Re: [RFC PATCH v2 1/3] powerpc/prom_init: Replace linux,sml-base/sml-size with linux,sml-log

[Stefan Berger]

On 3/11/24 13:24, Christophe Leroy wrote:
> Le 11/03/2024 à 14:20, Stefan Berger a écrit :
> > linux,sml-base holds the address of a buffer with the TPM log. This
> > buffer may become invalid after a kexec. To avoid accessing an invalid
> > address or corrupted buffer, embed the whole TPM log in the device tree
> > property linux,sml-log. This helps to protect the log since it is
> > properly carried across a kexec soft reboot with both of the kexec
> > syscalls.
> >
> > Avoid having the firmware ingest the whole TPM log when calling
> > prom_setprop but only create the linux,sml-log property as a place holder.
> > Insert the actual TPM log during the tree flattening phase.
> >
> > Fixes: 4a727429abec ("PPC64: Add support for instantiating SML from Open Firmware")
> > Suggested-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> > Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
> > ---

> > @@ -2645,6 +2645,17 @@ static void __init scan_dt_build_struct(phandle node, unsigned long *mem_start,
> >    		}
> >    		prev_name = sstart + soff;
> >    
> > +		if (!prom_strcmp("linux,sml-log", pname)) {
> > +			/* push property head */
> > +			dt_push_token(OF_DT_PROP, mem_start, mem_end);
> > +			dt_push_token(sml_size, mem_start, mem_end);
> > +			dt_push_token(soff, mem_start, mem_end);
> > +			/* push property content */
> > +			valp = make_room(mem_start, mem_end, sml_size, 1);
> > +			memcpy(valp, (void *)sml_base, sml_size);
>
> You can't cast a u64 into a pointer. If sml_base is an address, it must
> be declared as an unsigned long.
>
> Build with pmac32_defconfig :
>
>     CC      arch/powerpc/kernel/prom_init.o
> arch/powerpc/kernel/prom_init.c: In function 'scan_dt_build_struct':
> arch/powerpc/kernel/prom_init.c:2663:38: error: cast to pointer from
> integer of different size [-Werror=int-to-pointer-cast]
>    2663 |                         memcpy(valp, (void *)sml_base, sml_size);
>         |                                      ^
> cc1: all warnings being treated as errors
> make[4]: *** [scripts/Makefile.build:243:
> arch/powerpc/kernel/prom_init.o] Error 1

Next round will have this block under #ifdef CONFIG_PPC64.

Thanks.