linux-kernel - Re: [PATCH v4 3/7] vmalloc: Add text_alloc() and text

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Message-Id: <20200717175245.54758e3954abd1bcccfe5500@kernel.org>
Date:   Fri, 17 Jul 2020 17:52:45 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-mm@...ck.org (open list:MEMORY MANAGEMENT)
Subject: Re: [PATCH v4 3/7] vmalloc: Add text_alloc() and text_free()

On Fri, 17 Jul 2020 06:04:17 +0300
Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com> wrote:

> Introduce functions for allocating memory for dynamic trampolines, such
> as kprobes. An arch can promote the availability of these functions with
> CONFIG_ARCH_HAS_TEXT_ALLOC. Provide default/fallback implementation
> wrapping module_alloc() and module_memfree().

Doesn't it depend on CONFIG_MODULE?

Thank you,

> 
> Cc: Andi Kleen <ak@...ux.intel.com>
> Cc: Masami Hiramatsu <mhiramat@...nel.org>
> Suggested-by: Peter Zijlstra <peterz@...radead.org>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> ---
>  include/linux/vmalloc.h | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 0221f852a7e1..e981436e30b6 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -9,6 +9,7 @@
>  #include <asm/page.h>		/* pgprot_t */
>  #include <linux/rbtree.h>
>  #include <linux/overflow.h>
> +#include <linux/moduleloader.h>
>  
>  #include <asm/vmalloc.h>
>  
> @@ -249,4 +250,26 @@ pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
>  int register_vmap_purge_notifier(struct notifier_block *nb);
>  int unregister_vmap_purge_notifier(struct notifier_block *nb);
>  
> +#ifdef CONFIG_ARCH_HAS_TEXT_ALLOC
> +/*
> + * Allocate memory to be used for dynamic trampoline code.
> + */
> +void *text_alloc(unsigned long size);
> +
> +/*
> + * Free memory returned from text_alloc().
> + */
> +void text_free(void *region);
> +#else
> +static inline void *text_alloc(unsigned long size)
> +{
> +	return module_alloc(size);
> +}
> +
> +static inline void text_free(void *region)
> +{
> +	module_memfree(region);
> +}
> +#endif
> +
>  #endif /* _LINUX_VMALLOC_H */
> -- 
> 2.25.1
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>