target-xtensa: implement SIMCALL

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.

Note that simcalls that accept buffer addresses expect virtual addresses.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

Makefile.target

@@ -370,6 +370,7 @@ obj-alpha-y += vga.o cirrus_vga.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)
 

qemu-options.hx

@@ -2396,11 +2396,11 @@ 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)

target-xtensa/helpers.h

@@ -14,6 +14,7 @@ DEF_HELPER_0(restore_owb, void)
 DEF_HELPER_1(movsp, void, i32)
 DEF_HELPER_1(wsr_lbeg, void, i32)
 DEF_HELPER_1(wsr_lend, void, i32)
+DEF_HELPER_1(simcall, void, env)
 DEF_HELPER_0(dump_state, void)
 
 #include "def-helper.h"

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
@@ -726,7 +727,13 @@ static void disas_xtensa_insn(DisasContext *dc)
                         break;
 
                     case 1: /*SIMCALL*/
-                        TBD();
+                        if (semihosting_enabled) {
+                            gen_check_privilege(dc);
+                            gen_helper_simcall(cpu_env);
+                        } else {
+                            qemu_log("SIMCALL but semihosting is disabled\n");
+                            gen_exception_cause(dc, ILLEGAL_INSTRUCTION_CAUSE);
+                        }
                         break;
 
                     default:

xtensa-semi.c

+/*
+ * 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 "cpu.h"
+#include "dyngen-exec.h"
+#include "helpers.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_lseek = 19,
+    TARGET_SYS_select_one = 29,
+
+    TARGET_SYS_argc = 1000,
+    TARGET_SYS_argv_sz = 1001,
+    TARGET_SYS_argv = 1002,
+    TARGET_SYS_memset = 1004,
+};
+
+enum {
+    SELECT_ONE_READ   = 1,
+    SELECT_ONE_WRITE  = 2,
+    SELECT_ONE_EXCEPT = 3,
+};
+
+void HELPER(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:
+    case TARGET_SYS_write:
+        {
+            bool is_write = regs[2] == TARGET_SYS_write;
+            uint32_t fd = regs[3];
+            uint32_t vaddr = regs[4];
+            uint32_t len = regs[5];
+
+            while (len > 0) {
+                target_phys_addr_t paddr =
+                    cpu_get_phys_page_debug(env, vaddr);
+                uint32_t page_left =
+                    TARGET_PAGE_SIZE - (vaddr & (TARGET_PAGE_SIZE - 1));
+                uint32_t io_sz = page_left < len ? page_left : len;
+                target_phys_addr_t sz = io_sz;
+                void *buf = cpu_physical_memory_map(paddr, &sz, is_write);
+
+                if (buf) {
+                    vaddr += io_sz;
+                    len -= io_sz;
+                    regs[2] = is_write ?
+                        write(fd, buf, io_sz) :
+                        read(fd, buf, io_sz);
+                    regs[3] = errno;
+                    cpu_physical_memory_unmap(buf, sz, is_write, sz);
+                    if (regs[2] == -1) {
+                        break;
+                    }
+                } else {
+                    regs[2] = -1;
+                    regs[3] = EINVAL;
+                    break;
+                }
+            }
+        }
+        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_lseek:
+        regs[2] = lseek(regs[3], (off_t)(int32_t)regs[4], regs[5]);
+        regs[3] = errno;
+        break;
+
+    case TARGET_SYS_select_one:
+        {
+            uint32_t fd = regs[3];
+            uint32_t rq = regs[4];
+            uint32_t target_tv = regs[5];
+            uint32_t target_tvv[2];
+
+            struct timeval tv = {0};
+            fd_set fdset;
+
+            FD_ZERO(&fdset);
+            FD_SET(fd, &fdset);
+
+            if (target_tv) {
+                cpu_memory_rw_debug(env, target_tv,
+                        (uint8_t *)target_tvv, sizeof(target_tvv), 0);
+                tv.tv_sec = (int32_t)tswap32(target_tvv[0]);
+                tv.tv_usec = (int32_t)tswap32(target_tvv[1]);
+            }
+            regs[2] = select(fd + 1,
+                    rq == SELECT_ONE_READ   ? &fdset : NULL,
+                    rq == SELECT_ONE_WRITE  ? &fdset : NULL,
+                    rq == SELECT_ONE_EXCEPT ? &fdset : NULL,
+                    target_tv ? &tv : NULL);
+            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;
+    }
+}