On Wed, 25 May 2022 at 17:11, Sunil V L <[email protected]> wrote:
>
> The boot-hartid can be a 64bit value on RV64 platforms. Currently,
> the "boot-hartid" in DT is assumed to be 32bit only. This patch
> detects the size of the "boot-hartid" and uses 32bit or 64bit
> FDT reads appropriately.
>
> Signed-off-by: Sunil V L <[email protected]>
> ---
> drivers/firmware/efi/libstub/riscv-stub.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/firmware/efi/libstub/riscv-stub.c b/drivers/firmware/efi/libstub/riscv-stub.c
> index 9e85e58d1f27..d748533f1329 100644
> --- a/drivers/firmware/efi/libstub/riscv-stub.c
> +++ b/drivers/firmware/efi/libstub/riscv-stub.c
> @@ -29,7 +29,7 @@ static int get_boot_hartid_from_fdt(void)
> {
> const void *fdt;
> int chosen_node, len;
> - const fdt32_t *prop;
> + const void *prop;
>
> fdt = get_efi_config_table(DEVICE_TREE_GUID);
> if (!fdt)
> @@ -40,10 +40,16 @@ static int get_boot_hartid_from_fdt(void)
> return -EINVAL;
>
> prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
> - if (!prop || len != sizeof(u32))
> + if (!prop)
> + return -EINVAL;
> +
> + if (len == sizeof(u32))
> + hartid = (unsigned long) fdt32_to_cpu(*(fdt32_t *)prop);
> + else if (len == sizeof(u64))
> + hartid = (unsigned long) fdt64_to_cpu(*(fdt64_t *)prop);
Does RISC-V care about alignment? A 64-bit quantity is not guaranteed
to appear 64-bit aligned in the DT, and the cast violates C alignment
rules, so this should probably used get_unaligned_be64() or something
like that.
> + else
> return -EINVAL;
>
> - hartid = fdt32_to_cpu(*prop);
> return 0;
> }
>
> --
> 2.25.1
>
On 5/25/22 17:48, Ard Biesheuvel wrote:
> On Wed, 25 May 2022 at 17:11, Sunil V L <[email protected]> wrote:
>>
>> The boot-hartid can be a 64bit value on RV64 platforms. Currently,
>> the "boot-hartid" in DT is assumed to be 32bit only. This patch
>> detects the size of the "boot-hartid" and uses 32bit or 64bit
>> FDT reads appropriately.
>>
>> Signed-off-by: Sunil V L <[email protected]>
>> ---
>> drivers/firmware/efi/libstub/riscv-stub.c | 12 +++++++++---
>> 1 file changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/firmware/efi/libstub/riscv-stub.c b/drivers/firmware/efi/libstub/riscv-stub.c
>> index 9e85e58d1f27..d748533f1329 100644
>> --- a/drivers/firmware/efi/libstub/riscv-stub.c
>> +++ b/drivers/firmware/efi/libstub/riscv-stub.c
>> @@ -29,7 +29,7 @@ static int get_boot_hartid_from_fdt(void)
>> {
>> const void *fdt;
>> int chosen_node, len;
>> - const fdt32_t *prop;
>> + const void *prop;
>>
>> fdt = get_efi_config_table(DEVICE_TREE_GUID);
>> if (!fdt)
>> @@ -40,10 +40,16 @@ static int get_boot_hartid_from_fdt(void)
>> return -EINVAL;
>>
>> prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
>> - if (!prop || len != sizeof(u32))
>> + if (!prop)
>> + return -EINVAL;
>> +
>> + if (len == sizeof(u32))
>> + hartid = (unsigned long) fdt32_to_cpu(*(fdt32_t *)prop);
>> + else if (len == sizeof(u64))
>> + hartid = (unsigned long) fdt64_to_cpu(*(fdt64_t *)prop);
>
> Does RISC-V care about alignment? A 64-bit quantity is not guaranteed
> to appear 64-bit aligned in the DT, and the cast violates C alignment
> rules, so this should probably used get_unaligned_be64() or something
> like that.
When running in S-mode the SBI handles unaligned access but this has a
performance penalty.
We could use fdt64_to_cpu(__get_unaligned_t(fdt64_t, prop)) here.
Best regards
Heinrich
>
>
>> + else
>> return -EINVAL;
>>
>> - hartid = fdt32_to_cpu(*prop);
>> return 0;
>> }
>>
>> --
>> 2.25.1
>>
On Wed, May 25, 2022 at 06:09:05PM +0200, Heinrich Schuchardt wrote:
> On 5/25/22 17:48, Ard Biesheuvel wrote:
> > On Wed, 25 May 2022 at 17:11, Sunil V L <[email protected]> wrote:
> > >
> > > The boot-hartid can be a 64bit value on RV64 platforms. Currently,
> > > the "boot-hartid" in DT is assumed to be 32bit only. This patch
> > > detects the size of the "boot-hartid" and uses 32bit or 64bit
> > > FDT reads appropriately.
> > >
> > > Signed-off-by: Sunil V L <[email protected]>
> > > ---
> > > drivers/firmware/efi/libstub/riscv-stub.c | 12 +++++++++---
> > > 1 file changed, 9 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/firmware/efi/libstub/riscv-stub.c b/drivers/firmware/efi/libstub/riscv-stub.c
> > > index 9e85e58d1f27..d748533f1329 100644
> > > --- a/drivers/firmware/efi/libstub/riscv-stub.c
> > > +++ b/drivers/firmware/efi/libstub/riscv-stub.c
> > > @@ -29,7 +29,7 @@ static int get_boot_hartid_from_fdt(void)
> > > {
> > > const void *fdt;
> > > int chosen_node, len;
> > > - const fdt32_t *prop;
> > > + const void *prop;
> > >
> > > fdt = get_efi_config_table(DEVICE_TREE_GUID);
> > > if (!fdt)
> > > @@ -40,10 +40,16 @@ static int get_boot_hartid_from_fdt(void)
> > > return -EINVAL;
> > >
> > > prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
> > > - if (!prop || len != sizeof(u32))
> > > + if (!prop)
> > > + return -EINVAL;
> > > +
> > > + if (len == sizeof(u32))
> > > + hartid = (unsigned long) fdt32_to_cpu(*(fdt32_t *)prop);
> > > + else if (len == sizeof(u64))
> > > + hartid = (unsigned long) fdt64_to_cpu(*(fdt64_t *)prop);
> >
> > Does RISC-V care about alignment? A 64-bit quantity is not guaranteed
> > to appear 64-bit aligned in the DT, and the cast violates C alignment
> > rules, so this should probably used get_unaligned_be64() or something
> > like that.
>
> When running in S-mode the SBI handles unaligned access but this has a
> performance penalty.
>
> We could use fdt64_to_cpu(__get_unaligned_t(fdt64_t, prop)) here.
Thank you very much for the feedback. Have updated as per your
suggestion and sent V2.
Thanks
Sunil
>
> Best regards
>
> Heinrich
>
> >
> >
> > > + else
> > > return -EINVAL;
> > >
> > > - hartid = fdt32_to_cpu(*prop);
> > > return 0;
> > > }
> > >
> > > --
> > > 2.25.1
> > >
>