tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git x86/entry head: 552572a83438a85d885f4638d65dee36927920ce commit: a603685f0f8ab008afb582c6f319ceb2ad506537 [80/125] x86/entry: Convert double fault exception to IDTENTRY_DF config: i386-allyesconfig (attached as .config) compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0 reproduce: git checkout a603685f0f8ab008afb582c6f319ceb2ad506537 # save the attached .config to linux build tree make ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>, old ones prefixed by <<): arch/x86/kernel/doublefault_32.c: In function 'doublefault_shim': exc_double_fault(&regs, 0, cr2); ^~~~~~~~~~~~~~~~ do_page_fault arch/x86/kernel/doublefault_32.c: At top level: .ip = (unsigned long) asm_exc_double_fault, ^~~~~~~~~~~~~~~~~~~~ async_page_fault cc1: some warnings being treated as errors vim +73 arch/x86/kernel/doublefault_32.c 19 20 /* 21 * Called by double_fault with CR0.TS and EFLAGS.NT cleared. The CPU thinks 22 * we're running the doublefault task. Cannot return. 23 */ 24 asmlinkage noinstr void __noreturn doublefault_shim(void) 25 { 26 unsigned long cr2; 27 struct pt_regs regs; 28 29 BUILD_BUG_ON(sizeof(struct doublefault_stack) != PAGE_SIZE); 30 31 cr2 = native_read_cr2(); 32 33 /* Reset back to the normal kernel task. */ 34 force_reload_TR(); 35 set_df_gdt_entry(smp_processor_id()); 36 37 trace_hardirqs_off(); 38 39 /* 40 * Fill in pt_regs. A downside of doing this in C is that the unwinder 41 * won't see it (no ENCODE_FRAME_POINTER), so a nested stack dump 42 * won't successfully unwind to the source of the double fault. 43 * The main dump from exc_double_fault() is fine, though, since it 44 * uses these regs directly. 45 * 46 * If anyone ever cares, this could be moved to asm. 47 */ 48 regs.ss = TSS(ss); 49 regs.__ssh = 0; 50 regs.sp = TSS(sp); 51 regs.flags = TSS(flags); 52 regs.cs = TSS(cs); 53 /* We won't go through the entry asm, so we can leave __csh as 0. */ 54 regs.__csh = 0; 55 regs.ip = TSS(ip); 56 regs.orig_ax = 0; 57 regs.gs = TSS(gs); 58 regs.__gsh = 0; 59 regs.fs = TSS(fs); 60 regs.__fsh = 0; 61 regs.es = TSS(es); 62 regs.__esh = 0; 63 regs.ds = TSS(ds); 64 regs.__dsh = 0; 65 regs.ax = TSS(ax); 66 regs.bp = TSS(bp); 67 regs.di = TSS(di); 68 regs.si = TSS(si); 69 regs.dx = TSS(dx); 70 regs.cx = TSS(cx); 71 regs.bx = TSS(bx); 72 74 75 /* 76 * x86_32 does not save the original CR3 anywhere on a task switch. 77 * This means that, even if we wanted to return, we would need to find 78 * some way to reconstruct CR3. We could make a credible guess based 79 * on cpu_tlbstate, but that would be racy and would not account for 80 * PTI. 81 * 82 * Instead, don't bother. We can return through 83 * rewind_stack_do_exit() instead. 84 */ 85 panic("cannot return from double fault\n"); 86 } 87 88 DEFINE_PER_CPU_PAGE_ALIGNED(struct doublefault_stack, doublefault_stack) = { 89 .tss = { 90 /* 91 * No sp0 or ss0 -- we never run CPL != 0 with this TSS 92 * active. sp is filled in later. 93 */ 94 .ldt = 0, 95 .io_bitmap_base = IO_BITMAP_OFFSET_INVALID, 96 98 .flags = X86_EFLAGS_FIXED, 99 .es = __USER_DS, 100 .cs = __KERNEL_CS, 101 .ss = __KERNEL_DS, 102 .ds = __USER_DS, 103 .fs = __KERNEL_PERCPU, 104 #ifndef CONFIG_X86_32_LAZY_GS 105 .gs = __KERNEL_STACK_CANARY, 106 #endif 107 108 .__cr3 = __pa_nodebug(swapper_pg_dir), 109 }, 110 }; 111 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org