[PATCH v3 05/15] target/ppc: PMU: add instruction counting

[Daniel Henrique Barboza]

The PMU is already counting cycles by calculating time elapsed in
nanoseconds. Counting instructions is a different matter and requires
another approach.

This patch adds the capability of counting completed instructions
(Perf event PM_INST_CMPL) by counting the amount of instructions
translated in each translation block right before exiting it.

A new pmu_count_insns() helper in translation.c was added to do that.
After verifying that the PMU is running (MMCR0_FC bit not set), call
helper_insns_inc(). This new helper from power8_pmu.c will add the
instructions to the relevant counters. It'll also be responsible for
triggering counter negative overflows later on.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 target/ppc/cpu.h         |  1 +
 target/ppc/helper.h      |  1 +
 target/ppc/helper_regs.c |  3 ++
 target/ppc/power8_pmu.c  | 70 ++++++++++++++++++++++++++++++++++++----
 target/ppc/translate.c   | 46 ++++++++++++++++++++++++++
 5 files changed, 114 insertions(+), 7 deletions(-)

diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
index 74698a3600..4d4886ac74 100644
--- a/target/ppc/cpu.h
+++ b/target/ppc/cpu.h
@@ -628,6 +628,7 @@ enum {
     HFLAGS_FP = 13,  /* MSR_FP */
     HFLAGS_PR = 14,  /* MSR_PR */
     HFLAGS_PMCCCLEAR = 15, /* PMU MMCR0 PMCC equal to 0b00 */
+    HFLAGS_MMCR0FC = 16, /* MMCR0 FC bit */
     HFLAGS_VSX = 23, /* MSR_VSX if cpu has VSX */
     HFLAGS_VR = 25,  /* MSR_VR if cpu has VRE */
 
diff --git a/target/ppc/helper.h b/target/ppc/helper.h
index 5122632784..47dbbe6da1 100644
--- a/target/ppc/helper.h
+++ b/target/ppc/helper.h
@@ -21,6 +21,7 @@ DEF_HELPER_1(hrfid, void, env)
 DEF_HELPER_2(store_lpcr, void, env, tl)
 DEF_HELPER_2(store_pcr, void, env, tl)
 DEF_HELPER_2(store_mmcr0, void, env, tl)
+DEF_HELPER_2(insns_inc, void, env, i32)
 #endif
 DEF_HELPER_1(check_tlb_flush_local, void, env)
 DEF_HELPER_1(check_tlb_flush_global, void, env)
diff --git a/target/ppc/helper_regs.c b/target/ppc/helper_regs.c
index 4c1d9575ac..27d139edd8 100644
--- a/target/ppc/helper_regs.c
+++ b/target/ppc/helper_regs.c
@@ -109,6 +109,9 @@ static uint32_t hreg_compute_hflags_value(CPUPPCState *env)
     if (((env->spr[SPR_POWER_MMCR0] & MMCR0_PMCC) >> 18) == 0) {
         hflags |= 1 << HFLAGS_PMCCCLEAR;
     }
+    if (env->spr[SPR_POWER_MMCR0] & MMCR0_FC) {
+        hflags |= 1 << HFLAGS_MMCR0FC;
+    }
 
 #ifndef CONFIG_USER_ONLY
     if (!env->has_hv_mode || (msr & (1ull << MSR_HV))) {
diff --git a/target/ppc/power8_pmu.c b/target/ppc/power8_pmu.c
index 3f7b305f4f..9769c0ff35 100644
--- a/target/ppc/power8_pmu.c
+++ b/target/ppc/power8_pmu.c
@@ -31,10 +31,13 @@ static void update_PMC_PM_CYC(CPUPPCState *env, int sprn,
     env->spr[sprn] += time_delta;
 }
 
-static void update_programmable_PMC_reg(CPUPPCState *env, int sprn,
-                                        uint64_t time_delta)
+static uint8_t get_PMC_event(CPUPPCState *env, int sprn)
 {
-    uint8_t event, evt_extr;
+    uint8_t evt_extr = 0;
+
+    if (env->spr[SPR_POWER_MMCR1] == 0) {
+        return 0;
+    }
 
     switch (sprn) {
     case SPR_POWER_PMC1:
@@ -50,10 +53,16 @@ static void update_programmable_PMC_reg(CPUPPCState *env, 
int sprn,
         evt_extr = MMCR1_PMC4EVT_EXTR;
         break;
     default:
-        return;
+        return 0;
     }
 
-    event = extract64(env->spr[SPR_POWER_MMCR1], evt_extr, MMCR1_EVT_SIZE);
+    return extract64(env->spr[SPR_POWER_MMCR1], evt_extr, MMCR1_EVT_SIZE);
+}
+
+static void update_programmable_PMC_reg(CPUPPCState *env, int sprn,
+                                        uint64_t time_delta)
+{
+    uint8_t event = get_PMC_event(env, sprn);
 
     /*
      * MMCR0_PMC1SEL = 0xF0 is the architected PowerISA v3.1 event
@@ -99,8 +108,9 @@ void helper_store_mmcr0(CPUPPCState *env, target_ulong value)
 
     env->spr[SPR_POWER_MMCR0] = value;
 
-    /* MMCR0 writes can change HFLAGS_PMCCCLEAR */
-    if ((curr_value & MMCR0_PMCC) != (value & MMCR0_PMCC)) {
+    /* MMCR0 writes can change HFLAGS_PMCCCLEAR and HFLAGS_MMCR0FC */
+    if (((curr_value & MMCR0_PMCC) != (value & MMCR0_PMCC)) ||
+        (curr_FC != new_FC)) {
         hreg_compute_hflags(env);
     }
 
@@ -123,4 +133,50 @@ void helper_store_mmcr0(CPUPPCState *env, target_ulong 
value)
     }
 }
 
+static bool pmc_counting_insns(CPUPPCState *env, int sprn)
+{
+    bool ret = false;
+    uint8_t event;
+
+    if (sprn == SPR_POWER_PMC5) {
+        return true;
+    }
+
+    event = get_PMC_event(env, sprn);
+
+    /*
+     * Event 0x2 is an implementation-dependent event that IBM
+     * POWER chips implement (at least since POWER8) that is
+     * equivalent to PM_INST_CMPL. Let's support this event on
+     * all programmable PMCs.
+     *
+     * Event 0xFE is the PowerISA v3.1 architected event to
+     * sample PM_INST_CMPL using PMC1.
+     */
+    switch (sprn) {
+    case SPR_POWER_PMC1:
+        return event == 0x2 || event == 0xFE;
+    case SPR_POWER_PMC2:
+    case SPR_POWER_PMC3:
+    case SPR_POWER_PMC4:
+        return event == 0x2;
+    default:
+        break;
+    }
+
+    return ret;
+}
+
+/* This helper assumes that the PMC is running. */
+void helper_insns_inc(CPUPPCState *env, uint32_t num_insns)
+{
+    int sprn;
+
+    for (sprn = SPR_POWER_PMC1; sprn <= SPR_POWER_PMC5; sprn++) {
+        if (pmc_counting_insns(env, sprn)) {
+            env->spr[sprn] += num_insns;
+        }
+    }
+}
+
 #endif /* defined(TARGET_PPC64) && !defined(CONFIG_USER_ONLY) */
diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index c3e2e3d329..b7235a2be0 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -176,6 +176,7 @@ struct DisasContext {
     bool tm_enabled;
     bool gtse;
     bool pmcc_clear;
+    bool pmu_frozen;
     ppc_spr_t *spr_cb; /* Needed to check rights for mfspr/mtspr */
     int singlestep_enabled;
     uint32_t flags;
@@ -411,6 +412,12 @@ void spr_write_MMCR0(DisasContext *ctx, int sprn, int gprn)
      */
     gen_icount_io_start(ctx);
     gen_helper_store_mmcr0(cpu_env, cpu_gpr[gprn]);
+
+    /*
+     * End the translation block because MMCR0 writes can change
+     * ctx->pmu_frozen.
+     */
+    ctx->base.is_jmp = DISAS_EXIT_UPDATE;
 }
 #else
 void spr_write_MMCR0(DisasContext *ctx, int sprn, int gprn)
@@ -4407,6 +4414,22 @@ static inline void gen_update_cfar(DisasContext *ctx, 
target_ulong nip)
 #endif
 }
 
+#if defined(TARGET_PPC64) && !defined(CONFIG_USER_ONLY)
+static void pmu_count_insns(DisasContext *ctx)
+{
+    /* Do not bother calling the helper if the PMU is frozen */
+    if (ctx->pmu_frozen) {
+        return;
+    }
+
+    gen_helper_insns_inc(cpu_env, tcg_constant_i32(ctx->base.num_insns));
+}
+#else
+static void pmu_count_insns(DisasContext *ctx)
+{
+    return;
+}
+#endif
 static inline bool use_goto_tb(DisasContext *ctx, target_ulong dest)
 {
     return translator_use_goto_tb(&ctx->base, dest);
@@ -4421,9 +4444,17 @@ static void gen_lookup_and_goto_ptr(DisasContext *ctx)
         } else if (sse & (CPU_SINGLE_STEP | CPU_BRANCH_STEP)) {
             gen_helper_raise_exception(cpu_env, 
tcg_constant_i32(gen_prep_dbgex(ctx)));
         } else {
+            pmu_count_insns(ctx);
             tcg_gen_exit_tb(NULL, 0);
         }
     } else {
+        /*
+         * tcg_gen_lookup_and_goto_ptr will exit the TB if
+         * CF_NO_GOTO_PTR is set. Count insns now.
+         */
+        if (ctx->base.tb->flags & CF_NO_GOTO_PTR) {
+            pmu_count_insns(ctx);
+        }
         tcg_gen_lookup_and_goto_ptr();
     }
 }
@@ -4435,6 +4466,8 @@ static void gen_goto_tb(DisasContext *ctx, int n, 
target_ulong dest)
         dest = (uint32_t) dest;
     }
     if (use_goto_tb(ctx, dest)) {
+        pmu_count_insns(ctx);
+
         tcg_gen_goto_tb(n);
         tcg_gen_movi_tl(cpu_nip, dest & ~3);
         tcg_gen_exit_tb(ctx->base.tb, n);
@@ -8648,6 +8681,7 @@ static void ppc_tr_init_disas_context(DisasContextBase 
*dcbase, CPUState *cs)
     ctx->tm_enabled = (hflags >> HFLAGS_TM) & 1;
     ctx->gtse = (hflags >> HFLAGS_GTSE) & 1;
     ctx->pmcc_clear = (hflags >> HFLAGS_PMCCCLEAR) & 1;
+    ctx->pmu_frozen = (hflags >> HFLAGS_MMCR0FC) & 1;
 
     ctx->singlestep_enabled = 0;
     if ((hflags >> HFLAGS_SE) & 1) {
@@ -8767,6 +8801,8 @@ static void ppc_tr_tb_stop(DisasContextBase *dcbase, 
CPUState *cs)
     switch (is_jmp) {
     case DISAS_TOO_MANY:
         if (use_goto_tb(ctx, nip)) {
+            pmu_count_insns(ctx);
+
             tcg_gen_goto_tb(0);
             gen_update_nip(ctx, nip);
             tcg_gen_exit_tb(ctx->base.tb, 0);
@@ -8777,6 +8813,14 @@ static void ppc_tr_tb_stop(DisasContextBase *dcbase, 
CPUState *cs)
         gen_update_nip(ctx, nip);
         /* fall through */
     case DISAS_CHAIN:
+        /*
+         * tcg_gen_lookup_and_goto_ptr will exit the TB if
+         * CF_NO_GOTO_PTR is set. Count insns now.
+         */
+        if (ctx->base.tb->flags & CF_NO_GOTO_PTR) {
+            pmu_count_insns(ctx);
+        }
+
         tcg_gen_lookup_and_goto_ptr();
         break;
 
@@ -8784,6 +8828,8 @@ static void ppc_tr_tb_stop(DisasContextBase *dcbase, 
CPUState *cs)
         gen_update_nip(ctx, nip);
         /* fall through */
     case DISAS_EXIT:
+        pmu_count_insns(ctx);
+
         tcg_gen_exit_tb(NULL, 0);
         break;
 
-- 
2.31.1