From b1d30239ccde137bcd998437ef96d4af3a696415 Mon Sep 17 00:00:00 2001 From: Giorgio Dal Molin Date: Tue, 7 Apr 2020 17:31:11 +0200 Subject: ARM: i.MX: fixed enabling the MMU after switching in non secure mode. The Domain Access Control Register (DACR) in CP15 is banked between secure and non secure mode: there a copy of the reg. in secure mode and a second copy in non secure mode. As barebox boots on the imx7 SOC it runs in secure mode and initializes the secure-mode copy of DACR (with 0x00000001). After switching to non secure mode, for example with the command 'smc -n' or while booting a kernel image with global.bootm.secure_state=nonsecure, the active value of DACR is the copy in non-secure mode and that copy was still uninitialized and in an UNKNOWN state. This caused the cpu to hang as soon as the MMU was enabled in non-secure mode. We fix this by reading the DACR value in secure mode just before switching to non secure and then initializing it again with the same value. Signed-off-by: Giorgio Dal Molin Signed-off-by: Sascha Hauer --- arch/arm/cpu/mmu.h | 9 +++++++++ arch/arm/cpu/sm.c | 4 +++- 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/arch/arm/cpu/mmu.h b/arch/arm/cpu/mmu.h index 6e7a4c0350..c85e0ea050 100644 --- a/arch/arm/cpu/mmu.h +++ b/arch/arm/cpu/mmu.h @@ -39,6 +39,15 @@ static inline void set_ttbr(void *ttb) #define DOMAIN_CLIENT 1 #define DOMAIN_MANAGER 3 +static inline unsigned long get_domain(void) +{ + unsigned long dacr; + + asm volatile ("mrc p15, 0, %0, c3, c0, 0" : "=r"(dacr)); + + return dacr; +} + static inline void set_domain(unsigned val) { /* Set the Domain Access Control Register */ diff --git a/arch/arm/cpu/sm.c b/arch/arm/cpu/sm.c index 1f2c236d5a..cb33d96250 100644 --- a/arch/arm/cpu/sm.c +++ b/arch/arm/cpu/sm.c @@ -150,7 +150,7 @@ static bool armv7_have_security_extensions(void) int armv7_secure_monitor_install(void) { int mmuon; - unsigned long ttb, vbar; + unsigned long ttb, vbar, dacr; if (!armv7_have_security_extensions()) { pr_err("Security extensions not implemented.\n"); @@ -164,12 +164,14 @@ int armv7_secure_monitor_install(void) vbar = get_vbar(); ttb = get_ttbr(); + dacr = get_domain(); armv7_init_nonsec(); __armv7_secure_monitor_install(); set_ttbr((void *)ttb); set_vbar(vbar); + set_domain(dacr); if (mmuon) { /* -- cgit v1.2.3