Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 446 insertions, 0 deletions

diff --git a/linux-user/i386/cpu_loop.c b/linux-user/i386/cpu_loop.c
new file mode 100644
index 000000000..f6a1cc632
--- /dev/null
+++ b/linux-user/i386/cpu_loop.c
@@ -0,0 +1,446 @@
+/*
+ *  qemu user cpu loop
+ *
+ *  Copyright (c) 2003-2008 Fabrice Bellard
+ *
+ *  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 "qemu/osdep.h"
+#include "qemu-common.h"
+#include "qemu.h"
+#include "user-internals.h"
+#include "cpu_loop-common.h"
+#include "signal-common.h"
+#include "user-mmap.h"
+
+/***********************************************************/
+/* CPUX86 core interface */
+
+uint64_t cpu_get_tsc(CPUX86State *env)
+{
+    return cpu_get_host_ticks();
+}
+
+static void write_dt(void *ptr, unsigned long addr, unsigned long limit,
+              int flags)
+{
+    unsigned int e1, e2;
+    uint32_t *p;
+    e1 = (addr << 16) | (limit & 0xffff);
+    e2 = ((addr >> 16) & 0xff) | (addr & 0xff000000) | (limit & 0x000f0000);
+    e2 |= flags;
+    p = ptr;
+    p[0] = tswap32(e1);
+    p[1] = tswap32(e2);
+}
+
+static uint64_t *idt_table;
+#ifdef TARGET_X86_64
+static void set_gate64(void *ptr, unsigned int type, unsigned int dpl,
+                       uint64_t addr, unsigned int sel)
+{
+    uint32_t *p, e1, e2;
+    e1 = (addr & 0xffff) | (sel << 16);
+    e2 = (addr & 0xffff0000) | 0x8000 | (dpl << 13) | (type << 8);
+    p = ptr;
+    p[0] = tswap32(e1);
+    p[1] = tswap32(e2);
+    p[2] = tswap32(addr >> 32);
+    p[3] = 0;
+}
+/* only dpl matters as we do only user space emulation */
+static void set_idt(int n, unsigned int dpl)
+{
+    set_gate64(idt_table + n * 2, 0, dpl, 0, 0);
+}
+#else
+static void set_gate(void *ptr, unsigned int type, unsigned int dpl,
+                     uint32_t addr, unsigned int sel)
+{
+    uint32_t *p, e1, e2;
+    e1 = (addr & 0xffff) | (sel << 16);
+    e2 = (addr & 0xffff0000) | 0x8000 | (dpl << 13) | (type << 8);
+    p = ptr;
+    p[0] = tswap32(e1);
+    p[1] = tswap32(e2);
+}
+
+/* only dpl matters as we do only user space emulation */
+static void set_idt(int n, unsigned int dpl)
+{
+    set_gate(idt_table + n, 0, dpl, 0, 0);
+}
+#endif
+
+static void gen_signal(CPUX86State *env, int sig, int code, abi_ptr addr)
+{
+    target_siginfo_t info = {
+        .si_signo = sig,
+        .si_code = code,
+        ._sifields._sigfault._addr = addr
+    };
+
+    queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
+}
+
+#ifdef TARGET_X86_64
+static bool write_ok_or_segv(CPUX86State *env, abi_ptr addr, size_t len)
+{
+    /*
+     * For all the vsyscalls, NULL means "don't write anything" not
+     * "write it at address 0".
+     */
+    if (addr == 0 || access_ok(env_cpu(env), VERIFY_WRITE, addr, len)) {
+        return true;
+    }
+
+    env->error_code = PG_ERROR_W_MASK | PG_ERROR_U_MASK;
+    gen_signal(env, TARGET_SIGSEGV, TARGET_SEGV_MAPERR, addr);
+    return false;
+}
+
+/*
+ * Since v3.1, the kernel traps and emulates the vsyscall page.
+ * Entry points other than the official generate SIGSEGV.
+ */
+static void emulate_vsyscall(CPUX86State *env)
+{
+    int syscall;
+    abi_ulong ret;
+    uint64_t caller;
+
+    /*
+     * Validate the entry point.  We have already validated the page
+     * during translation to get here; now verify the offset.
+     */
+    switch (env->eip & ~TARGET_PAGE_MASK) {
+    case 0x000:
+        syscall = TARGET_NR_gettimeofday;
+        break;
+    case 0x400:
+        syscall = TARGET_NR_time;
+        break;
+    case 0x800:
+        syscall = TARGET_NR_getcpu;
+        break;
+    default:
+        goto sigsegv;
+    }
+
+    /*
+     * Validate the return address.
+     * Note that the kernel treats this the same as an invalid entry point.
+     */
+    if (get_user_u64(caller, env->regs[R_ESP])) {
+        goto sigsegv;
+    }
+
+    /*
+     * Validate the the pointer arguments.
+     */
+    switch (syscall) {
+    case TARGET_NR_gettimeofday:
+        if (!write_ok_or_segv(env, env->regs[R_EDI],
+                              sizeof(struct target_timeval)) ||
+            !write_ok_or_segv(env, env->regs[R_ESI],
+                              sizeof(struct target_timezone))) {
+            return;
+        }
+        break;
+    case TARGET_NR_time:
+        if (!write_ok_or_segv(env, env->regs[R_EDI], sizeof(abi_long))) {
+            return;
+        }
+        break;
+    case TARGET_NR_getcpu:
+        if (!write_ok_or_segv(env, env->regs[R_EDI], sizeof(uint32_t)) ||
+            !write_ok_or_segv(env, env->regs[R_ESI], sizeof(uint32_t))) {
+            return;
+        }
+        break;
+    default:
+        g_assert_not_reached();
+    }
+
+    /*
+     * Perform the syscall.  None of the vsyscalls should need restarting.
+     */
+    ret = do_syscall(env, syscall, env->regs[R_EDI], env->regs[R_ESI],
+                     env->regs[R_EDX], env->regs[10], env->regs[8],
+                     env->regs[9], 0, 0);
+    g_assert(ret != -TARGET_ERESTARTSYS);
+    g_assert(ret != -TARGET_QEMU_ESIGRETURN);
+    if (ret == -TARGET_EFAULT) {
+        goto sigsegv;
+    }
+    env->regs[R_EAX] = ret;
+
+    /* Emulate a ret instruction to leave the vsyscall page.  */
+    env->eip = caller;
+    env->regs[R_ESP] += 8;
+    return;
+
+ sigsegv:
+    /* Like force_sig(SIGSEGV).  */
+    gen_signal(env, TARGET_SIGSEGV, TARGET_SI_KERNEL, 0);
+}
+#endif
+
+void cpu_loop(CPUX86State *env)
+{
+    CPUState *cs = env_cpu(env);
+    int trapnr;
+    abi_ulong pc;
+    abi_ulong ret;
+
+    for(;;) {
+        cpu_exec_start(cs);
+        trapnr = cpu_exec(cs);
+        cpu_exec_end(cs);
+        process_queued_cpu_work(cs);
+
+        switch(trapnr) {
+        case 0x80:
+            /* linux syscall from int $0x80 */
+            ret = do_syscall(env,
+                             env->regs[R_EAX],
+                             env->regs[R_EBX],
+                             env->regs[R_ECX],
+                             env->regs[R_EDX],
+                             env->regs[R_ESI],
+                             env->regs[R_EDI],
+                             env->regs[R_EBP],
+                             0, 0);
+            if (ret == -TARGET_ERESTARTSYS) {
+                env->eip -= 2;
+            } else if (ret != -TARGET_QEMU_ESIGRETURN) {
+                env->regs[R_EAX] = ret;
+            }
+            break;
+#ifndef TARGET_ABI32
+        case EXCP_SYSCALL:
+            /* linux syscall from syscall instruction */
+            ret = do_syscall(env,
+                             env->regs[R_EAX],
+                             env->regs[R_EDI],
+                             env->regs[R_ESI],
+                             env->regs[R_EDX],
+                             env->regs[10],
+                             env->regs[8],
+                             env->regs[9],
+                             0, 0);
+            if (ret == -TARGET_ERESTARTSYS) {
+                env->eip -= 2;
+            } else if (ret != -TARGET_QEMU_ESIGRETURN) {
+                env->regs[R_EAX] = ret;
+            }
+            break;
+#endif
+#ifdef TARGET_X86_64
+        case EXCP_VSYSCALL:
+            emulate_vsyscall(env);
+            break;
+#endif
+        case EXCP0B_NOSEG:
+        case EXCP0C_STACK:
+            gen_signal(env, TARGET_SIGBUS, TARGET_SI_KERNEL, 0);
+            break;
+        case EXCP0D_GPF:
+            /* XXX: potential problem if ABI32 */
+#ifndef TARGET_X86_64
+            if (env->eflags & VM_MASK) {
+                handle_vm86_fault(env);
+                break;
+            }
+#endif
+            gen_signal(env, TARGET_SIGSEGV, TARGET_SI_KERNEL, 0);
+            break;
+        case EXCP0E_PAGE:
+            gen_signal(env, TARGET_SIGSEGV,
+                       (env->error_code & 1 ?
+                        TARGET_SEGV_ACCERR : TARGET_SEGV_MAPERR),
+                       env->cr[2]);
+            break;
+        case EXCP00_DIVZ:
+#ifndef TARGET_X86_64
+            if (env->eflags & VM_MASK) {
+                handle_vm86_trap(env, trapnr);
+                break;
+            }
+#endif
+            gen_signal(env, TARGET_SIGFPE, TARGET_FPE_INTDIV, env->eip);
+            break;
+        case EXCP01_DB:
+        case EXCP03_INT3:
+#ifndef TARGET_X86_64
+            if (env->eflags & VM_MASK) {
+                handle_vm86_trap(env, trapnr);
+                break;
+            }
+#endif
+            if (trapnr == EXCP01_DB) {
+                gen_signal(env, TARGET_SIGTRAP, TARGET_TRAP_BRKPT, env->eip);
+            } else {
+                gen_signal(env, TARGET_SIGTRAP, TARGET_SI_KERNEL, 0);
+            }
+            break;
+        case EXCP04_INTO:
+        case EXCP05_BOUND:
+#ifndef TARGET_X86_64
+            if (env->eflags & VM_MASK) {
+                handle_vm86_trap(env, trapnr);
+                break;
+            }
+#endif
+            gen_signal(env, TARGET_SIGSEGV, TARGET_SI_KERNEL, 0);
+            break;
+        case EXCP06_ILLOP:
+            gen_signal(env, TARGET_SIGILL, TARGET_ILL_ILLOPN, env->eip);
+            break;
+        case EXCP_INTERRUPT:
+            /* just indicate that signals should be handled asap */
+            break;
+        case EXCP_DEBUG:
+            gen_signal(env, TARGET_SIGTRAP, TARGET_TRAP_BRKPT, 0);
+            break;
+        case EXCP_ATOMIC:
+            cpu_exec_step_atomic(cs);
+            break;
+        default:
+            pc = env->segs[R_CS].base + env->eip;
+            EXCP_DUMP(env, "qemu: 0x%08lx: unhandled CPU exception 0x%x - aborting\n",
+                      (long)pc, trapnr);
+            abort();
+        }
+        process_pending_signals(env);
+    }
+}
+
+void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
+{
+    env->cr[0] = CR0_PG_MASK | CR0_WP_MASK | CR0_PE_MASK;
+    env->hflags |= HF_PE_MASK | HF_CPL_MASK;
+    if (env->features[FEAT_1_EDX] & CPUID_SSE) {
+        env->cr[4] |= CR4_OSFXSR_MASK;
+        env->hflags |= HF_OSFXSR_MASK;
+    }
+#ifndef TARGET_ABI32
+    /* enable 64 bit mode if possible */
+    if (!(env->features[FEAT_8000_0001_EDX] & CPUID_EXT2_LM)) {
+        fprintf(stderr, "The selected x86 CPU does not support 64 bit mode\n");
+        exit(EXIT_FAILURE);
+    }
+    env->cr[4] |= CR4_PAE_MASK;
+    env->efer |= MSR_EFER_LMA | MSR_EFER_LME;
+    env->hflags |= HF_LMA_MASK;
+#endif
+
+    /* flags setup : we activate the IRQs by default as in user mode */
+    env->eflags |= IF_MASK;
+
+    /* linux register setup */
+#ifndef TARGET_ABI32
+    env->regs[R_EAX] = regs->rax;
+    env->regs[R_EBX] = regs->rbx;
+    env->regs[R_ECX] = regs->rcx;
+    env->regs[R_EDX] = regs->rdx;
+    env->regs[R_ESI] = regs->rsi;
+    env->regs[R_EDI] = regs->rdi;
+    env->regs[R_EBP] = regs->rbp;
+    env->regs[R_ESP] = regs->rsp;
+    env->eip = regs->rip;
+#else
+    env->regs[R_EAX] = regs->eax;
+    env->regs[R_EBX] = regs->ebx;
+    env->regs[R_ECX] = regs->ecx;
+    env->regs[R_EDX] = regs->edx;
+    env->regs[R_ESI] = regs->esi;
+    env->regs[R_EDI] = regs->edi;
+    env->regs[R_EBP] = regs->ebp;
+    env->regs[R_ESP] = regs->esp;
+    env->eip = regs->eip;
+#endif
+
+    /* linux interrupt setup */
+#ifndef TARGET_ABI32
+    env->idt.limit = 511;
+#else
+    env->idt.limit = 255;
+#endif
+    env->idt.base = target_mmap(0, sizeof(uint64_t) * (env->idt.limit + 1),
+                                PROT_READ|PROT_WRITE,
+                                MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+    idt_table = g2h_untagged(env->idt.base);
+    set_idt(0, 0);
+    set_idt(1, 0);
+    set_idt(2, 0);
+    set_idt(3, 3);
+    set_idt(4, 3);
+    set_idt(5, 0);
+    set_idt(6, 0);
+    set_idt(7, 0);
+    set_idt(8, 0);
+    set_idt(9, 0);
+    set_idt(10, 0);
+    set_idt(11, 0);
+    set_idt(12, 0);
+    set_idt(13, 0);
+    set_idt(14, 0);
+    set_idt(15, 0);
+    set_idt(16, 0);
+    set_idt(17, 0);
+    set_idt(18, 0);
+    set_idt(19, 0);
+    set_idt(0x80, 3);
+
+    /* linux segment setup */
+    {
+        uint64_t *gdt_table;
+        env->gdt.base = target_mmap(0, sizeof(uint64_t) * TARGET_GDT_ENTRIES,
+                                    PROT_READ|PROT_WRITE,
+                                    MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+        env->gdt.limit = sizeof(uint64_t) * TARGET_GDT_ENTRIES - 1;
+        gdt_table = g2h_untagged(env->gdt.base);
+#ifdef TARGET_ABI32
+        write_dt(&gdt_table[__USER_CS >> 3], 0, 0xfffff,
+                 DESC_G_MASK | DESC_B_MASK | DESC_P_MASK | DESC_S_MASK |
+                 (3 << DESC_DPL_SHIFT) | (0xa << DESC_TYPE_SHIFT));
+#else
+        /* 64 bit code segment */
+        write_dt(&gdt_table[__USER_CS >> 3], 0, 0xfffff,
+                 DESC_G_MASK | DESC_B_MASK | DESC_P_MASK | DESC_S_MASK |
+                 DESC_L_MASK |
+                 (3 << DESC_DPL_SHIFT) | (0xa << DESC_TYPE_SHIFT));
+#endif
+        write_dt(&gdt_table[__USER_DS >> 3], 0, 0xfffff,
+                 DESC_G_MASK | DESC_B_MASK | DESC_P_MASK | DESC_S_MASK |
+                 (3 << DESC_DPL_SHIFT) | (0x2 << DESC_TYPE_SHIFT));
+    }
+    cpu_x86_load_seg(env, R_CS, __USER_CS);
+    cpu_x86_load_seg(env, R_SS, __USER_DS);
+#ifdef TARGET_ABI32
+    cpu_x86_load_seg(env, R_DS, __USER_DS);
+    cpu_x86_load_seg(env, R_ES, __USER_DS);
+    cpu_x86_load_seg(env, R_FS, __USER_DS);
+    cpu_x86_load_seg(env, R_GS, __USER_DS);
+    /* This hack makes Wine work... */
+    env->segs[R_FS].selector = 0;
+#else
+    cpu_x86_load_seg(env, R_DS, 0);
+    cpu_x86_load_seg(env, R_ES, 0);
+    cpu_x86_load_seg(env, R_FS, 0);
+    cpu_x86_load_seg(env, R_GS, 0);
+#endif
+}