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      1 /*	$NetBSD: linux_syscall.c,v 1.55 2023/10/05 19:41:04 ad Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1998, 2000 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Charles M. Hannum.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 __KERNEL_RCSID(0, "$NetBSD: linux_syscall.c,v 1.55 2023/10/05 19:41:04 ad Exp $");
     34 
     35 #include <sys/param.h>
     36 #include <sys/systm.h>
     37 #include <sys/proc.h>
     38 #include <sys/signal.h>
     39 #include <sys/syscall.h>
     40 #include <sys/syscallvar.h>
     41 
     42 #include <uvm/uvm_extern.h>
     43 
     44 #include <machine/cpu.h>
     45 #include <machine/psl.h>
     46 #include <machine/userret.h>
     47 
     48 #include <compat/linux/common/linux_types.h>
     49 #include <compat/linux/common/linux_errno.h>
     50 #include <compat/linux/linux_syscall.h>
     51 #include <compat/linux/common/linux_signal.h>
     52 #include <compat/linux/arch/i386/linux_machdep.h>
     53 
     54 static void linux_syscall(struct trapframe *);
     55 extern struct sysent linux_sysent[];
     56 extern const uint32_t linux_sysent_nomodbits[];
     57 
     58 void
     59 linux_syscall_intern(struct proc *p)
     60 {
     61 
     62 	p->p_md.md_syscall = linux_syscall;
     63 }
     64 
     65 /*
     66  * syscall(frame):
     67  *	System call request from POSIX system call gate interface to kernel.
     68  * Like trap(), argument is call by reference.
     69  */
     70 void
     71 linux_syscall(struct trapframe *frame)
     72 {
     73 	register const struct sysent *callp;
     74 	struct lwp *l;
     75 	int error;
     76 	register_t code, args[6], rval[2];
     77 
     78 	l = curlwp;
     79 
     80 	code = frame->tf_eax & (LINUX_SYS_NSYSENT - 1);
     81 	callp = linux_sysent;
     82 
     83 	callp += code;
     84 	/*
     85 	 * Linux passes the args in ebx, ecx, edx, esi, edi, ebp, in
     86 	 * increasing order.
     87 	 */
     88 	args[0] = frame->tf_ebx;
     89 	args[1] = frame->tf_ecx;
     90 	args[2] = frame->tf_edx;
     91 	args[3] = frame->tf_esi;
     92 	args[4] = frame->tf_edi;
     93 	args[5] = frame->tf_ebp;
     94 
     95 	rval[0] = 0;
     96 	rval[1] = 0;
     97 
     98 	if (__predict_false(l->l_proc->p_trace_enabled || KDTRACE_ENTRY(callp->sy_entry))) {
     99 		error = trace_enter(code, callp, args);
    100 		if (__predict_true(error == 0))
    101 			error = sy_call(callp, l, args, rval);
    102 	} else
    103 		error = sy_call(callp, l, args, rval);
    104 
    105 	if (__predict_true(error == 0)) {
    106 		frame->tf_eax = rval[0];
    107 		/*
    108 		 * XXX The linux libc code I (dsl) looked at doesn't use the
    109 		 * carry bit.
    110 		 * Values above 0xfffff000 are assumed to be errno values and
    111 		 * not result codes!
    112 		 */
    113 		frame->tf_eflags &= ~PSL_C;	/* carry bit */
    114 	} else {
    115 		switch (error) {
    116 		case ERESTART:
    117 			/*
    118 			 * The offset to adjust the PC by depends on whether
    119 			 * we entered the kernel through the trap or call gate.
    120 			 * We save the instruction size in tf_err on entry.
    121 			 */
    122 			frame->tf_eip -= frame->tf_err;
    123 			break;
    124 		case EJUSTRETURN:
    125 			/* nothing to do */
    126 			break;
    127 		default:
    128 			error = native_to_linux_errno[error];
    129 			frame->tf_eax = error;
    130 			frame->tf_eflags |= PSL_C;	/* carry bit */
    131 			break;
    132 		}
    133 	}
    134 	if (__predict_false(l->l_proc->p_trace_enabled || KDTRACE_ENTRY(callp->sy_return)))
    135 		trace_exit(code, callp, args, rval, error);
    136 
    137 	userret(l);
    138 }
    139