[PATCH v5 09/10] powerpc/fsl_booke/kaslr: support nokaslr cmdline parameter

[Jason Yan <yanaijie@huawei.com>]

One may want to disable kaslr when boot, so provide a cmdline parameter
'nokaslr' to support this.

Signed-off-by: Jason Yan <yanaijie@huawei.com>
Cc: Diana Craciun <diana.craciun@nxp.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Reviewed-by: Diana Craciun <diana.craciun@nxp.com>
Tested-by: Diana Craciun <diana.craciun@nxp.com>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/kernel/kaslr_booke.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/powerpc/kernel/kaslr_booke.c b/arch/powerpc/kernel/kaslr_booke.c
index c6b326424b54..436f9a03f385 100644
--- a/arch/powerpc/kernel/kaslr_booke.c
+++ b/arch/powerpc/kernel/kaslr_booke.c
@@ -361,6 +361,18 @@ static unsigned long __init kaslr_choose_location(void *dt_ptr, phys_addr_t size
 	return kaslr_offset;
 }
 
+static inline __init bool kaslr_disabled(void)
+{
+	char *str;
+
+	str = strstr(boot_command_line, "nokaslr");
+	if (str == boot_command_line ||
+	    (str > boot_command_line && *(str - 1) == ' '))
+		return true;
+
+	return false;
+}
+
 /*
  * To see if we need to relocate the kernel to a random offset
  * void *dt_ptr - address of the device tree
@@ -376,6 +388,8 @@ notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
 	kernel_sz = (unsigned long)_end - KERNELBASE;
 
 	kaslr_get_cmdline(dt_ptr);
+	if (kaslr_disabled())
+		return;
 
 	offset = kaslr_choose_location(dt_ptr, size, kernel_sz);
 
-- 
2.17.2