On 09/25/18 at 07:26pm, Borislav Petkov wrote: > IINM, the problem can be addressed in a simpler way by getting rid of > enc_bit and thus getting rid of the need to do relative addressing of > anything and simply doing the whole dance of figuring out the C-bit each > time. It probably wouldn't be even measurable... Couldn't agree more. Obviously enc_bit is redundent here. We only check eax each time, removing it can fix the RIP-relative addressing issue in kexec. diff --git a/arch/x86/boot/compressed/mem_encrypt.S b/arch/x86/boot/compressed/mem_encrypt.S index eaa843a52907..0b60eb867d25 100644 --- a/arch/x86/boot/compressed/mem_encrypt.S +++ b/arch/x86/boot/compressed/mem_encrypt.S @@ -27,19 +27,6 @@ ENTRY(get_sev_encryption_bit) push %edx push %edi - /* - * RIP-relative addressing is needed to access the encryption bit - * variable. Since we are running in 32-bit mode we need this call/pop - * sequence to get the proper relative addressing. - */ - call 1f -1: popl %edi - subl $1b, %edi - - movl enc_bit(%edi), %eax - cmpl $0, %eax - jge .Lsev_exit - /* Check if running under a hypervisor */ movl $1, %eax cpuid @@ -69,12 +56,10 @@ ENTRY(get_sev_encryption_bit) movl %ebx, %eax andl $0x3f, %eax /* Return the encryption bit location */ - movl %eax, enc_bit(%edi) jmp .Lsev_exit .Lno_sev: xor %eax, %eax - movl %eax, enc_bit(%edi) .Lsev_exit: pop %edi @@ -113,9 +98,6 @@ ENTRY(set_sev_encryption_mask) ENDPROC(set_sev_encryption_mask) .data -enc_bit: - .int 0xffffffff - #ifdef CONFIG_AMD_MEM_ENCRYPT .balign 8 GLOBAL(sme_me_mask) _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
