Hi Peter,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tip/x86/core]
[also build test WARNING on tip/master linus/master v5.13-rc1 next-20210510]
[cannot apply to bp/for-next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/H-Peter-Anvin/x86-irq-trap-and-interrupt-cleanups/20210511-085650
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 2c88d45edbb89029c1190bb3b136d2602f057c98
config: i386-randconfig-s002-20210511 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-341-g8af24329-dirty
        # https://github.com/0day-ci/linux/commit/c9c68d8ad1ef0923798c18f7e9a9570fa23aee0e
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review H-Peter-Anvin/x86-irq-trap-and-interrupt-cleanups/20210511-085650
        git checkout c9c68d8ad1ef0923798c18f7e9a9570fa23aee0e
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' W=1 ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>


sparse warnings: (new ones prefixed by >>)
>> arch/x86/kernel/machine_kexec_32.c:236:17: sparse: sparse: Using plain integer as NULL pointer

vim +236 arch/x86/kernel/machine_kexec_32.c

   188	
   189		save_ftrace_enabled = __ftrace_enabled_save();
   190	
   191		/* Interrupts aren't acceptable while we reboot */
   192		local_irq_disable();
   193		hw_breakpoint_disable();
   194	
   195		if (image->preserve_context) {
   196	#ifdef CONFIG_X86_IO_APIC
   197			/*
   198			 * We need to put APICs in legacy mode so that we can
   199			 * get timer interrupts in second kernel. kexec/kdump
   200			 * paths already have calls to restore_boot_irq_mode()
   201			 * in one form or other. kexec jump path also need one.
   202			 */
   203			clear_IO_APIC();
   204			restore_boot_irq_mode();
   205	#endif
   206		}
   207	
   208		control_page = page_address(image->control_code_page);
   209		memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
   210	
   211		relocate_kernel_ptr = control_page;
   212		page_list[PA_CONTROL_PAGE] = __pa(control_page);
   213		page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
   214		page_list[PA_PGD] = __pa(image->arch.pgd);
   215	
   216		if (image->type == KEXEC_TYPE_DEFAULT)
   217			page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
   218							<< PAGE_SHIFT);
   219	
   220		/*
   221		 * The segment registers are funny things, they have both a
   222		 * visible and an invisible part.  Whenever the visible part is
   223		 * set to a specific selector, the invisible part is loaded
   224		 * with from a table in memory.  At no other time is the
   225		 * descriptor table in memory accessed.
   226		 *
   227		 * I take advantage of this here by force loading the
   228		 * segments, before I zap the gdt with an invalid value.
   229		 */
   230		load_segments();
   231		/*
   232		 * The gdt & idt are now invalid.
   233		 * If you want to load them you must set up your own idt & gdt.
   234		 */
   235		idt_invalidate();
 > 236		set_gdt(0, 0);
   237	
   238		/* now call it */
   239		image->start = relocate_kernel_ptr((unsigned long)image->head,
   240						   (unsigned long)page_list,
   241						   image->start,
   242						   boot_cpu_has(X86_FEATURE_PAE),
   243						   image->preserve_context);
   244	

---
0-DAY CI Kernel Test Service, Intel Corporation
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