Thread (27 messages) flat view 27 messages, 10 authors, 2011-10-07

[PATCH] ARM: mmp: map sram as MT_MEMORY rather than MT_DEVICE

From: Russell King - ARM Linux <hidden>
Date: 2011-08-23 00:08:19
Also in: lkml

On Mon, Aug 22, 2011 at 04:47:40PM -0700, Andres Salomon wrote:
quoted hunk ↗ jump to hunk
The sram code allocates memory with ioremap, which assumes MT_DEVICE
for memory protections.  This explodes when we map sram for power
management purposes and then attempt to execute it (jump_to_lp_sram)
on the OLPC XO-1.75.  Instead, we want to specify MT_MEMORY, which
doesn't set the L_PTE_XN bit.

Signed-off-by: Andres Salomon <redacted>
---
 arch/arm/mach-mmp/sram.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

Eric, this patch is against the devel branch of your pxa tree.
diff --git a/arch/arm/mach-mmp/sram.c b/arch/arm/mach-mmp/sram.c
index 4304f95..ca4d3c1 100644
--- a/arch/arm/mach-mmp/sram.c
+++ b/arch/arm/mach-mmp/sram.c
@@ -21,6 +21,7 @@
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/genalloc.h>
+#include <asm/mach/map.h>
 
 #include <mach/sram.h>
 
@@ -87,7 +88,8 @@ static int __devinit sram_probe(struct platform_device *pdev)
 
 	info->sram_phys   = (phys_addr_t)res->start;
 	info->sram_size   = resource_size(res);
-	info->sram_virt   = ioremap(info->sram_phys, info->sram_size);
+	info->sram_virt   = __arm_ioremap(info->sram_phys, info->sram_size,
+					  MT_MEMORY);
Not a good idea fiddling about under the covers like that.  The reason
that MT_MEMORY is not in asm/io.h is to stop it being used like this -
MT_MEMORY etc are not meant for general purpose use.

It needs to be looked at properly rather than working behind the APIs,
and making my life a misery by doing so, preventing me from making
changes where necessary by this kind of back-door use.

I guess we need a new ioremap_xxx() variant to cope with this.
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