freebsd-skq/sys/amd64/ia32/ia32_syscall.c
Konstantin Belousov 95fd15898b Real hardware, as opposed to QEMU, does not allow to have a call gate
in long mode which transfers control to 32bit code segment. Unbreak
the lcall $7,$0 implementation on amd64 by putting the 64bit user code
segment' selector into call gate, and execute the 64bit trampoline
which converts the return frame into 32bit format and switches back to
32bit mode for executing int $0x80 trampoline.

Note that all jumps over the hoops are performed in the user mode.

MFC after:	1 week
2012-08-14 12:13:27 +00:00

256 lines
6.6 KiB
C

/*-
* Copyright (C) 1994, David Greenman
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the University of Utah, and William Jolitz.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University 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 REGENTS 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 REGENTS OR CONTRIBUTORS 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* 386 Trap and System call handling
*/
#include "opt_clock.h"
#include "opt_compat.h"
#include "opt_cpu.h"
#include "opt_isa.h"
#include <sys/param.h>
#include <sys/bus.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/pioctl.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/ptrace.h>
#include <sys/resourcevar.h>
#include <sys/signalvar.h>
#include <sys/syscall.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/uio.h>
#include <sys/vmmeter.h>
#include <security/audit/audit.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_kern.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <vm/vm_extern.h>
#include <machine/cpu.h>
#include <machine/intr_machdep.h>
#include <machine/md_var.h>
#include <compat/freebsd32/freebsd32_signal.h>
#include <compat/freebsd32/freebsd32_util.h>
#include <compat/ia32/ia32_signal.h>
#include <machine/psl.h>
#include <machine/segments.h>
#include <machine/specialreg.h>
#include <machine/sysarch.h>
#include <machine/frame.h>
#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/cpufunc.h>
#define IDTVEC(name) __CONCAT(X,name)
extern inthand_t IDTVEC(int0x80_syscall), IDTVEC(rsvd);
void ia32_syscall(struct trapframe *frame); /* Called from asm code */
void
ia32_set_syscall_retval(struct thread *td, int error)
{
cpu_set_syscall_retval(td, error);
}
int
ia32_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
{
struct proc *p;
struct trapframe *frame;
caddr_t params;
u_int32_t args[8];
int error, i;
p = td->td_proc;
frame = td->td_frame;
params = (caddr_t)frame->tf_rsp + sizeof(u_int32_t);
sa->code = frame->tf_rax;
/*
* Need to check if this is a 32 bit or 64 bit syscall.
*/
if (sa->code == SYS_syscall) {
/*
* Code is first argument, followed by actual args.
*/
sa->code = fuword32(params);
params += sizeof(int);
} else if (sa->code == SYS___syscall) {
/*
* Like syscall, but code is a quad, so as to maintain
* quad alignment for the rest of the arguments.
* We use a 32-bit fetch in case params is not
* aligned.
*/
sa->code = fuword32(params);
params += sizeof(quad_t);
}
if (p->p_sysent->sv_mask)
sa->code &= p->p_sysent->sv_mask;
if (sa->code >= p->p_sysent->sv_size)
sa->callp = &p->p_sysent->sv_table[0];
else
sa->callp = &p->p_sysent->sv_table[sa->code];
sa->narg = sa->callp->sy_narg;
if (params != NULL && sa->narg != 0)
error = copyin(params, (caddr_t)args,
(u_int)(sa->narg * sizeof(int)));
else
error = 0;
for (i = 0; i < sa->narg; i++)
sa->args[i] = args[i];
if (error == 0) {
td->td_retval[0] = 0;
td->td_retval[1] = frame->tf_rdx;
}
return (error);
}
#include "../../kern/subr_syscall.c"
void
ia32_syscall(struct trapframe *frame)
{
struct thread *td;
struct syscall_args sa;
register_t orig_tf_rflags;
int error;
ksiginfo_t ksi;
orig_tf_rflags = frame->tf_rflags;
td = curthread;
td->td_frame = frame;
error = syscallenter(td, &sa);
/*
* Traced syscall.
*/
if (orig_tf_rflags & PSL_T) {
frame->tf_rflags &= ~PSL_T;
ksiginfo_init_trap(&ksi);
ksi.ksi_signo = SIGTRAP;
ksi.ksi_code = TRAP_TRACE;
ksi.ksi_addr = (void *)frame->tf_rip;
trapsignal(td, &ksi);
}
syscallret(td, error, &sa);
}
static void
ia32_syscall_enable(void *dummy)
{
setidt(IDT_SYSCALL, &IDTVEC(int0x80_syscall), SDT_SYSIGT, SEL_UPL, 0);
}
static void
ia32_syscall_disable(void *dummy)
{
setidt(IDT_SYSCALL, &IDTVEC(rsvd), SDT_SYSIGT, SEL_KPL, 0);
}
SYSINIT(ia32_syscall, SI_SUB_EXEC, SI_ORDER_ANY, ia32_syscall_enable, NULL);
SYSUNINIT(ia32_syscall, SI_SUB_EXEC, SI_ORDER_ANY, ia32_syscall_disable, NULL);
#ifdef COMPAT_43
int
setup_lcall_gate(void)
{
struct i386_ldt_args uap;
struct user_segment_descriptor descs[2];
struct gate_descriptor *ssd;
uint32_t lcall_addr;
int error;
bzero(&uap, sizeof(uap));
uap.start = 0;
uap.num = 2;
/*
* This is the easiest way to cut the space for system
* descriptor in ldt. Manually adjust the descriptor type to
* the call gate later.
*/
bzero(&descs[0], sizeof(descs));
descs[0].sd_type = SDT_SYSNULL;
descs[1].sd_type = SDT_SYSNULL;
error = amd64_set_ldt(curthread, &uap, descs);
if (error != 0)
return (error);
lcall_addr = curproc->p_sysent->sv_psstrings - sz_lcall_tramp;
mtx_lock(&dt_lock);
ssd = (struct gate_descriptor *)(curproc->p_md.md_ldt->ldt_base);
bzero(ssd, sizeof(*ssd));
ssd->gd_looffset = lcall_addr;
ssd->gd_hioffset = lcall_addr >> 16;
ssd->gd_selector = _ucodesel;
ssd->gd_type = SDT_SYSCGT;
ssd->gd_dpl = SEL_UPL;
ssd->gd_p = 1;
mtx_unlock(&dt_lock);
return (0);
}
#endif