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-rw-r--r--target/arm/cpu.h3
-rw-r--r--target/arm/helper.c112
-rw-r--r--target/arm/helper.h2
-rw-r--r--target/arm/translate.c22
-rw-r--r--target/arm/translate.h1
5 files changed, 140 insertions, 0 deletions
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index ed30693..0b10aef 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -57,6 +57,7 @@
#define EXCP_NOCP 17 /* v7M NOCP UsageFault */
#define EXCP_INVSTATE 18 /* v7M INVSTATE UsageFault */
#define EXCP_STKOF 19 /* v8M STKOF UsageFault */
+#define EXCP_LAZYFP 20 /* v7M fault during lazy FP stacking */
/* NB: add new EXCP_ defines to the array in arm_log_exception() too */
#define ARMV7M_EXCP_RESET 1
@@ -3172,6 +3173,8 @@ FIELD(TBFLAG_A32, NS, 6, 1)
FIELD(TBFLAG_A32, VFPEN, 7, 1)
FIELD(TBFLAG_A32, CONDEXEC, 8, 8)
FIELD(TBFLAG_A32, SCTLR_B, 16, 1)
+/* For M profile only, set if FPCCR.LSPACT is set */
+FIELD(TBFLAG_A32, LSPACT, 18, 1)
/* For M profile only, set if we must create a new FP context */
FIELD(TBFLAG_A32, NEW_FP_CTXT_NEEDED, 19, 1)
/* For M profile only, set if FPCCR.S does not match current security state */
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 41531390..b11f8aa 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -7378,6 +7378,12 @@ void HELPER(v7m_blxns)(CPUARMState *env, uint32_t dest)
g_assert_not_reached();
}
+void HELPER(v7m_preserve_fp_state)(CPUARMState *env)
+{
+ /* translate.c should never generate calls here in user-only mode */
+ g_assert_not_reached();
+}
+
uint32_t HELPER(v7m_tt)(CPUARMState *env, uint32_t addr, uint32_t op)
{
/* The TT instructions can be used by unprivileged code, but in
@@ -7737,6 +7743,97 @@ pend_fault:
return false;
}
+void HELPER(v7m_preserve_fp_state)(CPUARMState *env)
+{
+ /*
+ * Preserve FP state (because LSPACT was set and we are about
+ * to execute an FP instruction). This corresponds to the
+ * PreserveFPState() pseudocode.
+ * We may throw an exception if the stacking fails.
+ */
+ ARMCPU *cpu = arm_env_get_cpu(env);
+ bool is_secure = env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_S_MASK;
+ bool negpri = !(env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_HFRDY_MASK);
+ bool is_priv = !(env->v7m.fpccr[is_secure] & R_V7M_FPCCR_USER_MASK);
+ bool splimviol = env->v7m.fpccr[is_secure] & R_V7M_FPCCR_SPLIMVIOL_MASK;
+ uint32_t fpcar = env->v7m.fpcar[is_secure];
+ bool stacked_ok = true;
+ bool ts = is_secure && (env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_TS_MASK);
+ bool take_exception;
+
+ /* Take the iothread lock as we are going to touch the NVIC */
+ qemu_mutex_lock_iothread();
+
+ /* Check the background context had access to the FPU */
+ if (!v7m_cpacr_pass(env, is_secure, is_priv)) {
+ armv7m_nvic_set_pending_lazyfp(env->nvic, ARMV7M_EXCP_USAGE, is_secure);
+ env->v7m.cfsr[is_secure] |= R_V7M_CFSR_NOCP_MASK;
+ stacked_ok = false;
+ } else if (!is_secure && !extract32(env->v7m.nsacr, 10, 1)) {
+ armv7m_nvic_set_pending_lazyfp(env->nvic, ARMV7M_EXCP_USAGE, M_REG_S);
+ env->v7m.cfsr[M_REG_S] |= R_V7M_CFSR_NOCP_MASK;
+ stacked_ok = false;
+ }
+
+ if (!splimviol && stacked_ok) {
+ /* We only stack if the stack limit wasn't violated */
+ int i;
+ ARMMMUIdx mmu_idx;
+
+ mmu_idx = arm_v7m_mmu_idx_all(env, is_secure, is_priv, negpri);
+ for (i = 0; i < (ts ? 32 : 16); i += 2) {
+ uint64_t dn = *aa32_vfp_dreg(env, i / 2);
+ uint32_t faddr = fpcar + 4 * i;
+ uint32_t slo = extract64(dn, 0, 32);
+ uint32_t shi = extract64(dn, 32, 32);
+
+ if (i >= 16) {
+ faddr += 8; /* skip the slot for the FPSCR */
+ }
+ stacked_ok = stacked_ok &&
+ v7m_stack_write(cpu, faddr, slo, mmu_idx, STACK_LAZYFP) &&
+ v7m_stack_write(cpu, faddr + 4, shi, mmu_idx, STACK_LAZYFP);
+ }
+
+ stacked_ok = stacked_ok &&
+ v7m_stack_write(cpu, fpcar + 0x40,
+ vfp_get_fpscr(env), mmu_idx, STACK_LAZYFP);
+ }
+
+ /*
+ * We definitely pended an exception, but it's possible that it
+ * might not be able to be taken now. If its priority permits us
+ * to take it now, then we must not update the LSPACT or FP regs,
+ * but instead jump out to take the exception immediately.
+ * If it's just pending and won't be taken until the current
+ * handler exits, then we do update LSPACT and the FP regs.
+ */
+ take_exception = !stacked_ok &&
+ armv7m_nvic_can_take_pending_exception(env->nvic);
+
+ qemu_mutex_unlock_iothread();
+
+ if (take_exception) {
+ raise_exception_ra(env, EXCP_LAZYFP, 0, 1, GETPC());
+ }
+
+ env->v7m.fpccr[is_secure] &= ~R_V7M_FPCCR_LSPACT_MASK;
+
+ if (ts) {
+ /* Clear s0 to s31 and the FPSCR */
+ int i;
+
+ for (i = 0; i < 32; i += 2) {
+ *aa32_vfp_dreg(env, i / 2) = 0;
+ }
+ vfp_set_fpscr(env, 0);
+ }
+ /*
+ * Otherwise s0 to s15 and FPSCR are UNKNOWN; we choose to leave them
+ * unchanged.
+ */
+}
+
/* Write to v7M CONTROL.SPSEL bit for the specified security bank.
* This may change the current stack pointer between Main and Process
* stack pointers if it is done for the CONTROL register for the current
@@ -9062,6 +9159,7 @@ static void arm_log_exception(int idx)
[EXCP_NOCP] = "v7M NOCP UsageFault",
[EXCP_INVSTATE] = "v7M INVSTATE UsageFault",
[EXCP_STKOF] = "v8M STKOF UsageFault",
+ [EXCP_LAZYFP] = "v7M exception during lazy FP stacking",
};
if (idx >= 0 && idx < ARRAY_SIZE(excnames)) {
@@ -9355,6 +9453,12 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
return;
}
break;
+ case EXCP_LAZYFP:
+ /*
+ * We already pended the specific exception in the NVIC in the
+ * v7m_preserve_fp_state() helper function.
+ */
+ break;
default:
cpu_abort(cs, "Unhandled exception 0x%x\n", cs->exception_index);
return; /* Never happens. Keep compiler happy. */
@@ -13483,6 +13587,14 @@ void cpu_get_tb_cpu_state(CPUARMState *env, target_ulong *pc,
flags = FIELD_DP32(flags, TBFLAG_A32, NEW_FP_CTXT_NEEDED, 1);
}
+ if (arm_feature(env, ARM_FEATURE_M)) {
+ bool is_secure = env->v7m.fpccr[M_REG_S] & R_V7M_FPCCR_S_MASK;
+
+ if (env->v7m.fpccr[is_secure] & R_V7M_FPCCR_LSPACT_MASK) {
+ flags = FIELD_DP32(flags, TBFLAG_A32, LSPACT, 1);
+ }
+ }
+
*pflags = flags;
*cs_base = 0;
}
diff --git a/target/arm/helper.h b/target/arm/helper.h
index a09566f..0a3a805 100644
--- a/target/arm/helper.h
+++ b/target/arm/helper.h
@@ -69,6 +69,8 @@ DEF_HELPER_2(v7m_blxns, void, env, i32)
DEF_HELPER_3(v7m_tt, i32, env, i32, i32)
+DEF_HELPER_1(v7m_preserve_fp_state, void, env)
+
DEF_HELPER_2(v8m_stackcheck, void, env, i32)
DEF_HELPER_4(access_check_cp_reg, void, env, ptr, i32, i32)
diff --git a/target/arm/translate.c b/target/arm/translate.c
index edb66e7..4f29d09 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -3424,6 +3424,27 @@ static int disas_vfp_insn(DisasContext *s, uint32_t insn)
if (arm_dc_feature(s, ARM_FEATURE_M)) {
/* Handle M-profile lazy FP state mechanics */
+ /* Trigger lazy-state preservation if necessary */
+ if (s->v7m_lspact) {
+ /*
+ * Lazy state saving affects external memory and also the NVIC,
+ * so we must mark it as an IO operation for icount.
+ */
+ if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
+ gen_io_start();
+ }
+ gen_helper_v7m_preserve_fp_state(cpu_env);
+ if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
+ gen_io_end();
+ }
+ /*
+ * If the preserve_fp_state helper doesn't throw an exception
+ * then it will clear LSPACT; we don't need to repeat this for
+ * any further FP insns in this TB.
+ */
+ s->v7m_lspact = false;
+ }
+
/* Update ownership of FP context: set FPCCR.S to match current state */
if (s->v8m_fpccr_s_wrong) {
TCGv_i32 tmp;
@@ -13390,6 +13411,7 @@ static void arm_tr_init_disas_context(DisasContextBase *dcbase, CPUState *cs)
dc->v8m_fpccr_s_wrong = FIELD_EX32(tb_flags, TBFLAG_A32, FPCCR_S_WRONG);
dc->v7m_new_fp_ctxt_needed =
FIELD_EX32(tb_flags, TBFLAG_A32, NEW_FP_CTXT_NEEDED);
+ dc->v7m_lspact = FIELD_EX32(tb_flags, TBFLAG_A32, LSPACT);
dc->cp_regs = cpu->cp_regs;
dc->features = env->features;
diff --git a/target/arm/translate.h b/target/arm/translate.h
index ed8ae2e..c2348de 100644
--- a/target/arm/translate.h
+++ b/target/arm/translate.h
@@ -42,6 +42,7 @@ typedef struct DisasContext {
bool v8m_stackcheck; /* true if we need to perform v8M stack limit checks */
bool v8m_fpccr_s_wrong; /* true if v8M FPCCR.S != v8m_secure */
bool v7m_new_fp_ctxt_needed; /* ASPEN set but no active FP context */
+ bool v7m_lspact; /* FPCCR.LSPACT set */
/* Immediate value in AArch32 SVC insn; must be set if is_jmp == DISAS_SWI
* so that top level loop can generate correct syndrome information.
*/