From 1c101da8b971a36695319dce7a24711dc567a0dd Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Wed, 27 Nov 2019 10:30:15 +0000 Subject: arm64: mte: Allow user control of the tag check mode via prctl() By default, even if PROT_MTE is set on a memory range, there is no tag check fault reporting (SIGSEGV). Introduce a set of option to the exiting prctl(PR_SET_TAGGED_ADDR_CTRL) to allow user control of the tag check fault mode: PR_MTE_TCF_NONE - no reporting (default) PR_MTE_TCF_SYNC - synchronous tag check fault reporting PR_MTE_TCF_ASYNC - asynchronous tag check fault reporting These options translate into the corresponding SCTLR_EL1.TCF0 bitfield, context-switched by the kernel. Note that the kernel accesses to the user address space (e.g. read() system call) are not checked if the user thread tag checking mode is PR_MTE_TCF_NONE or PR_MTE_TCF_ASYNC. If the tag checking mode is PR_MTE_TCF_SYNC, the kernel makes a best effort to check its user address accesses, however it cannot always guarantee it. Signed-off-by: Catalin Marinas Cc: Will Deacon --- arch/arm64/include/asm/processor.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/arm64/include/asm/processor.h') diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index 240fe5e5b720..80e7f0573309 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -151,6 +151,9 @@ struct thread_struct { struct ptrauth_keys_user keys_user; struct ptrauth_keys_kernel keys_kernel; #endif +#ifdef CONFIG_ARM64_MTE + u64 sctlr_tcf0; +#endif }; static inline void arch_thread_struct_whitelist(unsigned long *offset, -- cgit v1.2.3