From: Michael Ellerman <mpe@ellerman•id.au>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux•ibm.com>,
linuxppc-dev@lists•ozlabs.org
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux•ibm.com>,
linuxram@us•ibm.com, bauerman@linux•ibm.com
Subject: Re: [PATCH v5 08/26] powerpc/book3s64/pkeys: Convert execute key support to static key
Date: Mon, 06 Jul 2020 17:19:58 +1000 [thread overview]
Message-ID: <87o8ot5cv5.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20200619135850.47155-9-aneesh.kumar@linux.ibm.com>
"Aneesh Kumar K.V" <aneesh.kumar@linux•ibm.com> 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
next prev parent reply other threads:[~2020-07-06 7:19 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-19 13:58 [PATCH v5 00/26] powerpc/book3s/64/pkeys: Simplify the code Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 01/26] powerpc/book3s64/pkeys: Fixup bit numbering Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 02/26] powerpc/book3s64/pkeys: pkeys are supported only on hash on book3s Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 03/26] powerpc/book3s64/pkeys: Move pkey related bits in the linux page table Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 04/26] powerpc/book3s64/pkeys: Explain key 1 reservation details Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 05/26] powerpc/book3s64/pkeys: Simplify the key initialization Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 06/26] powerpc/book3s64/pkeys: Prevent key 1 modification from userspace Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 07/26] powerpc/book3s64/pkeys: kill cpu feature key CPU_FTR_PKEY Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 08/26] powerpc/book3s64/pkeys: Convert execute key support to static key Aneesh Kumar K.V
2020-07-06 7:19 ` Michael Ellerman [this message]
2020-07-06 8:47 ` Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 09/26] powerpc/book3s64/pkeys: Simplify pkey disable branch Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 10/26] powerpc/book3s64/pkeys: Convert pkey_total to max_pkey Aneesh Kumar K.V
2020-07-06 7:04 ` Michael Ellerman
2020-07-06 7:20 ` Aneesh Kumar K.V
2020-07-07 1:26 ` Michael Ellerman
2020-06-19 13:58 ` [PATCH v5 11/26] powerpc/book3s64/pkeys: Make initial_allocation_mask static Aneesh Kumar K.V
2020-07-06 7:04 ` Michael Ellerman
2020-07-06 8:48 ` Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 12/26] powerpc/book3s64/pkeys: Mark all the pkeys above max pkey as reserved Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 13/26] powerpc/book3s64/pkeys: Enable MMU_FTR_PKEY Aneesh Kumar K.V
2020-07-06 13:10 ` Michael Ellerman
2020-07-06 14:09 ` Aneesh Kumar K.V
2020-07-06 17:17 ` Aneesh Kumar K.V
2020-07-07 1:02 ` Michael Ellerman
2020-06-19 13:58 ` [PATCH v5 14/26] powerpc/book3s64/kuep: Add MMU_FTR_KUEP Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 15/26] powerpc/book3s64/pkeys: Use execute_pkey_disable static key Aneesh Kumar K.V
2020-07-06 7:20 ` Michael Ellerman
2020-07-06 8:49 ` Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 16/26] powerpc/book3s64/pkeys: Use MMU_FTR_PKEY instead of pkey_disabled " Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 17/26] powerpc/book3s64/keys: Print information during boot Aneesh Kumar K.V
2020-07-06 7:52 ` Michael Ellerman
2020-06-19 13:58 ` [PATCH v5 18/26] powerpc/book3s64/keys/kuap: Reset AMR/IAMR values on kexec Aneesh Kumar K.V
2020-07-06 12:29 ` Michael Ellerman
2020-07-06 14:39 ` Aneesh Kumar K.V
2020-07-07 1:07 ` Michael Ellerman
2020-06-19 13:58 ` [PATCH v5 19/26] powerpc/book3s64/kuap: Move KUAP related function outside radix Aneesh Kumar K.V
2020-07-06 12:41 ` Michael Ellerman
2020-07-06 14:41 ` Aneesh Kumar K.V
2020-07-07 1:22 ` Michael Ellerman
2020-06-19 13:58 ` [PATCH v5 20/26] powerpc/book3s64/kuep: Move KUEP " Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 21/26] powerpc/book3s64/kuap: Rename MMU_FTR_RADIX_KUAP to MMU_FTR_KUAP Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 22/26] powerpc/book3s64/kuap/kuep: Make KUAP and KUEP a subfeature of PPC_MEM_KEYS Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 23/26] powerpc/book3s64/kuap: Move UAMOR setup to key init function Aneesh Kumar K.V
2020-07-07 6:05 ` Michael Ellerman
2020-07-07 11:25 ` Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 24/26] powerpc/selftest/ptrave-pkey: Rename variables to make it easier to follow code Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 25/26] powerpc/selftest/ptrace-pkey: Update the test to mark an invalid pkey correctly Aneesh Kumar K.V
2020-06-19 13:58 ` [PATCH v5 26/26] powerpc/selftest/ptrace-pkey: IAMR and uamor cannot be updated by ptrace Aneesh Kumar K.V
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