blob: 72bc33f2269ec74907fbc33d31b4e800f9074d8f [file] [log] [blame]
/*
* Copyright (c) 2017-2024, Arm Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <assert.h>
#include <inttypes.h>
#include <stdint.h>
#include <string.h>
#include <arch_helpers.h>
#include <arch_features.h>
#include <bl31/ehf.h>
#include <bl31/interrupt_mgmt.h>
#include <common/bl_common.h>
#include <common/debug.h>
#include <common/runtime_svc.h>
#include <lib/cassert.h>
#include <services/sdei.h>
#include "sdei_private.h"
/* x0-x17 GPREGS context */
#define SDEI_SAVED_GPREGS 18U
/* Maximum preemption nesting levels: Critical priority and Normal priority */
#define MAX_EVENT_NESTING 2U
/* Per-CPU SDEI state access macro */
#define sdei_get_this_pe_state() (&cpu_state[plat_my_core_pos()])
/* Structure to store information about an outstanding dispatch */
typedef struct sdei_dispatch_context {
sdei_ev_map_t *map;
uint64_t x[SDEI_SAVED_GPREGS];
jmp_buf *dispatch_jmp;
/* Exception state registers */
uint64_t elr_el3;
uint64_t spsr_el3;
#if DYNAMIC_WORKAROUND_CVE_2018_3639
/* CVE-2018-3639 mitigation state */
uint64_t disable_cve_2018_3639;
#endif
} sdei_dispatch_context_t;
/* Per-CPU SDEI state data */
typedef struct sdei_cpu_state {
sdei_dispatch_context_t dispatch_stack[MAX_EVENT_NESTING];
unsigned short stack_top; /* Empty ascending */
bool pe_masked;
bool pending_enables;
} sdei_cpu_state_t;
/* SDEI states for all cores in the system */
static sdei_cpu_state_t cpu_state[PLATFORM_CORE_COUNT];
int64_t sdei_pe_mask(void)
{
int64_t ret = 0;
sdei_cpu_state_t *state = sdei_get_this_pe_state();
/*
* Return value indicates whether this call had any effect in the mask
* status of this PE.
*/
if (!state->pe_masked) {
state->pe_masked = true;
ret = 1;
}
return ret;
}
void sdei_pe_unmask(void)
{
unsigned int i;
sdei_ev_map_t *map;
sdei_entry_t *se;
sdei_cpu_state_t *state = sdei_get_this_pe_state();
uint64_t my_mpidr = read_mpidr_el1() & MPIDR_AFFINITY_MASK;
/*
* If there are pending enables, iterate through the private mappings
* and enable those bound maps that are in enabled state. Also, iterate
* through shared mappings and enable interrupts of events that are
* targeted to this PE.
*/
if (state->pending_enables) {
for_each_private_map(i, map) {
se = get_event_entry(map);
if (is_map_bound(map) && GET_EV_STATE(se, ENABLED))
plat_ic_enable_interrupt(map->intr);
}
for_each_shared_map(i, map) {
se = get_event_entry(map);
sdei_map_lock(map);
if (is_map_bound(map) && GET_EV_STATE(se, ENABLED) &&
(se->reg_flags == SDEI_REGF_RM_PE) &&
(se->affinity == my_mpidr)) {
plat_ic_enable_interrupt(map->intr);
}
sdei_map_unlock(map);
}
}
state->pending_enables = false;
state->pe_masked = false;
}
/* Push a dispatch context to the dispatch stack */
static sdei_dispatch_context_t *push_dispatch(void)
{
sdei_cpu_state_t *state = sdei_get_this_pe_state();
sdei_dispatch_context_t *disp_ctx;
/* Cannot have more than max events */
assert(state->stack_top < MAX_EVENT_NESTING);
disp_ctx = &state->dispatch_stack[state->stack_top];
state->stack_top++;
return disp_ctx;
}
/* Pop a dispatch context to the dispatch stack */
static sdei_dispatch_context_t *pop_dispatch(void)
{
sdei_cpu_state_t *state = sdei_get_this_pe_state();
if (state->stack_top == 0U)
return NULL;
assert(state->stack_top <= MAX_EVENT_NESTING);
state->stack_top--;
return &state->dispatch_stack[state->stack_top];
}
/* Retrieve the context at the top of dispatch stack */
static sdei_dispatch_context_t *get_outstanding_dispatch(void)
{
sdei_cpu_state_t *state = sdei_get_this_pe_state();
if (state->stack_top == 0U)
return NULL;
assert(state->stack_top <= MAX_EVENT_NESTING);
return &state->dispatch_stack[state->stack_top - 1U];
}
static sdei_dispatch_context_t *save_event_ctx(sdei_ev_map_t *map,
void *tgt_ctx)
{
sdei_dispatch_context_t *disp_ctx;
const gp_regs_t *tgt_gpregs;
const el3_state_t *tgt_el3;
assert(tgt_ctx != NULL);
tgt_gpregs = get_gpregs_ctx(tgt_ctx);
tgt_el3 = get_el3state_ctx(tgt_ctx);
disp_ctx = push_dispatch();
assert(disp_ctx != NULL);
disp_ctx->map = map;
/* Save general purpose and exception registers */
memcpy(disp_ctx->x, tgt_gpregs, sizeof(disp_ctx->x));
disp_ctx->spsr_el3 = read_ctx_reg(tgt_el3, CTX_SPSR_EL3);
disp_ctx->elr_el3 = read_ctx_reg(tgt_el3, CTX_ELR_EL3);
return disp_ctx;
}
static void restore_event_ctx(const sdei_dispatch_context_t *disp_ctx, void *tgt_ctx)
{
gp_regs_t *tgt_gpregs;
el3_state_t *tgt_el3;
assert(tgt_ctx != NULL);
tgt_gpregs = get_gpregs_ctx(tgt_ctx);
tgt_el3 = get_el3state_ctx(tgt_ctx);
CASSERT(sizeof(disp_ctx->x) == (SDEI_SAVED_GPREGS * sizeof(uint64_t)),
foo);
/* Restore general purpose and exception registers */
memcpy(tgt_gpregs, disp_ctx->x, sizeof(disp_ctx->x));
write_ctx_reg(tgt_el3, CTX_SPSR_EL3, disp_ctx->spsr_el3);
write_ctx_reg(tgt_el3, CTX_ELR_EL3, disp_ctx->elr_el3);
#if DYNAMIC_WORKAROUND_CVE_2018_3639
cve_2018_3639_t *tgt_cve_2018_3639;
tgt_cve_2018_3639 = get_cve_2018_3639_ctx(tgt_ctx);
/* Restore CVE-2018-3639 mitigation state */
write_ctx_reg(tgt_cve_2018_3639, CTX_CVE_2018_3639_DISABLE,
disp_ctx->disable_cve_2018_3639);
#endif
}
static void save_secure_context(void)
{
cm_el1_sysregs_context_save(SECURE);
}
/* Restore Secure context and arrange to resume it at the next ERET */
static void restore_and_resume_secure_context(void)
{
cm_el1_sysregs_context_restore(SECURE);
cm_set_next_eret_context(SECURE);
}
/*
* Restore Non-secure context and arrange to resume it at the next ERET. Return
* pointer to the Non-secure context.
*/
static cpu_context_t *restore_and_resume_ns_context(void)
{
cpu_context_t *ns_ctx;
cm_el1_sysregs_context_restore(NON_SECURE);
cm_set_next_eret_context(NON_SECURE);
ns_ctx = cm_get_context(NON_SECURE);
assert(ns_ctx != NULL);
return ns_ctx;
}
/*
* Prepare for ERET:
* - Set the ELR to the registered handler address
* - Set the SPSR register as described in the SDEI documentation and
* the AArch64.TakeException() pseudocode function in
* ARM DDI 0487F.c page J1-7635
*/
static void sdei_set_elr_spsr(sdei_entry_t *se, sdei_dispatch_context_t *disp_ctx)
{
unsigned int client_el = sdei_client_el();
u_register_t sdei_spsr = SPSR_64(client_el, MODE_SP_ELX,
DISABLE_ALL_EXCEPTIONS);
u_register_t interrupted_pstate = disp_ctx->spsr_el3;
/* Check the SPAN bit in the client el SCTLR */
u_register_t client_el_sctlr;
if (client_el == MODE_EL2) {
client_el_sctlr = read_sctlr_el2();
} else {
client_el_sctlr = read_sctlr_el1();
}
/*
* Check whether to force the PAN bit or use the value in the
* interrupted EL according to the check described in
* TakeException. Since the client can only be Non-Secure
* EL2 or El1 some of the conditions in ElIsInHost() we know
* will always be True.
* When the client_el is EL2 we know that there will be a SPAN
* bit in SCTLR_EL2 as we have already checked for the condition
* HCR_EL2.E2H = 1 and HCR_EL2.TGE = 1
*/
u_register_t hcr_el2 = read_hcr();
bool el_is_in_host = (read_feat_vhe_id_field() != 0U) &&
(hcr_el2 & HCR_TGE_BIT) &&
(hcr_el2 & HCR_E2H_BIT);
if (is_feat_pan_supported() &&
((client_el == MODE_EL1) ||
(client_el == MODE_EL2 && el_is_in_host)) &&
((client_el_sctlr & SCTLR_SPAN_BIT) == 0U)) {
sdei_spsr |= SPSR_PAN_BIT;
} else {
sdei_spsr |= (interrupted_pstate & SPSR_PAN_BIT);
}
/* If SSBS is implemented, take the value from the client el SCTLR */
u_register_t ssbs_enabled = (read_id_aa64pfr1_el1()
>> ID_AA64PFR1_EL1_SSBS_SHIFT)
& ID_AA64PFR1_EL1_SSBS_MASK;
if (ssbs_enabled != SSBS_UNAVAILABLE) {
u_register_t ssbs_bit = ((client_el_sctlr & SCTLR_DSSBS_BIT)
>> SCTLR_DSSBS_SHIFT)
<< SPSR_SSBS_SHIFT_AARCH64;
sdei_spsr |= ssbs_bit;
}
/* If MTE is implemented in the client el set the TCO bit */
if (is_feat_mte_supported()) {
sdei_spsr |= SPSR_TCO_BIT_AARCH64;
}
/* Take the DIT field from the pstate of the interrupted el */
sdei_spsr |= (interrupted_pstate & SPSR_DIT_BIT);
cm_set_elr_spsr_el3(NON_SECURE, (uintptr_t) se->ep, sdei_spsr);
}
/*
* Populate the Non-secure context so that the next ERET will dispatch to the
* SDEI client.
*/
static void setup_ns_dispatch(sdei_ev_map_t *map, sdei_entry_t *se,
cpu_context_t *ctx, jmp_buf *dispatch_jmp)
{
sdei_dispatch_context_t *disp_ctx;
/* Push the event and context */
disp_ctx = save_event_ctx(map, ctx);
/*
* Setup handler arguments:
*
* - x0: Event number
* - x1: Handler argument supplied at the time of event registration
* - x2: Interrupted PC
* - x3: Interrupted SPSR
*/
SMC_SET_GP(ctx, CTX_GPREG_X0, (uint64_t) map->ev_num);
SMC_SET_GP(ctx, CTX_GPREG_X1, se->arg);
SMC_SET_GP(ctx, CTX_GPREG_X2, disp_ctx->elr_el3);
SMC_SET_GP(ctx, CTX_GPREG_X3, disp_ctx->spsr_el3);
/* Setup the elr and spsr register to prepare for ERET */
sdei_set_elr_spsr(se, disp_ctx);
#if DYNAMIC_WORKAROUND_CVE_2018_3639
cve_2018_3639_t *tgt_cve_2018_3639;
tgt_cve_2018_3639 = get_cve_2018_3639_ctx(ctx);
/* Save CVE-2018-3639 mitigation state */
disp_ctx->disable_cve_2018_3639 = read_ctx_reg(tgt_cve_2018_3639,
CTX_CVE_2018_3639_DISABLE);
/* Force SDEI handler to execute with mitigation enabled by default */
write_ctx_reg(tgt_cve_2018_3639, CTX_CVE_2018_3639_DISABLE, 0);
#endif
disp_ctx->dispatch_jmp = dispatch_jmp;
}
/* Handle a triggered SDEI interrupt while events were masked on this PE */
static void handle_masked_trigger(sdei_ev_map_t *map, sdei_entry_t *se,
sdei_cpu_state_t *state, unsigned int intr_raw)
{
uint64_t my_mpidr __unused = (read_mpidr_el1() & MPIDR_AFFINITY_MASK);
bool disable = false;
/* Nothing to do for event 0 */
if (map->ev_num == SDEI_EVENT_0)
return;
/*
* For a private event, or for a shared event specifically routed to
* this CPU, we disable interrupt, leave the interrupt pending, and do
* EOI.
*/
if (is_event_private(map) || (se->reg_flags == SDEI_REGF_RM_PE))
disable = true;
if (se->reg_flags == SDEI_REGF_RM_PE)
assert(se->affinity == my_mpidr);
if (disable) {
plat_ic_disable_interrupt(map->intr);
plat_ic_set_interrupt_pending(map->intr);
plat_ic_end_of_interrupt(intr_raw);
state->pending_enables = true;
return;
}
/*
* We just received a shared event with routing set to ANY PE. The
* interrupt can't be delegated on this PE as SDEI events are masked.
* However, because its routing mode is ANY, it is possible that the
* event can be delegated on any other PE that hasn't masked events.
* Therefore, we set the interrupt back pending so as to give other
* suitable PEs a chance of handling it.
*/
assert(plat_ic_is_spi(map->intr) != 0);
plat_ic_set_interrupt_pending(map->intr);
/*
* Leaving the same interrupt pending also means that the same interrupt
* can target this PE again as soon as this PE leaves EL3. Whether and
* how often that happens depends on the implementation of GIC.
*
* We therefore call a platform handler to resolve this situation.
*/
plat_sdei_handle_masked_trigger(my_mpidr, map->intr);
/* This PE is masked. We EOI the interrupt, as it can't be delegated */
plat_ic_end_of_interrupt(intr_raw);
}
/* SDEI main interrupt handler */
int sdei_intr_handler(uint32_t intr_raw, uint32_t flags, void *handle,
void *cookie)
{
sdei_entry_t *se;
cpu_context_t *ctx;
sdei_ev_map_t *map;
const sdei_dispatch_context_t *disp_ctx;
unsigned int sec_state;
sdei_cpu_state_t *state;
uint32_t intr;
jmp_buf dispatch_jmp;
const uint64_t mpidr = read_mpidr_el1();
/*
* To handle an event, the following conditions must be true:
*
* 1. Event must be signalled
* 2. Event must be enabled
* 3. This PE must be a target PE for the event
* 4. PE must be unmasked for SDEI
* 5. If this is a normal event, no event must be running
* 6. If this is a critical event, no critical event must be running
*
* (1) and (2) are true when this function is running
* (3) is enforced in GIC by selecting the appropriate routing option
* (4) is satisfied by client calling PE_UNMASK
* (5) and (6) is enforced using interrupt priority, the RPR, in GIC:
* - Normal SDEI events belong to Normal SDE priority class
* - Critical SDEI events belong to Critical CSDE priority class
*
* The interrupt has already been acknowledged, and therefore is active,
* so no other PE can handle this event while we are at it.
*
* Find if this is an SDEI interrupt. There must be an event mapped to
* this interrupt
*/
intr = plat_ic_get_interrupt_id(intr_raw);
map = find_event_map_by_intr(intr, (plat_ic_is_spi(intr) != 0));
if (map == NULL) {
ERROR("No SDEI map for interrupt %u\n", intr);
panic();
}
/*
* Received interrupt number must either correspond to event 0, or must
* be bound interrupt.
*/
assert((map->ev_num == SDEI_EVENT_0) || is_map_bound(map));
se = get_event_entry(map);
state = sdei_get_this_pe_state();
if (state->pe_masked) {
/*
* Interrupts received while this PE was masked can't be
* dispatched.
*/
SDEI_LOG("interrupt %u on %" PRIx64 " while PE masked\n",
map->intr, mpidr);
if (is_event_shared(map))
sdei_map_lock(map);
handle_masked_trigger(map, se, state, intr_raw);
if (is_event_shared(map))
sdei_map_unlock(map);
return 0;
}
/* Insert load barrier for signalled SDEI event */
if (map->ev_num == SDEI_EVENT_0)
dmbld();
if (is_event_shared(map))
sdei_map_lock(map);
/* Assert shared event routed to this PE had been configured so */
if (is_event_shared(map) && (se->reg_flags == SDEI_REGF_RM_PE)) {
assert(se->affinity == (mpidr & MPIDR_AFFINITY_MASK));
}
if (!can_sdei_state_trans(se, DO_DISPATCH)) {
SDEI_LOG("SDEI event 0x%x can't be dispatched; state=0x%x\n",
map->ev_num, se->state);
/*
* If the event is registered, leave the interrupt pending so
* that it's delivered when the event is enabled.
*/
if (GET_EV_STATE(se, REGISTERED))
plat_ic_set_interrupt_pending(map->intr);
/*
* The interrupt was disabled or unregistered after the handler
* started to execute, which means now the interrupt is already
* disabled and we just need to EOI the interrupt.
*/
plat_ic_end_of_interrupt(intr_raw);
if (is_event_shared(map))
sdei_map_unlock(map);
return 0;
}
disp_ctx = get_outstanding_dispatch();
if (is_event_critical(map)) {
/*
* If this event is Critical, and if there's an outstanding
* dispatch, assert the latter is a Normal dispatch. Critical
* events can preempt an outstanding Normal event dispatch.
*/
if (disp_ctx != NULL)
assert(is_event_normal(disp_ctx->map));
} else {
/*
* If this event is Normal, assert that there are no outstanding
* dispatches. Normal events can't preempt any outstanding event
* dispatches.
*/
assert(disp_ctx == NULL);
}
sec_state = get_interrupt_src_ss(flags);
if (is_event_shared(map))
sdei_map_unlock(map);
SDEI_LOG("ACK %" PRIx64 ", ev:0x%x ss:%d spsr:%lx ELR:%lx\n",
mpidr, map->ev_num, sec_state, read_spsr_el3(), read_elr_el3());
ctx = handle;
/*
* Check if we interrupted secure state. Perform a context switch so
* that we can delegate to NS.
*/
if (sec_state == SECURE) {
save_secure_context();
ctx = restore_and_resume_ns_context();
}
/* Synchronously dispatch event */
setup_ns_dispatch(map, se, ctx, &dispatch_jmp);
begin_sdei_synchronous_dispatch(&dispatch_jmp);
/*
* We reach here when client completes the event.
*
* If the cause of dispatch originally interrupted the Secure world,
* resume Secure.
*
* No need to save the Non-secure context ahead of a world switch: the
* Non-secure context was fully saved before dispatch, and has been
* returned to its pre-dispatch state.
*/
if (sec_state == SECURE)
restore_and_resume_secure_context();
/*
* The event was dispatched after receiving SDEI interrupt. With
* the event handling completed, EOI the corresponding
* interrupt.
*/
if ((map->ev_num != SDEI_EVENT_0) && !is_map_bound(map)) {
ERROR("Invalid SDEI mapping: ev=0x%x\n", map->ev_num);
panic();
}
plat_ic_end_of_interrupt(intr_raw);
return 0;
}
/*
* Explicitly dispatch the given SDEI event.
*
* When calling this API, the caller must be prepared for the SDEI dispatcher to
* restore and make Non-secure context as active. This call returns only after
* the client has completed the dispatch. Then, the Non-secure context will be
* active, and the following ERET will return to Non-secure.
*
* Should the caller require re-entry to Secure, it must restore the Secure
* context and program registers for ERET.
*/
int sdei_dispatch_event(int ev_num)
{
sdei_entry_t *se;
sdei_ev_map_t *map;
cpu_context_t *ns_ctx;
sdei_dispatch_context_t *disp_ctx;
sdei_cpu_state_t *state;
jmp_buf dispatch_jmp;
/* Can't dispatch if events are masked on this PE */
state = sdei_get_this_pe_state();
if (state->pe_masked)
return -1;
/* Event 0 can't be dispatched */
if (ev_num == SDEI_EVENT_0)
return -1;
/* Locate mapping corresponding to this event */
map = find_event_map(ev_num);
if (map == NULL)
return -1;
/* Only explicit events can be dispatched */
if (!is_map_explicit(map))
return -1;
/* Examine state of dispatch stack */
disp_ctx = get_outstanding_dispatch();
if (disp_ctx != NULL) {
/*
* There's an outstanding dispatch. If the outstanding dispatch
* is critical, no more dispatches are possible.
*/
if (is_event_critical(disp_ctx->map))
return -1;
/*
* If the outstanding dispatch is Normal, only critical events
* can be dispatched.
*/
if (is_event_normal(map))
return -1;
}
se = get_event_entry(map);
if (!can_sdei_state_trans(se, DO_DISPATCH))
return -1;
/*
* Prepare for NS dispatch by restoring the Non-secure context and
* marking that as active.
*/
ns_ctx = restore_and_resume_ns_context();
/* Activate the priority corresponding to the event being dispatched */
ehf_activate_priority(sdei_event_priority(map));
/* Dispatch event synchronously */
setup_ns_dispatch(map, se, ns_ctx, &dispatch_jmp);
begin_sdei_synchronous_dispatch(&dispatch_jmp);
/*
* We reach here when client completes the event.
*
* Deactivate the priority level that was activated at the time of
* explicit dispatch.
*/
ehf_deactivate_priority(sdei_event_priority(map));
return 0;
}
static void end_sdei_synchronous_dispatch(jmp_buf *buffer)
{
longjmp(*buffer, 1);
}
int sdei_event_complete(bool resume, uint64_t pc)
{
sdei_dispatch_context_t *disp_ctx;
sdei_entry_t *se;
sdei_ev_map_t *map;
cpu_context_t *ctx;
sdei_action_t act;
unsigned int client_el = sdei_client_el();
/* Return error if called without an active event */
disp_ctx = get_outstanding_dispatch();
if (disp_ctx == NULL)
return SDEI_EDENY;
/* Validate resumption point */
if (resume && (plat_sdei_validate_entry_point(pc, client_el) != 0))
return SDEI_EDENY;
map = disp_ctx->map;
assert(map != NULL);
se = get_event_entry(map);
if (is_event_shared(map))
sdei_map_lock(map);
act = resume ? DO_COMPLETE_RESUME : DO_COMPLETE;
if (!can_sdei_state_trans(se, act)) {
if (is_event_shared(map))
sdei_map_unlock(map);
return SDEI_EDENY;
}
if (is_event_shared(map))
sdei_map_unlock(map);
/* Having done sanity checks, pop dispatch */
(void) pop_dispatch();
SDEI_LOG("EOI:%lx, %d spsr:%lx elr:%lx\n", read_mpidr_el1(),
map->ev_num, read_spsr_el3(), read_elr_el3());
/*
* Restore Non-secure to how it was originally interrupted. Once done,
* it's up-to-date with the saved copy.
*/
ctx = cm_get_context(NON_SECURE);
restore_event_ctx(disp_ctx, ctx);
if (resume) {
/*
* Complete-and-resume call. Prepare the Non-secure context
* (currently active) for complete and resume.
*/
cm_set_elr_spsr_el3(NON_SECURE, pc, SPSR_64(client_el,
MODE_SP_ELX, DISABLE_ALL_EXCEPTIONS));
/*
* Make it look as if a synchronous exception were taken at the
* supplied Non-secure resumption point. Populate SPSR and
* ELR_ELx so that an ERET from there works as expected.
*
* The assumption is that the client, if necessary, would have
* saved any live content in these registers before making this
* call.
*/
if (client_el == MODE_EL2) {
write_elr_el2(disp_ctx->elr_el3);
write_spsr_el2(disp_ctx->spsr_el3);
} else {
/* EL1 */
write_elr_el1(disp_ctx->elr_el3);
write_spsr_el1(disp_ctx->spsr_el3);
}
}
/* End the outstanding dispatch */
end_sdei_synchronous_dispatch(disp_ctx->dispatch_jmp);
return 0;
}
int64_t sdei_event_context(void *handle, unsigned int param)
{
sdei_dispatch_context_t *disp_ctx;
if (param >= SDEI_SAVED_GPREGS)
return SDEI_EINVAL;
/* Get outstanding dispatch on this CPU */
disp_ctx = get_outstanding_dispatch();
if (disp_ctx == NULL)
return SDEI_EDENY;
assert(disp_ctx->map != NULL);
if (!can_sdei_state_trans(get_event_entry(disp_ctx->map), DO_CONTEXT))
return SDEI_EDENY;
/*
* No locking is required for the Running status as this is the only CPU
* which can complete the event
*/
return (int64_t) disp_ctx->x[param];
}