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 15/26] powerpc/book3s64/pkeys: Use execute_pkey_disable static key
Date: Mon, 06 Jul 2020 17:20:31 +1000 [thread overview]
Message-ID: <87mu4d5cu8.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20200619135850.47155-16-aneesh.kumar@linux.ibm.com>
"Aneesh Kumar K.V" <aneesh.kumar@linux•ibm.com> writes:
> Use execute_pkey_disabled static key to check for execute key support instead
> of pkey_disabled.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux•ibm.com>
> ---
> arch/powerpc/include/asm/pkeys.h | 10 +---------
> arch/powerpc/mm/book3s64/pkeys.c | 5 ++++-
> 2 files changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
> index 47c81d41ea9a..09fbaa409ac4 100644
> --- a/arch/powerpc/include/asm/pkeys.h
> +++ b/arch/powerpc/include/asm/pkeys.h
> @@ -126,15 +126,7 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
> * Try to dedicate one of the protection keys to be used as an
> * execute-only protection key.
> */
> -extern int __execute_only_pkey(struct mm_struct *mm);
> -static inline int execute_only_pkey(struct mm_struct *mm)
> -{
> - if (static_branch_likely(&pkey_disabled))
> - return -1;
> -
> - return __execute_only_pkey(mm);
> -}
> -
> +extern int execute_only_pkey(struct mm_struct *mm);
> extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma,
> int prot, int pkey);
> static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma,
> diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c
> index bbba9c601e14..fed4f159011b 100644
> --- a/arch/powerpc/mm/book3s64/pkeys.c
> +++ b/arch/powerpc/mm/book3s64/pkeys.c
> @@ -345,8 +345,11 @@ void thread_pkey_regs_init(struct thread_struct *thread)
> write_uamor(default_uamor);
> }
>
> -int __execute_only_pkey(struct mm_struct *mm)
> +int execute_only_pkey(struct mm_struct *mm)
> {
> + if (static_branch_likely(&execute_pkey_disabled))
> + return -1;
> +
> return mm->context.execute_only_pkey;
> }
That adds the overhead of a function call, but then uses a static_key to
avoid an easy to predict branch, which seems like a bad tradeoff. And
it's not a performance critical path AFAICS.
Anyway this seems unnecessary:
pkey_early_init_devtree()
{
...
if (unlikely(max_pkey <= execute_only_key)) {
/*
* Insufficient number of keys to support
* execute only key. Mark it unavailable.
*/
execute_only_key = -1;
void pkey_mm_init(struct mm_struct *mm)
{
...
mm->context.execute_only_pkey = execute_only_key;
}
ie. Can't it just be:
static inline int execute_only_pkey(struct mm_struct *mm)
{
return mm->context.execute_only_pkey;
}
cheers
next prev parent reply other threads:[~2020-07-06 7:20 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
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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87mu4d5cu8.fsf@mpe.ellerman.id.au \
--to=mpe@ellerman$(echo .)id.au \
--cc=aneesh.kumar@linux$(echo .)ibm.com \
--cc=bauerman@linux$(echo .)ibm.com \
--cc=linuxppc-dev@lists$(echo .)ozlabs.org \
--cc=linuxram@us$(echo .)ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox