powerpc: Punch a hole in /dev/mem for librtas
With CONFIG_STRICT_DEVMEM=y, user space cannot read any part of /dev/mem.
Since this breaks librtas, punch a hole in /dev/mem to allow access to the
rmo_buffer that librtas needs.
Anton Blanchard reported the problem and helped with the fix.
A quick test for this patch:
# cat /proc/rtas/rmo_buffer
000000000f190000 10000
# python -c "print 0x000000000f190000 / 0x10000"
3865
# dd if=/dev/mem of=/tmp/foo count=1 bs=64k skip=3865
1+0 records in
1+0 records out
65536 bytes (66 kB) copied, 0.000205235 s, 319 MB/s
# dd if=/dev/mem of=/tmp/foo
dd: reading `/dev/mem': Operation not permitted
0+0 records in
0+0 records out
0 bytes (0 B) copied, 0.00022519 s, 0.0 kB/s
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 83d819f..395f42d 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -51,6 +51,7 @@
#include <asm/vdso.h>
#include <asm/fixmap.h>
#include <asm/swiotlb.h>
+#include <asm/rtas.h>
#include "mmu_decl.h"
@@ -600,6 +601,8 @@
return 0;
if (!page_is_ram(pfn))
return 1;
+ if (page_is_rtas_user_buf(pfn))
+ return 1;
return 0;
}
#endif /* CONFIG_STRICT_DEVMEM */