Hi Dmitry,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on c34f157421f6905e6b4a79a312e9175dce2bc607]

url:    https://github.com/0day-ci/linux/commits/Dmitry-Safonov/Add-generic-user_landing-tracking/20201109-090354
base:    c34f157421f6905e6b4a79a312e9175dce2bc607
config: riscv-allmodconfig (attached as .config)
compiler: riscv64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/04586680978b048abe74dd892c5b1fcde7c486a3
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Dmitry-Safonov/Add-generic-user_landing-tracking/20201109-090354
        git checkout 04586680978b048abe74dd892c5b1fcde7c486a3
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=riscv 

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

All warnings (new ones prefixed by >>):

   In file included from include/linux/elf.h:6,
                    from arch/riscv/kernel/vdso.c:9:
   arch/riscv/include/asm/elf.h:8: error: unterminated #ifndef
       8 | #ifndef _ASM_RISCV_ELF_H
         | 
   arch/riscv/kernel/vdso.c: In function 'arch_setup_additional_pages':
>> arch/riscv/kernel/vdso.c:62:27: warning: variable 'vvar_base' set but not used [-Wunused-but-set-variable]
      62 |  unsigned long vdso_base, vvar_base, vdso_len;
         |                           ^~~~~~~~~

vim +/vvar_base +62 arch/riscv/kernel/vdso.c

   > 9	#include <linux/elf.h>
    10	#include <linux/mm.h>
    11	#include <linux/slab.h>
    12	#include <linux/binfmts.h>
    13	#include <linux/err.h>
    14	#include <asm/page.h>
    15	#ifdef GENERIC_TIME_VSYSCALL
    16	#include <vdso/datapage.h>
    17	#else
    18	#include <asm/vdso.h>
    19	#endif
    20	
    21	extern char vdso_start[], vdso_end[];
    22	
    23	static unsigned int vdso_pages;
    24	static struct page **vdso_pagelist;
    25	
    26	/*
    27	 * The vDSO data page.
    28	 */
    29	static union {
    30		struct vdso_data	data;
    31		u8			page[PAGE_SIZE];
    32	} vdso_data_store __page_aligned_data;
    33	struct vdso_data *vdso_data = &vdso_data_store.data;
    34	
    35	static int __init vdso_init(void)
    36	{
    37		unsigned int i;
    38	
    39		vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
    40		vdso_pagelist =
    41			kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL);
    42		if (unlikely(vdso_pagelist == NULL)) {
    43			pr_err("vdso: pagelist allocation failed\n");
    44			return -ENOMEM;
    45		}
    46	
    47		for (i = 0; i < vdso_pages; i++) {
    48			struct page *pg;
    49	
    50			pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
    51			vdso_pagelist[i] = pg;
    52		}
    53		vdso_pagelist[i] = virt_to_page(vdso_data);
    54	
    55		return 0;
    56	}
    57	arch_initcall(vdso_init);
    58	
    59	int arch_setup_additional_pages(unsigned long *sysinfo_ehdr)
    60	{
    61		struct mm_struct *mm = current->mm;
  > 62		unsigned long vdso_base, vvar_base, vdso_len;
    63		int ret;
    64	
    65		vdso_len = (vdso_pages + 1) << PAGE_SHIFT;
    66	
    67		mmap_write_lock(mm);
    68		vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
    69		if (IS_ERR_VALUE(vdso_base)) {
    70			ret = vdso_base;
    71			goto end;
    72		}
    73	
    74		/*
    75		 * Put vDSO base into mm struct. We need to do this before calling
    76		 * install_special_mapping or the perf counter mmap tracking code
    77		 * will fail to recognise it as a vDSO (since arch_vma_name fails).
    78		 */
    79		mm->context.vdso = (void *)vdso_base;
    80	
    81		ret =
    82		   install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
    83			(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
    84			vdso_pagelist);
    85	
    86		if (unlikely(ret)) {
    87			mm->context.vdso = NULL;
    88			goto end;
    89		}
    90	
    91		vvar_base = vdso_base + (vdso_pages << PAGE_SHIFT);
    92		ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
    93			(VM_READ | VM_MAYREAD), &vdso_pagelist[vdso_pages]);
    94	
    95		if (unlikely(ret))
    96			mm->context.vdso = NULL;
    97		else
    98			*sysinfo_ehdr = vdso_base;
    99	end:
   100		mmap_write_unlock(mm);
   101		return ret;
   102	}
   103	

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