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authorPeter Maydell <peter.maydell@linaro.org>2016-01-21 14:15:09 +0000
committerPeter Maydell <peter.maydell@linaro.org>2016-01-21 14:15:09 +0000
commit3809951bf61605974b91578c582de4da28f8ed07 (patch)
treee0da6f83fc5ca05243192be6f33c473882e565c6 /target-arm
parent3d6f761713745dfed7d2ccfe98077d213a6a6eba (diff)
downloadqemu-arm-3809951bf61605974b91578c582de4da28f8ed07.tar.gz
target-arm: Handle exception return from AArch64 to non-EL0 AArch32
Remove the assumptions that the AArch64 exception return code was making about a return to AArch32 always being a return to EL0. This includes pulling out the illegal-SPSR checks so we can apply them for return to 32 bit as well as return to 64-bit. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Diffstat (limited to 'target-arm')
-rw-r--r--target-arm/op_helper.c80
1 files changed, 59 insertions, 21 deletions
diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
index 7b6b3fd97c..b9f51e0822 100644
--- a/target-arm/op_helper.c
+++ b/target-arm/op_helper.c
@@ -641,12 +641,51 @@ void HELPER(pre_smc)(CPUARMState *env, uint32_t syndrome)
}
}
+static int el_from_spsr(uint32_t spsr)
+{
+ /* Return the exception level that this SPSR is requesting a return to,
+ * or -1 if it is invalid (an illegal return)
+ */
+ if (spsr & PSTATE_nRW) {
+ switch (spsr & CPSR_M) {
+ case ARM_CPU_MODE_USR:
+ return 0;
+ case ARM_CPU_MODE_HYP:
+ return 2;
+ case ARM_CPU_MODE_FIQ:
+ case ARM_CPU_MODE_IRQ:
+ case ARM_CPU_MODE_SVC:
+ case ARM_CPU_MODE_ABT:
+ case ARM_CPU_MODE_UND:
+ case ARM_CPU_MODE_SYS:
+ return 1;
+ case ARM_CPU_MODE_MON:
+ /* Returning to Mon from AArch64 is never possible,
+ * so this is an illegal return.
+ */
+ default:
+ return -1;
+ }
+ } else {
+ if (extract32(spsr, 1, 1)) {
+ /* Return with reserved M[1] bit set */
+ return -1;
+ }
+ if (extract32(spsr, 0, 4) == 1) {
+ /* return to EL0 with M[0] bit set */
+ return -1;
+ }
+ return extract32(spsr, 2, 2);
+ }
+}
+
void HELPER(exception_return)(CPUARMState *env)
{
int cur_el = arm_current_el(env);
unsigned int spsr_idx = aarch64_banked_spsr_index(cur_el);
uint32_t spsr = env->banked_spsr[spsr_idx];
int new_el;
+ bool return_to_aa64 = (spsr & PSTATE_nRW) == 0;
aarch64_save_sp(env, cur_el);
@@ -663,35 +702,34 @@ void HELPER(exception_return)(CPUARMState *env)
spsr &= ~PSTATE_SS;
}
- if (spsr & PSTATE_nRW) {
- /* TODO: We currently assume EL1/2/3 are running in AArch64. */
+ new_el = el_from_spsr(spsr);
+ if (new_el == -1) {
+ goto illegal_return;
+ }
+ if (new_el > cur_el
+ || (new_el == 2 && !arm_feature(env, ARM_FEATURE_EL2))) {
+ /* Disallow return to an EL which is unimplemented or higher
+ * than the current one.
+ */
+ goto illegal_return;
+ }
+
+ if (new_el != 0 && arm_el_is_aa64(env, new_el) != return_to_aa64) {
+ /* Return to an EL which is configured for a different register width */
+ goto illegal_return;
+ }
+
+ if (!return_to_aa64) {
env->aarch64 = 0;
- new_el = 0;
- env->uncached_cpsr = 0x10;
+ env->uncached_cpsr = spsr & CPSR_M;
cpsr_write(env, spsr, ~0);
if (!arm_singlestep_active(env)) {
env->uncached_cpsr &= ~PSTATE_SS;
}
aarch64_sync_64_to_32(env);
- env->regs[15] = env->elr_el[1] & ~0x1;
+ env->regs[15] = env->elr_el[cur_el] & ~0x1;
} else {
- new_el = extract32(spsr, 2, 2);
- if (new_el > cur_el
- || (new_el == 2 && !arm_feature(env, ARM_FEATURE_EL2))) {
- /* Disallow return to an EL which is unimplemented or higher
- * than the current one.
- */
- goto illegal_return;
- }
- if (extract32(spsr, 1, 1)) {
- /* Return with reserved M[1] bit set */
- goto illegal_return;
- }
- if (new_el == 0 && (spsr & PSTATE_SP)) {
- /* Return to EL0 with M[0] bit set */
- goto illegal_return;
- }
env->aarch64 = 1;
pstate_write(env, spsr);
if (!arm_singlestep_active(env)) {