[U-Boot,RFC] ARM: create .secure_stack section only for PSCI

Jon Master reports that QEMU refuses to load a U-Boot image built
with CONFIG_ARMV7_NONSEC, but without CONFIG_ARMV7_PSCI since
commit 5a3aae68c74e ("ARM: armv7: guard memory reserve for PSCI
with #ifdef CONFIG_ARMV7_PSCI").

It looks like only PSCI that needs the Secure stack, so move
the #ifdef to guard the whole of .secure_stack allocation in order
not to create the empty section.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reported-by: Jon Masters <jcm@redhat.com>
Link: http://patchwork.ozlabs.org/patch/664025/
---

With this commit, the SECURE_MAX_SIZE check will go inside
the #ifdef CONFIG_ARMV7_PSCI, so this patch is probably wrong.

I am CCing Chen-Yu Tsai.  He mostly expanded this linker script
for PSCI work, so I hope he can suggest the correct way
for fixing this problem.


 arch/arm/cpu/u-boot.lds | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

On Mon, Sep 26, 2016 at 1:21 PM, Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
> Jon Master reports that QEMU refuses to load a U-Boot image built
> with CONFIG_ARMV7_NONSEC, but without CONFIG_ARMV7_PSCI since
> commit 5a3aae68c74e ("ARM: armv7: guard memory reserve for PSCI
> with #ifdef CONFIG_ARMV7_PSCI").
>
> It looks like only PSCI that needs the Secure stack, so move
> the #ifdef to guard the whole of .secure_stack allocation in order
> not to create the empty section.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> Reported-by: Jon Masters <jcm@redhat.com>
> Link: http://patchwork.ozlabs.org/patch/664025/
> ---
>
> With this commit, the SECURE_MAX_SIZE check will go inside
> the #ifdef CONFIG_ARMV7_PSCI, so this patch is probably wrong.

I wonder if you could move the SECURE_MAX_SIZE check outside of
the secure_stack section. I might have put it where it is because
of some issues, but I can't remember.

> I am CCing Chen-Yu Tsai.  He mostly expanded this linker script
> for PSCI work, so I hope he can suggest the correct way
> for fixing this problem.

The patch looks good. Though I wonder if you need to guard the
__secure_stack_start and __secure_stack_end symbols in
arch/arm/lib/sections.c as well. Otherwise they might end up
in the data section?


Regards
ChenYu

>
>  arch/arm/cpu/u-boot.lds | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/cpu/u-boot.lds b/arch/arm/cpu/u-boot.lds
> index 0a5fae6..37d4c60 100644
> --- a/arch/arm/cpu/u-boot.lds
> +++ b/arch/arm/cpu/u-boot.lds
> @@ -74,6 +74,7 @@ SECTIONS
>                 *(._secure.data)
>         }
>
> +#ifdef CONFIG_ARMV7_PSCI
>         .secure_stack ALIGN(ADDR(.secure_data) + SIZEOF(.secure_data),
>                             CONSTANT(COMMONPAGESIZE)) (NOLOAD) :
>  #ifdef __ARMV7_PSCI_STACK_IN_RAM
> @@ -83,10 +84,10 @@ SECTIONS
>  #endif
>         {
>                 KEEP(*(.__secure_stack_start))
> -#ifdef CONFIG_ARMV7_PSCI
> +
>                 /* Skip addreses for stack */
>                 . = . + CONFIG_ARMV7_PSCI_NR_CPUS * ARM_PSCI_STACK_SIZE;
> -#endif
> +
>                 /* Align end of stack section to page boundary */
>                 . = ALIGN(CONSTANT(COMMONPAGESIZE));
>
> @@ -109,6 +110,8 @@ SECTIONS
>         . = LOADADDR(.secure_stack);
>  #endif
>
> +#endif
> +
>         .__secure_end : AT(ADDR(.__secure_end)) {
>                 *(.__secure_end)
>                 LONG(0x1d1071c);        /* Must output something to reset LMA */
> --
> 1.9.1
>

On Mon, Sep 26, 2016 at 02:21:30PM +0900, Masahiro Yamada wrote:

> Jon Master reports that QEMU refuses to load a U-Boot image built
> with CONFIG_ARMV7_NONSEC, but without CONFIG_ARMV7_PSCI since
> commit 5a3aae68c74e ("ARM: armv7: guard memory reserve for PSCI
> with #ifdef CONFIG_ARMV7_PSCI").
> 
> It looks like only PSCI that needs the Secure stack, so move
> the #ifdef to guard the whole of .secure_stack allocation in order
> not to create the empty section.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> Reported-by: Jon Masters <jcm@redhat.com>
> Link: http://patchwork.ozlabs.org/patch/664025/

We're close I think, but this breaks boards like ls1021aqds_nor_lpuart

On Mon, Sep 26, 2016 at 02:21:30PM +0900, Masahiro Yamada wrote:

> Jon Master reports that QEMU refuses to load a U-Boot image built
> with CONFIG_ARMV7_NONSEC, but without CONFIG_ARMV7_PSCI since
> commit 5a3aae68c74e ("ARM: armv7: guard memory reserve for PSCI
> with #ifdef CONFIG_ARMV7_PSCI").
> 
> It looks like only PSCI that needs the Secure stack, so move
> the #ifdef to guard the whole of .secure_stack allocation in order
> not to create the empty section.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> Reported-by: Jon Masters <jcm@redhat.com>
> Link: http://patchwork.ozlabs.org/patch/664025/

Applied to u-boot/master, thanks!

... and no, I don't know how / why this caused build failures before,
but it did and I replicated it at the time too.  But I just got a
clean build everywhere.  And I've added vexpress-a15 and vexpress-a9 via
QEMU to my test setup now.