From 503eea451903142d08dc664d536738871953557d Mon Sep 17 00:00:00 2001 From: Patrick Delaunay Date: Fri, 5 Feb 2021 13:53:36 +0100 Subject: [PATCH] arm: cp15: update DACR value to activate access control Update the initial value of Domain Access Control Register (DACR) and set by default the access permission to client (DACR_Dn_CLIENT = 1U) for each of the 16 domains and no more to all-supervisor (DACR_Dn_MANAGER = 3U). This patch allows to activate the domain checking in MMU against the permission bits in the translation tables and avoids prefetching issue on ARMv7 [1]. Today it was already done for OMAP2 architecture ./arch/arm/mach-omap2/omap-cache.c::arm_init_domains introduced by commit de63ac278cba ("ARM: mmu: Set domain permissions to client access") which fixes lot of speculative prefetch aborts seen on OMAP5 secure devices. [1] https://developer.arm.com/documentation/ddi0406/b/System-Level-Architecture/Virtual-Memory-System-Architecture--VMSA-/Memory-access-control/The-Execute-Never--XN--attribute-and-instruction-prefetching Signed-off-by: Patrick Delaunay Reported-by: Ard Biesheuvel Signed-off-by: Patrick Delaunay --- arch/arm/lib/cache-cp15.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/arm/lib/cache-cp15.c b/arch/arm/lib/cache-cp15.c index 24050e5bdd..4854c39a35 100644 --- a/arch/arm/lib/cache-cp15.c +++ b/arch/arm/lib/cache-cp15.c @@ -203,9 +203,12 @@ static inline void mmu_setup(void) asm volatile("mcr p15, 0, %0, c2, c0, 0" : : "r" (gd->arch.tlb_addr) : "memory"); #endif - /* Set the access control to all-supervisor */ + /* + * initial value of Domain Access Control Register (DACR) + * Set the access control to client (1U) for each of the 16 domains + */ asm volatile("mcr p15, 0, %0, c3, c0, 0" - : : "r" (~0)); + : : "r" (0x55555555)); arm_init_domains();