diff options
| author | Kai Huang <kai.huang@intel.com> | 2024-08-25 20:18:06 +1200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2024-08-25 14:29:39 +0200 |
| commit | ea49cdb26e7cffc261ceb1db26707e6d337fa104 (patch) | |
| tree | 187a545b15f4da0d853c12a793c278d52145bbcf /arch/x86/kernel/relocate_kernel_64.S | |
| parent | 3c41ad39f179c0e41f585975eb6834cd14f286ec (diff) | |
x86/kexec: Add comments around swap_pages() assembly to improve readability
The current assembly around swap_pages() in the relocate_kernel() takes
some time to follow because the use of registers can be easily lost when
the line of assembly goes long. Add a couple of comments to clarify the
code around swap_pages() to improve readability.
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/all/8b52b0b8513a34b2a02fb4abb05c6700c2821475.1724573384.git.kai.huang@intel.com
Diffstat (limited to 'arch/x86/kernel/relocate_kernel_64.S')
| -rw-r--r-- | arch/x86/kernel/relocate_kernel_64.S | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S index f7a3ca3dee53..e9e88c342f75 100644 --- a/arch/x86/kernel/relocate_kernel_64.S +++ b/arch/x86/kernel/relocate_kernel_64.S @@ -170,6 +170,7 @@ 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 @@ -289,18 +290,21 @@ SYM_CODE_START_LOCAL_NOALIGN(swap_pages) movq %rcx, %rsi /* For ever source page do a copy */ andq $0xfffffffffffff000, %rsi - movq %rdi, %rdx - movq %rsi, %rax + movq %rdi, %rdx /* Save destination page to %rdx */ + movq %rsi, %rax /* Save source page to %rax */ + /* copy source page to swap page */ movq %r10, %rdi movl $512, %ecx rep ; movsq + /* copy destination page to source page */ movq %rax, %rdi movq %rdx, %rsi movl $512, %ecx rep ; movsq + /* copy swap page to destination page */ movq %rdx, %rdi movq %r10, %rsi movl $512, %ecx |