On 27 February 2018 at 17:27, Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> The memory we are accessing through virtual address has no IO side
> effects. Moreover, for IO memory we have to use special accessors,
> which we don't use.
>
Not 100% relevant in this context, but perhaps interesting
nonetheless: using device mappings to access things like firmware
tables or other structured data will break ARM and other non-x86
architectures that do not tolerate unaligned accessed to device
memory.
> Due to above, convert the driver to use memremap() instead of ioremap().
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Acked-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> ---
> drivers/firmware/efi/apple-properties.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/firmware/efi/apple-properties.c b/drivers/firmware/efi/apple-properties.c
> index b9602e0d7b50..adaa9a3714b9 100644
> --- a/drivers/firmware/efi/apple-properties.c
> +++ b/drivers/firmware/efi/apple-properties.c
> @@ -19,6 +19,7 @@
>
> #include <linux/bootmem.h>
> #include <linux/efi.h>
> +#include <linux/io.h>
> #include <linux/platform_data/x86/apple.h>
> #include <linux/property.h>
> #include <linux/slab.h>
> @@ -189,7 +190,7 @@ static int __init map_properties(void)
>
> pa_data = boot_params.hdr.setup_data;
> while (pa_data) {
> - data = ioremap(pa_data, sizeof(*data));
> + data = memremap(pa_data, sizeof(*data), MEMREMAP_WB);
> if (!data) {
> pr_err("cannot map setup_data header\n");
> return -ENOMEM;
> @@ -197,14 +198,14 @@ static int __init map_properties(void)
>
> if (data->type != SETUP_APPLE_PROPERTIES) {
> pa_data = data->next;
> - iounmap(data);
> + memunmap(data);
> continue;
> }
>
> data_len = data->len;
> - iounmap(data);
> + memunmap(data);
>
> - data = ioremap(pa_data, sizeof(*data) + data_len);
> + data = memremap(pa_data, sizeof(*data) + data_len, MEMREMAP_WB);
> if (!data) {
> pr_err("cannot map setup_data payload\n");
> return -ENOMEM;
> @@ -229,7 +230,7 @@ static int __init map_properties(void)
> * to avoid breaking the chain of ->next pointers.
> */
> data->len = 0;
> - iounmap(data);
> + memunmap(data);
> free_bootmem_late(pa_data + sizeof(*data), data_len);
>
> return ret;
> --
> 2.16.1
>
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