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target/arm: Implement MSR/MRS access to NS banked registers

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In v8M the MSR and MRS instructions have extra register value
encodings to allow secure code to access the non-secure banked
version of various special registers.

(We don't implement the MSPLIM_NS or PSPLIM_NS aliases, because
we don't currently implement the stack limit registers at all.)

Backports commit 50f11062d4c896408731d6a286bcd116d1e08465 from qemu
This commit is contained in:
Peter Maydell 2018-03-05 00:53:04 -05:00 committed by Lioncash
parent f31c3b32fb
commit 4b8bdda695
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GPG key ID: 4E3C3CC1031BA9C7
1 changed files with 110 additions and 0 deletions
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110
qemu/target/arm/helper.c
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@ -8165,12 +8165,68 @@ uint32_t HELPER(v7m_mrs)(CPUARMState *env, uint32_t reg)
break;
case 20: /* CONTROL */
return env->v7m.control[env->v7m.secure];
case 0x94: /* CONTROL_NS */
/* We have to handle this here because unprivileged Secure code
* can read the NS CONTROL register.
*/
if (!env->v7m.secure) {
return 0;
}
return env->v7m.control[M_REG_NS];
}
if (el == 0) {
return 0; /* unprivileged reads others as zero */
}
if (arm_feature(env, ARM_FEATURE_M_SECURITY)) {
switch (reg) {
case 0x88: /* MSP_NS */
if (!env->v7m.secure) {
return 0;
}
return env->v7m.other_ss_msp;
case 0x89: /* PSP_NS */
if (!env->v7m.secure) {
return 0;
}
return env->v7m.other_ss_psp;
case 0x90: /* PRIMASK_NS */
if (!env->v7m.secure) {
return 0;
}
return env->v7m.primask[M_REG_NS];
case 0x91: /* BASEPRI_NS */
if (!env->v7m.secure) {
return 0;
}
return env->v7m.basepri[M_REG_NS];
case 0x93: /* FAULTMASK_NS */
if (!env->v7m.secure) {
return 0;
}
return env->v7m.faultmask[M_REG_NS];
case 0x98: /* SP_NS */
{
/* This gives the non-secure SP selected based on whether we're
* currently in handler mode or not, using the NS CONTROL.SPSEL.
*/
bool spsel = env->v7m.control[M_REG_NS] & R_V7M_CONTROL_SPSEL_MASK;
if (!env->v7m.secure) {
return 0;
}
if (!arm_v7m_is_handler_mode(env) && spsel) {
return env->v7m.other_ss_psp;
} else {
return env->v7m.other_ss_msp;
}
}
default:
break;
}
}
switch (reg) {
case 8: /* MSP */
return (env->v7m.control[env->v7m.secure] & R_V7M_CONTROL_SPSEL_MASK) ?
@ -8210,6 +8266,60 @@ void HELPER(v7m_msr)(CPUARMState *env, uint32_t maskreg, uint32_t val)
return;
}
if (arm_feature(env, ARM_FEATURE_M_SECURITY)) {
switch (reg) {
case 0x88: /* MSP_NS */
if (!env->v7m.secure) {
return;
}
env->v7m.other_ss_msp = val;
return;
case 0x89: /* PSP_NS */
if (!env->v7m.secure) {
return;
}
env->v7m.other_ss_psp = val;
return;
case 0x90: /* PRIMASK_NS */
if (!env->v7m.secure) {
return;
}
env->v7m.primask[M_REG_NS] = val & 1;
return;
case 0x91: /* BASEPRI_NS */
if (!env->v7m.secure) {
return;
}
env->v7m.basepri[M_REG_NS] = val & 0xff;
return;
case 0x93: /* FAULTMASK_NS */
if (!env->v7m.secure) {
return;
}
env->v7m.faultmask[M_REG_NS] = val & 1;
return;
case 0x98: /* SP_NS */
{
/* This gives the non-secure SP selected based on whether we're
* currently in handler mode or not, using the NS CONTROL.SPSEL.
*/
bool spsel = env->v7m.control[M_REG_NS] & R_V7M_CONTROL_SPSEL_MASK;
if (!env->v7m.secure) {
return;
}
if (!arm_v7m_is_handler_mode(env) && spsel) {
env->v7m.other_ss_psp = val;
} else {
env->v7m.other_ss_msp = val;
}
return;
}
default:
break;
}
}
switch (reg) {
case 0:
case 1: