On Tue, Jan 23, 2018 at 12:28:00PM +0000, Suzuki K Poulose wrote:
> While processing the list of capabilities, it is useful to
> filter out some of the entries based on the given type to
> allow better control. This can be used later for handling
> LOCAL vs SYSTEM wide capabilities and more.
>
> Signed-off-by: Suzuki K Poulose <[email protected]>
> ---
> arch/arm64/include/asm/cpufeature.h | 5 +++++
> arch/arm64/kernel/cpufeature.c | 30 ++++++++++++++++++++----------
> 2 files changed, 25 insertions(+), 10 deletions(-)
>
> diff --git a/arch/arm64/include/asm/cpufeature.h
> b/arch/arm64/include/asm/cpufeature.h
> index 27d037bb0451..a621d2184227 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -99,6 +99,11 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0;
> /* Is it safe for a late CPU to miss this capability when system has it */
> #define ARM64_CPUCAP_LATE_CPU_SAFE_TO_MISS BIT(3)
>
> +#define ARM64_CPUCAP_TYPE_ALL \
> + (ARM64_CPUCAP_SCOPE_LOCAL_CPU |\
> + ARM64_CPUCAP_SCOPE_SYSTEM |\
> + ARM64_CPUCAP_LATE_CPU_SAFE_TO_HAVE |\
> + ARM64_CPUCAP_LATE_CPU_SAFE_TO_MISS)
Nit: can we have another tab between | and \?
This will help to make missing |s stand out more if/when more entries
are added to this list in future.
> /*
> * CPU errata detected at boot time based on feature of one or more CPUs.
> * It is not safe for a late CPU to have this feature when the system doesn't
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 79737034a628..198c5daddd65 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -1180,9 +1180,11 @@ static bool __this_cpu_has_cap(const struct
> arm64_cpu_capabilities *cap_array,
> }
>
> static void update_cpu_capabilities(const struct arm64_cpu_capabilities
> *caps,
> - const char *info)
> + u16 cap_type, const char *info)
Semantically "cap_type" represents a set of accepted types, not a single
type here.
Can we rename it to "cap_types", "cap_type_mask" or similar?
> {
> for (; caps->matches; caps++) {
> + if (!(caps->type & cap_type))
> + continue;
Minor nit: insert a blank line here?
To me, lack of a blank line suggests that the code will always fall
through to the next line, which is not the case after
return/continue/break/goto.
Alternatively:
if (!(caps->type & cap_type) ||
!caps->matches(caps, caps->def_scope))
continue;
still seems fairly intelligible ...[1]
> if (!caps->matches(caps, cpucap_default_scope(caps)))
> continue;
>
> @@ -1204,12 +1206,13 @@ static int __enable_cpu_capability(void *arg)
> * Run through the enabled capabilities and enable() it on all active
> * CPUs
> */
> -static void __init enable_cpu_capabilities(const struct
> arm64_cpu_capabilities *caps)
> +static void __init
> +enable_cpu_capabilities(const struct arm64_cpu_capabilities *caps, u16
> caps_type)
The "caps_type" argument should be named consistently with the
corresponding argument to update_cpu_capabilities().
> {
> for (; caps->matches; caps++) {
> unsigned int num = caps->capability;
>
> - if (!cpus_have_cap(num))
> + if (!(caps->type & caps_type) || !cpus_have_cap(num))
[1]... and would match the approach taken here.
> continue;
>
> /* Ensure cpus_have_const_cap(num) works */
> @@ -1231,12 +1234,16 @@ static void __init enable_cpu_capabilities(const
> struct arm64_cpu_capabilities *
> * Run through the list of capabilities to check for conflicts.
> * Returns "false" on conflicts.
> */
> -static bool __verify_local_cpu_caps(const struct arm64_cpu_capabilities
> *caps_list)
> +static bool __verify_local_cpu_caps(const struct arm64_cpu_capabilities
> *caps_list,
> + u16 caps_type)
> {
> bool cpu_has_cap, system_has_cap;
> const struct arm64_cpu_capabilities *caps = caps_list;
>
> for (; caps->matches; caps++) {
> + if (!(caps->type & caps_type))
> + continue;
> +
> cpu_has_cap = __this_cpu_has_cap(caps_list, caps->capability);
> system_has_cap = cpus_have_cap(caps->capability);
>
> @@ -1299,7 +1306,7 @@ verify_local_elf_hwcaps(const struct
> arm64_cpu_capabilities *caps)
>
> static void verify_local_cpu_features(void)
> {
> - if (!__verify_local_cpu_caps(arm64_features))
> + if (!__verify_local_cpu_caps(arm64_features, ARM64_CPUCAP_TYPE_ALL))
> cpu_die_early();
> }
>
> @@ -1327,18 +1334,20 @@ static void verify_sve_features(void)
> */
> static void verify_local_cpu_errata_workarounds(void)
> {
> - if (__verify_local_cpu_caps(arm64_errata))
> + if (!__verify_local_cpu_caps(arm64_errata, ARM64_CPUCAP_TYPE_ALL))
> cpu_die_early();
Did you mean to insert the ! here?
[...]
Cheers
---Dave
