Re: [PATCH v4 09/10] powerpc/fsl_booke/kaslr: support nokaslr cmdline parameter

On 2019/8/6 15:59, Christophe Leroy wrote:

Le 05/08/2019 à 08:43, Jason Yan a écrit :

quoted

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 <redacted>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <redacted>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <redacted>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Kees Cook <redacted>
Reviewed-by: Diana Craciun <redacted>
Tested-by: Diana Craciun <redacted>

Reviewed-by: Christophe Leroy <redacted>

Tiny comment below.

quoted

---
  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 4b3f19a663fc..7c3cb41e7122 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;

I don't think additional () are needed for the left part 'str == 
boot_command_line'

Agree.

quoted

+
+    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);

.