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nvic: Handle banked exceptions in nvic_recompute_state()

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Update the nvic_recompute_state() code to handle the security
extension and its associated banked registers.

Code that uses the resulting cached state (ie the irq
acknowledge and complete code) will be updated in a later
commit.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 1505240046-11454-9-git-send-email-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2017-09-12 19:13:55 +01:00
parent e1be0a576b
commit ff96c64aec
2 changed files with 147 additions and 5 deletions
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151
hw/intc/armv7m_nvic.c
View File

@ -54,6 +54,8 @@
* (higher than the highest possible priority value)
*/
#define NVIC_NOEXC_PRIO 0x100
/* Maximum priority of non-secure exceptions when AIRCR.PRIS is set */
#define NVIC_NS_PRIO_LIMIT 0x80
static const uint8_t nvic_id[] = {
0x00, 0xb0, 0x1b, 0x00, 0x0d, 0xe0, 0x05, 0xb1
@ -126,13 +128,139 @@ static bool nvic_isrpending(NVICState *s)
return false;
}
static bool exc_is_banked(int exc)
{
/* Return true if this is one of the limited set of exceptions which
* are banked (and thus have state in sec_vectors[])
*/
return exc == ARMV7M_EXCP_HARD ||
exc == ARMV7M_EXCP_MEM ||
exc == ARMV7M_EXCP_USAGE ||
exc == ARMV7M_EXCP_SVC ||
exc == ARMV7M_EXCP_PENDSV ||
exc == ARMV7M_EXCP_SYSTICK;
}
/* Return a mask word which clears the subpriority bits from
* a priority value for an M-profile exception, leaving only
* the group priority.
*/
static inline uint32_t nvic_gprio_mask(NVICState *s)
static inline uint32_t nvic_gprio_mask(NVICState *s, bool secure)
{
return ~0U << (s->prigroup[M_REG_NS] + 1);
return ~0U << (s->prigroup[secure] + 1);
}
static bool exc_targets_secure(NVICState *s, int exc)
{
/* Return true if this non-banked exception targets Secure state. */
if (!arm_feature(&s->cpu->env, ARM_FEATURE_M_SECURITY)) {
return false;
}
if (exc >= NVIC_FIRST_IRQ) {
return !s->itns[exc];
}
/* Function shouldn't be called for banked exceptions. */
assert(!exc_is_banked(exc));
switch (exc) {
case ARMV7M_EXCP_NMI:
case ARMV7M_EXCP_BUS:
return !(s->cpu->env.v7m.aircr & R_V7M_AIRCR_BFHFNMINS_MASK);
case ARMV7M_EXCP_SECURE:
return true;
case ARMV7M_EXCP_DEBUG:
/* TODO: controlled by DEMCR.SDME, which we don't yet implement */
return false;
default:
/* reset, and reserved (unused) low exception numbers.
* We'll get called by code that loops through all the exception
* numbers, but it doesn't matter what we return here as these
* non-existent exceptions will never be pended or active.
*/
return true;
}
}
static int exc_group_prio(NVICState *s, int rawprio, bool targets_secure)
{
/* Return the group priority for this exception, given its raw
* (group-and-subgroup) priority value and whether it is targeting
* secure state or not.
*/
if (rawprio < 0) {
return rawprio;
}
rawprio &= nvic_gprio_mask(s, targets_secure);
/* AIRCR.PRIS causes us to squash all NS priorities into the
* lower half of the total range
*/
if (!targets_secure &&
(s->cpu->env.v7m.aircr & R_V7M_AIRCR_PRIS_MASK)) {
rawprio = (rawprio >> 1) + NVIC_NS_PRIO_LIMIT;
}
return rawprio;
}
/* Recompute vectpending and exception_prio for a CPU which implements
* the Security extension
*/
static void nvic_recompute_state_secure(NVICState *s)
{
int i, bank;
int pend_prio = NVIC_NOEXC_PRIO;
int active_prio = NVIC_NOEXC_PRIO;
int pend_irq = 0;
bool pending_is_s_banked = false;
/* R_CQRV: precedence is by:
* - lowest group priority; if both the same then
* - lowest subpriority; if both the same then
* - lowest exception number; if both the same (ie banked) then
* - secure exception takes precedence
* Compare pseudocode RawExecutionPriority.
* Annoyingly, now we have two prigroup values (for S and NS)
* we can't do the loop comparison on raw priority values.
*/
for (i = 1; i < s->num_irq; i++) {
for (bank = M_REG_S; bank >= M_REG_NS; bank--) {
VecInfo *vec;
int prio;
bool targets_secure;
if (bank == M_REG_S) {
if (!exc_is_banked(i)) {
continue;
}
vec = &s->sec_vectors[i];
targets_secure = true;
} else {
vec = &s->vectors[i];
targets_secure = !exc_is_banked(i) && exc_targets_secure(s, i);
}
prio = exc_group_prio(s, vec->prio, targets_secure);
if (vec->enabled && vec->pending && prio < pend_prio) {
pend_prio = prio;
pend_irq = i;
pending_is_s_banked = (bank == M_REG_S);
}
if (vec->active && prio < active_prio) {
active_prio = prio;
}
}
}
s->vectpending_is_s_banked = pending_is_s_banked;
s->vectpending = pend_irq;
s->vectpending_prio = pend_prio;
s->exception_prio = active_prio;
trace_nvic_recompute_state_secure(s->vectpending,
s->vectpending_is_s_banked,
s->vectpending_prio,
s->exception_prio);
}
/* Recompute vectpending and exception_prio */
@ -143,6 +271,18 @@ static void nvic_recompute_state(NVICState *s)
int active_prio = NVIC_NOEXC_PRIO;
int pend_irq = 0;
/* In theory we could write one function that handled both
* the "security extension present" and "not present"; however
* the security related changes significantly complicate the
* recomputation just by themselves and mixing both cases together
* would be even worse, so we retain a separate non-secure-only
* version for CPUs which don't implement the security extension.
*/
if (arm_feature(&s->cpu->env, ARM_FEATURE_M_SECURITY)) {
nvic_recompute_state_secure(s);
return;
}
for (i = 1; i < s->num_irq; i++) {
VecInfo *vec = &s->vectors[i];
@ -156,11 +296,11 @@ static void nvic_recompute_state(NVICState *s)
}
if (active_prio > 0) {
active_prio &= nvic_gprio_mask(s);
active_prio &= nvic_gprio_mask(s, false);
}
if (pend_prio > 0) {
pend_prio &= nvic_gprio_mask(s);
pend_prio &= nvic_gprio_mask(s, false);
}
s->vectpending = pend_irq;
@ -186,7 +326,8 @@ static inline int nvic_exec_prio(NVICState *s)
} else if (env->v7m.primask[env->v7m.secure]) {
running = 0;
} else if (env->v7m.basepri[env->v7m.secure] > 0) {
running = env->v7m.basepri[env->v7m.secure] & nvic_gprio_mask(s);
running = env->v7m.basepri[env->v7m.secure] &
nvic_gprio_mask(s, env->v7m.secure);
} else {
running = NVIC_NOEXC_PRIO; /* lower than any possible priority */
}

1
hw/intc/trace-events
View File

@ -168,6 +168,7 @@ gicv3_redist_send_sgi(uint32_t cpu, int irq) "GICv3 redistributor 0x%x pending S
# hw/intc/armv7m_nvic.c
nvic_recompute_state(int vectpending, int vectpending_prio, int exception_prio) "NVIC state recomputed: vectpending %d vectpending_prio %d exception_prio %d"
nvic_recompute_state_secure(int vectpending, bool vectpending_is_s_banked, int vectpending_prio, int exception_prio) "NVIC state recomputed: vectpending %d is_s_banked %d vectpending_prio %d exception_prio %d"
nvic_set_prio(int irq, uint8_t prio) "NVIC set irq %d priority %d"
nvic_irq_update(int vectpending, int pendprio, int exception_prio, int level) "NVIC vectpending %d pending prio %d exception_prio %d: setting irq line to %d"
nvic_escalate_prio(int irq, int irqprio, int runprio) "NVIC escalating irq %d to HardFault: insufficient priority %d >= %d"