[PATCH 3/4] target/ppc: Add clrbhrb and mfbhrbe instructions

[Glenn Miles <milesg@linux.vnet.ibm.com>]

Add support for the clrbhrb and mfbhrbe instructions.

Since neither instruction is believed to be critical to
performance, both instructions were implemented using helper
functions.

Access to both instructions is controlled by bits in the
HFSCR (for privileged state) and MMCR0 (for problem state).
A new function, helper_mmcr0_facility_check, was added for
checking MMCR0[BHRBA] and raising a facility_unavailable exception
if required.

Signed-off-by: Glenn Miles <milesg@linux.vnet.ibm.com>
---
 target/ppc/cpu.h         |  1 +
 target/ppc/helper.h      |  4 ++++
 target/ppc/misc_helper.c | 43 ++++++++++++++++++++++++++++++++++++++++
 target/ppc/translate.c   | 13 ++++++++++++
 4 files changed, 61 insertions(+)

diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
index bda1afb700..ee81ede4ee 100644
--- a/target/ppc/cpu.h
+++ b/target/ppc/cpu.h
@@ -541,6 +541,7 @@ FIELD(MSR, LE, MSR_LE, 1)
 
 /* HFSCR bits */
 #define HFSCR_MSGP     PPC_BIT(53) /* Privileged Message Send Facilities */
+#define HFSCR_BHRB     PPC_BIT(59) /* BHRB Instructions */
 #define HFSCR_IC_MSGP  0xA
 
 #define DBCR0_ICMP (1 << 27)
diff --git a/target/ppc/helper.h b/target/ppc/helper.h
index 1a3d9a7e57..bbc32ff114 100644
--- a/target/ppc/helper.h
+++ b/target/ppc/helper.h
@@ -816,3 +816,7 @@ DEF_HELPER_4(DSCLIQ, void, env, fprp, fprp, i32)
 
 DEF_HELPER_1(tbegin, void, env)
 DEF_HELPER_FLAGS_1(fixup_thrm, TCG_CALL_NO_RWG, void, env)
+
+DEF_HELPER_1(clrbhrb, void, env)
+DEF_HELPER_FLAGS_2(mfbhrbe, TCG_CALL_NO_WG, i64, env, i32)
+
diff --git a/target/ppc/misc_helper.c b/target/ppc/misc_helper.c
index 692d058665..45abe04f66 100644
--- a/target/ppc/misc_helper.c
+++ b/target/ppc/misc_helper.c
@@ -139,6 +139,17 @@ void helper_fscr_facility_check(CPUPPCState *env, uint32_t bit,
 #endif
 }
 
+static void helper_mmcr0_facility_check(CPUPPCState *env, uint32_t bit,
+                                 uint32_t sprn, uint32_t cause)
+{
+#ifdef TARGET_PPC64
+    if (FIELD_EX64(env->msr, MSR, PR) &&
+        !(env->spr[SPR_POWER_MMCR0] & (1ULL << bit))) {
+        raise_fu_exception(env, bit, sprn, cause, GETPC());
+    }
+#endif
+}
+
 void helper_msr_facility_check(CPUPPCState *env, uint32_t bit,
                                uint32_t sprn, uint32_t cause)
 {
@@ -351,3 +362,35 @@ void helper_fixup_thrm(CPUPPCState *env)
         env->spr[i] = v;
     }
 }
+
+void helper_clrbhrb(CPUPPCState *env)
+{
+    helper_hfscr_facility_check(env, HFSCR_BHRB, "clrbhrb", FSCR_IC_BHRB);
+
+    helper_mmcr0_facility_check(env, MMCR0_BHRBA, 0, FSCR_IC_BHRB);
+
+    memset(env->bhrb, 0, sizeof(env->bhrb));
+}
+
+uint64_t helper_mfbhrbe(CPUPPCState *env, uint32_t bhrbe)
+{
+    unsigned int index;
+
+    helper_hfscr_facility_check(env, HFSCR_BHRB, "mfbhrbe", FSCR_IC_BHRB);
+
+    helper_mmcr0_facility_check(env, MMCR0_BHRBA, 0, FSCR_IC_BHRB);
+
+    if ((bhrbe >= env->bhrb_num_entries) ||
+       (env->spr[SPR_POWER_MMCR0] & MMCR0_PMAE)) {
+        return 0;
+    }
+
+    /*
+     * Note: bhrb_offset is the byte offset for writing the
+     * next entry (over the oldest entry), which is why we
+     * must offset bhrbe by 1 to get to the 0th entry.
+     */
+    index = ((env->bhrb_offset / sizeof(uint64_t)) - (bhrbe + 1)) %
+            env->bhrb_num_entries;
+    return env->bhrb[index];
+}
diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index 7824475f54..b330871793 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -6549,12 +6549,25 @@ static void gen_brh(DisasContext *ctx)
 }
 #endif
 
+static void gen_clrbhrb(DisasContext *ctx)
+{
+    gen_helper_clrbhrb(cpu_env);
+}
+
+static void gen_mfbhrbe(DisasContext *ctx)
+{
+    TCGv_i32 bhrbe = tcg_constant_i32(_SPR(ctx->opcode));
+    gen_helper_mfbhrbe(cpu_gpr[rD(ctx->opcode)], cpu_env, bhrbe);
+}
+
 static opcode_t opcodes[] = {
 #if defined(TARGET_PPC64)
 GEN_HANDLER_E(brd, 0x1F, 0x1B, 0x05, 0x0000F801, PPC_NONE, PPC2_ISA310),
 GEN_HANDLER_E(brw, 0x1F, 0x1B, 0x04, 0x0000F801, PPC_NONE, PPC2_ISA310),
 GEN_HANDLER_E(brh, 0x1F, 0x1B, 0x06, 0x0000F801, PPC_NONE, PPC2_ISA310),
 #endif
+GEN_HANDLER_E(clrbhrb, 0x1F, 0x0E, 0x0D, 0x3FFF801, PPC_NONE, PPC2_ISA207S),
+GEN_HANDLER_E(mfbhrbe, 0x1F, 0x0E, 0x09, 0x0000001, PPC_NONE, PPC2_ISA207S),
 GEN_HANDLER(invalid, 0x00, 0x00, 0x00, 0xFFFFFFFF, PPC_NONE),
 #if defined(TARGET_PPC64)
 GEN_HANDLER_E(cmpeqb, 0x1F, 0x00, 0x07, 0x00600000, PPC_NONE, PPC2_ISA300),
-- 
2.31.1