From 266885f50f8b358307b1d4f3ec13e08491d4145f Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Sun, 4 Mar 2018 01:16:58 -0500 Subject: [PATCH] target/arm: Don't allow guest to make System space executable for M profile For an M profile v7PMSA, the system space (0xe0000000 - 0xffffffff) can never be executable, even if the guest tries to set the MPU registers up that way. Enforce this restriction. Backports commit bf446a11dfb17ae7d8ed2b61a2444804eb458075 from qemu --- qemu/target/arm/helper.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/qemu/target/arm/helper.c b/qemu/target/arm/helper.c index 5d4d1212..87b7c36d 100644 --- a/qemu/target/arm/helper.c +++ b/qemu/target/arm/helper.c @@ -7519,6 +7519,14 @@ static inline bool m_is_ppb_region(CPUARMState *env, uint32_t address) extract32(address, 20, 12) == 0xe00; } +static inline bool m_is_system_region(CPUARMState *env, uint32_t address) +{ + /* True if address is in the M profile system region + * 0xe0000000 - 0xffffffff + */ + return arm_feature(env, ARM_FEATURE_M) && extract32(address, 29, 3) == 0x7; +} + static bool get_phys_addr_pmsav7(CPUARMState *env, uint32_t address, int access_type, ARMMMUIdx mmu_idx, hwaddr *phys_ptr, int *prot, uint32_t *fsr) @@ -7622,6 +7630,12 @@ static bool get_phys_addr_pmsav7(CPUARMState *env, uint32_t address, get_phys_addr_pmsav7_default(env, mmu_idx, address, prot); } else { /* a MPU hit! */ uint32_t ap = extract32(env->pmsav7.dracr[n], 8, 3); + uint32_t xn = extract32(env->pmsav7.dracr[n], 12, 1); + + if (m_is_system_region(env, address)) { + /* System space is always execute never */ + xn = 1; + } if (is_user) { /* User mode AP bit decoding */ switch (ap) { @@ -7662,7 +7676,7 @@ static bool get_phys_addr_pmsav7(CPUARMState *env, uint32_t address, } /* execute never */ - if (env->pmsav7.dracr[n] & (1 << 12)) { + if (xn) { *prot &= ~PAGE_EXEC; } }