From 4b65a5db362783ab4b04ca1c1d2ad70ed9b0ba2a Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Fri, 1 Jul 2016 16:53:00 +0100 Subject: arm64: Introduce uaccess_{disable,enable} functionality based on TTBR0_EL1 This patch adds the uaccess macros/functions to disable access to user space by setting TTBR0_EL1 to a reserved zeroed page. Since the value written to TTBR0_EL1 must be a physical address, for simplicity this patch introduces a reserved_ttbr0 page at a constant offset from swapper_pg_dir. The uaccess_disable code uses the ttbr1_el1 value adjusted by the reserved_ttbr0 offset. Enabling access to user is done by restoring TTBR0_EL1 with the value from the struct thread_info ttbr0 variable. Interrupts must be disabled during the uaccess_ttbr0_enable code to ensure the atomicity of the thread_info.ttbr0 read and TTBR0_EL1 write. This patch also moves the get_thread_info asm macro from entry.S to assembler.h for reuse in the uaccess_ttbr0_* macros. Cc: Will Deacon Cc: James Morse Cc: Kees Cook Cc: Mark Rutland Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/kernel-pgtable.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'arch/arm64/include/asm/kernel-pgtable.h') diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h index 7e51d1b57c0c..7803343e5881 100644 --- a/arch/arm64/include/asm/kernel-pgtable.h +++ b/arch/arm64/include/asm/kernel-pgtable.h @@ -19,6 +19,7 @@ #ifndef __ASM_KERNEL_PGTABLE_H #define __ASM_KERNEL_PGTABLE_H +#include #include /* @@ -54,6 +55,12 @@ #define SWAPPER_DIR_SIZE (SWAPPER_PGTABLE_LEVELS * PAGE_SIZE) #define IDMAP_DIR_SIZE (IDMAP_PGTABLE_LEVELS * PAGE_SIZE) +#ifdef CONFIG_ARM64_SW_TTBR0_PAN +#define RESERVED_TTBR0_SIZE (PAGE_SIZE) +#else +#define RESERVED_TTBR0_SIZE (0) +#endif + /* Initial memory map size */ #if ARM64_SWAPPER_USES_SECTION_MAPS #define SWAPPER_BLOCK_SHIFT SECTION_SHIFT -- cgit v1.2.3-59-g8ed1b