Re: [PATCH] of/kexec: Omit kaslr-seed when kexecing with nokaslr

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在 2023/9/8 22:58, Rob Herring 写道:
On Fri, Sep 8, 2023 at 5:45 AM Song Shuai <songshuaishuai@xxxxxxxxxxx> wrote:

The chosen node always adds the kaslr-seed property which is needless
for the kernels kexeced with the cmdline contained "nokaslr".

So omit the kaslr-seed when kexecing with nokaslr.

The kexec'ed kernel can ignore bootargs with CONFIG_CMDLINE_FORCE. So
you don't know if kaslr-seed will be used or not.

You are correct. In addition, unlike the EFI Stub, Kexec is unable to
determine whether the kexec'ed kernel supports RANDOMIZE_BASE,
hence it is appropriate to emit the kaslr-seed unconditionally like
those out-of-linux bootloaders.

Apologies for bothering you with this incorrect patch.

Signed-off-by: Song Shuai <songshuaishuai@xxxxxxxxxxx>
---
  drivers/of/kexec.c | 15 ++++++++++++---
  1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
index f26d2ba8a371..c0d53b10cb70 100644
--- a/drivers/of/kexec.c
+++ b/drivers/of/kexec.c
@@ -19,6 +19,7 @@
  #include <linux/random.h>
  #include <linux/slab.h>
  #include <linux/types.h>
+#include <linux/string.h>

  #define RNG_SEED_SIZE          128

@@ -263,6 +264,14 @@ static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
  }
  #endif /* CONFIG_IMA_KEXEC */

+static bool is_nokaslr_cmdline(const char *cmdline)
+{
+       char *str;
+
+       str = strstr(cmdline, "nokaslr");
+       return str == cmdline || (str > cmdline && *(str - 1) == ' ');

Yet another copy of the same code. That's a clue to refactor into a
common function.

Rob


--
Thanks
Song Shuai




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