ARM: Add arm_memblock_steal() to allocate memory away from the kernel

Several platforms are now using the memblock_alloc+memblock_free+
memblock_remove trick to obtain memory which won't be mapped in the
kernel's page tables.  Most platforms do this (correctly) in the
->reserve callback.  However, OMAP has started to call these functions
outside of this callback, and this is extremely unsafe - memory will
not be unmapped, and could well be given out after memblock is no
longer responsible for its management.

So, provide arm_memblock_steal() to perform this function, and ensure
that it panic()s if it is used inappropriately.  Convert everyone
over, including OMAP.

As a result, OMAP with OMAP4_ERRATA_I688 enabled will panic on boot
with this change.  Mark this option as BROKEN and make it depend on
BROKEN.  OMAP needs to be fixed, or 137d105d50 (ARM: OMAP4: Fix
errata i688 with MPU interconnect barriers.) reverted until such
time it can be fixed correctly.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 2 insertions, 11 deletions

diff --git a/arch/arm/mach-omap2/omap-secure.c b/arch/arm/mach-omap2/omap-secure.c
index 69f3c72d959b..d8f8ef40290f 100644
--- a/arch/arm/mach-omap2/omap-secure.c
+++ b/arch/arm/mach-omap2/omap-secure.c
@@ -16,6 +16,7 @@
 #include <linux/memblock.h>
 
 #include <asm/cacheflush.h>
+#include <asm/memblock.h>
 
 #include <mach/omap-secure.h>
 
@@ -57,20 +58,10 @@ u32 omap_secure_dispatcher(u32 idx, u32 flag, u32 nargs, u32 arg1, u32 arg2,
 /* Allocate the memory to save secure ram */
 int __init omap_secure_ram_reserve_memblock(void)
 {
-        phys_addr_t paddr;
         u32 size = OMAP_SECURE_RAM_STORAGE;
 
         size = ALIGN(size, SZ_1M);
-        paddr = memblock_alloc(size, SZ_1M);
-        if (!paddr) {
-                pr_err("%s: failed to reserve %x bytes\n",
-                                __func__, size);
-                return -ENOMEM;
-        }
-        memblock_free(paddr, size);
-        memblock_remove(paddr, size);
-
-        omap_secure_memblock_base = paddr;
+        omap_secure_memblock_base = arm_memblock_steal(size, SZ_1M);
 
         return 0;
 }