"Aneesh Kumar K.V" <[email protected]> writes:
> Convert the bool to a static key like pkey_disabled.
I'm not convinced this is worth the added complexity of a static key.
It's not used in any performance critical paths, except for context
switch, but that's already guarded by:
if (old_thread->iamr != new_thread->iamr)
Which should always be false on machines which don't have the execute
key enabled.
cheers
> diff --git a/arch/powerpc/mm/book3s64/pkeys.c
> b/arch/powerpc/mm/book3s64/pkeys.c
> index 9e68a08799ee..7d400d5a4076 100644
> --- a/arch/powerpc/mm/book3s64/pkeys.c
> +++ b/arch/powerpc/mm/book3s64/pkeys.c
> @@ -13,13 +13,13 @@
> #include <linux/of_device.h>
>
> DEFINE_STATIC_KEY_TRUE(pkey_disabled);
> +DEFINE_STATIC_KEY_FALSE(execute_pkey_disabled);
> int pkeys_total; /* Total pkeys as per device tree */
> u32 initial_allocation_mask; /* Bits set for the initially allocated keys
> */
> /*
> * Keys marked in the reservation list cannot be allocated by userspace
> */
> u32 reserved_allocation_mask;
> -static bool pkey_execute_disable_supported;
> static u64 default_amr;
> static u64 default_iamr;
> /* Allow all keys to be modified by default */
> @@ -116,9 +116,7 @@ static int pkey_initialize(void)
> * execute_disable support. Instead we use a PVR check.
> */
> if (pvr_version_is(PVR_POWER7) || pvr_version_is(PVR_POWER7p))
> - pkey_execute_disable_supported = false;
> - else
> - pkey_execute_disable_supported = true;
> + static_branch_enable(&execute_pkey_disabled);
>
> #ifdef CONFIG_PPC_4K_PAGES
> /*
> @@ -214,7 +212,7 @@ static inline void write_amr(u64 value)
>
> static inline u64 read_iamr(void)
> {
> - if (!likely(pkey_execute_disable_supported))
> + if (static_branch_unlikely(&execute_pkey_disabled))
> return 0x0UL;
>
> return mfspr(SPRN_IAMR);
> @@ -222,7 +220,7 @@ static inline u64 read_iamr(void)
>
> static inline void write_iamr(u64 value)
> {
> - if (!likely(pkey_execute_disable_supported))
> + if (static_branch_unlikely(&execute_pkey_disabled))
> return;
>
> mtspr(SPRN_IAMR, value);
> @@ -282,7 +280,7 @@ int __arch_set_user_pkey_access(struct task_struct *tsk,
> int pkey,
> return -EINVAL;
>
> if (init_val & PKEY_DISABLE_EXECUTE) {
> - if (!pkey_execute_disable_supported)
> + if (static_branch_unlikely(&execute_pkey_disabled))
> return -EINVAL;
> new_iamr_bits |= IAMR_EX_BIT;
> }
> --
> 2.26.2
