x86/kexec: Make kexec (mostly) work in 5-level paging mode

[GitHub/LineageOS/android_kernel_motorola_exynos9610.git] / arch / x86 / kernel / relocate_kernel_64.S

diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index 307d3bac5f04ece485ac1fe42226ee111c0c6e85..11eda21eb697df6d8439206cad890d0e24c7de71 100644 (file)
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -68,6 +68,9 @@ relocate_kernel:
        movq    %cr4, %rax
        movq    %rax, CR4(%r11)
 
+       /* Save CR4. Required to enable the right paging mode later. */
+       movq    %rax, %r13
+
        /* zero out flags, and disable interrupts */
        pushq $0
        popfq
@@ -126,8 +129,13 @@ identity_mapped:
        /*
         * Set cr4 to a known state:
         *  - physical address extension enabled
+        *  - 5-level paging, if it was enabled before
         */
        movl    $X86_CR4_PAE, %eax
+       testq   $X86_CR4_LA57, %r13
+       jz      1f
+       orl     $X86_CR4_LA57, %eax
+1:
        movq    %rax, %cr4
 
        jmp 1f