sym_to_pfn
unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
pfn = sym_to_pfn(vdso_info[abi].vdso_code_start);
pfn_pte(sym_to_pfn(kasan_early_shadow_page),
unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
pfn = sym_to_pfn(vdso_info->vdso_code_start);