@@ -8452,6 +8452,8 @@ static void do_v7m_exception_exit(ARMCPU *cpu)
bool rettobase = false;
bool exc_secure = false;
bool return_to_secure;
+ bool ftype;
+ bool restore_s16_s31;
/* If we're not in Handler mode then jumps to magic exception-exit
* addresses don't have magic behaviour. However for the v8M
@@ -8489,6 +8491,16 @@ static void do_v7m_exception_exit(ARMCPU *cpu)
excret);
}
+ ftype = excret & R_V7M_EXCRET_FTYPE_MASK;
+
+ if (!arm_feature(env, ARM_FEATURE_VFP) && !ftype) {
+ qemu_log_mask(LOG_GUEST_ERROR, "M profile: zero FTYPE in exception "
+ "exit PC value 0x%" PRIx32 " is UNPREDICTABLE "
+ "if FPU not present\n",
+ excret);
+ ftype = true;
+ }
+
if (arm_feature(env, ARM_FEATURE_M_SECURITY)) {
/* EXC_RETURN.ES validation check (R_SMFL). We must do this before
* we pick which FAULTMASK to clear.
@@ -8589,6 +8601,30 @@ static void do_v7m_exception_exit(ARMCPU *cpu)
*/
write_v7m_control_spsel_for_secstate(env, return_to_sp_process, exc_secure);
+ /*
+ * Clear scratch FP values left in caller saved registers; this
+ * must happen before any kind of tail chaining.
+ */
+ if ((env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_CLRONRET_MASK) &&
+ (env->v7m.control[M_REG_S] & R_V7M_CONTROL_FPCA_MASK)) {
+ if (env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_LSPACT_MASK) {
+ env->v7m.sfsr |= R_V7M_SFSR_LSERR_MASK;
+ armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, false);
+ qemu_log_mask(CPU_LOG_INT, "...taking SecureFault on existing "
+ "stackframe: error during lazy state deactivation\n");
+ v7m_exception_taken(cpu, excret, true, false);
+ return;
+ } else {
+ /* Clear s0..s15 and FPSCR */
+ int i;
+
+ for (i = 0; i < 16; i += 2) {
+ *aa32_vfp_dreg(env, i / 2) = 0;
+ }
+ vfp_set_fpscr(env, 0);
+ }
+ }
+
if (sfault) {
env->v7m.sfsr |= R_V7M_SFSR_INVER_MASK;
armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, false);
@@ -8750,8 +8786,105 @@ static void do_v7m_exception_exit(ARMCPU *cpu)
}
}
+ if (!ftype) {
+ /* FP present and we need to handle it */
+ if (!return_to_secure &&
+ (env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_LSPACT_MASK)) {
+ armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, false);
+ env->v7m.sfsr |= R_V7M_SFSR_LSERR_MASK;
+ qemu_log_mask(CPU_LOG_INT,
+ "...taking SecureFault on existing stackframe: "
+ "Secure LSPACT set but exception return is "
+ "not to secure state\n");
+ v7m_exception_taken(cpu, excret, true, false);
+ return;
+ }
+
+ restore_s16_s31 = return_to_secure &&
+ (env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_TS_MASK);
+
+ if (env->v7m.fpccr[return_to_secure] & R_V7M_FPCCR_LSPACT_MASK) {
+ /* State in FPU is still valid, just clear LSPACT */
+ env->v7m.fpccr[return_to_secure] &= ~R_V7M_FPCCR_LSPACT_MASK;
+ } else {
+ int i;
+ uint32_t fpscr;
+ bool cpacr_pass, nsacr_pass;
+
+ cpacr_pass = v7m_cpacr_pass(env, return_to_secure,
+ return_to_priv);
+ nsacr_pass = return_to_secure ||
+ extract32(env->v7m.nsacr, 10, 1);
+
+ if (!cpacr_pass) {
+ armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE,
+ return_to_secure);
+ env->v7m.cfsr[return_to_secure] |= R_V7M_CFSR_NOCP_MASK;
+ qemu_log_mask(CPU_LOG_INT,
+ "...taking UsageFault on existing "
+ "stackframe: CPACR.CP10 prevents unstacking "
+ "FP regs\n");
+ v7m_exception_taken(cpu, excret, true, false);
+ return;
+ } else if (!nsacr_pass) {
+ armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE, true);
+ env->v7m.cfsr[M_REG_S] |= R_V7M_CFSR_INVPC_MASK;
+ qemu_log_mask(CPU_LOG_INT,
+ "...taking Secure UsageFault on existing "
+ "stackframe: NSACR.CP10 prevents unstacking "
+ "FP regs\n");
+ v7m_exception_taken(cpu, excret, true, false);
+ return;
+ }
+
+ for (i = 0; i < (restore_s16_s31 ? 32 : 16); i += 2) {
+ uint32_t slo, shi;
+ uint64_t dn;
+ uint32_t faddr = frameptr + 0x20 + 4 * i;
+
+ if (i >= 16) {
+ faddr += 8; /* Skip the slot for the FPSCR */
+ }
+
+ pop_ok = pop_ok &&
+ v7m_stack_read(cpu, &slo, faddr, mmu_idx) &&
+ v7m_stack_read(cpu, &shi, faddr + 4, mmu_idx);
+
+ if (!pop_ok) {
+ break;
+ }
+
+ dn = (uint64_t)shi << 32 | slo;
+ *aa32_vfp_dreg(env, i / 2) = dn;
+ }
+ pop_ok = pop_ok &&
+ v7m_stack_read(cpu, &fpscr, frameptr + 0x60, mmu_idx);
+ if (pop_ok) {
+ vfp_set_fpscr(env, fpscr);
+ }
+ if (!pop_ok) {
+ /*
+ * These regs are 0 if security extension present;
+ * otherwise merely UNKNOWN. We zero always.
+ */
+ for (i = 0; i < (restore_s16_s31 ? 32 : 16); i += 2) {
+ *aa32_vfp_dreg(env, i / 2) = 0;
+ }
+ vfp_set_fpscr(env, 0);
+ }
+ }
+ }
+ env->v7m.control[M_REG_S] = FIELD_DP32(env->v7m.control[M_REG_S],
+ V7M_CONTROL, FPCA, !ftype);
+
/* Commit to consuming the stack frame */
frameptr += 0x20;
+ if (!ftype) {
+ frameptr += 0x48;
+ if (restore_s16_s31) {
+ frameptr += 0x40;
+ }
+ }
/* Undo stack alignment (the SPREALIGN bit indicates that the original
* pre-exception SP was not 8-aligned and we added a padding word to
* align it, so we undo this by ORing in the bit that increases it
@@ -8764,7 +8897,14 @@ static void do_v7m_exception_exit(ARMCPU *cpu)
*frame_sp_p = frameptr;
}
/* This xpsr_write() will invalidate frame_sp_p as it may switch stack */
- xpsr_write(env, xpsr, ~XPSR_SPREALIGN);
+ xpsr_write(env, xpsr, ~(XPSR_SPREALIGN | XPSR_SFPA));
+
+ if (env->v7m.secure) {
+ bool sfpa = xpsr & XPSR_SFPA;
+
+ env->v7m.control[M_REG_S] = FIELD_DP32(env->v7m.control[M_REG_S],
+ V7M_CONTROL, SFPA, sfpa);
+ }
/* The restored xPSR exception field will be zero if we're
* resuming in Thread mode. If that doesn't match what the
Handle floating point registers in exception return. This corresponds to pseudocode functions ValidateExceptionReturn(), ExceptionReturn(), PopStack() and ConsumeExcStackFrame(). Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- target/arm/helper.c | 142 +++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 141 insertions(+), 1 deletion(-) -- 2.20.1