x86/kexec: Mark relocate_kernel page as ROX instead of RWX

All writes to the page now happen before it gets marked as executable
(or after it's already switched to the identmap page tables where it's
OK to be RWX).

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20241205153343.3275139-14-dwmw2@infradead.org

diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index c9fd60f8f80658d522da2de3649a1c36a3534817..9232ad1562c8891af9c6ae6bdf9d4feb13217198 100644 (file)
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -323,7 +323,7 @@ int machine_kexec_prepare(struct kimage *image)
 
        __memcpy(control_page, __relocate_kernel_start, reloc_end - reloc_start);
 
-       set_memory_x((unsigned long)control_page, 1);
+       set_memory_rox((unsigned long)control_page, 1);
 
        return 0;
 }
@@ -333,6 +333,7 @@ void machine_kexec_cleanup(struct kimage *image)
        void *control_page = page_address(image->control_code_page);
 
        set_memory_nx((unsigned long)control_page, 1);
+       set_memory_rw((unsigned long)control_page, 1);
 
        free_transition_pgtable(image);
 }