nios2: Add usermode binaries emulation

Add missing bits for qemu-user required for emulating Altera Nios2
userspace binaries.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Chris Wulff <crwulff@gmail.com>
Cc: Jeff Da Silva <jdasilva@altera.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Sandra Loosemore <sandra@codesourcery.com>
Cc: Yves Vandervennet <yvanderv@altera.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Message-Id: <20170118220146.489-4-marex@denx.de>
Signed-off-by: Richard Henderson <rth@twiddle.net>

1 files changed, 138 insertions, 2 deletions

diff --git a/linux-user/main.c b/linux-user/main.c
index db4eb68..f5c8557 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -68,8 +68,11 @@ do {                                                                    \
  * This way we will never overlap with our own libraries or binaries or stack
  * or anything else that QEMU maps.
  */
-# ifdef TARGET_MIPS
-/* MIPS only supports 31 bits of virtual address space for user space */
+# if defined(TARGET_MIPS) || defined(TARGET_NIOS2)
+/*
+ * MIPS only supports 31 bits of virtual address space for user space.
+ * Nios2 also only supports 31 bits.
+ */
 unsigned long reserved_va = 0x77000000;
 # else
 unsigned long reserved_va = 0xf7000000;
@@ -2462,6 +2465,109 @@ error:
 }
 #endif
 
+#ifdef TARGET_NIOS2
+
+void cpu_loop(CPUNios2State *env)
+{
+    CPUState *cs = ENV_GET_CPU(env);
+    Nios2CPU *cpu = NIOS2_CPU(cs);
+    target_siginfo_t info;
+    int trapnr, gdbsig, ret;
+
+    for (;;) {
+        cpu_exec_start(cs);
+        trapnr = cpu_exec(cs);
+        cpu_exec_end(cs);
+        gdbsig = 0;
+
+        switch (trapnr) {
+        case EXCP_INTERRUPT:
+            /* just indicate that signals should be handled asap */
+            break;
+        case EXCP_TRAP:
+            if (env->regs[R_AT] == 0) {
+                abi_long ret;
+                qemu_log_mask(CPU_LOG_INT, "\nSyscall\n");
+
+                ret = do_syscall(env, env->regs[2],
+                                 env->regs[4], env->regs[5], env->regs[6],
+                                 env->regs[7], env->regs[8], env->regs[9],
+                                 0, 0);
+
+                if (env->regs[2] == 0) {    /* FIXME: syscall 0 workaround */
+                    ret = 0;
+                }
+
+                env->regs[2] = abs(ret);
+                /* Return value is 0..4096 */
+                env->regs[7] = (ret > 0xfffffffffffff000ULL);
+                env->regs[CR_ESTATUS] = env->regs[CR_STATUS];
+                env->regs[CR_STATUS] &= ~0x3;
+                env->regs[R_EA] = env->regs[R_PC] + 4;
+                env->regs[R_PC] += 4;
+                break;
+            } else {
+                qemu_log_mask(CPU_LOG_INT, "\nTrap\n");
+
+                env->regs[CR_ESTATUS] = env->regs[CR_STATUS];
+                env->regs[CR_STATUS] &= ~0x3;
+                env->regs[R_EA] = env->regs[R_PC] + 4;
+                env->regs[R_PC] = cpu->exception_addr;
+
+                gdbsig = TARGET_SIGTRAP;
+                break;
+            }
+        case 0xaa:
+            switch (env->regs[R_PC]) {
+            /*case 0x1000:*/  /* TODO:__kuser_helper_version */
+            case 0x1004:      /* __kuser_cmpxchg */
+                start_exclusive();
+                if (env->regs[4] & 0x3) {
+                    goto kuser_fail;
+                }
+                ret = get_user_u32(env->regs[2], env->regs[4]);
+                if (ret) {
+                    end_exclusive();
+                    goto kuser_fail;
+                }
+                env->regs[2] -= env->regs[5];
+                if (env->regs[2] == 0) {
+                    put_user_u32(env->regs[6], env->regs[4]);
+                }
+                end_exclusive();
+                env->regs[R_PC] = env->regs[R_RA];
+                break;
+            /*case 0x1040:*/  /* TODO:__kuser_sigtramp */
+            default:
+                ;
+kuser_fail:
+                info.si_signo = TARGET_SIGSEGV;
+                info.si_errno = 0;
+                /* TODO: check env->error_code */
+                info.si_code = TARGET_SEGV_MAPERR;
+                info._sifields._sigfault._addr = env->regs[R_PC];
+                queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
+            }
+            break;
+        default:
+            EXCP_DUMP(env, "\nqemu: unhandled CPU exception %#x - aborting\n",
+                     trapnr);
+            gdbsig = TARGET_SIGILL;
+            break;
+        }
+        if (gdbsig) {
+            gdb_handlesig(cs, gdbsig);
+            if (gdbsig != TARGET_SIGTRAP) {
+                exit(EXIT_FAILURE);
+            }
+        }
+
+        process_pending_signals(env);
+    }
+}
+
+#endif /* TARGET_NIOS2 */
+
 #ifdef TARGET_OPENRISC
 
 void cpu_loop(CPUOpenRISCState *env)
@@ -4632,6 +4738,36 @@ int main(int argc, char **argv, char **envp)
             restore_snan_bit_mode(env);
         }
     }
+#elif defined(TARGET_NIOS2)
+    {
+        env->regs[0] = 0;
+        env->regs[1] = regs->r1;
+        env->regs[2] = regs->r2;
+        env->regs[3] = regs->r3;
+        env->regs[4] = regs->r4;
+        env->regs[5] = regs->r5;
+        env->regs[6] = regs->r6;
+        env->regs[7] = regs->r7;
+        env->regs[8] = regs->r8;
+        env->regs[9] = regs->r9;
+        env->regs[10] = regs->r10;
+        env->regs[11] = regs->r11;
+        env->regs[12] = regs->r12;
+        env->regs[13] = regs->r13;
+        env->regs[14] = regs->r14;
+        env->regs[15] = regs->r15;
+        /* TODO: unsigned long  orig_r2; */
+        env->regs[R_RA] = regs->ra;
+        env->regs[R_FP] = regs->fp;
+        env->regs[R_SP] = regs->sp;
+        env->regs[R_GP] = regs->gp;
+        env->regs[CR_ESTATUS] = regs->estatus;
+        env->regs[R_EA] = regs->ea;
+        /* TODO: unsigned long  orig_r7; */
+
+        /* Emulate eret when starting thread. */
+        env->regs[R_PC] = regs->ea;
+    }
 #elif defined(TARGET_OPENRISC)
     {
         int i;