[Qemu-devel] [PATCH 22/26] target-xtensa: implement SIMCALL

[Max Filippov <jcmvbkbc@gmail.com>]

Tensilica iss provides support for applications running in freestanding
environment through SIMCALL command. It is used by Tensilica libc to
access argc/argv, for file I/O, etc.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
RFC -> PATCH changes:
- use -semihosting to implement SIMCALL;
- fix user memory manipulation code;
- fill in errno for failure cases;
- rename SYS_* to TARGET_SYS_*;
---
 Makefile.target           |    1 +
 qemu-options.hx           |    4 +-
 target-xtensa/cpu.h       |    1 +
 target-xtensa/helpers.h   |    1 +
 target-xtensa/op_helper.c |    5 ++
 target-xtensa/translate.c |    8 ++-
 xtensa-semi.c             |  176 +++++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 193 insertions(+), 3 deletions(-)
 create mode 100644 xtensa-semi.c

diff --git a/Makefile.target b/Makefile.target
index ca0db72..1ce0521 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -380,6 +380,7 @@ obj-alpha-y = alpha_palcode.o
 
 obj-xtensa-y += xtensa_pic.o
 obj-xtensa-y += xtensa_sample.o
+obj-xtensa-y += xtensa-semi.o
 
 main.o: QEMU_CFLAGS+=$(GPROF_CFLAGS)
 
diff --git a/qemu-options.hx b/qemu-options.hx
index 82e085a..e2acbf4 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2328,11 +2328,11 @@ STEXI
 Set OpenBIOS nvram @var{variable} to given @var{value} (PPC, SPARC only).
 ETEXI
 DEF("semihosting", 0, QEMU_OPTION_semihosting,
-    "-semihosting    semihosting mode\n", QEMU_ARCH_ARM | QEMU_ARCH_M68K)
+    "-semihosting    semihosting mode\n", QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA)
 STEXI
 @item -semihosting
 @findex -semihosting
-Semihosting mode (ARM, M68K only).
+Semihosting mode (ARM, M68K, Xtensa only).
 ETEXI
 DEF("old-param", 0, QEMU_OPTION_old_param,
     "-old-param      old param mode\n", QEMU_ARCH_ARM)
diff --git a/target-xtensa/cpu.h b/target-xtensa/cpu.h
index 793a6b5..55d81e9 100644
--- a/target-xtensa/cpu.h
+++ b/target-xtensa/cpu.h
@@ -226,6 +226,7 @@ int cpu_xtensa_signal_handler(int host_signum, void *pinfo, void *puc);
 void xtensa_cpu_list(FILE *f, fprintf_function cpu_fprintf);
 void xtensa_sync_window_from_phys(CPUState *env);
 void xtensa_sync_phys_from_window(CPUState *env);
+void simcall(CPUState *env);
 
 static inline int xtensa_option_enabled(const XtensaConfig *config, int opt)
 {
diff --git a/target-xtensa/helpers.h b/target-xtensa/helpers.h
index 7babf73..87c7cc5 100644
--- a/target-xtensa/helpers.h
+++ b/target-xtensa/helpers.h
@@ -13,6 +13,7 @@ DEF_HELPER_2(window_check, void, i32, i32)
 DEF_HELPER_0(restore_owb, void)
 DEF_HELPER_1(movsp, void, i32)
 DEF_HELPER_1(wsr_lend, void, i32)
+DEF_HELPER_0(simcall, void)
 DEF_HELPER_0(dump_state, void)
 
 #include "def-helper.h"
diff --git a/target-xtensa/op_helper.c b/target-xtensa/op_helper.c
index 3a0fa01..b170dbe 100644
--- a/target-xtensa/op_helper.c
+++ b/target-xtensa/op_helper.c
@@ -291,6 +291,11 @@ void HELPER(wsr_lend)(uint32_t v)
     }
 }
 
+void HELPER(simcall)(void)
+{
+    simcall(env);
+}
+
 void HELPER(dump_state)(void)
 {
     cpu_dump_state(env, stderr, fprintf, 0);
diff --git a/target-xtensa/translate.c b/target-xtensa/translate.c
index 6e66f3f..b40218d 100644
--- a/target-xtensa/translate.c
+++ b/target-xtensa/translate.c
@@ -35,6 +35,7 @@
 #include "disas.h"
 #include "tcg-op.h"
 #include "qemu-log.h"
+#include "sysemu.h"
 
 #include "helpers.h"
 #define GEN_HELPER 1
@@ -675,7 +676,12 @@ static void disas_xtensa_insn(DisasContext *dc)
                         break;
 
                     case 1: /*SIMCALL*/
-                        TBD();
+                        if (semihosting_enabled) {
+                            gen_helper_simcall();
+                        } else {
+                            qemu_log("SIMCALL but semihosting is disabled\n");
+                            gen_exception_cause(dc, ILLEGAL_INSTRUCTION_CAUSE);
+                        }
                         break;
 
                     default:
diff --git a/xtensa-semi.c b/xtensa-semi.c
new file mode 100644
index 0000000..2ce6cc1
--- /dev/null
+++ b/xtensa-semi.c
@@ -0,0 +1,176 @@
+/*
+ * Copyright (c) 2011, Max Filippov, Open Source and Linux Lab.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the Open Source and Linux Lab nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+#include <stddef.h>
+#include "exec.h"
+#include "qemu-log.h"
+
+enum {
+    TARGET_SYS_exit = 1,
+    TARGET_SYS_read = 3,
+    TARGET_SYS_write = 4,
+    TARGET_SYS_open = 5,
+    TARGET_SYS_close = 6,
+
+    TARGET_SYS_argc = 1000,
+    TARGET_SYS_argv_sz = 1001,
+    TARGET_SYS_argv = 1002,
+    TARGET_SYS_memset = 1004,
+};
+
+void simcall(CPUState *env)
+{
+    uint32_t *regs = env->regs;
+
+    switch (regs[2]) {
+    case TARGET_SYS_exit:
+        qemu_log("exit(%d) simcall\n", regs[3]);
+        exit(regs[3]);
+        break;
+
+    case TARGET_SYS_read:
+        {
+            target_phys_addr_t len = regs[5];
+            void *buf = cpu_physical_memory_map(regs[4], &len, 1);
+
+            if (buf) {
+                regs[2] = read(regs[3], buf, len);
+                regs[3] = errno;
+                cpu_physical_memory_unmap(buf, len, 1, len);
+            } else {
+                regs[2] = -1;
+                regs[3] = EINVAL;
+            }
+        }
+        break;
+
+    case TARGET_SYS_write:
+        {
+            target_phys_addr_t len = regs[5];
+            void *buf = cpu_physical_memory_map(regs[4], &len, 0);
+
+            if (buf) {
+                regs[2] = write(regs[3], buf, len);
+                regs[3] = errno;
+                cpu_physical_memory_unmap(buf, len, 0, len);
+            } else {
+                regs[2] = -1;
+                regs[3] = EINVAL;
+            }
+        }
+        break;
+
+    case TARGET_SYS_open:
+        {
+            char name[1024];
+            int rc;
+            int i;
+
+            for (i = 0; i < ARRAY_SIZE(name); ++i) {
+                rc = cpu_memory_rw_debug(
+                        env, regs[3] + i, (uint8_t *)name + i, 1, 0);
+                if (rc != 0 || name[i] == 0) {
+                    break;
+                }
+            }
+
+            if (rc == 0 && i < ARRAY_SIZE(name)) {
+                regs[2] = open(name, regs[4], regs[5]);
+                regs[3] = errno;
+            } else {
+                regs[2] = -1;
+                regs[3] = EINVAL;
+            }
+        }
+        break;
+
+    case TARGET_SYS_close:
+        if (regs[3] < 3) {
+            regs[2] = regs[3] = 0;
+        } else {
+            regs[2] = close(regs[3]);
+            regs[3] = errno;
+        }
+        break;
+
+    case TARGET_SYS_argc:
+        regs[2] = 1;
+        regs[3] = 0;
+        break;
+
+    case TARGET_SYS_argv_sz:
+        regs[2] = 128;
+        regs[3] = 0;
+        break;
+
+    case TARGET_SYS_argv:
+        {
+            struct Argv {
+                uint32_t argptr[2];
+                char text[120];
+            } argv = {
+                {0, 0},
+                "test"
+            };
+
+            argv.argptr[0] = tswap32(regs[3] + offsetof(struct Argv, text));
+            cpu_memory_rw_debug(
+                    env, regs[3], (uint8_t *)&argv, sizeof(argv), 1);
+        }
+        break;
+
+    case TARGET_SYS_memset:
+        {
+            uint32_t base = regs[3];
+            uint32_t sz = regs[5];
+
+            while (sz) {
+                target_phys_addr_t len = sz;
+                void *buf = cpu_physical_memory_map(base, &len, 1);
+
+                if (buf && len) {
+                    memset(buf, regs[4], len);
+                    cpu_physical_memory_unmap(buf, len, 1, len);
+                } else {
+                    len = 1;
+                }
+                base += len;
+                sz -= len;
+            }
+            regs[2] = regs[3];
+            regs[3] = 0;
+        }
+        break;
+
+    default:
+        qemu_log("%s(%d): not implemented\n", __func__, regs[2]);
+        break;
+    }
+}
-- 
1.7.3.4