arch/arm64/kernel/signal.c:1046:36: 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:   7503345ac5f5e82fd9a36d6e6b447c016376403a
commit: 5d8b172e7005c6b42c16a0952c1d8873051d68ae arm64: Add Kconfig for Guarded Control Stack (GCS)
date:   9 weeks ago
config: arm64-randconfig-r133-20241208 (https://download.01.org/0day-ci/archive/20241208/202412082005.OBJ0BbWs-lkp@intel.com/config)
compiler: clang version 20.0.0git (https://github.com/llvm/llvm-project 592c0fe55f6d9a811028b5f3507be91458ab2713)
reproduce: (https://download.01.org/0day-ci/archive/20241208/202412082005.OBJ0BbWs-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/202412082005.OBJ0BbWs-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> arch/arm64/kernel/signal.c:1046:36: sparse: sparse: cast removes address space '__user' of expression
   arch/arm64/kernel/signal.c:1054:9: sparse: sparse: cast removes address space '__user' of expression
   arch/arm64/kernel/signal.c:1461:26: sparse: sparse: incorrect type in assignment (different address spaces) @@     expected void ( [noderef] [usertype] __user *[assigned] [usertype] sigtramp )( ... ) @@     got void * @@
   arch/arm64/kernel/signal.c:1461:26: sparse:     expected void ( [noderef] [usertype] __user *[assigned] [usertype] sigtramp )( ... )
   arch/arm64/kernel/signal.c:1461:26: sparse:     got void *

vim +/__user +1046 arch/arm64/kernel/signal.c

2c020ed8d148f7 Catalin Marinas 2012-03-05  1010  
eaf62ce1563b85 Mark Brown      2024-10-01  1011  #ifdef CONFIG_ARM64_GCS
eaf62ce1563b85 Mark Brown      2024-10-01  1012  static int gcs_restore_signal(void)
eaf62ce1563b85 Mark Brown      2024-10-01  1013  {
eaf62ce1563b85 Mark Brown      2024-10-01  1014  	unsigned long __user *gcspr_el0;
eaf62ce1563b85 Mark Brown      2024-10-01  1015  	u64 cap;
eaf62ce1563b85 Mark Brown      2024-10-01  1016  	int ret;
eaf62ce1563b85 Mark Brown      2024-10-01  1017  
eaf62ce1563b85 Mark Brown      2024-10-01  1018  	if (!system_supports_gcs())
eaf62ce1563b85 Mark Brown      2024-10-01  1019  		return 0;
eaf62ce1563b85 Mark Brown      2024-10-01  1020  
eaf62ce1563b85 Mark Brown      2024-10-01  1021  	if (!(current->thread.gcs_el0_mode & PR_SHADOW_STACK_ENABLE))
eaf62ce1563b85 Mark Brown      2024-10-01  1022  		return 0;
eaf62ce1563b85 Mark Brown      2024-10-01  1023  
eaf62ce1563b85 Mark Brown      2024-10-01  1024  	gcspr_el0 = (unsigned long __user *)read_sysreg_s(SYS_GCSPR_EL0);
eaf62ce1563b85 Mark Brown      2024-10-01  1025  
eaf62ce1563b85 Mark Brown      2024-10-01  1026  	/*
eaf62ce1563b85 Mark Brown      2024-10-01  1027  	 * Ensure that any changes to the GCS done via GCS operations
eaf62ce1563b85 Mark Brown      2024-10-01  1028  	 * are visible to the normal reads we do to validate the
eaf62ce1563b85 Mark Brown      2024-10-01  1029  	 * token.
eaf62ce1563b85 Mark Brown      2024-10-01  1030  	 */
eaf62ce1563b85 Mark Brown      2024-10-01  1031  	gcsb_dsync();
eaf62ce1563b85 Mark Brown      2024-10-01  1032  
eaf62ce1563b85 Mark Brown      2024-10-01  1033  	/*
eaf62ce1563b85 Mark Brown      2024-10-01  1034  	 * GCSPR_EL0 should be pointing at a capped GCS, read the cap.
eaf62ce1563b85 Mark Brown      2024-10-01  1035  	 * We don't enforce that this is in a GCS page, if it is not
eaf62ce1563b85 Mark Brown      2024-10-01  1036  	 * then faults will be generated on GCS operations - the main
eaf62ce1563b85 Mark Brown      2024-10-01  1037  	 * concern is to protect GCS pages.
eaf62ce1563b85 Mark Brown      2024-10-01  1038  	 */
eaf62ce1563b85 Mark Brown      2024-10-01  1039  	ret = copy_from_user(&cap, gcspr_el0, sizeof(cap));
eaf62ce1563b85 Mark Brown      2024-10-01  1040  	if (ret)
eaf62ce1563b85 Mark Brown      2024-10-01  1041  		return -EFAULT;
eaf62ce1563b85 Mark Brown      2024-10-01  1042  
eaf62ce1563b85 Mark Brown      2024-10-01  1043  	/*
eaf62ce1563b85 Mark Brown      2024-10-01  1044  	 * Check that the cap is the actual GCS before replacing it.
eaf62ce1563b85 Mark Brown      2024-10-01  1045  	 */
eaf62ce1563b85 Mark Brown      2024-10-01 @1046  	if (!gcs_signal_cap_valid((u64)gcspr_el0, cap))
eaf62ce1563b85 Mark Brown      2024-10-01  1047  		return -EINVAL;
eaf62ce1563b85 Mark Brown      2024-10-01  1048  
eaf62ce1563b85 Mark Brown      2024-10-01  1049  	/* Invalidate the token to prevent reuse */
eaf62ce1563b85 Mark Brown      2024-10-01  1050  	put_user_gcs(0, (__user void*)gcspr_el0, &ret);
eaf62ce1563b85 Mark Brown      2024-10-01  1051  	if (ret != 0)
eaf62ce1563b85 Mark Brown      2024-10-01  1052  		return -EFAULT;
eaf62ce1563b85 Mark Brown      2024-10-01  1053  
eaf62ce1563b85 Mark Brown      2024-10-01  1054  	write_sysreg_s(gcspr_el0 + 1, SYS_GCSPR_EL0);
eaf62ce1563b85 Mark Brown      2024-10-01  1055  
eaf62ce1563b85 Mark Brown      2024-10-01  1056  	return 0;
eaf62ce1563b85 Mark Brown      2024-10-01  1057  }
eaf62ce1563b85 Mark Brown      2024-10-01  1058  

:::::: The code at line 1046 was first introduced by commit
:::::: eaf62ce1563b8557e3550acb97d5086120168750 arm64/signal: Set up and restore the GCS context for signal handlers

:::::: TO: Mark Brown <broonie@kernel.org>
:::::: CC: Catalin Marinas <catalin.marinas@arm.com>

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