Adding "kaslr-seed" to dtb enables triggering kaslr, or kernel virtual
address randomization, at secondary kernel boot. We always do this as
it will have no harm on kaslr-incapable kernel.

We don't have any "switch" to turn off this feature directly, but still
can suppress it by passing "nokaslr" as a kernel boot argument.

Signed-off-by: AKASHI Takahiro <takahiro.aka...@linaro.org>
Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
---
 arch/arm64/kernel/machine_kexec_file.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm64/kernel/machine_kexec_file.c 
b/arch/arm64/kernel/machine_kexec_file.c
index 261564df7210..99d771afe88e 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -16,6 +16,7 @@
 #include <linux/libfdt.h>
 #include <linux/memblock.h>
 #include <linux/of_fdt.h>
+#include <linux/random.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/vmalloc.h>
@@ -161,6 +162,12 @@ static int setup_dtb(struct kimage *image,
                }
        }
 
+       /* add kaslr-seed */
+       get_random_bytes(&value, sizeof(value));
+       ret = fdt_setprop(buf, nodeoffset, "kaslr-seed", &value, sizeof(value));
+       if (ret)
+               goto out_err;
+
        /* trim a buffer */
        fdt_pack(buf);
        *dtb_buf = buf;
-- 
2.17.0


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