[PATCH 18/23] security: optee: add optee_extract_fdto helper

[Marco Felsch]

On 26-01-15, Ahmad Fatoum wrote:
> Hello Marco,
> 
> On 11/10/25 9:34 PM, Marco Felsch wrote:
> > Add a helper to extract the added OP-TEE FDT overlay fragments from the
> > FDT provided via arg2 during the boot phase into a dedicated buffer.
> > 
> > The dedicated overlay buffer can be used later on by the PBL code to
> > apply the overlay to the barebox runtime DTB and to the kernel DTB.
> > 
> > Signed-off-by: Marco Felsch <m.felsch at pengutronix.de>
> > ---
> >  include/tee/optee.h |  6 ++++++
> >  security/optee.c    | 44 ++++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 50 insertions(+)
> > 
> > diff --git a/include/tee/optee.h b/include/tee/optee.h
> > index 10e829c04f8832c4c04771800f1963e25f425482..679662a6e6944da59d24d6268ebcf5dff19d0980 100644
> > --- a/include/tee/optee.h
> > +++ b/include/tee/optee.h
> > @@ -37,6 +37,7 @@ int optee_verify_header (const struct optee_header *hdr);
> >  
> >  void optee_set_membase(const struct optee_header *hdr);
> >  int optee_get_membase(u64 *membase);
> > +int optee_extract_fdto(const void *fdt, void *fdto, unsigned int fdto_sz);
> >  
> >  #else
> >  
> > @@ -49,6 +50,11 @@ static inline int optee_get_membase(u64 *membase)
> >  	return -ENOSYS;
> >  }
> >  
> > +static inline int optee_extract_fdto(const void *fdt, void *fdto, unsigned int fdto_sz)
> > +{
> > +	return 0;
> > +}
> > +
> >  #endif /* CONFIG_HAVE_OPTEE */
> >  
> >  #ifdef __PBL__
> > diff --git a/security/optee.c b/security/optee.c
> > index 422bc1c90924ba8ab266b1aa8d06e52c819d2010..3750bb6f496af990d77f3629b470b174dd7a7c7a 100644
> > --- a/security/optee.c
> > +++ b/security/optee.c
> > @@ -5,7 +5,9 @@
> >  #include <tee/optee.h>
> >  #include <linux/printk.h>
> >  #include <linux/errno.h>
> > +#include <linux/libfdt.h>
> >  #include <linux/limits.h>
> > +#include <pbl.h>
> >  
> >  static u64 optee_membase = U64_MAX;
> >  
> > @@ -60,3 +62,45 @@ void optee_set_membase(const struct optee_header *hdr)
> >  	optee_membase = (u64)hdr->init_load_addr_hi << 32;
> >  	optee_membase |= hdr->init_load_addr_lo;
> >  }
> > +
> > +int optee_extract_fdto(const void *fdt, void *fdto, unsigned int fdto_sz)
> > +{
> > +	int err;
> > +	int subnode;
> > +
> > +	err = fdt_check_header(fdt);
> > +	if (err) {
> > +		pr_err("Invalid device tree blob: %s\n", fdt_strerror(err));
> > +		return err;
> > +	}
> > +
> > +	err = fdt_create_empty_tree(fdto, fdto_sz);
> > +	if (err) {
> > +		pr_err("Failed to initialize OP-TEE FDTO space: %s\n", fdt_strerror(err));
> > +		return err;
> > +	}
> > +
> > +	fdt_for_each_subnode(subnode, fdt, 0) {
> > +		const char *name;
> > +		int len;
> > +
> > +		name = fdt_get_name(fdt, subnode, &len);
> > +		if (!name) {
> > +			pr_warn("Failed to query FDT node name: %s\n", fdt_strerror(len));
> > +			continue;
> > +		}
> > +
> > +		if (strncmp(name, "fragment@", 9) != 0) {
> > +			pr_debug("Skip node %s\n", name);
> > +			continue;
> > +		}
> > +
> > +		err |= fdt_copy_node(fdt, fdto, "/", name);
> 
> Aren't these sequential error codes? OR'ing them will produce a
> non-sensical error code if there are different error codes returned.

That's true.

> Better change to:
> 
> 	ret = fdt_copy_node(fdt, fdto, "/", name);
> 	if (ret)
> 		err = ret;

Hm, but this would hide previous errors too. Of course we could break
the loop in the error case. I will add this to the v2.

> with err being initialized as zero.

Sure.

Regards,
  Marco

> 
> > +	}
> > +
> > +	/* Clear the FDTO memory to not supply incomplete overlays */
> > +	if (err)
> > +		memset(fdto, 0, fdto_sz);
> > +
> > +	return err;
> > +}
> > 
> 
> -- 
> Pengutronix e.K.                  |                             |
> Steuerwalder Str. 21              | http://www.pengutronix.de/  |
> 31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |
> 
> 

-- 
#gernperDu 
#CallMeByMyFirstName

Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | https://www.pengutronix.de/ |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-9    |