freebsd-skq/sys/amd64/ia32/ia32_syscall.c
kib d0d6e7c817 Change the way the lcall $7,$0 is reflected to usermode. Instead of
setting call gate, which must be 64 bit, put a code segment descriptor
into ldt slot 0.

This way, syscall shim does not switch temporary to 64bit trampoline,
and does not create a window where signal delivery interrupts 64 bit
mode (signal handler cannot return).  The cost is shim running with
non-zero based segment in %cs, which requires vfork() handling make
more assumptions.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2014-12-27 23:19:08 +00:00

251 lines
6.4 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], tmp;
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.
*/
error = fueword32(params, &tmp);
if (error == -1)
return (EFAULT);
sa->code = tmp;
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.
*/
error = fueword32(params, &tmp);
if (error == -1)
return (EFAULT);
sa->code = tmp;
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 desc;
uint32_t lcall_addr;
int error;
bzero(&uap, sizeof(uap));
uap.start = 0;
uap.num = 1;
lcall_addr = curproc->p_sysent->sv_psstrings - sz_lcall_tramp;
bzero(&desc, sizeof(desc));
desc.sd_type = SDT_MEMERA;
desc.sd_dpl = SEL_UPL;
desc.sd_p = 1;
desc.sd_def32 = 1;
desc.sd_gran = 1;
desc.sd_lolimit = 0xffff;
desc.sd_hilimit = 0xf;
desc.sd_lobase = lcall_addr;
desc.sd_hibase = lcall_addr >> 24;
error = amd64_set_ldt(curthread, &uap, &desc);
if (error != 0)
return (error);
return (0);
}
#endif