linux-kernel - Re: ioctl.c:undefined reference to `__get_user

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Message-ID: <a022694d-426a-0415-83de-4cc5cd9d1d38@infradead.org>
Date:   Sun, 16 May 2021 23:49:07 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     kernel test robot <lkp@...el.com>,
        Steve French <stfrench@...rosoft.com>,
        LAK <linux-arm-kernel@...ts.infradead.org>
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org,
        Shyam Prasad N <sprasad@...rosoft.com>
Subject: Re: ioctl.c:undefined reference to `__get_user_bad'

On 5/10/21 5:53 PM, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   142b507f911c5a502dbb8f603216cb0ea8a79a48
> commit: 7ba3d1cdb7988ccfbc6e4995dee04510c85fefbc smb3.1.1: allow dumping keys for multiuser mounts
> date:   7 days ago
> config: arm-randconfig-s031-20210510 (attached as .config)
> compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0
> reproduce:
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # apt-get install sparse
>         # sparse version: v0.6.3-341-g8af24329-dirty
>         # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7ba3d1cdb7988ccfbc6e4995dee04510c85fefbc
>         git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>         git fetch --no-tags linus master
>         git checkout 7ba3d1cdb7988ccfbc6e4995dee04510c85fefbc
>         # save the attached .config to linux build tree
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' W=1 ARCH=arm 
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@...el.com>
> 
> All errors (new ones prefixed by >>):
> 
>    arm-linux-gnueabi-ld: fs/cifs/ioctl.o: in function `cifs_dump_full_key':
>>> ioctl.c:(.text+0x44): undefined reference to `__get_user_bad'
> 
> ---

# CONFIG_MMU is not set

and arch/arm/include/asm/uaccess.h does not implement get_user(size 8 bytes)
for the non-MMU case:

#define __get_user_err(x, ptr, err)					\
do {									\
	unsigned long __gu_addr = (unsigned long)(ptr);			\
	unsigned long __gu_val;						\
	unsigned int __ua_flags;					\
	__chk_user_ptr(ptr);						\
	might_fault();							\
	__ua_flags = uaccess_save_and_enable();				\
	switch (sizeof(*(ptr))) {					\
	case 1:	__get_user_asm_byte(__gu_val, __gu_addr, err);	break;	\
	case 2:	__get_user_asm_half(__gu_val, __gu_addr, err);	break;	\
	case 4:	__get_user_asm_word(__gu_val, __gu_addr, err);	break;	\
	default: (__gu_val) = __get_user_bad();				\
	}								\
	uaccess_restore(__ua_flags);					\
	(x) = (__typeof__(*(ptr)))__gu_val;				\
} while (0)


-- 
~Randy