From: Fabian Aggeler <aggel...@ethz.ch>
bits when modifying CPSR.
Signed-off-by: Fabian Aggeler <aggel...@ethz.ch>
Signed-off-by: Greg Bellows <greg.bell...@linaro.org>
---------------
v3 -> v4
- Fixed up conditions for ignoring CPSR.A/F updates by isolating to v7 and
checking for the existence of EL3 and non-existence of EL2.
Signed-off-by: Greg Bellows <greg.bell...@linaro.org>
---
target-arm/helper.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 59 insertions(+), 3 deletions(-)
diff --git a/target-arm/helper.c b/target-arm/helper.c
index a22fcb2..2af8fbb 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -3645,9 +3645,6 @@ void cpsr_write(CPUARMState *env, uint32_t val, uint32_t
mask)
env->GE = (val >> 16) & 0xf;
}
- env->daif &= ~(CPSR_AIF & mask);
- env->daif |= val & CPSR_AIF & mask;
-
if ((env->uncached_cpsr ^ val) & mask & CPSR_M) {
if (bad_mode_switch(env, val & CPSR_M)) {
/* Attempt to switch to an invalid mode: this is UNPREDICTABLE.
@@ -3659,6 +3656,65 @@ void cpsr_write(CPUARMState *env, uint32_t val, uint32_t
mask)
switch_mode(env, val & CPSR_M);
}
}
+
+ /* In a V7 implementation that incldoes the security extensions but does
+ * not include Virtualization Extensions the SCR.FW and SCR.AW bits control
+ * whether non-secure software is allowed to change the CPSR_F and CPSR_A
+ * bits respectively.
+ *
+ * In a V8 implementation, it is permitted for privileged software to
+ * change the CPSR A/F bits regardless of the SCR.AW/FW bits. However,
+ * when the SPSR is copied to the CPSR, the SCR.AW/FW bits control whether
+ * the CPSR.A/F bits are copied.
+ */
+ if (!arm_feature(env, ARM_FEATURE_V8)) {
+ if ((mask & CPSR_A) &&
+ (val & CPSR_A) != (env->uncached_cpsr & CPSR_A) &&
+ arm_feature(env, ARM_FEATURE_EL3) &&
+ !arm_feature(env, ARM_FEATURE_EL2) &&
+ !(env->cp15.scr_el3 & SCR_AW) && !arm_is_secure(env)) {
+ qemu_log_mask(LOG_GUEST_ERROR,
+ "Ignoring attempt to switch CPSR_A flag from "
+ "non-secure world with SCR.AW bit clear\n");
+ mask &= ~CPSR_A;
+ }
+
+ if ((mask & CPSR_F) &&
+ (val & CPSR_F) != (env->uncached_cpsr & CPSR_F)) {
+ /*
+ * The existence of the security extension (EL3) and the
+ * non-existence of the virtualization extension affects whether
+ * the CPSR.F bit can be modified.
+ */
+ if (arm_feature(env, ARM_FEATURE_EL3) &&
+ !arm_feature(env, ARM_FEATURE_EL2)) {
+ /* CPSR.F cannot be changed in nonsecure with SCR.FW clear */
+ if (!(env->cp15.scr_el3 & SCR_FW) && !arm_is_secure(env)) {
+ qemu_log_mask(LOG_GUEST_ERROR,
+ "Ignoring attempt to switch CPSR_F flag from
"
+ "non-secure world with SCR.FW bit clear\n");
+ mask &= ~CPSR_F;
+ }
+
+ /* Check whether non-maskable FIQ (NMFI) support is enabled.
+ * If this bit is set software is not allowed to mask
+ * FIQs, but is allowed to set CPSR_F to 0.
+ */
+ if ((A32_BANKED_CURRENT_REG_GET(env, sctlr) & SCTLR_NMFI) &&
+ (val & CPSR_F)) {
+ qemu_log_mask(LOG_GUEST_ERROR,
+ "Ignoring attempt to enable CPSR_F flag "
+ "(non-maskable FIQ [NMFI] support "
+ "enabled)\n");
+ mask &= ~CPSR_F;
+ }
+ }
+ }
+ }
+
+ env->daif &= ~(CPSR_AIF & mask);
+ env->daif |= val & CPSR_AIF & mask;
+
mask &= ~CACHED_CPSR_BITS;
env->uncached_cpsr = (env->uncached_cpsr & ~mask) | (val & mask);
}
--
1.8.3.2
