From: David Woodhouse <dwmw@xxxxxxxxxxxx> Add more comments explaining what each register contains, and save the preserve_context flag to a non-clobbered register sooner, to keep things simpler. Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Acked-by: Kai Huang <kai.huang@xxxxxxxxx> --- arch/x86/kernel/relocate_kernel_64.S | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S index e9e88c342f75..7ee32bcb6e01 100644 --- a/arch/x86/kernel/relocate_kernel_64.S +++ b/arch/x86/kernel/relocate_kernel_64.S @@ -100,6 +100,9 @@ SYM_CODE_START_NOALIGN(relocate_kernel) movq %r10, CP_PA_SWAP_PAGE(%r11) movq %rdi, CP_PA_BACKUP_PAGES_MAP(%r11) + /* Save the preserve_context to %r11 as swap_pages clobbers %rcx. */ + movq %rcx, %r11 + /* Switch to the identity mapped page tables */ movq %r9, %cr3 @@ -116,6 +119,14 @@ SYM_CODE_END(relocate_kernel) SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) UNWIND_HINT_END_OF_STACK + /* + * %rdi indirection page + * %rdx start address + * %r11 preserve_context + * %r12 host_mem_enc_active + * %r13 original CR4 when relocate_kernel() was invoked + */ + /* set return address to 0 if not preserving context */ pushq $0 /* store the start address on the stack */ @@ -170,8 +181,6 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) wbinvd .Lsme_off: - /* Save the preserve_context to %r11 as swap_pages clobbers %rcx. */ - movq %rcx, %r11 call swap_pages /* @@ -183,13 +192,14 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) movq %cr3, %rax movq %rax, %cr3 + testq %r11, %r11 /* preserve_context */ + jnz .Lrelocate + /* * set all of the registers to known values * leave %rsp alone */ - testq %r11, %r11 - jnz .Lrelocate xorl %eax, %eax xorl %ebx, %ebx xorl %ecx, %ecx -- 2.47.0
