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 <bhe@redhat.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Baoquan He <bhe@redhat.com>
Cc: <stable@vger.kernel.org> # v4.14+
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Fixes: 77ef56e4f0
("x86: Enable 5-level paging support via CONFIG_X86_5LEVEL=y")
Link: http://lkml.kernel.org/r/20180129110845.26633-1-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
hifive-unleashed-5.1
parent
72906f3893
commit
5bf3031699
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@ -68,6 +68,9 @@ relocate_kernel:
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movq %cr4, %rax
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movq %rax, CR4(%r11)
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/* Save CR4. Required to enable the right paging mode later. */
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movq %rax, %r13
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/* zero out flags, and disable interrupts */
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pushq $0
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popfq
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@ -126,8 +129,13 @@ identity_mapped:
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/*
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* Set cr4 to a known state:
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* - physical address extension enabled
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* - 5-level paging, if it was enabled before
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*/
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movl $X86_CR4_PAE, %eax
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testq $X86_CR4_LA57, %r13
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jz 1f
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orl $X86_CR4_LA57, %eax
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1:
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movq %rax, %cr4
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jmp 1f
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