Re: [PATCH v2 1/2] efi: esrt: use memremap not ioremap to access ESRT table in memory

["Baicar, Tyler" <tbaicar-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>]

On 2/15/2016 4:32 AM, Ard Biesheuvel wrote:
> On ARM and arm64, ioremap() and memremap() are not interchangeable like
> on x86, and the use of ioremap() on ordinary RAM is typically flagged
> as an error if the memory region being mapped is also covered by the
> linear mapping, since that would lead to aliases with conflicting
> cacheability attributes.
>
> Since what we are dealing with is not an I/O region with side effects,
> using ioremap() here is arguably incorrect anyway, so let's replace
> it with memremap instead. Also add a missing unmap on the success path,
> and drop a memblock_remove() call which does not belong here, this far
> into the boot sequence.
>
> Cc: Peter Jones <pjones-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

Tested-by: Tyler Baicar<tbaicar-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>

> ---
>   drivers/firmware/efi/esrt.c | 16 ++++++++--------
>   1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/firmware/efi/esrt.c b/drivers/firmware/efi/esrt.c
> index 22c5285f7705..f096a0a26dbd 100644
> --- a/drivers/firmware/efi/esrt.c
> +++ b/drivers/firmware/efi/esrt.c
> @@ -16,6 +16,7 @@
>   #include <linux/device.h>
>   #include <linux/efi.h>
>   #include <linux/init.h>
> +#include <linux/io.h>
>   #include <linux/kernel.h>
>   #include <linux/kobject.h>
>   #include <linux/list.h>
> @@ -385,15 +386,15 @@ static void cleanup_entry_list(void)
>   static int __init esrt_sysfs_init(void)
>   {
>   	int error;
> -	struct efi_system_resource_table __iomem *ioesrt;
> +	struct efi_system_resource_table *memesrt;
>   
>   	pr_debug("esrt-sysfs: loading.\n");
>   	if (!esrt_data || !esrt_data_size)
>   		return -ENOSYS;
>   
> -	ioesrt = ioremap(esrt_data, esrt_data_size);
> -	if (!ioesrt) {
> -		pr_err("ioremap(%pa, %zu) failed.\n", &esrt_data,
> +	memesrt = memremap(esrt_data, esrt_data_size, MEMREMAP_WB);
> +	if (!memesrt) {
> +		pr_err("memremap(%pa, %zu, MEMREMAP_WB) failed.\n", &esrt_data,
>   		       esrt_data_size);
>   		return -ENOMEM;
>   	}
> @@ -401,11 +402,12 @@ static int __init esrt_sysfs_init(void)
>   	esrt = kmalloc(esrt_data_size, GFP_KERNEL);
>   	if (!esrt) {
>   		pr_err("kmalloc failed. (wanted %zu bytes)\n", esrt_data_size);
> -		iounmap(ioesrt);
> +		memunmap(memesrt);
>   		return -ENOMEM;
>   	}
>   
> -	memcpy_fromio(esrt, ioesrt, esrt_data_size);
> +	memcpy(esrt, memesrt, esrt_data_size);
> +	memunmap(memesrt);
>   
>   	esrt_kobj = kobject_create_and_add("esrt", efi_kobj);
>   	if (!esrt_kobj) {
> @@ -432,8 +434,6 @@ static int __init esrt_sysfs_init(void)
>   	if (error)
>   		goto err_cleanup_list;
>   
> -	memblock_remove(esrt_data, esrt_data_size);
> -
>   	pr_debug("esrt-sysfs: loaded.\n");
>   
>   	return 0;
Thanks,
Tyler

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