Re: [PATCH v5 29/32] x86/mm: Add support to encrypt the kernel in-place

Tom Lendacky
2017-05-31T13:13:13Z

On 5/31/2017 4:51 AM, Borislav Petkov wrote:
> On Tue, May 30, 2017 at 11:39:07AM -0500, Tom Lendacky wrote:
>> Yes, it's from objtool:
>>
>> arch/x86/mm/mem_encrypt_boot.o: warning: objtool: .text+0xd2: return
>> instruction outside of a callable function
>
> Oh, well, let's make it a global symbol then. Who knows, we might have
> to live-patch it someday :-)

Can do.

Thanks,
Tom

>
> ---
> diff --git a/arch/x86/mm/mem_encrypt_boot.S b/arch/x86/mm/mem_encrypt_boot.S
> index fb58f9f953e3..7720b0050840 100644
> --- a/arch/x86/mm/mem_encrypt_boot.S
> +++ b/arch/x86/mm/mem_encrypt_boot.S
> @@ -47,9 +47,9 @@ ENTRY(sme_encrypt_execute)
> movq %rdx, %r12 /* Kernel length */
>
> /* Copy encryption routine into the workarea */
> - movq %rax, %rdi /* Workarea encryption routine */
> - leaq .Lenc_start(%rip), %rsi /* Encryption routine */
> - movq $(.Lenc_stop - .Lenc_start), %rcx /* Encryption routine length */
> + movq %rax, %rdi /* Workarea encryption routine */
> + leaq __enc_copy(%rip), %rsi /* Encryption routine */
> + movq $(.L__enc_copy_end - __enc_copy), %rcx /* Encryption routine length */
> rep movsb
>
> /* Setup registers for call */
> @@ -70,8 +70,7 @@ ENTRY(sme_encrypt_execute)
> ret
> ENDPROC(sme_encrypt_execute)
>
> -.Lenc_start:
> -ENTRY(sme_enc_routine)
> +ENTRY(__enc_copy)
> /*
> * Routine used to encrypt kernel.
> * This routine must be run outside of the kernel proper since
> @@ -147,5 +146,5 @@ ENTRY(sme_enc_routine)
> wrmsr
>
> ret
> -ENDPROC(sme_enc_routine)
> -.Lenc_stop:
> +.L__enc_copy_end:
> +ENDPROC(__enc_copy)
>