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[Qemu-devel] [PATCH v2] target/arm: Implement NSACR gating of floating p
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PATCH v2] target/arm: Implement NSACR gating of floating point |
Date: |
Fri, 10 May 2019 12:03:57 +0100 |
The NSACR register allows secure code to configure the FPU
to be inaccessible to non-secure code. If the NSACR.CP10
bit is set then:
* NS accesses to the FPU trap as UNDEF (ie to NS EL1 or EL2)
* CPACR.{CP10,CP11} behave as if RAZ/WI
* HCPTR.{TCP11,TCP10} behave as if RAO/WI
Note that we do not implement the NSACR.NSASEDIS bit which
gates only access to Advanced SIMD, in the same way that
we don't implement the equivalent CPACR.ASEDIS and HCPTR.TASE.
Signed-off-by: Peter Maydell <address@hidden>
---
Changes v1->v2:
* fixed bug in cptr_el2_read() that meant we were forcing
HCPTR.{TCP11,TCP10} to 0 when they should be 1
---
target/arm/helper.c | 75 +++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 73 insertions(+), 2 deletions(-)
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 1e6eb0d0f36..f1fcce0313b 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -928,9 +928,36 @@ static void cpacr_write(CPUARMState *env, const
ARMCPRegInfo *ri,
}
value &= mask;
}
+
+ /*
+ * For A-profile AArch32 EL3 (but not M-profile secure mode), if NSACR.CP10
+ * is 0 then CPACR.{CP11,CP10} ignore writes and read as 0b00.
+ */
+ if (arm_feature(env, ARM_FEATURE_EL3) && !arm_el_is_aa64(env, 3) &&
+ !arm_is_secure(env) && !extract32(env->cp15.nsacr, 10, 1)) {
+ value &= ~(0xf << 20);
+ value |= env->cp15.cpacr_el1 & (0xf << 20);
+ }
+
env->cp15.cpacr_el1 = value;
}
+static uint64_t cpacr_read(CPUARMState *env, const ARMCPRegInfo *ri)
+{
+ /*
+ * For A-profile AArch32 EL3 (but not M-profile secure mode), if NSACR.CP10
+ * is 0 then CPACR.{CP11,CP10} ignore writes and read as 0b00.
+ */
+ uint64_t value = env->cp15.cpacr_el1;
+
+ if (arm_feature(env, ARM_FEATURE_EL3) && !arm_el_is_aa64(env, 3) &&
+ !arm_is_secure(env) && !extract32(env->cp15.nsacr, 10, 1)) {
+ value &= ~(0xf << 20);
+ }
+ return value;
+}
+
+
static void cpacr_reset(CPUARMState *env, const ARMCPRegInfo *ri)
{
/* Call cpacr_write() so that we reset with the correct RAO bits set
@@ -996,7 +1023,7 @@ static const ARMCPRegInfo v6_cp_reginfo[] = {
{ .name = "CPACR", .state = ARM_CP_STATE_BOTH, .opc0 = 3,
.crn = 1, .crm = 0, .opc1 = 0, .opc2 = 2, .accessfn = cpacr_access,
.access = PL1_RW, .fieldoffset = offsetof(CPUARMState, cp15.cpacr_el1),
- .resetfn = cpacr_reset, .writefn = cpacr_write },
+ .resetfn = cpacr_reset, .writefn = cpacr_write, .readfn = cpacr_read },
REGINFO_SENTINEL
};
@@ -4681,6 +4708,36 @@ uint64_t arm_hcr_el2_eff(CPUARMState *env)
return ret;
}
+static void cptr_el2_write(CPUARMState *env, const ARMCPRegInfo *ri,
+ uint64_t value)
+{
+ /*
+ * For A-profile AArch32 EL3, if NSACR.CP10
+ * is 0 then HCPTR.{TCP11,TCP10} ignore writes and read as 1.
+ */
+ if (arm_feature(env, ARM_FEATURE_EL3) && !arm_el_is_aa64(env, 3) &&
+ !arm_is_secure(env) && !extract32(env->cp15.nsacr, 10, 1)) {
+ value &= ~(0x3 << 10);
+ value |= env->cp15.cptr_el[2] & (0x3 << 10);
+ }
+ env->cp15.cptr_el[2] = value;
+}
+
+static uint64_t cptr_el2_read(CPUARMState *env, const ARMCPRegInfo *ri)
+{
+ /*
+ * For A-profile AArch32 EL3, if NSACR.CP10
+ * is 0 then HCPTR.{TCP11,TCP10} ignore writes and read as 1.
+ */
+ uint64_t value = env->cp15.cptr_el[2];
+
+ if (arm_feature(env, ARM_FEATURE_EL3) && !arm_el_is_aa64(env, 3) &&
+ !arm_is_secure(env) && !extract32(env->cp15.nsacr, 10, 1)) {
+ value |= 0x3 << 10;
+ }
+ return value;
+}
+
static const ARMCPRegInfo el2_cp_reginfo[] = {
{ .name = "HCR_EL2", .state = ARM_CP_STATE_AA64,
.type = ARM_CP_IO,
@@ -4728,7 +4785,8 @@ static const ARMCPRegInfo el2_cp_reginfo[] = {
{ .name = "CPTR_EL2", .state = ARM_CP_STATE_BOTH,
.opc0 = 3, .opc1 = 4, .crn = 1, .crm = 1, .opc2 = 2,
.access = PL2_RW, .accessfn = cptr_access, .resetvalue = 0,
- .fieldoffset = offsetof(CPUARMState, cp15.cptr_el[2]) },
+ .fieldoffset = offsetof(CPUARMState, cp15.cptr_el[2]),
+ .readfn = cptr_el2_read, .writefn = cptr_el2_write },
{ .name = "MAIR_EL2", .state = ARM_CP_STATE_BOTH,
.opc0 = 3, .opc1 = 4, .crn = 10, .crm = 2, .opc2 = 0,
.access = PL2_RW, .fieldoffset = offsetof(CPUARMState, cp15.mair_el[2]),
@@ -13527,6 +13585,19 @@ int fp_exception_el(CPUARMState *env, int cur_el)
break;
}
+ /*
+ * The NSACR allows A-profile AArch32 EL3 and M-profile secure mode
+ * to control non-secure access to the FPU. It doesn't have any
+ * effect if EL3 is AArch64 or if EL3 doesn't exist at all.
+ */
+ if ((arm_feature(env, ARM_FEATURE_EL3) && !arm_el_is_aa64(env, 3) &&
+ cur_el <= 2 && !arm_is_secure_below_el3(env))) {
+ if (!extract32(env->cp15.nsacr, 10, 1)) {
+ /* FP insns act as UNDEF */
+ return cur_el == 2 ? 2 : 1;
+ }
+ }
+
/* For the CPTR registers we don't need to guard with an ARM_FEATURE
* check because zero bits in the registers mean "don't trap".
*/
--
2.20.1
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