linux-kernel - Re: [PATCH] Added ability to vmalloc executable memory

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Date:   Fri, 9 Dec 2022 13:17:06 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Xander Moerkerken <xandermoerkerken@...il.com>
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Xander Moerkerken <xander.moerkerken@...il.com>,
        Xander Moerkerken <xander.moerkerken@...on.com>
Subject: Re: [PATCH] Added ability to vmalloc executable memory

On Fri, Dec 09, 2022 at 02:10:52PM +0100, Xander Moerkerken wrote:
> From: Xander Moerkerken <xander.moerkerken@...il.com>
> 
> Since release 5.8-rc1 the pgprot got removed from __vmalloc
> because the only usage was PAGE_KERNEL as argument.
> However, this removes the ability to input other arguments
> such as 'PAGE_KERNEL_EXEC', which can be used to allocate
> memory in which you can execute. For this reason a new
> function is introduced called '__vmalloc_exec'.
> 
> Signed-off-by: Xander Moerkerken <xander.moerkerken@...on.com>

What is this going to be used for? There's no user from this patch alone, as a
module or otherwise.

Mark.

> ---
>  include/linux/vmalloc.h | 1 +
>  mm/vmalloc.c            | 8 ++++++++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 096d48aa3437..10c46513b6b2 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -147,6 +147,7 @@ extern void *vzalloc_node(unsigned long size, int node) __alloc_size(1);
>  extern void *vmalloc_32(unsigned long size) __alloc_size(1);
>  extern void *vmalloc_32_user(unsigned long size) __alloc_size(1);
>  extern void *__vmalloc(unsigned long size, gfp_t gfp_mask) __alloc_size(1);
> +extern void *__vmalloc_exec(unsigned long size, gfp_t gfp_mask) __alloc_size(1);
>  extern void *__vmalloc_node_range(unsigned long size, unsigned long align,
>  			unsigned long start, unsigned long end, gfp_t gfp_mask,
>  			pgprot_t prot, unsigned long vm_flags, int node,
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index ccaa461998f3..8fd01ed7082b 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -3294,6 +3294,14 @@ void *__vmalloc(unsigned long size, gfp_t gfp_mask)
>  }
>  EXPORT_SYMBOL(__vmalloc);
>  
> +
> +void *__vmalloc_exec(unsigned long size, gfp_t gfp_mask)
> +{
> +	return __vmalloc_node_prot(size, 1, gfp_mask, PAGE_KERNEL_EXEC,
> +	                          NUMA_NO_NODE, __builtin_return_address(0));
> +}
> +EXPORT_SYMBOL(__vmalloc_exec);
> +
>  /**
>   * vmalloc - allocate virtually contiguous memory
>   * @size:    allocation size
> -- 
> 2.37.2
>