[RFC 3/4] Misc: SRAM: Hack for allowing executable code in SRAM.
Tony Lindgren
tony at atomide.com
Wed Sep 4 14:06:39 EDT 2013
* Russ Dill <Russ.Dill at ti.com> [130903 09:52]:
> The generic SRAM mechanism does not ioremap memory in a
> manner that allows code to be executed from SRAM. There is
> currently no generic way to request ioremap to return a
> memory area with execution allowed.
>
> Insert a temporary hack for proof of concept on ARM.
>
> Signed-off-by: Russ Dill <Russ.Dill at ti.com>
> ---
> drivers/misc/sram.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
> index 08baaab..e059a23 100644
> --- a/drivers/misc/sram.c
> +++ b/drivers/misc/sram.c
> @@ -31,6 +31,7 @@
> #include <linux/genalloc.h>
> #include <linux/sram.h>
> #include <asm-generic/cacheflush.h>
> +#include <asm/io.h>
>
> #define SRAM_GRANULARITY 32
>
> @@ -138,7 +139,7 @@ static int sram_probe(struct platform_device *pdev)
> int ret;
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> - virt_base = devm_ioremap_resource(&pdev->dev, res);
> + virt_base = __arm_ioremap_exec(res->start, resource_size(res), false);
> if (IS_ERR(virt_base))
> return PTR_ERR(virt_base);
You can get rid of this hack by defining ioremap_exec in
include/asm-generic/io.h the same way as ioremap_nocache
is done:
#ifndef ioremap_exec
#define ioremap_exec ioremap
#endif
Then the arch that need ioremap_exec can define and
implement it. Needs to be reviewed on LKML naturally :)
Regards,
Tony
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