diff mbox

[PATCHv3,08/11] arm64: Check for selected granule support

Message ID 561EC58B.9080408@arm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jeremy Linton Oct. 14, 2015, 9:13 p.m. UTC 
On 10/14/2015 06:20 AM, Suzuki K. Poulose wrote:

> + * Checks if the selected granule size is supported by the CPU.
> + * If it doesn't park the CPU

The problem is when you park the boot CPU.

I think for EFI there is a slightly better error mechanism. This tweak 
will print an error and return to the EFI boot manager rather than 
hanging the machine without any notification. Now it prints:

EFI stub: Booting Linux Kernel...
EFI stub: ERROR: 16K granule not supported by this machine
EFI stub: ERROR: Failed to relocate kernel
FS4:\>


Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
---
  arch/arm64/kernel/efi-stub.c | 14 ++++++++++++++
  1 file changed, 14 insertions(+)

         /* Relocate the image, if required. */
         kernel_size = _edata - _text;

Comments

Suzuki K Poulose Oct. 15, 2015, 9:48 a.m. UTC | #1 
On 14/10/15 22:13, Jeremy Linton wrote:
> On 10/14/2015 06:20 AM, Suzuki K. Poulose wrote:
>
>> + * Checks if the selected granule size is supported by the CPU.
>> + * If it doesn't park the CPU
>
> The problem is when you park the boot CPU.
>
> I think for EFI there is a slightly better error mechanism. This tweak will print an
> error and return to the EFI boot manager rather than hanging the machine without any
>  notification. Now it prints:
>
> EFI stub: Booting Linux Kernel...
> EFI stub: ERROR: 16K granule not supported by this machine
> EFI stub: ERROR: Failed to relocate kernel
> FS4:\>

Nice ! I will pick this up.

>
>
> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
> ---
>   arch/arm64/kernel/efi-stub.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
>
> diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c
> index 816120e..90fb868 100644
> --- a/arch/arm64/kernel/efi-stub.c
> +++ b/arch/arm64/kernel/efi-stub.c
> @@ -25,6 +25,20 @@ efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,
>          unsigned long kernel_size, kernel_memsize = 0;
>          unsigned long nr_pages;
>          void *old_image_addr = (void *)*image_addr;
> +       u32 aa64mmfr0_el1;
> +
> +#ifdef CONFIG_ARM64_16K_PAGES

I would prefer to have it on for all page sizes and not just 16K, to be on a safer side

> +       /*
> +        * check to see if this kernel image is
> +        * compatible with the current system
> +        */
> +       asm volatile("mrs %0, ID_AA64MMFR0_EL1" : "=r" (aa64mmfr0_el1));
> +       aa64mmfr0_el1 >>= ID_AA64MMFR0_TGRAN16_SHIFT;
> +       if ((aa64mmfr0_el1 & ID_AA64MMFR0_TGRAN4_ON) == 0) {
> +               pr_efi_err(sys_table_arg, "16K granule not supported by this machine\n");
> +               return EFI_UNSUPPORTED;
> +       }
> +#endif

Thanks
Suzuki
Mark Rutland Oct. 15, 2015, 10:45 a.m. UTC | #2 
On Wed, Oct 14, 2015 at 04:13:47PM -0500, Jeremy Linton wrote:
> On 10/14/2015 06:20 AM, Suzuki K. Poulose wrote:
> 
> >+ * Checks if the selected granule size is supported by the CPU.
> >+ * If it doesn't park the CPU
> 
> The problem is when you park the boot CPU.
> 
> I think for EFI there is a slightly better error mechanism. This
> tweak will print an error and return to the EFI boot manager rather
> than hanging the machine without any notification. Now it prints:
> 
> EFI stub: Booting Linux Kernel...
> EFI stub: ERROR: 16K granule not supported by this machine
> EFI stub: ERROR: Failed to relocate kernel
> FS4:\>

Neat. We should definitely have checks like this in the stub.

However, we still need checks in head.S, given !EFI systems, SMP, and
kexec, so this is a complementary mechanism.

Thanks,
Mark.

> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
> ---
>  arch/arm64/kernel/efi-stub.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c
> index 816120e..90fb868 100644
> --- a/arch/arm64/kernel/efi-stub.c
> +++ b/arch/arm64/kernel/efi-stub.c
> @@ -25,6 +25,20 @@ efi_status_t __init
> handle_kernel_image(efi_system_table_t *sys_table_arg,
>         unsigned long kernel_size, kernel_memsize = 0;
>         unsigned long nr_pages;
>         void *old_image_addr = (void *)*image_addr;
> +       u32 aa64mmfr0_el1;
> +
> +#ifdef CONFIG_ARM64_16K_PAGES
> +       /*
> +        * check to see if this kernel image is
> +        * compatible with the current system
> +        */
> +       asm volatile("mrs %0, ID_AA64MMFR0_EL1" : "=r" (aa64mmfr0_el1));
> +       aa64mmfr0_el1 >>= ID_AA64MMFR0_TGRAN16_SHIFT;
> +       if ((aa64mmfr0_el1 & ID_AA64MMFR0_TGRAN4_ON) == 0) {
> +               pr_efi_err(sys_table_arg, "16K granule not supported
> by this machine\n");
> +               return EFI_UNSUPPORTED;
> +       }
> +#endif
> 
>         /* Relocate the image, if required. */
>         kernel_size = _edata - _text;
> -- 
> 2.4.3
> 
> 
> 
> 
> 
> 
>
diff mbox

Patch

diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c
index 816120e..90fb868 100644
--- a/arch/arm64/kernel/efi-stub.c
+++ b/arch/arm64/kernel/efi-stub.c
@@ -25,6 +25,20 @@  efi_status_t __init 
handle_kernel_image(efi_system_table_t *sys_table_arg,
         unsigned long kernel_size, kernel_memsize = 0;
         unsigned long nr_pages;
         void *old_image_addr = (void *)*image_addr;
+       u32 aa64mmfr0_el1;
+
+#ifdef CONFIG_ARM64_16K_PAGES
+       /*
+        * check to see if this kernel image is
+        * compatible with the current system
+        */
+       asm volatile("mrs %0, ID_AA64MMFR0_EL1" : "=r" (aa64mmfr0_el1));
+       aa64mmfr0_el1 >>= ID_AA64MMFR0_TGRAN16_SHIFT;
+       if ((aa64mmfr0_el1 & ID_AA64MMFR0_TGRAN4_ON) == 0) {
+               pr_efi_err(sys_table_arg, "16K granule not supported by 
this machine\n");
+               return EFI_UNSUPPORTED;
+       }
+#endif