bsd-user:Add CPU initialization and management functions

Added function to initialize ARM CPU and check if it supports 64-bit mode.
Implemented CPU loop function to handle exceptions and emulate execution of instructions.
Added function to clone CPU state to create a new thread.
Included AArch64 specific CPU functions for bsd-user to set and receive thread-local-storage
value from the tpidr_el0 register.
Introduced structure for storing CPU register states for BSD-USER.

Signed-off-by: Stacey Son <sson@FreeBSD.org>
Signed-off-by: Ajeet Singh <itachis@FreeBSD.org>
Co-authored-by: Kyle Evans <kevans@freebsd.org>
Co-authored-by: Sean Bruno <sbruno@freebsd.org>
Co-authored-by: Jessica Clarke <jrtc27@jrtc27.com>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20240707191128.10509-2-itachis@FreeBSD.org>
Signed-off-by: Warner Losh <imp@bsdimp.com>

3 files changed, 274 insertions, 0 deletions

diff --git a/bsd-user/aarch64/target_arch_cpu.c b/bsd-user/aarch64/target_arch_cpu.c
new file mode 100644
index 0000000000..b2fa59efaf
--- /dev/null
+++ b/bsd-user/aarch64/target_arch_cpu.c
@@ -0,0 +1,31 @@
+/*
+ * ARM AArch64 specific CPU for bsd-user
+ *
+ * Copyright (c) 2015 Stacey Son
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+#include "qemu/osdep.h"
+#include "target_arch.h"
+
+/* See cpu_set_user_tls() in arm64/arm64/vm_machdep.c */
+void target_cpu_set_tls(CPUARMState *env, target_ulong newtls)
+{
+    env->cp15.tpidr_el[0] = newtls;
+}
+
+target_ulong target_cpu_get_tls(CPUARMState *env)
+{
+    return env->cp15.tpidr_el[0];
+}
diff --git a/bsd-user/aarch64/target_arch_cpu.h b/bsd-user/aarch64/target_arch_cpu.h
new file mode 100644
index 0000000000..5c150bb7e9
--- /dev/null
+++ b/bsd-user/aarch64/target_arch_cpu.h
@@ -0,0 +1,192 @@
+/*
+ *  ARM AArch64 cpu init and loop
+ *
+ * Copyright (c) 2015 Stacey Son
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef TARGET_ARCH_CPU_H
+#define TARGET_ARCH_CPU_H
+
+#include "target_arch.h"
+#include "signal-common.h"
+#include "target/arm/syndrome.h"
+
+#define TARGET_DEFAULT_CPU_MODEL "any"
+
+static inline void target_cpu_init(CPUARMState *env,
+    struct target_pt_regs *regs)
+{
+    int i;
+
+    if (!(arm_feature(env, ARM_FEATURE_AARCH64))) {
+        fprintf(stderr, "The selected ARM CPU does not support 64 bit mode\n");
+        exit(1);
+    }
+    for (i = 0; i < 31; i++) {
+        env->xregs[i] = regs->regs[i];
+    }
+    env->pc = regs->pc;
+    env->xregs[31] = regs->sp;
+}
+
+
+static inline void target_cpu_loop(CPUARMState *env)
+{
+    CPUState *cs = env_cpu(env);
+    int trapnr, ec, fsc, si_code, si_signo;
+    uint64_t code, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8;
+    uint32_t pstate;
+    abi_long ret;
+
+    for (;;) {
+        cpu_exec_start(cs);
+        trapnr = cpu_exec(cs);
+        cpu_exec_end(cs);
+        process_queued_cpu_work(cs);
+
+        switch (trapnr) {
+        case EXCP_SWI:
+            /* See arm64/arm64/trap.c cpu_fetch_syscall_args() */
+            code = env->xregs[8];
+            if (code == TARGET_FREEBSD_NR_syscall ||
+                code == TARGET_FREEBSD_NR___syscall) {
+                code = env->xregs[0];
+                arg1 = env->xregs[1];
+                arg2 = env->xregs[2];
+                arg3 = env->xregs[3];
+                arg4 = env->xregs[4];
+                arg5 = env->xregs[5];
+                arg6 = env->xregs[6];
+                arg7 = env->xregs[7];
+                arg8 = 0;
+            } else {
+                arg1 = env->xregs[0];
+                arg2 = env->xregs[1];
+                arg3 = env->xregs[2];
+                arg4 = env->xregs[3];
+                arg5 = env->xregs[4];
+                arg6 = env->xregs[5];
+                arg7 = env->xregs[6];
+                arg8 = env->xregs[7];
+            }
+            ret = do_freebsd_syscall(env, code, arg1, arg2, arg3,
+                    arg4, arg5, arg6, arg7, arg8);
+            /*
+             * The carry bit is cleared for no error; set for error.
+             * See arm64/arm64/vm_machdep.c cpu_set_syscall_retval()
+             */
+            pstate = pstate_read(env);
+            if (ret >= 0) {
+                pstate &= ~PSTATE_C;
+                env->xregs[0] = ret;
+            } else if (ret == -TARGET_ERESTART) {
+                env->pc -= 4;
+                break;
+            } else if (ret != -TARGET_EJUSTRETURN) {
+                pstate |= PSTATE_C;
+                env->xregs[0] = -ret;
+            }
+            pstate_write(env, pstate);
+            break;
+
+        case EXCP_INTERRUPT:
+            /* Just indicate that signals should be handle ASAP. */
+            break;
+
+        case EXCP_UDEF:
+            force_sig_fault(TARGET_SIGILL, TARGET_ILL_ILLOPN, env->pc);
+            break;
+
+
+        case EXCP_PREFETCH_ABORT:
+        case EXCP_DATA_ABORT:
+            /* We should only arrive here with EC in {DATAABORT, INSNABORT}. */
+            ec = syn_get_ec(env->exception.syndrome);
+            assert(ec == EC_DATAABORT || ec == EC_INSNABORT);
+
+            /* Both EC have the same format for FSC, or close enough. */
+            fsc = extract32(env->exception.syndrome, 0, 6);
+            switch (fsc) {
+            case 0x04 ... 0x07: /* Translation fault, level {0-3} */
+                si_signo = TARGET_SIGSEGV;
+                si_code = TARGET_SEGV_MAPERR;
+                break;
+            case 0x09 ... 0x0b: /* Access flag fault, level {1-3} */
+            case 0x0d ... 0x0f: /* Permission fault, level {1-3} */
+                si_signo = TARGET_SIGSEGV;
+                si_code = TARGET_SEGV_ACCERR;
+                break;
+            case 0x11: /* Synchronous Tag Check Fault */
+                si_signo = TARGET_SIGSEGV;
+                si_code = /* TARGET_SEGV_MTESERR; */ TARGET_SEGV_ACCERR;
+                break;
+            case 0x21: /* Alignment fault */
+                si_signo = TARGET_SIGBUS;
+                si_code = TARGET_BUS_ADRALN;
+                break;
+            default:
+                g_assert_not_reached();
+            }
+            force_sig_fault(si_signo, si_code, env->exception.vaddress);
+            break;
+
+        case EXCP_DEBUG:
+        case EXCP_BKPT:
+            force_sig_fault(TARGET_SIGTRAP, TARGET_TRAP_BRKPT, env->pc);
+            break;
+
+        case EXCP_ATOMIC:
+            cpu_exec_step_atomic(cs);
+            break;
+
+        case EXCP_YIELD:
+            /* nothing to do here for user-mode, just resume guest code */
+            break;
+        default:
+            fprintf(stderr, "qemu: unhandled CPU exception 0x%x - aborting\n",
+                    trapnr);
+            cpu_dump_state(cs, stderr, 0);
+            abort();
+        } /* switch() */
+        process_pending_signals(env);
+        /*
+         * Exception return on AArch64 always clears the exclusive
+         * monitor, so any return to running guest code implies this.
+         * A strex (successful or otherwise) also clears the monitor, so
+         * we don't need to specialcase EXCP_STREX.
+         */
+        env->exclusive_addr = -1;
+    } /* for (;;) */
+}
+
+
+/* See arm64/arm64/vm_machdep.c cpu_fork() */
+static inline void target_cpu_clone_regs(CPUARMState *env, target_ulong newsp)
+{
+    if (newsp) {
+        env->xregs[31] = newsp;
+    }
+    env->regs[0] = 0;
+    env->regs[1] = 0;
+    pstate_write(env, 0);
+}
+
+static inline void target_cpu_reset(CPUArchState *env)
+{
+}
+
+
+#endif /* TARGET_ARCH_CPU_H */
diff --git a/bsd-user/aarch64/target_syscall.h b/bsd-user/aarch64/target_syscall.h
new file mode 100644
index 0000000000..08ae913c42
--- /dev/null
+++ b/bsd-user/aarch64/target_syscall.h
@@ -0,0 +1,51 @@
+/*
+ * ARM AArch64 specific CPU for bsd-user
+ *
+ * Copyright (c) 2015 Stacey D. Son <sson at Freebsd>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef BSD_USER_AARCH64_TARGET_SYSCALL_H
+#define BSD_USER_AARCH64_TARGET_SYSCALL_H
+
+/*
+ * The aarch64 registers are named:
+ *
+ * x0 through x30 - for 64-bit-wide access (same registers)
+ * Register '31' is one of two registers depending on the instruction context:
+ *  For instructions dealing with the stack, it is the stack pointer, named rsp
+ *  For all other instructions, it is a "zero" register, which returns 0 when
+ *  read and discards data when written - named rzr (xzr, wzr)
+ *
+ * Usage during syscall/function call:
+ * r0-r7 are used for arguments and return values
+ * For syscalls, the syscall number is in r8
+ * r9-r15 are for temporary values (may get trampled)
+ * r16-r18 are used for intra-procedure-call and platform values (avoid)
+ * The called routine is expected to preserve r19-r28
+ * r29 and r30 are used as the frame register and link register (avoid)
+ * See the ARM Procedure Call Reference for details.
+ */
+struct target_pt_regs {
+    uint64_t    regs[31];
+    uint64_t    sp;
+    uint64_t    pc;
+    uint64_t    pstate;
+};
+
+#define TARGET_HW_MACHINE       "arm64"
+#define TARGET_HW_MACHINE_ARCH  "aarch64"
+
+#endif /* BSD_USER_AARCH64_TARGET_SYSCALL_H */