Re: [linux-next:master 8145/11162] arch/arm/kernel/traps.c:198:37: sparse: sparse: incorrect type in assignment (different base types)

["Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>]

On 2022/9/29 23:07, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   de90d455a35e474a184c898e66a6a108c3a99434
> commit: f640b1a57f8e9e513e26aa5b3ee0b905dfebfcf2 [8145/11162] ARM: 9225/1: Make the dumped instructions are consistent with the disassembled ones
> config: arm-randconfig-s043-20220925
> compiler: arm-linux-gnueabi-gcc (GCC) 12.1.0
> 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: v0.6.4-39-gce1a6720-dirty
>         # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=f640b1a57f8e9e513e26aa5b3ee0b905dfebfcf2
>         git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
>         git fetch --no-tags linux-next master
>         git checkout f640b1a57f8e9e513e26aa5b3ee0b905dfebfcf2
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=arm SHELL=/bin/bash
> 
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> 
> sparse warnings: (new ones prefixed by >>)
>    arch/arm/kernel/traps.c:191:39: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected void const volatile [noderef] __user *ptr @@     got unsigned short [usertype] * @@
>    arch/arm/kernel/traps.c:191:39: sparse:     expected void const volatile [noderef] __user *ptr
>    arch/arm/kernel/traps.c:191:39: sparse:     got unsigned short [usertype] *
>    arch/arm/kernel/traps.c:193:39: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected void const volatile [noderef] __user *ptr @@     got unsigned int [usertype] * @@
>    arch/arm/kernel/traps.c:193:39: sparse:     expected void const volatile [noderef] __user *ptr
>    arch/arm/kernel/traps.c:193:39: sparse:     got unsigned int [usertype] *

These warnings are not caused by this patch. I will use another patch to fix them.

                        if (thumb)
-                               bad = get_user(val, &((u16 *)addr)[i]);
+                               bad = get_user(val, &((u16 __user *)addr)[i]);
                        else
-                               bad = get_user(val, &((u32 *)addr)[i]);
+                               bad = get_user(val, &((u32 __user *)addr)[i]);



>>> arch/arm/kernel/traps.c:198:37: sparse: sparse: incorrect type in assignment (different base types) @@     expected unsigned int [addressable] [assigned] val @@     got restricted __le16 [usertype] @@
>    arch/arm/kernel/traps.c:198:37: sparse:     expected unsigned int [addressable] [assigned] val
>    arch/arm/kernel/traps.c:198:37: sparse:     got restricted __le16 [usertype]
>>> arch/arm/kernel/traps.c:200:37: sparse: sparse: incorrect type in assignment (different base types) @@     expected unsigned int [addressable] [assigned] val @@     got restricted __le32 [usertype] @@
>    arch/arm/kernel/traps.c:200:37: sparse:     expected unsigned int [addressable] [assigned] val
>    arch/arm/kernel/traps.c:200:37: sparse:     got restricted __le32 [usertype]

OK, to clear this static check warning, I need to add "(__force unsigned int)"
to perform the forced type conversion, because it requires that the type of
'val' be "__le16" or "__le32".

>    arch/arm/kernel/traps.c:465:33: sparse: sparse: cast removes address space '__user' of expression
>    arch/arm/kernel/traps.c:468:41: sparse: sparse: cast removes address space '__user' of expression
>    arch/arm/kernel/traps.c:473:33: sparse: sparse: cast removes address space '__user' of expression
> 
> vim +198 arch/arm/kernel/traps.c
> 
>    164	
>    165	static void dump_instr(const char *lvl, struct pt_regs *regs)
>    166	{
>    167		unsigned long addr = instruction_pointer(regs);
>    168		const int thumb = thumb_mode(regs);
>    169		const int width = thumb ? 4 : 8;
>    170		char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
>    171		int i;
>    172	
>    173		/*
>    174		 * Note that we now dump the code first, just in case the backtrace
>    175		 * kills us.
>    176		 */
>    177	
>    178		for (i = -4; i < 1 + !!thumb; i++) {
>    179			unsigned int val, bad;
>    180	
>    181			if (!user_mode(regs)) {
>    182				if (thumb) {
>    183					u16 val16;
>    184					bad = get_kernel_nofault(val16, &((u16 *)addr)[i]);
>    185					val = val16;
>    186				} else {
>    187					bad = get_kernel_nofault(val, &((u32 *)addr)[i]);
>    188				}
>    189			} else {
>    190				if (thumb)
>    191					bad = get_user(val, &((u16 *)addr)[i]);
>    192				else
>    193					bad = get_user(val, &((u32 *)addr)[i]);
>    194			}
>    195	
>    196			if (IS_ENABLED(CONFIG_CPU_ENDIAN_BE8)) {
>    197				if (thumb)
>  > 198					val = cpu_to_le16(val);
>    199				else
>  > 200					val = cpu_to_le32(val);
>    201			}
>    202	
>    203			if (!bad)
>    204				p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
>    205						width, val);
>    206			else {
>    207				p += sprintf(p, "bad PC value");
>    208				break;
>    209			}
>    210		}
>    211		printk("%sCode: %s\n", lvl, str);
>    212	}
>    213	
> 

-- 
Regards,
  Zhen Lei