diff options
| author | David Woodhouse | 2024-12-05 15:05:08 +0000 |
|---|---|---|
| committer | Ingo Molnar | 2024-12-06 10:41:58 +0100 |
| commit | 207bdf7f72ae8b1764de294ae59bdf5b015082bd (patch) | |
| tree | 41dc9c6755175cd006568d1de75e57ea712525ac | |
| parent | fe8ec69baa9dbaf37cae4f3458d2d5e09bf6d87e (diff) | |
x86/kexec: Clean up and document register use in relocate_kernel_64.S
Add more comments explaining what each register contains, and save the
preserve_context flag to a non-clobbered register sooner, to keep things
simpler.
No change in behavior intended.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Kai Huang <kai.huang@intel.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: https://lore.kernel.org/r/20241205153343.3275139-3-dwmw2@infradead.org
| -rw-r--r-- | arch/x86/kernel/relocate_kernel_64.S | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S index 1236f25fc8d1..92478e2e254f 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 |