diff mbox series

[RFC,v1,06/43] tcg: Introduce tcg-global-mappings

Message ID 20241121014947.18666-7-anjo@rev.ng (mailing list archive)
State New
Headers show
Series Introduce helper-to-tcg | expand

Commit Message

Anton Johansson Nov. 21, 2024, 1:49 a.m. UTC
Adds a cpu_mapping struct to describe, in a declarative fashion, the
mapping between fields in a struct, and a corresponding TCG global.  As
such, tcg_global_mem_new() can be automatically called given an array of
cpu_mappings.

This change is not limited to helper-to-tcg, but will be required in
future commits to map between offsets into CPUArchState and TCGv
globals in a target-agnostic way.

Signed-off-by: Anton Johansson <anjo@rev.ng>
---
 include/tcg/tcg-global-mappings.h | 111 ++++++++++++++++++++++++++++++
 tcg/meson.build                   |   1 +
 tcg/tcg-global-mappings.c         |  61 ++++++++++++++++
 3 files changed, 173 insertions(+)
 create mode 100644 include/tcg/tcg-global-mappings.h
 create mode 100644 tcg/tcg-global-mappings.c
diff mbox series

Patch

diff --git a/include/tcg/tcg-global-mappings.h b/include/tcg/tcg-global-mappings.h
new file mode 100644
index 0000000000..736380fb20
--- /dev/null
+++ b/include/tcg/tcg-global-mappings.h
@@ -0,0 +1,111 @@ 
+/*
+ *  Copyright(c) 2024 rev.ng Labs Srl. All Rights Reserved.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef TCG_GLOBAL_MAP_H
+#define TCG_GLOBAL_MAP_H
+
+#include "qemu/osdep.h"
+
+/**
+ * cpu_tcg_mapping: Declarative mapping of offsets into a struct to global
+ *                  TCGvs.  Parseable by LLVM-based tools.
+ * @tcg_var_name: String name of the TCGv to use as destination of the mapping.
+ * @tcg_var_base_address: Address of the above TCGv.
+ * @cpu_var_names: Array of printable names of TCGvs, used when calling
+ *                 tcg_global_mem_new from init_cpu_tcg_mappings.
+ * @cpu_var_base_offset: Base offset of field in the source struct.
+ * @cpu_var_size: Size of field in the source struct, if the field is an array,
+ *                this holds the size of the element type.
+ * @cpu_var_stride: Stride between array elements in the source struct.  This
+ *                  can be greater than the element size when mapping a field
+ *                  in an array of structs.
+ * @number_of_elements: Number of elements of array in the source struct.
+ */
+typedef struct cpu_tcg_mapping {
+    const char *tcg_var_name;
+    void *tcg_var_base_address;
+
+    const char *const *cpu_var_names;
+    size_t cpu_var_base_offset;
+    size_t cpu_var_size;
+    size_t cpu_var_stride;
+
+    size_t number_of_elements;
+} cpu_tcg_mapping;
+
+#define STRUCT_SIZEOF_FIELD(S, member) sizeof(((S *)0)->member)
+
+#define STRUCT_ARRAY_SIZE(S, array)                                            \
+    (STRUCT_SIZEOF_FIELD(S, array) / STRUCT_SIZEOF_FIELD(S, array[0]))
+
+/*
+ * Following are a few macros that aid in constructing
+ * `cpu_tcg_mapping`s for a few common cases.
+ */
+
+/* Map between single CPU register and to TCG global */
+#define CPU_TCG_MAP(struct_type, tcg_var, cpu_var, name_str)                   \
+    (cpu_tcg_mapping)                                                          \
+    {                                                                          \
+        .tcg_var_name = stringify(tcg_var), .tcg_var_base_address = &tcg_var,  \
+        .cpu_var_names = (const char *[]){name_str},                           \
+        .cpu_var_base_offset = offsetof(struct_type, cpu_var),                 \
+        .cpu_var_size = STRUCT_SIZEOF_FIELD(struct_type, cpu_var),             \
+        .cpu_var_stride = 0, .number_of_elements = 1,                          \
+    }
+
+/* Map between array of CPU registers and array of TCG globals. */
+#define CPU_TCG_MAP_ARRAY(struct_type, tcg_var, cpu_var, names)                \
+    (cpu_tcg_mapping)                                                          \
+    {                                                                          \
+        .tcg_var_name = #tcg_var, .tcg_var_base_address = tcg_var,             \
+        .cpu_var_names = names,                                                \
+        .cpu_var_base_offset = offsetof(struct_type, cpu_var),                 \
+        .cpu_var_size = STRUCT_SIZEOF_FIELD(struct_type, cpu_var[0]),          \
+        .cpu_var_stride = STRUCT_SIZEOF_FIELD(struct_type, cpu_var[0]),        \
+        .number_of_elements = STRUCT_ARRAY_SIZE(struct_type, cpu_var),         \
+    }
+
+/*
+ * Map between single member in an array of structs to an array
+ * of TCG globals, e.g. maps
+ *
+ *     cpu_state.array_of_structs[i].member
+ *
+ * to
+ *
+ *     tcg_global_member[i]
+ */
+#define CPU_TCG_MAP_ARRAY_OF_STRUCTS(struct_type, tcg_var, cpu_struct,         \
+                                     cpu_var, names)                           \
+    (cpu_tcg_mapping)                                                          \
+    {                                                                          \
+        .tcg_var_name = #tcg_var, .tcg_var_base_address = tcg_var,             \
+        .cpu_var_names = names,                                                \
+        .cpu_var_base_offset = offsetof(struct_type, cpu_struct[0].cpu_var),   \
+        .cpu_var_size =                                                        \
+            STRUCT_SIZEOF_FIELD(struct_type, cpu_struct[0].cpu_var),           \
+        .cpu_var_stride = STRUCT_SIZEOF_FIELD(struct_type, cpu_struct[0]),     \
+        .number_of_elements = STRUCT_ARRAY_SIZE(struct_type, cpu_struct),      \
+    }
+
+extern cpu_tcg_mapping tcg_global_mappings[];
+extern size_t tcg_global_mapping_count;
+
+void init_cpu_tcg_mappings(cpu_tcg_mapping *mappings, size_t size);
+
+#endif /* TCG_GLOBAL_MAP_H */
diff --git a/tcg/meson.build b/tcg/meson.build
index 69ebb4908a..a0d6b09d85 100644
--- a/tcg/meson.build
+++ b/tcg/meson.build
@@ -13,6 +13,7 @@  tcg_ss.add(files(
   'tcg-op-ldst.c',
   'tcg-op-gvec.c',
   'tcg-op-vec.c',
+  'tcg-global-mappings.c',
 ))
 
 if get_option('tcg_interpreter')
diff --git a/tcg/tcg-global-mappings.c b/tcg/tcg-global-mappings.c
new file mode 100644
index 0000000000..cc1f07fae4
--- /dev/null
+++ b/tcg/tcg-global-mappings.c
@@ -0,0 +1,61 @@ 
+/*
+ *  Copyright(c) 2024 rev.ng Labs Srl. All Rights Reserved.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "tcg/tcg-global-mappings.h"
+#include "tcg/tcg-op-common.h"
+#include "tcg/tcg.h"
+
+void init_cpu_tcg_mappings(cpu_tcg_mapping *mappings, size_t size)
+{
+    uintptr_t tcg_addr;
+    size_t cpu_offset;
+    const char *name;
+    cpu_tcg_mapping m;
+
+    /*
+     * Paranoid assertion, this should always hold since
+     * they're typedef'd to pointers. But you never know!
+     */
+    g_assert(sizeof(TCGv_i32) == sizeof(TCGv_i64));
+
+    /*
+     * Loop over entries in tcg_global_mappings and
+     * create the `mapped to` TCGv's.
+     */
+    for (int i = 0; i < size; ++i) {
+        m = mappings[i];
+
+        for (int j = 0; j < m.number_of_elements; ++j) {
+            /*
+             * Here we are using the fact that
+             * sizeof(TCGv_i32) == sizeof(TCGv_i64) == sizeof(TCGv)
+             */
+            assert(sizeof(TCGv_i32) == sizeof(TCGv_i64));
+            tcg_addr = (uintptr_t)m.tcg_var_base_address + j * sizeof(TCGv_i32);
+            cpu_offset = m.cpu_var_base_offset + j * m.cpu_var_stride;
+            name = m.cpu_var_names[j];
+
+            if (m.cpu_var_size < 8) {
+                *(TCGv_i32 *)tcg_addr =
+                    tcg_global_mem_new_i32(tcg_env, cpu_offset, name);
+            } else {
+                *(TCGv_i64 *)tcg_addr =
+                    tcg_global_mem_new_i64(tcg_env, cpu_offset, name);
+            }
+        }
+    }
+}