From dd17143fcecdc2b8845de1b0c251fa4e49b0f572 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Thu, 20 Apr 2023 10:21:16 +0100 Subject: [PATCH] target/arm: Implement FEAT_PAN3 FEAT_PAN3 adds an EPAN bit to SCTLR_EL1 and SCTLR_EL2, which allows the PAN bit to make memory non-privileged-read/write if it is user-executable as well as if it is user-read/write. Implement this feature and enable it in the AArch64 'max' CPU. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Message-id: 20230331145045.2584941-4-peter.maydell@linaro.org --- docs/system/arm/emulation.rst | 1 + target/arm/cpu.h | 5 +++++ target/arm/cpu64.c | 2 +- target/arm/ptw.c | 14 +++++++++++++- 4 files changed, 20 insertions(+), 2 deletions(-) diff --git a/docs/system/arm/emulation.rst b/docs/system/arm/emulation.rst index 2062d71261..7338987875 100644 --- a/docs/system/arm/emulation.rst +++ b/docs/system/arm/emulation.rst @@ -56,6 +56,7 @@ the following architecture extensions: - FEAT_MTE3 (MTE Asymmetric Fault Handling) - FEAT_PAN (Privileged access never) - FEAT_PAN2 (AT S1E1R and AT S1E1W instruction variants affected by PSTATE.PAN) +- FEAT_PAN3 (Support for SCTLR_ELx.EPAN) - FEAT_PAuth (Pointer authentication) - FEAT_PMULL (PMULL, PMULL2 instructions) - FEAT_PMUv3p1 (PMU Extensions v3.1) diff --git a/target/arm/cpu.h b/target/arm/cpu.h index c097cae988..d469a2637b 100644 --- a/target/arm/cpu.h +++ b/target/arm/cpu.h @@ -3823,6 +3823,11 @@ static inline bool isar_feature_aa64_ats1e1(const ARMISARegisters *id) return FIELD_EX64(id->id_aa64mmfr1, ID_AA64MMFR1, PAN) >= 2; } +static inline bool isar_feature_aa64_pan3(const ARMISARegisters *id) +{ + return FIELD_EX64(id->id_aa64mmfr1, ID_AA64MMFR1, PAN) >= 3; +} + static inline bool isar_feature_aa64_hcx(const ARMISARegisters *id) { return FIELD_EX64(id->id_aa64mmfr1, ID_AA64MMFR1, HCX) != 0; diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c index 0fb07cc7b6..735ca54163 100644 --- a/target/arm/cpu64.c +++ b/target/arm/cpu64.c @@ -1302,7 +1302,7 @@ static void aarch64_max_initfn(Object *obj) t = FIELD_DP64(t, ID_AA64MMFR1, VH, 1); /* FEAT_VHE */ t = FIELD_DP64(t, ID_AA64MMFR1, HPDS, 1); /* FEAT_HPDS */ t = FIELD_DP64(t, ID_AA64MMFR1, LO, 1); /* FEAT_LOR */ - t = FIELD_DP64(t, ID_AA64MMFR1, PAN, 2); /* FEAT_PAN2 */ + t = FIELD_DP64(t, ID_AA64MMFR1, PAN, 3); /* FEAT_PAN3 */ t = FIELD_DP64(t, ID_AA64MMFR1, XNX, 1); /* FEAT_XNX */ t = FIELD_DP64(t, ID_AA64MMFR1, ETS, 1); /* FEAT_ETS */ t = FIELD_DP64(t, ID_AA64MMFR1, HCX, 1); /* FEAT_HCX */ diff --git a/target/arm/ptw.c b/target/arm/ptw.c index 6d72950a79..bd75da8dbc 100644 --- a/target/arm/ptw.c +++ b/target/arm/ptw.c @@ -947,6 +947,7 @@ static int get_S2prot(CPUARMState *env, int s2ap, int xn, bool s1_is_el0) static int get_S1prot(CPUARMState *env, ARMMMUIdx mmu_idx, bool is_aa64, int ap, int ns, int xn, int pxn) { + ARMCPU *cpu = env_archcpu(env); bool is_user = regime_is_user(env, mmu_idx); int prot_rw, user_rw; bool have_wxn; @@ -958,8 +959,19 @@ static int get_S1prot(CPUARMState *env, ARMMMUIdx mmu_idx, bool is_aa64, if (is_user) { prot_rw = user_rw; } else { + /* + * PAN controls can forbid data accesses but don't affect insn fetch. + * Plain PAN forbids data accesses if EL0 has data permissions; + * PAN3 forbids data accesses if EL0 has either data or exec perms. + * Note that for AArch64 the 'user can exec' case is exactly !xn. + * We make the IMPDEF choices that SCR_EL3.SIF and Realm EL2&0 + * do not affect EPAN. + */ if (user_rw && regime_is_pan(env, mmu_idx)) { - /* PAN forbids data accesses but doesn't affect insn fetch */ + prot_rw = 0; + } else if (cpu_isar_feature(aa64_pan3, cpu) && is_aa64 && + regime_is_pan(env, mmu_idx) && + (regime_sctlr(env, mmu_idx) & SCTLR_EPAN) && !xn) { prot_rw = 0; } else { prot_rw = simple_ap_to_rw_prot_is_user(ap, false);