[PATCH 1/3] vmcore: Convert copy_oldmem_page() to take an iov_iter

[kernel test robot]

Hi "Matthew,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on tip/x86/core]
[also build test ERROR on arm64/for-next/core powerpc/next s390/features linus/master v5.16-rc5]
[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/Matthew-Wilcox-Oracle/Convert-vmcore-to-use-an-iov_iter/20211213-080748
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git e463a09af2f0677b9485a7e8e4e70b396b2ffb6f
config: riscv-randconfig-r012-20211213 (https://download.01.org/0day-ci/archive/20211213/202112131020.pSJ77Cjj-lkp@intel.com/config)
compiler: riscv64-linux-gcc (GCC) 11.2.0
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/e1684ad72e2cce57ac90ae1270668753f1aa6c60
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Matthew-Wilcox-Oracle/Convert-vmcore-to-use-an-iov_iter/20211213-080748
        git checkout e1684ad72e2cce57ac90ae1270668753f1aa6c60
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=riscv SHELL=/bin/bash arch/riscv/kernel/ fs/proc/

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

All errors (new ones prefixed by >>):

   arch/riscv/kernel/crash_dump.c: In function 'copy_oldmem_page':
>> arch/riscv/kernel/crash_dump.c:35:17: error: implicit declaration of function 'copy_to_iter'; did you mean 'copy_to_user'? [-Werror=implicit-function-declaration]
      35 |         csize = copy_to_iter(vaddr + offset, csize, iter);
         |                 ^~~~~~~~~~~~
         |                 copy_to_user
   cc1: some warnings being treated as errors
--
   fs/proc/vmcore.c:135:9: warning: no previous prototype for 'read_from_oldmem_iter' [-Wmissing-prototypes]
     135 | ssize_t read_from_oldmem_iter(struct iov_iter *iter, size_t count,
         |         ^~~~~~~~~~~~~~~~~~~~~
   fs/proc/vmcore.c: In function 'read_from_oldmem_iter':
>> fs/proc/vmcore.c:157:31: error: implicit declaration of function 'iov_iter_zero' [-Werror=implicit-function-declaration]
     157 |                         tmp = iov_iter_zero(nr_bytes, iter);
         |                               ^~~~~~~~~~~~~
   fs/proc/vmcore.c: In function 'read_from_oldmem':
>> fs/proc/vmcore.c:187:25: error: storage size of 'iter' isn't known
     187 |         struct iov_iter iter;
         |                         ^~~~
   fs/proc/vmcore.c:188:22: error: storage size of 'iov' isn't known
     188 |         struct iovec iov;
         |                      ^~~
>> fs/proc/vmcore.c:189:21: error: storage size of 'kvec' isn't known
     189 |         struct kvec kvec;
         |                     ^~~~
   fs/proc/vmcore.c:194:17: error: implicit declaration of function 'iov_iter_init'; did you mean 'klist_iter_init'? [-Werror=implicit-function-declaration]
     194 |                 iov_iter_init(&iter, READ, &iov, 1, count);
         |                 ^~~~~~~~~~~~~
         |                 klist_iter_init
>> fs/proc/vmcore.c:198:17: error: implicit declaration of function 'iov_iter_kvec' [-Werror=implicit-function-declaration]
     198 |                 iov_iter_kvec(&iter, READ, &kvec, 1, count);
         |                 ^~~~~~~~~~~~~
   fs/proc/vmcore.c:189:21: warning: unused variable 'kvec' [-Wunused-variable]
     189 |         struct kvec kvec;
         |                     ^~~~
   fs/proc/vmcore.c:188:22: warning: unused variable 'iov' [-Wunused-variable]
     188 |         struct iovec iov;
         |                      ^~~
   fs/proc/vmcore.c:187:25: warning: unused variable 'iter' [-Wunused-variable]
     187 |         struct iov_iter iter;
         |                         ^~~~
   fs/proc/vmcore.c:202:1: error: control reaches end of non-void function [-Werror=return-type]
     202 | }
         | ^
   cc1: some warnings being treated as errors


vim +35 arch/riscv/kernel/crash_dump.c

    10	
    11	/**
    12	 * copy_oldmem_page() - copy one page from old kernel memory
    13	 * @pfn: page frame number to be copied
    14	 * @buf: buffer where the copied page is placed
    15	 * @csize: number of bytes to copy
    16	 * @offset: offset in bytes into the page
    17	 * @userbuf: if set, @buf is in a user address space
    18	 *
    19	 * This function copies one page from old kernel memory into buffer pointed by
    20	 * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes
    21	 * copied or negative error in case of failure.
    22	 */
    23	ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
    24				 size_t csize, unsigned long offset)
    25	{
    26		void *vaddr;
    27	
    28		if (!csize)
    29			return 0;
    30	
    31		vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB);
    32		if (!vaddr)
    33			return -ENOMEM;
    34	
  > 35		csize = copy_to_iter(vaddr + offset, csize, iter);

---
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