(void *fdt, unsigned long membase[], unsigned long
> memsize[], size_t num);
>
> @@ -34,6 +37,7 @@ int fdt_copy_node(const void *src_fdt, void *dest_fdt,
> const char *path,
> int pbl_barebox_verify(const void *compressed_start, unsigned int len,
> const void *hash, unsigned int hash_len);
> int pbl_load_fdt(const void *fdt, void *dest, int destsize);
> +int fdt_remove_secure_chosen_stdout(void *fdt);
>
> #endif
>
> diff --git a/pbl/console.c b/pbl/console.c
> index
> 66652320149db5cdb9d365c5b05a9ac0903935d2..b3f2ac60b5e23b487c0d098d5c2ac5c3f2c8acdc
> 100644
> --- a/pbl/console.c
> +++ b/pbl/console.c
> @@ -4,6 +4,7 @@
> #include <debug_ll.h>
> #include <asm/sections.h>
> #include <linux/err.h>
> +#include <pbl.h>
>
> /*
> * Put these in the data section so that they survive the clearing of the
> @@ -12,6 +13,23 @@
> static __attribute__ ((section(".data"))) ulong putc_offset;
> static __attribute__ ((section(".data"))) void *putc_ctx;
>
> +/*
> + * No special segment handling required, since the value doesn't need to
> survive.
> + * The secure-os is loaded only once very early. Therefore this variable is
> + * checked only once too.
> + */
> +static int disable_secure_chosen_stdout;
> +
> +void pbl_set_disable_secure_chosen_stdout(void)
> +{
> + disable_secure_chosen_stdout = 1;
> +}
> +
> +int pbl_disable_secure_chosen_stdout(void)
> +{
> + return disable_secure_chosen_stdout;
> +}
What are these for? fdt_remove_secure_chosen_stdout() uses none of the
three symbols defined above.
> +
> /**
> * pbl_set_putc() - setup UART used for PBL console
> * @putc: The putc function.
> diff --git a/pbl/fdt.c b/pbl/fdt.c
> index
> fa61c3c71298a2e036e0d324c09d452d8f0f7bbe..d8160e4a09867aab91dc89de5dc7b00dd08a4155
> 100644
> --- a/pbl/fdt.c
> +++ b/pbl/fdt.c
> @@ -342,3 +342,29 @@ int fdt_copy_node(const void *src_fdt, void *dest_fdt,
> const char *path,
>
> return _fdt_copy_node(src_fdt, src_node, dest_fdt, dest_node);
> }
> +
> +int fdt_remove_secure_chosen_stdout(void *fdt)
> +{
> + int sec_chosen;
> + int ret;
> +
> + if (!fdt)
> + return 0;
> +
> + sec_chosen = fdt_path_offset(fdt, "/secure-chosen");
> + /* No secure-chosen node found, nothing to do */
> + if (sec_chosen < 0)
> + return 0;
> +
> + ret = fdt_delprop(fdt, sec_chosen, "stdout-path");
> + if (ret) {
> + if (ret == -FDT_ERR_NOTFOUND)
> + return 0;
> +
> + pr_warn("Failed to delete /secure-chosen/stdout-path with:%s\n",
> + fdt_strerror(ret));
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
>
--
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