diff options
| author | Kirill A. Shutemov <[email protected]> | 2018-01-29 14:08:45 +0300 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2018-01-31 08:39:40 +0100 |
| commit | 5bf30316991d5bcda046343ee77d823cf16fdd03 (patch) | |
| tree | 8f5f7413461e1a77bf6407fc6a3aa3fdee58c374 | |
| parent | 72906f38934a49faf4d2d38ea9ae32adcf7d5d0c (diff) | |
x86/kexec: Make kexec (mostly) work in 5-level paging mode
Currently kexec() will crash when switching into a 5-level paging
enabled kernel.
I missed that we need to change relocate_kernel() to set CR4.LA57
flag if the kernel has 5-level paging enabled.
I avoided using #ifdef CONFIG_X86_5LEVEL here and inferred if we need to
enable 5-level paging from previous CR4 value. This way the code is
ready for boot-time switching between paging modes.
With this patch applied, in addition to kexec 4-to-4 which always worked,
we can kexec 4-to-5 and 5-to-5 - while 5-to-4 will need more work.
Reported-by: Baoquan He <[email protected]>
Signed-off-by: Kirill A. Shutemov <[email protected]>
Tested-by: Baoquan He <[email protected]>
Cc: <[email protected]> # v4.14+
Cc: Borislav Petkov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Fixes: 77ef56e4f0fb ("x86: Enable 5-level paging support via CONFIG_X86_5LEVEL=y")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | arch/x86/kernel/relocate_kernel_64.S | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S index 307d3bac5f04..11eda21eb697 100644 --- 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 |