The init_transition_pgtable() function sets up transitional page tables. It ensures that the relocate_kernel() function is present in the identity mapping at the same location as in the kernel page tables. relocate_kernel() switches to the identity mapping, and the function must be present at the same location in the virtual address space before and after switching page tables. init_transition_pgtable() maps a copy of relocate_kernel() in image->control_code_page at the relocate_kernel() virtual address, but the original physical address of relocate_kernel() would also work. It is safe to use original relocate_kernel() physical address cannot be overwritten until swap_pages() is called, and the relocate_kernel() virtual address will not be used by then. Map the original relocate_kernel() at the relocate_kernel() virtual address in the identity mapping. It is preparation to replace the init_transition_pgtable() implementation with a call to kernel_ident_mapping_init(). Note that while relocate_kernel() switches to the identity mapping, it does not flush global TLB entries (CR4.PGE is not cleared). This means that in most cases, the kernel still runs relocate_kernel() from the original physical address before the change. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Reviewed-by: Kai Huang <kai.huang@xxxxxxxxx> --- arch/x86/kernel/machine_kexec_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c index 9c9ac606893e..645690e81c2d 100644 --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -157,7 +157,7 @@ static int init_transition_pgtable(struct kimage *image, pgd_t *pgd) pte_t *pte; vaddr = (unsigned long)relocate_kernel; - paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE); + paddr = __pa(relocate_kernel); pgd += pgd_index(vaddr); if (!pgd_present(*pgd)) { p4d = (p4d_t *)get_zeroed_page(GFP_KERNEL); -- 2.45.2