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target-arm: respect SCR.FW, SCR.AW and SCTLR.NMFI

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Add checks of SCR AW/FW bits when performing writes of CPSR. These SCR bits
are used to control whether the CPSR masking bits can be adjusted from
non-secure state.

Backports commit 6e8801f9dea9e10449f4fd7d85dbe8cab708a686 from qemu
This commit is contained in:
Fabian Aggeler 2018-02-11 19:29:59 -05:00 committed by Lioncash
parent 9087027b85
commit 44fc779c6a
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GPG key ID: 4E3C3CC1031BA9C7
1 changed files with 54 additions and 0 deletions
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54
qemu/target-arm/helper.c
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@ -3155,6 +3155,8 @@ uint32_t cpsr_read(CPUARMState *env)
void cpsr_write(CPUARMState *env, uint32_t val, uint32_t mask)
{
uint32_t changed_daif;
if (mask & CPSR_NZCV) {
env->ZF = (~val) & CPSR_Z;
env->NF = val;
@ -3177,6 +3179,58 @@ void cpsr_write(CPUARMState *env, uint32_t val, uint32_t mask)
env->GE = (val >> 16) & 0xf;
}
/* In a V7 implementation that includes 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.
*/
if (!arm_feature(env, ARM_FEATURE_V8) &&
arm_feature(env, ARM_FEATURE_EL3) &&
!arm_feature(env, ARM_FEATURE_EL2) &&
!arm_is_secure(env)) {
changed_daif = (env->daif ^ val) & mask;
if (changed_daif & CPSR_A) {
/* Check to see if we are allowed to change the masking of async
* abort exceptions from a non-secure state.
*/
if (!(env->cp15.scr_el3 & SCR_AW)) {
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 (changed_daif & CPSR_F) {
/* Check to see if we are allowed to change the masking of FIQ
* exceptions from a non-secure state.
*/
if (!(env->cp15.scr_el3 & SCR_FW)) {
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;