From 9f3419315f3cdc41a7318e4d50ba18a592b30c8c Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Wed, 27 Nov 2019 10:00:27 +0000 Subject: arm64: mte: Add PROT_MTE support to mmap() and mprotect() To enable tagging on a memory range, the user must explicitly opt in via a new PROT_MTE flag passed to mmap() or mprotect(). Since this is a new memory type in the AttrIndx field of a pte, simplify the or'ing of these bits over the protection_map[] attributes by making MT_NORMAL index 0. There are two conditions for arch_vm_get_page_prot() to return the MT_NORMAL_TAGGED memory type: (1) the user requested it via PROT_MTE, registered as VM_MTE in the vm_flags, and (2) the vma supports MTE, decided during the mmap() call (only) and registered as VM_MTE_ALLOWED. arch_calc_vm_prot_bits() is responsible for registering the user request as VM_MTE. The newly introduced arch_calc_vm_flag_bits() sets VM_MTE_ALLOWED if the mapping is MAP_ANONYMOUS. An MTE-capable filesystem (RAM-based) may be able to set VM_MTE_ALLOWED during its mmap() file ops call. In addition, update VM_DATA_DEFAULT_FLAGS to allow mprotect(PROT_MTE) on stack or brk area. The Linux mmap() syscall currently ignores unknown PROT_* flags. In the presence of MTE, an mmap(PROT_MTE) on a file which does not support MTE will not report an error and the memory will not be mapped as Normal Tagged. For consistency, mprotect(PROT_MTE) will not report an error either if the memory range does not support MTE. Two subsequent patches in the series will propose tightening of this behaviour. Co-developed-by: Vincenzo Frascino Signed-off-by: Vincenzo Frascino Signed-off-by: Catalin Marinas Cc: Will Deacon --- arch/arm64/include/asm/memory.h | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) (limited to 'arch/arm64/include/asm/memory.h') diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index 1e0a78266410..e424fc3a68cb 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -126,14 +126,18 @@ /* * Memory types available. + * + * IMPORTANT: MT_NORMAL must be index 0 since vm_get_page_prot() may 'or' in + * the MT_NORMAL_TAGGED memory type for PROT_MTE mappings. Note + * that protection_map[] only contains MT_NORMAL attributes. */ -#define MT_DEVICE_nGnRnE 0 -#define MT_DEVICE_nGnRE 1 -#define MT_DEVICE_GRE 2 -#define MT_NORMAL_NC 3 -#define MT_NORMAL 4 -#define MT_NORMAL_WT 5 -#define MT_NORMAL_TAGGED 6 +#define MT_NORMAL 0 +#define MT_NORMAL_TAGGED 1 +#define MT_NORMAL_NC 2 +#define MT_NORMAL_WT 3 +#define MT_DEVICE_nGnRnE 4 +#define MT_DEVICE_nGnRE 5 +#define MT_DEVICE_GRE 6 /* * Memory types for Stage-2 translation -- cgit v1.2.3