plugins: save value during memory accesses

Different code paths handle memory accesses:
- tcg generated code
- load/store helpers
- atomic helpers

This value is saved in cpu->neg.plugin_mem_value_{high,low}. Values are
written only for accessed word size (upper bits are not set).

Atomic operations are doing read/write at the same time, so we generate
two memory callbacks instead of one, to allow plugins to access distinct
values.

For now, we can have access only up to 128 bits, thus split this in two
64 bits words. When QEMU will support wider operations, we'll be able to
reconsider this.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-Id: <20240724194708.1843704-2-pierrick.bouvier@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240916085400.1046925-5-alex.bennee@linaro.org>

1 files changed, 59 insertions, 7 deletions

diff --git a/tcg/tcg-op-ldst.c b/tcg/tcg-op-ldst.c
index 8510160258..23dc807f11 100644
--- a/tcg/tcg-op-ldst.c
+++ b/tcg/tcg-op-ldst.c
@@ -148,11 +148,11 @@ static TCGv_i64 plugin_maybe_preserve_addr(TCGTemp *addr)
     return NULL;
 }
 
+#ifdef CONFIG_PLUGIN
 static void
 plugin_gen_mem_callbacks(TCGv_i64 copy_addr, TCGTemp *orig_addr, MemOpIdx oi,
                          enum qemu_plugin_mem_rw rw)
 {
-#ifdef CONFIG_PLUGIN
     if (tcg_ctx->plugin_insn != NULL) {
         qemu_plugin_meminfo_t info = make_plugin_meminfo(oi, rw);
 
@@ -172,6 +172,54 @@ plugin_gen_mem_callbacks(TCGv_i64 copy_addr, TCGTemp *orig_addr, MemOpIdx oi,
             }
         }
     }
+}
+#endif
+
+static void
+plugin_gen_mem_callbacks_i32(TCGv_i32 val,
+                             TCGv_i64 copy_addr, TCGTemp *orig_addr,
+                             MemOpIdx oi, enum qemu_plugin_mem_rw rw)
+{
+#ifdef CONFIG_PLUGIN
+    if (tcg_ctx->plugin_insn != NULL) {
+        tcg_gen_st_i32(val, tcg_env,
+                       offsetof(CPUState, neg.plugin_mem_value_low) -
+                       sizeof(CPUState) + (HOST_BIG_ENDIAN * 4));
+        plugin_gen_mem_callbacks(copy_addr, orig_addr, oi, rw);
+    }
+#endif
+}
+
+static void
+plugin_gen_mem_callbacks_i64(TCGv_i64 val,
+                             TCGv_i64 copy_addr, TCGTemp *orig_addr,
+                             MemOpIdx oi, enum qemu_plugin_mem_rw rw)
+{
+#ifdef CONFIG_PLUGIN
+    if (tcg_ctx->plugin_insn != NULL) {
+        tcg_gen_st_i64(val, tcg_env,
+                       offsetof(CPUState, neg.plugin_mem_value_low) -
+                       sizeof(CPUState));
+        plugin_gen_mem_callbacks(copy_addr, orig_addr, oi, rw);
+    }
+#endif
+}
+
+static void
+plugin_gen_mem_callbacks_i128(TCGv_i128 val,
+                             TCGv_i64 copy_addr, TCGTemp *orig_addr,
+                             MemOpIdx oi, enum qemu_plugin_mem_rw rw)
+{
+#ifdef CONFIG_PLUGIN
+    if (tcg_ctx->plugin_insn != NULL) {
+        tcg_gen_st_i64(TCGV128_LOW(val), tcg_env,
+                       offsetof(CPUState, neg.plugin_mem_value_low) -
+                       sizeof(CPUState));
+        tcg_gen_st_i64(TCGV128_HIGH(val), tcg_env,
+                       offsetof(CPUState, neg.plugin_mem_value_high) -
+                       sizeof(CPUState));
+        plugin_gen_mem_callbacks(copy_addr, orig_addr, oi, rw);
+    }
 #endif
 }
 
@@ -203,7 +251,8 @@ static void tcg_gen_qemu_ld_i32_int(TCGv_i32 val, TCGTemp *addr,
         opc = INDEX_op_qemu_ld_a64_i32;
     }
     gen_ldst(opc, tcgv_i32_temp(val), NULL, addr, oi);
-    plugin_gen_mem_callbacks(copy_addr, addr, orig_oi, QEMU_PLUGIN_MEM_R);
+    plugin_gen_mem_callbacks_i32(val, copy_addr, addr, orig_oi,
+                                 QEMU_PLUGIN_MEM_R);
 
     if ((orig_memop ^ memop) & MO_BSWAP) {
         switch (orig_memop & MO_SIZE) {
@@ -271,7 +320,7 @@ static void tcg_gen_qemu_st_i32_int(TCGv_i32 val, TCGTemp *addr,
         }
     }
     gen_ldst(opc, tcgv_i32_temp(val), NULL, addr, oi);
-    plugin_gen_mem_callbacks(NULL, addr, orig_oi, QEMU_PLUGIN_MEM_W);
+    plugin_gen_mem_callbacks_i32(val, NULL, addr, orig_oi, QEMU_PLUGIN_MEM_W);
 
     if (swap) {
         tcg_temp_free_i32(swap);
@@ -324,7 +373,8 @@ static void tcg_gen_qemu_ld_i64_int(TCGv_i64 val, TCGTemp *addr,
         opc = INDEX_op_qemu_ld_a64_i64;
     }
     gen_ldst_i64(opc, val, addr, oi);
-    plugin_gen_mem_callbacks(copy_addr, addr, orig_oi, QEMU_PLUGIN_MEM_R);
+    plugin_gen_mem_callbacks_i64(val, copy_addr, addr, orig_oi,
+                                 QEMU_PLUGIN_MEM_R);
 
     if ((orig_memop ^ memop) & MO_BSWAP) {
         int flags = (orig_memop & MO_SIGN
@@ -396,7 +446,7 @@ static void tcg_gen_qemu_st_i64_int(TCGv_i64 val, TCGTemp *addr,
         opc = INDEX_op_qemu_st_a64_i64;
     }
     gen_ldst_i64(opc, val, addr, oi);
-    plugin_gen_mem_callbacks(NULL, addr, orig_oi, QEMU_PLUGIN_MEM_W);
+    plugin_gen_mem_callbacks_i64(val, NULL, addr, orig_oi, QEMU_PLUGIN_MEM_W);
 
     if (swap) {
         tcg_temp_free_i64(swap);
@@ -606,7 +656,8 @@ static void tcg_gen_qemu_ld_i128_int(TCGv_i128 val, TCGTemp *addr,
                            tcg_constant_i32(orig_oi));
     }
 
-    plugin_gen_mem_callbacks(ext_addr, addr, orig_oi, QEMU_PLUGIN_MEM_R);
+    plugin_gen_mem_callbacks_i128(val, ext_addr, addr, orig_oi,
+                                  QEMU_PLUGIN_MEM_R);
 }
 
 void tcg_gen_qemu_ld_i128_chk(TCGv_i128 val, TCGTemp *addr, TCGArg idx,
@@ -722,7 +773,8 @@ static void tcg_gen_qemu_st_i128_int(TCGv_i128 val, TCGTemp *addr,
                            tcg_constant_i32(orig_oi));
     }
 
-    plugin_gen_mem_callbacks(ext_addr, addr, orig_oi, QEMU_PLUGIN_MEM_W);
+    plugin_gen_mem_callbacks_i128(val, ext_addr, addr, orig_oi,
+                                  QEMU_PLUGIN_MEM_W);
 }
 
 void tcg_gen_qemu_st_i128_chk(TCGv_i128 val, TCGTemp *addr, TCGArg idx,