From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Jordan Niethe <jniethe5@gmail.com>, linuxppc-dev@lists.ozlabs.org
Cc: ajd@linux.ibm.com, npiggin@gmail.com, cmr@codefail.de,
aneesh.kumar@linux.ibm.com, naveen.n.rao@linux.ibm.com,
dja@axtens.net
Subject: Re: [PATCH v11 2/9] powerpc/lib/code-patching: Set up Strict RWX patching earlier
Date: Thu, 29 Apr 2021 06:53:30 +0200 [thread overview]
Message-ID: <d7f28ca3-bf4b-01c4-9706-b4f2061314b1@csgroup.eu> (raw)
In-Reply-To: <20210429031602.2606654-3-jniethe5@gmail.com>
Le 29/04/2021 à 05:15, Jordan Niethe a écrit :
> setup_text_poke_area() is a late init call so it runs before
> mark_rodata_ro() and after the init calls. This lets all the init code
> patching simply write to their locations. In the future, kprobes is
> going to allocate its instruction pages RO which means they will need
> setup_text__poke_area() to have been already called for their code
> patching. However, init_kprobes() (which allocates and patches some
> instruction pages) is an early init call so it happens before
> setup_text__poke_area().
>
> start_kernel() calls poking_init() before any of the init calls. On
> powerpc, poking_init() is currently a nop. setup_text_poke_area() relies
> on kernel virtual memory, cpu hotplug and per_cpu_areas being setup.
> setup_per_cpu_areas(), boot_cpu_hotplug_init() and mm_init() are called
> before poking_init().
>
> Turn setup_text_poke_area() into poking_init().
I can't remember, maybe I already asked the question:
Have you done some performance measurement or at least some performance analysis ?
Christophe
>
> Reviewed-by: Russell Currey <ruscur@russell.cc>
> Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
> ---
> v9: New to series
> ---
> arch/powerpc/lib/code-patching.c | 12 ++++--------
> 1 file changed, 4 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
> index 870b30d9be2f..15296207e1ba 100644
> --- a/arch/powerpc/lib/code-patching.c
> +++ b/arch/powerpc/lib/code-patching.c
> @@ -70,14 +70,11 @@ static int text_area_cpu_down(unsigned int cpu)
> }
>
> /*
> - * Run as a late init call. This allows all the boot time patching to be done
> - * simply by patching the code, and then we're called here prior to
> - * mark_rodata_ro(), which happens after all init calls are run. Although
> - * BUG_ON() is rude, in this case it should only happen if ENOMEM, and we judge
> - * it as being preferable to a kernel that will crash later when someone tries
> - * to use patch_instruction().
> + * Although BUG_ON() is rude, in this case it should only happen if ENOMEM, and
> + * we judge it as being preferable to a kernel that will crash later when
> + * someone tries to use patch_instruction().
> */
> -static int __init setup_text_poke_area(void)
> +int __init poking_init(void)
> {
> BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
> "powerpc/text_poke:online", text_area_cpu_up,
> @@ -85,7 +82,6 @@ static int __init setup_text_poke_area(void)
>
> return 0;
> }
> -late_initcall(setup_text_poke_area);
>
> /*
> * This can be called for kernel text or a module.
>
next prev parent reply other threads:[~2021-04-29 4:54 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 3:15 [PATCH v11 0/9] powerpc: Further Strict RWX support Jordan Niethe
2021-04-29 3:15 ` [PATCH v11 1/9] powerpc/mm: Implement set_memory() routines Jordan Niethe
2021-04-29 7:32 ` Christophe Leroy
2021-05-03 5:02 ` Jordan Niethe
2021-04-29 3:15 ` [PATCH v11 2/9] powerpc/lib/code-patching: Set up Strict RWX patching earlier Jordan Niethe
2021-04-29 4:53 ` Christophe Leroy [this message]
2021-05-05 5:22 ` Jordan Niethe
2021-04-29 3:15 ` [PATCH v11 3/9] powerpc: Always define MODULES_{VADDR,END} Jordan Niethe
2021-04-29 5:04 ` Christophe Leroy
2021-05-03 5:39 ` Jordan Niethe
2021-05-03 5:57 ` Christophe Leroy
2021-05-03 6:16 ` Jordan Niethe
2021-05-03 6:22 ` Christophe Leroy
2021-05-03 6:26 ` Jordan Niethe
2021-05-03 6:32 ` Christophe Leroy
2021-04-29 3:15 ` [PATCH v11 4/9] powerpc/kprobes: Mark newly allocated probes as ROX Jordan Niethe
2021-04-29 3:15 ` [PATCH v11 5/9] powerpc/bpf: Remove bpf_jit_free() Jordan Niethe
2021-04-29 3:15 ` [PATCH v11 6/9] powerpc/bpf: Write protect JIT code Jordan Niethe
2021-04-29 3:16 ` [PATCH v11 7/9] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX Jordan Niethe
2021-04-29 3:16 ` [PATCH v11 8/9] powerpc/mm: implement set_memory_attr() Jordan Niethe
2021-04-29 3:16 ` [PATCH v11 9/9] powerpc/32: use set_memory_attr() Jordan Niethe
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