[Qemu-devel] [PATCH 3/7] target-ppc: retain l{w,d}arx loaded value

[Nathan Froyd <froydnj@codesourcery.com>]

We do this so we can check on the corresponding stc{w,d}x. whether the
value has changed.  It's a poor man's form of implementing atomic
operations and is valid only for NPTL usermode Linux emulation.

Signed-off-by: Nathan Froyd <froydnj@codesourcery.com>
---
 target-ppc/cpu.h       |    4 +++-
 target-ppc/helper.c    |    2 +-
 target-ppc/machine.c   |    4 ++--
 target-ppc/op_helper.c |    4 ++--
 target-ppc/translate.c |   13 +++++++++----
 5 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index fe2257d..7935fcd 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -561,7 +561,9 @@ struct CPUPPCState {
     /* XER */
     target_ulong xer;
     /* Reservation address */
-    target_ulong reserve;
+    target_ulong reserve_addr;
+    /* Reservation value */
+    target_ulong reserve_val;
 
     /* Those ones are used in supervisor mode only */
     /* machine state register */
diff --git a/target-ppc/helper.c b/target-ppc/helper.c
index b7162df..6eca2e5 100644
--- a/target-ppc/helper.c
+++ b/target-ppc/helper.c
@@ -2805,7 +2805,7 @@ void cpu_ppc_reset (void *opaque)
         env->msr |= (1ULL << MSR_SF);
 #endif
     hreg_compute_hflags(env);
-    env->reserve = (target_ulong)-1ULL;
+    env->reserve_addr = (target_ulong)-1ULL;
     /* Be sure no exception or interrupt is pending */
     env->pending_interrupts = 0;
     env->exception_index = POWERPC_EXCP_NONE;
diff --git a/target-ppc/machine.c b/target-ppc/machine.c
index 99ba3eb..deb2e2d 100644
--- a/target-ppc/machine.c
+++ b/target-ppc/machine.c
@@ -20,7 +20,7 @@ void cpu_save(QEMUFile *f, void *opaque)
     for (i = 0; i < 8; i++)
         qemu_put_be32s(f, &env->crf[i]);
     qemu_put_betls(f, &env->xer);
-    qemu_put_betls(f, &env->reserve);
+    qemu_put_betls(f, &env->reserve_addr);
     qemu_put_betls(f, &env->msr);
     for (i = 0; i < 4; i++)
         qemu_put_betls(f, &env->tgpr[i]);
@@ -107,7 +107,7 @@ int cpu_load(QEMUFile *f, void *opaque, int version_id)
     for (i = 0; i < 8; i++)
         qemu_get_be32s(f, &env->crf[i]);
     qemu_get_betls(f, &env->xer);
-    qemu_get_betls(f, &env->reserve);
+    qemu_get_betls(f, &env->reserve_addr);
     qemu_get_betls(f, &env->msr);
     for (i = 0; i < 4; i++)
         qemu_get_betls(f, &env->tgpr[i]);
diff --git a/target-ppc/op_helper.c b/target-ppc/op_helper.c
index ad6d8ee..812282c 100644
--- a/target-ppc/op_helper.c
+++ b/target-ppc/op_helper.c
@@ -329,8 +329,8 @@ static void do_dcbz(target_ulong addr, int dcache_line_size)
     for (i = 0 ; i < dcache_line_size ; i += 4) {
         stl(addr + i , 0);
     }
-    if (env->reserve == addr)
-        env->reserve = (target_ulong)-1ULL;
+    if (env->reserve_addr == addr)
+        env->reserve_addr = (target_ulong)-1ULL;
 }
 
 void helper_dcbz(target_ulong addr)
diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index 58818c2..06282b6 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -158,7 +158,8 @@ void ppc_translate_init(void)
                                  offsetof(CPUState, xer), "xer");
 
     cpu_reserve = tcg_global_mem_new(TCG_AREG0,
-                                     offsetof(CPUState, reserve), "reserve");
+                                     offsetof(CPUState, reserve_addr),
+                                     "reserve_addr");
 
     cpu_fpscr = tcg_global_mem_new_i32(TCG_AREG0,
                                        offsetof(CPUState, fpscr), "fpscr");
@@ -3006,12 +3007,14 @@ static void gen_isync(DisasContext *ctx)
 static void gen_lwarx(DisasContext *ctx)
 {
     TCGv t0;
+    TCGv gpr = cpu_gpr[rD(ctx->opcode)];
     gen_set_access_type(ctx, ACCESS_RES);
     t0 = tcg_temp_local_new();
     gen_addr_reg_index(ctx, t0);
     gen_check_align(ctx, t0, 0x03);
-    gen_qemu_ld32u(ctx, cpu_gpr[rD(ctx->opcode)], t0);
+    gen_qemu_ld32u(ctx, gpr, t0);
     tcg_gen_mov_tl(cpu_reserve, t0);
+    tcg_gen_st_tl(gpr, cpu_env, offsetof(CPUState, reserve_val));
     tcg_temp_free(t0);
 }
 
@@ -3041,12 +3044,14 @@ static void gen_stwcx_(DisasContext *ctx)
 static void gen_ldarx(DisasContext *ctx)
 {
     TCGv t0;
+    TCGv gpr = cpu_gpr[rD(ctx->opcode)];
     gen_set_access_type(ctx, ACCESS_RES);
     t0 = tcg_temp_local_new();
     gen_addr_reg_index(ctx, t0);
     gen_check_align(ctx, t0, 0x07);
-    gen_qemu_ld64(ctx, cpu_gpr[rD(ctx->opcode)], t0);
+    gen_qemu_ld64(ctx, gpr, t0);
     tcg_gen_mov_tl(cpu_reserve, t0);
+    tcg_gen_st_tl(gpr, cpu_env, offsetof(CPUState, reserve_val));
     tcg_temp_free(t0);
 }
 
@@ -8834,7 +8839,7 @@ void cpu_dump_state (CPUState *env, FILE *f,
             a = 'E';
         cpu_fprintf(f, " %c%c", a, env->crf[i] & 0x01 ? 'O' : ' ');
     }
-    cpu_fprintf(f, " ]             RES " ADDRX "\n", env->reserve);
+    cpu_fprintf(f, " ]             RES " ADDRX "\n", env->reserve_addr);
     for (i = 0; i < 32; i++) {
         if ((i & (RFPL - 1)) == 0)
             cpu_fprintf(f, "FPR%02d", i);
-- 
1.6.3.2