arch/x86/kernel/shstk.c:295:55: sparse: sparse: cast removes address space '__user' of expression

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   52b1853b080a082ec3749c3a9577f6c71b1d4a90
commit: 05e36022c0543ba55a3de55af455b00cb3eb4fcc x86/shstk: Handle signals for shadow stack
date:   5 months ago
config: x86_64-randconfig-123-20240106 (https://download.01.org/0day-ci/archive/20240108/202401080003.duO4RmjK-lkp@intel.com/config)
compiler: ClangBuiltLinux clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240108/202401080003.duO4RmjK-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202401080003.duO4RmjK-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
   arch/x86/kernel/shstk.c:244:29: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected unsigned long long [noderef] [usertype] __user *addr @@     got void *[noderef] __user @@
   arch/x86/kernel/shstk.c:244:29: sparse:     expected unsigned long long [noderef] [usertype] __user *addr
   arch/x86/kernel/shstk.c:244:29: sparse:     got void *[noderef] __user
>> arch/x86/kernel/shstk.c:295:55: sparse: sparse: cast removes address space '__user' of expression

vim +/__user +295 arch/x86/kernel/shstk.c

   271	
   272	int setup_signal_shadow_stack(struct ksignal *ksig)
   273	{
   274		void __user *restorer = ksig->ka.sa.sa_restorer;
   275		unsigned long ssp;
   276		int err;
   277	
   278		if (!cpu_feature_enabled(X86_FEATURE_USER_SHSTK) ||
   279		    !features_enabled(ARCH_SHSTK_SHSTK))
   280			return 0;
   281	
   282		if (!restorer)
   283			return -EINVAL;
   284	
   285		ssp = get_user_shstk_addr();
   286		if (unlikely(!ssp))
   287			return -EINVAL;
   288	
   289		err = shstk_push_sigframe(&ssp);
   290		if (unlikely(err))
   291			return err;
   292	
   293		/* Push restorer address */
   294		ssp -= SS_FRAME_SIZE;
 > 295		err = write_user_shstk_64((u64 __user *)ssp, (u64)restorer);
   296		if (unlikely(err))
   297			return -EFAULT;
   298	
   299		fpregs_lock_and_load();
   300		wrmsrl(MSR_IA32_PL3_SSP, ssp);
   301		fpregs_unlock();
   302	
   303		return 0;
   304	}
   305	

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