Messages in this thread | | | Date | Wed, 25 May 2022 18:09:05 +0200 | Subject | Re: [PATCH 5/5] riscv/efi_stub: Support for 64bit boot-hartid | From | Heinrich Schuchardt <> |
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On 5/25/22 17:48, Ard Biesheuvel wrote: > On Wed, 25 May 2022 at 17:11, Sunil V L <sunilvl@ventanamicro.com> 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 <sunilvl@ventanamicro.com> >> --- >> 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 >>
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