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From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Jordan Niethe <jniethe5@gmail.com>, linuxppc-dev@lists.ozlabs.org
Cc: christophe.leroy@c-s.fr, ajd@linux.ibm.com, npiggin@gmail.com,
	naveen.n.rao@linux.ibm.com, dja@axtens.net
Subject: Re: [PATCH v9 2/8] powerpc/lib/code-patching: Set up Strict RWX patching earlier
Date: Tue, 16 Mar 2021 07:32:57 +0100	[thread overview]
Message-ID: <bd0e37b6-22cb-6dbc-1ef8-b6eac4b4c6e6@csgroup.eu> (raw)
In-Reply-To: <20210316031741.1004850-2-jniethe5@gmail.com>



Le 16/03/2021 à 04:17, 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().
> 
> 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 2333625b5e31..b28afa1133db 100644
> --- a/arch/powerpc/lib/code-patching.c
> +++ b/arch/powerpc/lib/code-patching.c
> @@ -65,14 +65,11 @@ 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().

Please use WARN_ON(), see why at https://www.kernel.org/doc/html/latest/process/deprecated.html

>    */
> -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,
> @@ -80,7 +77,6 @@ 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.
> 

  parent reply	other threads:[~2021-03-16  6:33 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-16  3:17 [PATCH v9 1/8] powerpc/mm: Implement set_memory() routines Jordan Niethe
2021-03-16  3:17 ` [PATCH v9 2/8] powerpc/lib/code-patching: Set up Strict RWX patching earlier Jordan Niethe
2021-03-16  3:36   ` Russell Currey
2021-03-16  6:32   ` Christophe Leroy [this message]
2021-03-17  0:38     ` Jordan Niethe
2021-03-17 12:04       ` Michael Ellerman
2021-03-16  3:17 ` [PATCH v9 3/8] powerpc/kprobes: Mark newly allocated probes as RO Jordan Niethe
2021-03-16  6:44   ` Christophe Leroy
2021-03-17  0:50     ` Jordan Niethe
2021-03-17  0:52     ` Jordan Niethe
2021-03-17  6:12   ` Christophe Leroy
2021-03-18  2:42     ` Jordan Niethe
2021-03-16  3:17 ` [PATCH v9 4/8] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime Jordan Niethe
2021-03-16  6:47   ` Christophe Leroy
2021-03-16  3:17 ` [PATCH v9 5/8] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX Jordan Niethe
2021-03-16  6:51   ` Christophe Leroy
2021-03-17  2:15     ` Jordan Niethe
2021-03-17  5:43       ` Christophe Leroy
2021-03-16  3:17 ` [PATCH v9 6/8] powerpc/configs: Enable STRICT_MODULE_RWX in skiroot_defconfig Jordan Niethe
2021-03-16  3:17 ` [PATCH v9 7/8] powerpc/mm: implement set_memory_attr() Jordan Niethe
2021-03-16  7:25   ` Christophe Leroy
2021-03-17  0:54     ` Jordan Niethe
2021-03-16  3:17 ` [PATCH v9 8/8] powerpc/32: use set_memory_attr() Jordan Niethe
2021-03-19  1:19 ` [PATCH v9 1/8] powerpc/mm: Implement set_memory() routines Michael Ellerman

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