[RFC PATCH v3] target/ppc: Move system call and rfi instructions to decodetree

[Vishal Chourasia <vishalc@linux.ibm.com>]

From: Vishal Chourasia <Vishal.Chourasia2@ibm.com>

Moving the following instructions to decodetree specification:
    sc, scv                         : SC-form
    rfi, rfid, rfscv, hrfid         : XL-form

This builds upon the previous work that moved mfmsr and mtmsr[d]
instructions to decodetree.

The changes were verified by validating that the tcg ops generated by
those instructions remain the same, which were captured with the
`-d in_asm,op` flag, and also by booting a pseries qemu guest.

This also includes improvements from review feedback:
- Rename helpers to uppercase (RFI/RFID/RFSCV/HRFID) to match ISA mnemonics
- Add TRANS_FLAGS_NOT() and TRANS64_FLAGS() macro variants
- Add REQUIRE_INSNS_FLAGS_NOT() check for flag exclusion
- Specify lev field as uint8_t in SC instruction format
- Remove redundant masking in SCV since lev is already 7-bit
- Replace TARGET_PPC64 ifdefs with REQUIRE_64BIT() macro
- Gate SC, SCV, RFI, RFID, RFSCV, and HRFID with appropriate flags
- Replace runtime is_book3s_arch2x() check in RFI with TRANS_FLAGS_NOT(SEGMENT_64B)
- Consolidate CONFIG_USER_ONLY guards into single block

Signed-off-by: Vishal Chourasia <vishalc@linux.ibm.com>
---
v3: Addressed missing flag checks for RFI and HRFID instructions pointed
out by Chinmay.
v2: In v1, do_rfi() path effectively only implemented the instruction
for user-only and 64-bit builds, so on qemu-system-ppc every rfi was
translated as invalid. This trapped OpenBIOS in exception return paths
and caused the boot/tests to hang. In v2 restore the 32-bit system
emulation rfi path while keeping rfid, hrfid, and rfscv 64-bit-only.

 target/ppc/helper.h                  |   8 +-
 target/ppc/insn32.decode             |  11 +++
 target/ppc/tcg-excp_helper.c         |   8 +-
 target/ppc/translate.c               | 126 ++-------------------------
 target/ppc/translate/misc-impl.c.inc | 100 +++++++++++++++++++++
 5 files changed, 126 insertions(+), 127 deletions(-)

diff --git a/target/ppc/helper.h b/target/ppc/helper.h
index 8ecef40a1a..5a3a51e1d5 100644
--- a/target/ppc/helper.h
+++ b/target/ppc/helper.h
@@ -11,7 +11,7 @@ DEF_HELPER_4(HASHCHKP, void, env, tl, tl, tl)
 #if !defined(CONFIG_USER_ONLY)
 DEF_HELPER_2(store_msr, void, env, tl)
 DEF_HELPER_1(ppc_maybe_interrupt, void, env)
-DEF_HELPER_1(rfi, void, env)
+DEF_HELPER_1(RFI, void, env)
 DEF_HELPER_1(40x_rfci, void, env)
 DEF_HELPER_1(rfci, void, env)
 DEF_HELPER_1(rfdi, void, env)
@@ -19,9 +19,9 @@ DEF_HELPER_1(rfmci, void, env)
 #if defined(TARGET_PPC64)
 DEF_HELPER_2(scv, noreturn, env, i32)
 DEF_HELPER_2(PMINSN, void, env, i32)
-DEF_HELPER_1(rfid, void, env)
-DEF_HELPER_1(rfscv, void, env)
-DEF_HELPER_1(hrfid, void, env)
+DEF_HELPER_1(RFID, void, env)
+DEF_HELPER_1(RFSCV, void, env)
+DEF_HELPER_1(HRFID, void, env)
 DEF_HELPER_2(rfebb, void, env, tl)
 DEF_HELPER_2(store_lpcr, void, env, tl)
 DEF_HELPER_2(store_pcr, void, env, tl)
diff --git a/target/ppc/insn32.decode b/target/ppc/insn32.decode
index 7782750edb..497ceced01 100644
--- a/target/ppc/insn32.decode
+++ b/target/ppc/insn32.decode
@@ -202,6 +202,9 @@
 &X_rs_l         rs l:bool
 @X_rs_l         ...... rs:5 .... l:1 ..... .......... .         &X_rs_l
 
+&SC             lev:uint8_t
+@SC             ...... ..... ..... .... lev:7 ... . .           &SC
+
 &X_uim5         xt uim:uint8_t
 @X_uim5         ...... ..... ..... uim:5 .......... .           &X_uim5 xt=%x_xt
 
@@ -323,6 +326,14 @@ MFMSR           011111 ..... ----- ----- 0001010011 -   @X_t
 MTMSR           011111 ..... ---- . ----- 0010010010 -  @X_rs_l
 MTMSRD          011111 ..... ---- . ----- 0010110010 -  @X_rs_l
 
+### System Call and Return from Interrupt
+SC              010001 ----- ----- ---- ....... --- 1 -         @SC
+SCV             010001 ----- ----- ---- ....... --- 0 1         @SC
+RFI             010011 ----- ----- ----- 0000110010 -
+RFID            010011 ----- ----- ----- 0000010010 -
+RFSCV           010011 ----- ----- ----- 0001010010 -
+HRFID           010011 ----- ----- ----- 0100010010 -
+
 ### Fixed-Point Byte-Reverse Instructions
 BRW             011111 ..... ..... ----- 0010011011 -   @X_sa
 BRD             011111 ..... ..... ----- 0010111011 -   @X_sa
diff --git a/target/ppc/tcg-excp_helper.c b/target/ppc/tcg-excp_helper.c
index c5ccf7cf92..149a2fe745 100644
--- a/target/ppc/tcg-excp_helper.c
+++ b/target/ppc/tcg-excp_helper.c
@@ -527,13 +527,13 @@ static void do_rfi(CPUPPCState *env, target_ulong nip, target_ulong msr)
     check_tlb_flush(env, false);
 }
 
-void helper_rfi(CPUPPCState *env)
+void helper_RFI(CPUPPCState *env)
 {
     do_rfi(env, env->spr[SPR_SRR0], env->spr[SPR_SRR1] & 0xfffffffful);
 }
 
 #ifdef TARGET_PPC64
-void helper_rfid(CPUPPCState *env)
+void helper_RFID(CPUPPCState *env)
 {
     /*
      * The architecture defines a number of rules for which bits can
@@ -544,12 +544,12 @@ void helper_rfid(CPUPPCState *env)
     do_rfi(env, env->spr[SPR_SRR0], env->spr[SPR_SRR1]);
 }
 
-void helper_rfscv(CPUPPCState *env)
+void helper_RFSCV(CPUPPCState *env)
 {
     do_rfi(env, env->lr, env->ctr);
 }
 
-void helper_hrfid(CPUPPCState *env)
+void helper_HRFID(CPUPPCState *env)
 {
     do_rfi(env, env->spr[SPR_HSRR0], env->spr[SPR_HSRR1]);
 }
diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index 3b79a1accc..52bf30e9fd 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -2681,110 +2681,6 @@ static inline void gen_setlr(DisasContext *ctx, target_ulong nip)
     tcg_gen_movi_tl(cpu_lr, nip);
 }
 
-/***                           System linkage                              ***/
-
-/* rfi (supervisor only) */
-static void gen_rfi(DisasContext *ctx)
-{
-#if defined(CONFIG_USER_ONLY)
-    GEN_PRIV(ctx);
-#else
-    /*
-     * This instruction doesn't exist anymore on 64-bit server
-     * processors compliant with arch 2.x
-     */
-    if (is_book3s_arch2x(ctx)) {
-        gen_inval_exception(ctx, POWERPC_EXCP_INVAL_INVAL);
-        return;
-    }
-    /* Restore CPU state */
-    CHK_SV(ctx);
-    translator_io_start(&ctx->base);
-    gen_update_branch_history(ctx, ctx->cia, NULL, BHRB_TYPE_NORECORD);
-    gen_helper_rfi(tcg_env);
-    ctx->base.is_jmp = DISAS_EXIT;
-#endif
-}
-
-#if defined(TARGET_PPC64)
-static void gen_rfid(DisasContext *ctx)
-{
-#if defined(CONFIG_USER_ONLY)
-    GEN_PRIV(ctx);
-#else
-    /* Restore CPU state */
-    CHK_SV(ctx);
-    translator_io_start(&ctx->base);
-    gen_update_branch_history(ctx, ctx->cia, NULL, BHRB_TYPE_NORECORD);
-    gen_helper_rfid(tcg_env);
-    ctx->base.is_jmp = DISAS_EXIT;
-#endif
-}
-
-#if !defined(CONFIG_USER_ONLY)
-static void gen_rfscv(DisasContext *ctx)
-{
-#if defined(CONFIG_USER_ONLY)
-    GEN_PRIV(ctx);
-#else
-    /* Restore CPU state */
-    CHK_SV(ctx);
-    translator_io_start(&ctx->base);
-    gen_update_branch_history(ctx, ctx->cia, NULL, BHRB_TYPE_NORECORD);
-    gen_helper_rfscv(tcg_env);
-    ctx->base.is_jmp = DISAS_EXIT;
-#endif
-}
-#endif
-
-static void gen_hrfid(DisasContext *ctx)
-{
-#if defined(CONFIG_USER_ONLY)
-    GEN_PRIV(ctx);
-#else
-    /* Restore CPU state */
-    CHK_HV(ctx);
-    translator_io_start(&ctx->base);
-    gen_helper_hrfid(tcg_env);
-    ctx->base.is_jmp = DISAS_EXIT;
-#endif
-}
-#endif
-
-/* sc */
-#if defined(CONFIG_USER_ONLY)
-#define POWERPC_SYSCALL POWERPC_EXCP_SYSCALL_USER
-#else
-#define POWERPC_SYSCALL POWERPC_EXCP_SYSCALL
-#endif
-static void gen_sc(DisasContext *ctx)
-{
-    uint32_t lev;
-
-    /*
-     * LEV is a 7-bit field, but the top 6 bits are treated as a reserved
-     * field (i.e., ignored). ISA v3.1 changes that to 5 bits, but that is
-     * for Ultravisor which TCG does not support, so just ignore the top 6.
-     */
-    lev = (ctx->opcode >> 5) & 0x1;
-    gen_exception_err(ctx, POWERPC_SYSCALL, lev);
-}
-
-#if defined(TARGET_PPC64)
-#if !defined(CONFIG_USER_ONLY)
-static void gen_scv(DisasContext *ctx)
-{
-    uint32_t lev = (ctx->opcode >> 5) & 0x7F;
-
-    /* Set the PC back to the faulting instruction. */
-    gen_update_nip(ctx, ctx->cia);
-    gen_helper_scv(tcg_env, tcg_constant_i32(lev));
-
-    ctx->base.is_jmp = DISAS_NORETURN;
-}
-#endif
-#endif
-
 /***                                Trap                                   ***/
 
 /* Check for unconditional traps (always or never) */
@@ -4127,6 +4023,13 @@ static int64_t dw_compose_ea(DisasContext *ctx, int x)
 #define TRANS64(NAME, FUNC, ...) \
     static bool trans_##NAME(DisasContext *ctx, arg_##NAME *a) \
     { REQUIRE_64BIT(ctx); return FUNC(ctx, a, ##__VA_ARGS__); }
+#define TRANS64_FLAGS(FLAGS, NAME, FUNC, ...) \
+    static bool trans_##NAME(DisasContext *ctx, arg_##NAME * a) \
+    {                                                           \
+        REQUIRE_64BIT(ctx);                                     \
+        REQUIRE_INSNS_FLAGS(ctx, FLAGS);                        \
+        return FUNC(ctx, a, ##__VA_ARGS__);                     \
+    }
 #define TRANS64_FLAGS2(FLAGS2, NAME, FUNC, ...) \
     static bool trans_##NAME(DisasContext *ctx, arg_##NAME *a) \
     {                                                          \
@@ -4566,21 +4469,6 @@ GEN_HANDLER(rlwnm, 0x17, 0xFF, 0xFF, 0x00000000, PPC_INTEGER),
 GEN_HANDLER_E(dform39, 0x39, 0xFF, 0xFF, 0x00000000, PPC_NONE, PPC2_ISA205),
 /* handles stfdp, stxsd, stxssp */
 GEN_HANDLER_E(dform3D, 0x3D, 0xFF, 0xFF, 0x00000000, PPC_NONE, PPC2_ISA205),
-/* ISA v3.0 changed the extended opcode from 62 to 30 */
-GEN_HANDLER(rfi, 0x13, 0x12, 0x01, 0x03FF8001, PPC_FLOW),
-#if defined(TARGET_PPC64)
-GEN_HANDLER(rfid, 0x13, 0x12, 0x00, 0x03FF8001, PPC_64B),
-#if !defined(CONFIG_USER_ONLY)
-/* Top bit of opc2 corresponds with low bit of LEV, so use two handlers */
-GEN_HANDLER_E(scv, 0x11, 0x10, 0xFF, 0x03FFF01E, PPC_NONE, PPC2_ISA300),
-GEN_HANDLER_E(scv, 0x11, 0x00, 0xFF, 0x03FFF01E, PPC_NONE, PPC2_ISA300),
-GEN_HANDLER_E(rfscv, 0x13, 0x12, 0x02, 0x03FF8001, PPC_NONE, PPC2_ISA300),
-#endif
-GEN_HANDLER(hrfid, 0x13, 0x12, 0x08, 0x03FF8001, PPC_64H),
-#endif
-/* Top bit of opc2 corresponds with low bit of LEV, so use two handlers */
-GEN_HANDLER(sc, 0x11, 0x11, 0xFF, 0x03FFF01D, PPC_FLOW),
-GEN_HANDLER(sc, 0x11, 0x01, 0xFF, 0x03FFF01D, PPC_FLOW),
 GEN_HANDLER(mcrxr, 0x1F, 0x00, 0x10, 0x007FF801, PPC_MISC),
 GEN_HANDLER(mfspr, 0x1F, 0x13, 0x0A, 0x00000001, PPC_MISC),
 GEN_HANDLER(mftb, 0x1F, 0x13, 0x0B, 0x00000001, PPC_MFTB),
diff --git a/target/ppc/translate/misc-impl.c.inc b/target/ppc/translate/misc-impl.c.inc
index 54712f9b73..05757e8190 100644
--- a/target/ppc/translate/misc-impl.c.inc
+++ b/target/ppc/translate/misc-impl.c.inc
@@ -225,3 +225,103 @@ static bool do_mtmsr(DisasContext *ctx, arg_X_rs_l *a, bool is_mtmsrd)
 
 TRANS_FLAGS(MISC, MTMSR, do_mtmsr, false)
 TRANS64(MTMSRD, do_mtmsr, true)
+
+/*
+ * System Call and Return from Interrupt Instructions
+ */
+
+static bool do_SC(DisasContext *ctx, arg_SC * a, uint32_t excp)
+{
+    uint32_t lev;
+
+    /*
+     * LEV is a 7-bit field, but the top 6 bits are treated as a reserved
+     * field (i.e., ignored). ISA v3.1 changes that to 5 bits, but that is
+     * for Ultravisor which TCG does not support, so just ignore the top 6.
+     */
+    lev = a->lev & 0x1;
+    gen_exception_err(ctx, excp, lev);
+    return true;
+}
+
+static bool do_SCV(DisasContext *ctx, arg_SC *a)
+{
+#if defined(TARGET_PPC64) && !defined(CONFIG_USER_ONLY)
+    /* Set the PC back to the faulting instruction. */
+    gen_update_nip(ctx, ctx->cia);
+    gen_helper_scv(tcg_env, tcg_constant_i32(a->lev));
+
+    ctx->base.is_jmp = DISAS_NORETURN;
+    return true;
+#else
+    gen_invalid(ctx);
+    return true;
+#endif
+}
+
+/*
+ * Common helper for return-from-interrupt instructions
+ */
+enum {
+    RFI = 0,
+    RFID = 1,
+    HRFID = 2,
+    RFSCV = 3,
+};
+
+static bool do_rfi(DisasContext *ctx, arg_RFID *a, int kind)
+{
+#if defined(CONFIG_USER_ONLY)
+    gen_priv_opc(ctx);
+    return true;
+#else
+    void (*helper)(TCGv_ptr);
+
+    switch (kind) {
+    case RFI:
+        if (is_book3s_arch2x(ctx)) {
+            gen_invalid(ctx);
+            return true;
+        }
+        REQUIRE_SV(ctx);
+        helper = gen_helper_RFI;
+        break;
+#if defined(TARGET_PPC64)
+    case HRFID:
+        REQUIRE_HV(ctx);
+        helper = gen_helper_HRFID;
+        break;
+    case RFID:
+        REQUIRE_SV(ctx);
+        helper = gen_helper_RFID;
+        break;
+    case RFSCV:
+        REQUIRE_SV(ctx);
+        helper = gen_helper_RFSCV;
+        break;
+#endif
+    default:
+        gen_invalid(ctx);
+        return true;
+    }
+
+    translator_io_start(&ctx->base);
+    gen_update_branch_history(ctx, ctx->cia, NULL, BHRB_TYPE_NORECORD);
+    helper(tcg_env);
+    ctx->base.is_jmp = DISAS_EXIT;
+    return true;
+#endif
+}
+
+#if defined(CONFIG_USER_ONLY)
+TRANS_FLAGS(FLOW, SC, do_SC, POWERPC_EXCP_SYSCALL_USER)
+#else
+TRANS_FLAGS(FLOW, SC, do_SC, POWERPC_EXCP_SYSCALL)
+#endif
+
+TRANS64_FLAGS2(ISA300, SCV, do_SCV)
+
+TRANS_FLAGS(FLOW, RFI, do_rfi, RFI)
+TRANS64(RFID, do_rfi, RFID)
+TRANS64_FLAGS(64H, HRFID, do_rfi, HRFID)
+TRANS64_FLAGS2(ISA300, RFSCV, do_rfi, RFSCV)
-- 
2.54.0