[PATCH v3 08/14] target/ppc: Fix gen_sc to use correct nip

[BALATON Zoltan]

Most exceptions are raised with nip pointing to the faulting
instruction but the sc instruction generating a syscall exception
leaves nip pointing to next instruction. Fix gen_sc to not use
gen_exception_err() which sets nip back but correctly set nip to
pc_next so we don't have to patch this in the exception handlers.

This changes the nip logged in dump_syscall and dump_hcall debug
functions but now this matches how nip would be on a real CPU.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
---
 target/ppc/excp_helper.c | 39 ---------------------------------------
 target/ppc/translate.c   |  8 +++++---
 2 files changed, 5 insertions(+), 42 deletions(-)

diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
index f19a0f2d1d..903216c2a6 100644
--- a/target/ppc/excp_helper.c
+++ b/target/ppc/excp_helper.c
@@ -495,12 +495,6 @@ static void powerpc_excp_40x(PowerPCCPU *cpu, int excp)
         break;
     case POWERPC_EXCP_SYSCALL:   /* System call exception                    */
         dump_syscall(env);
-
-        /*
-         * We need to correct the NIP which in this case is supposed
-         * to point to the next instruction
-         */
-        env->nip += 4;
         break;
     case POWERPC_EXCP_FIT:       /* Fixed-interval timer interrupt           */
         trace_ppc_excp_print("FIT");
@@ -611,12 +605,6 @@ static void powerpc_excp_6xx(PowerPCCPU *cpu, int excp)
         break;
     case POWERPC_EXCP_SYSCALL:   /* System call exception                    */
         dump_syscall(env);
-
-        /*
-         * We need to correct the NIP which in this case is supposed
-         * to point to the next instruction
-         */
-        env->nip += 4;
         break;
     case POWERPC_EXCP_FPU:       /* Floating-point unavailable exception     */
     case POWERPC_EXCP_DECR:      /* Decrementer exception                    */
@@ -759,13 +747,6 @@ static void powerpc_excp_7xx(PowerPCCPU *cpu, int excp)
         } else {
             dump_syscall(env);
         }
-
-        /*
-         * We need to correct the NIP which in this case is supposed
-         * to point to the next instruction
-         */
-        env->nip += 4;
-
         /*
          * The Virtual Open Firmware (VOF) relies on the 'sc 1'
          * instruction to communicate with QEMU. The pegasos2 machine
@@ -910,13 +891,6 @@ static void powerpc_excp_74xx(PowerPCCPU *cpu, int excp)
         } else {
             dump_syscall(env);
         }
-
-        /*
-         * We need to correct the NIP which in this case is supposed
-         * to point to the next instruction
-         */
-        env->nip += 4;
-
         /*
          * The Virtual Open Firmware (VOF) relies on the 'sc 1'
          * instruction to communicate with QEMU. The pegasos2 machine
@@ -1075,12 +1049,6 @@ static void powerpc_excp_booke(PowerPCCPU *cpu, int excp)
         break;
     case POWERPC_EXCP_SYSCALL:   /* System call exception                    */
         dump_syscall(env);
-
-        /*
-         * We need to correct the NIP which in this case is supposed
-         * to point to the next instruction
-         */
-        env->nip += 4;
         break;
     case POWERPC_EXCP_FPU:       /* Floating-point unavailable exception     */
     case POWERPC_EXCP_APU:       /* Auxiliary processor unavailable          */
@@ -1322,13 +1290,6 @@ static void powerpc_excp_books(PowerPCCPU *cpu, int excp)
         } else {
             dump_syscall(env);
         }
-
-        /*
-         * We need to correct the NIP which in this case is supposed
-         * to point to the next instruction
-         */
-        env->nip += 4;
-
         /* "PAPR mode" built-in hypercall emulation */
         if (lev == 1 && books_vhyp_handles_hcall(cpu)) {
             PPCVirtualHypervisorClass *vhc =
diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index a32a9b8a5f..4260d3d66f 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -4419,10 +4419,12 @@ static void gen_hrfid(DisasContext *ctx)
 #endif
 static void gen_sc(DisasContext *ctx)
 {
-    uint32_t lev;
+    uint32_t lev = (ctx->opcode >> 5) & 0x7F;
 
-    lev = (ctx->opcode >> 5) & 0x7F;
-    gen_exception_err(ctx, POWERPC_SYSCALL, lev);
+    gen_update_nip(ctx, ctx->base.pc_next);
+    gen_helper_raise_exception_err(cpu_env, tcg_constant_i32(POWERPC_SYSCALL),
+                                   tcg_constant_i32(lev));
+    ctx->base.is_jmp = DISAS_NORETURN;
 }
 
 #if defined(TARGET_PPC64)
-- 
2.30.9