[Qemu-devel] [PATCH 13/32] ppc: Don't update NIP in lswi/lswx/stswi/stswx

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

Instead, pass GETPC() result to the corresponding helpers. This
requires a bit of fiddling to get the PC (hopefully) right in
the case where we generate a program check, though the hacks there
are temporary, a subsequent patch will clean this all up by always
having the nip already set to the right instruction when taking
the fault.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 target-ppc/excp_helper.c |  8 ++++++++
 target-ppc/mem_helper.c  | 26 ++++++++++++++++----------
 target-ppc/translate.c   | 18 ++++++++----------
 3 files changed, 32 insertions(+), 20 deletions(-)

diff --git a/target-ppc/excp_helper.c b/target-ppc/excp_helper.c
index 91fdf4b..563c7bc 100644
--- a/target-ppc/excp_helper.c
+++ b/target-ppc/excp_helper.c
@@ -285,6 +285,10 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
             LOG_EXCP("Invalid instruction at " TARGET_FMT_lx "\n", env->nip);
             msr |= 0x00080000;
             env->spr[SPR_BOOKE_ESR] = ESR_PIL;
+            /* Some invalids will have the PC in the right place already */
+            if (env->error_code & POWERPC_EXCP_INVAL_LSWX) {
+                goto store_next;
+            }
             break;
         case POWERPC_EXCP_PRIV:
             msr |= 0x00040000;
@@ -306,6 +310,10 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
         srr1 = SPR_HSRR1;
         new_msr |= (target_ulong)MSR_HVB;
         new_msr |= env->msr & ((target_ulong)1 << MSR_RI);
+        /* Some invalids will have the PC in the right place already */
+        if (env->error_code == (POWERPC_EXCP_INVAL|POWERPC_EXCP_INVAL_LSWX)) {
+                goto store_next;
+        }
         goto store_current;
     case POWERPC_EXCP_FPU:       /* Floating-point unavailable exception     */
         goto store_current;
diff --git a/target-ppc/mem_helper.c b/target-ppc/mem_helper.c
index e4ed377..de96c91 100644
--- a/target-ppc/mem_helper.c
+++ b/target-ppc/mem_helper.c
@@ -77,23 +77,30 @@ void helper_stmw(CPUPPCState *env, target_ulong addr, uint32_t reg)
     }
 }
 
-void helper_lsw(CPUPPCState *env, target_ulong addr, uint32_t nb, uint32_t reg)
+static void do_lsw(CPUPPCState *env, target_ulong addr, uint32_t nb,
+                   uint32_t reg, uintptr_t raddr)
 {
     int sh;
 
     for (; nb > 3; nb -= 4) {
-        env->gpr[reg] = cpu_ldl_data(env, addr);
+        env->gpr[reg] = cpu_ldl_data_ra(env, addr, raddr);
         reg = (reg + 1) % 32;
         addr = addr_add(env, addr, 4);
     }
     if (unlikely(nb > 0)) {
         env->gpr[reg] = 0;
         for (sh = 24; nb > 0; nb--, sh -= 8) {
-            env->gpr[reg] |= cpu_ldub_data(env, addr) << sh;
+            env->gpr[reg] |= cpu_ldub_data_ra(env, addr, raddr) << sh;
             addr = addr_add(env, addr, 1);
         }
     }
 }
+
+void helper_lsw(CPUPPCState *env, target_ulong addr, uint32_t nb, uint32_t reg)
+{
+    do_lsw(env, addr, nb, reg, GETPC());
+}
+
 /* PPC32 specification says we must generate an exception if
  * rA is in the range of registers to be loaded.
  * In an other hand, IBM says this is valid, but rA won't be loaded.
@@ -106,12 +113,11 @@ void helper_lswx(CPUPPCState *env, target_ulong addr, uint32_t reg,
         int num_used_regs = (xer_bc + 3) / 4;
         if (unlikely((ra != 0 && lsw_reg_in_range(reg, num_used_regs, ra)) ||
                      lsw_reg_in_range(reg, num_used_regs, rb))) {
-            env->nip += 4;     /* Compensate the "nip - 4" from gen_lswx() */
-            helper_raise_exception_err(env, POWERPC_EXCP_PROGRAM,
-                                       POWERPC_EXCP_INVAL |
-                                       POWERPC_EXCP_INVAL_LSWX);
+            raise_exception_err_ra(env, POWERPC_EXCP_PROGRAM,
+                                   POWERPC_EXCP_INVAL |
+                                   POWERPC_EXCP_INVAL_LSWX, GETPC());
         } else {
-            helper_lsw(env, addr, xer_bc, reg);
+            do_lsw(env, addr, xer_bc, reg, GETPC());
         }
     }
 }
@@ -122,13 +128,13 @@ void helper_stsw(CPUPPCState *env, target_ulong addr, uint32_t nb,
     int sh;
 
     for (; nb > 3; nb -= 4) {
-        cpu_stl_data(env, addr, env->gpr[reg]);
+        cpu_stl_data_ra(env, addr, env->gpr[reg], GETPC());
         reg = (reg + 1) % 32;
         addr = addr_add(env, addr, 4);
     }
     if (unlikely(nb > 0)) {
         for (sh = 24; nb > 0; nb--, sh -= 8) {
-            cpu_stb_data(env, addr, (env->gpr[reg] >> sh) & 0xFF);
+            cpu_stb_data_ra(env, addr, (env->gpr[reg] >> sh) & 0xFF, GETPC());
             addr = addr_add(env, addr, 1);
         }
     }
diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index a05fed7..9d2e923 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -2701,12 +2701,16 @@ static void gen_lswi(DisasContext *ctx)
         nb = 32;
     nr = (nb + 3) / 4;
     if (unlikely(lsw_reg_in_range(start, nr, ra))) {
+        /* The handler expects the PC to point to *this* instruction,
+         * so setting ctx->exception here prevents it from being
+         * improperly updated again by gen_inval_exception
+         */
+        gen_update_nip(ctx, ctx->nip - 4);
+        ctx->exception = POWERPC_EXCP_HV_EMU;
         gen_inval_exception(ctx, POWERPC_EXCP_INVAL_LSWX);
         return;
     }
     gen_set_access_type(ctx, ACCESS_INT);
-    /* NIP cannot be restored if the memory exception comes from an helper */
-    gen_update_nip(ctx, ctx->nip - 4);
     t0 = tcg_temp_new();
     gen_addr_register(ctx, t0);
     t1 = tcg_const_i32(nb);
@@ -2723,8 +2727,6 @@ static void gen_lswx(DisasContext *ctx)
     TCGv t0;
     TCGv_i32 t1, t2, t3;
     gen_set_access_type(ctx, ACCESS_INT);
-    /* NIP cannot be restored if the memory exception comes from an helper */
-    gen_update_nip(ctx, ctx->nip - 4);
     t0 = tcg_temp_new();
     gen_addr_reg_index(ctx, t0);
     t1 = tcg_const_i32(rD(ctx->opcode));
@@ -2744,8 +2746,6 @@ static void gen_stswi(DisasContext *ctx)
     TCGv_i32 t1, t2;
     int nb = NB(ctx->opcode);
     gen_set_access_type(ctx, ACCESS_INT);
-    /* NIP cannot be restored if the memory exception comes from an helper */
-    gen_update_nip(ctx, ctx->nip - 4);
     t0 = tcg_temp_new();
     gen_addr_register(ctx, t0);
     if (nb == 0)
@@ -2764,8 +2764,6 @@ static void gen_stswx(DisasContext *ctx)
     TCGv t0;
     TCGv_i32 t1, t2;
     gen_set_access_type(ctx, ACCESS_INT);
-    /* NIP cannot be restored if the memory exception comes from an helper */
-    gen_update_nip(ctx, ctx->nip - 4);
     t0 = tcg_temp_new();
     gen_addr_reg_index(ctx, t0);
     t1 = tcg_temp_new_i32();
@@ -3846,7 +3844,7 @@ static void gen_dcbz(DisasContext *ctx)
 static void gen_dst(DisasContext *ctx)
 {
     if (rA(ctx->opcode) == 0) {
-        gen_inval_exception(ctx, POWERPC_EXCP_INVAL_LSWX);
+        gen_inval_exception(ctx, POWERPC_EXCP_INVAL_INVAL);
     } else {
         /* interpreted as no-op */
     }
@@ -3856,7 +3854,7 @@ static void gen_dst(DisasContext *ctx)
 static void gen_dstst(DisasContext *ctx)
 {
     if (rA(ctx->opcode) == 0) {
-        gen_inval_exception(ctx, POWERPC_EXCP_INVAL_LSWX);
+        gen_inval_exception(ctx, POWERPC_EXCP_INVAL_INVAL);
     } else {
         /* interpreted as no-op */
     }
-- 
2.7.4