From 3d2403fd10a1dbb359b154af41ffed9f2a7520e8 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Wed, 2 Dec 2020 13:15:55 +0000 Subject: arm64: uaccess: remove set_fs() Now that the uaccess primitives dont take addr_limit into account, we have no need to manipulate this via set_fs() and get_fs(). Remove support for these, along with some infrastructure this renders redundant. We no longer need to flip UAO to access kernel memory under KERNEL_DS, and head.S unconditionally clears UAO for all kernel configurations via an ERET in init_kernel_el. Thus, we don't need to dynamically flip UAO, nor do we need to context-switch it. However, we still need to adjust PAN during SDEI entry. Masking of __user pointers no longer needs to use the dynamic value of addr_limit, and can use a constant derived from the maximum possible userspace task size. A new TASK_SIZE_MAX constant is introduced for this, which is also used by core code. In configurations supporting 52-bit VAs, this may include a region of unusable VA space above a 48-bit TTBR0 limit, but never includes any portion of TTBR1. Note that TASK_SIZE_MAX is an exclusive limit, while USER_DS and KERNEL_DS were inclusive limits, and is converted to a mask by subtracting one. As the SDEI entry code repurposes the otherwise unnecessary pt_regs::orig_addr_limit field to store the TTBR1 of the interrupted context, for now we rename that to pt_regs::sdei_ttbr1. In future we can consider factoring that out. Signed-off-by: Mark Rutland Acked-by: James Morse Cc: Christoph Hellwig Cc: Will Deacon Link: https://lore.kernel.org/r/20201202131558.39270-10-mark.rutland@arm.com Signed-off-by: Catalin Marinas --- arch/arm64/Kconfig | 1 - 1 file changed, 1 deletion(-) (limited to 'arch/arm64/Kconfig') diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 0f8b2e35ba99..6fae3ec1f2b6 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -195,7 +195,6 @@ config ARM64 select PCI_SYSCALL if PCI select POWER_RESET select POWER_SUPPLY - select SET_FS select SPARSE_IRQ select SWIOTLB select SYSCTL_EXCEPTION_TRACE -- cgit From 1517c4facf2e66401394998dba1ee236fd261310 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Wed, 2 Dec 2020 13:15:58 +0000 Subject: arm64: uaccess: remove vestigal UAO support Now that arm64 no longer uses UAO, remove the vestigal feature detection code and Kconfig text. Signed-off-by: Mark Rutland Cc: Christoph Hellwig Cc: James Morse Cc: Will Deacon Link: https://lore.kernel.org/r/20201202131558.39270-13-mark.rutland@arm.com Signed-off-by: Catalin Marinas --- arch/arm64/Kconfig | 21 --------------------- 1 file changed, 21 deletions(-) (limited to 'arch/arm64/Kconfig') diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 6fae3ec1f2b6..8d13b9135634 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1427,27 +1427,6 @@ endmenu menu "ARMv8.2 architectural features" -config ARM64_UAO - bool "Enable support for User Access Override (UAO)" - default y - help - User Access Override (UAO; part of the ARMv8.2 Extensions) - causes the 'unprivileged' variant of the load/store instructions to - be overridden to be privileged. - - This option changes get_user() and friends to use the 'unprivileged' - variant of the load/store instructions. This ensures that user-space - really did have access to the supplied memory. When addr_limit is - set to kernel memory the UAO bit will be set, allowing privileged - access to kernel memory. - - Choosing this option will cause copy_to_user() et al to use user-space - memory permissions. - - The feature is detected at runtime, the kernel will use the - regular load/store instructions if the cpu does not implement the - feature. - config ARM64_PMEM bool "Enable support for persistent memory" select ARCH_HAS_PMEM_API -- cgit