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freebsd-nq/sys/amd64/ia32/ia32_signal.c
Konstantin Belousov d6e029adbe In r197963, a race with thread being selected for signal delivery 
while in kernel mode, and later changing signal mask to block the
signal, was fixed for sigprocmask(2) and ptread_exit(3). The same race
exists for sigreturn(2), setcontext(2) and swapcontext(2) syscalls.

Use kern_sigprocmask() instead of direct manipulation of td_sigmask to
reschedule newly blocked signals, closing the race.

Reviewed by:	davidxu
Tested by:	pho
MFC after:	1 month
2009-10-27 10:47:58 +00:00

745 lines
22 KiB
C
Raw Blame History

/*-
* Copyright (c) 2003 Peter Wemm
* Copyright (c) 1982, 1987, 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* 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.
* 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("$FreeBSD$");
#include "opt_compat.h"
#include <sys/param.h>
#include <sys/exec.h>
#include <sys/fcntl.h>
#include <sys/imgact.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/mman.h>
#include <sys/namei.h>
#include <sys/pioctl.h>
#include <sys/proc.h>
#include <sys/procfs.h>
#include <sys/resourcevar.h>
#include <sys/systm.h>
#include <sys/signalvar.h>
#include <sys/stat.h>
#include <sys/sx.h>
#include <sys/syscall.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/vnode.h>
#include <vm/vm.h>
#include <vm/vm_kern.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_extern.h>
#include <compat/freebsd32/freebsd32_signal.h>
#include <compat/freebsd32/freebsd32_util.h>
#include <compat/freebsd32/freebsd32_proto.h>
#include <compat/ia32/ia32_signal.h>
#include <machine/psl.h>
#include <machine/segments.h>
#include <machine/specialreg.h>
#include <machine/frame.h>
#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/cpufunc.h>
#ifdef COMPAT_FREEBSD4
static void freebsd4_ia32_sendsig(sig_t, ksiginfo_t *, sigset_t *);
#endif
static void ia32_get_fpcontext(struct thread *td, struct ia32_mcontext *mcp);
static int ia32_set_fpcontext(struct thread *td, const struct ia32_mcontext *mcp);
#define CS_SECURE(cs) (ISPL(cs) == SEL_UPL)
#define EFL_SECURE(ef, oef) ((((ef) ^ (oef)) & ~PSL_USERCHANGE) == 0)
static void
ia32_get_fpcontext(struct thread *td, struct ia32_mcontext *mcp)
{
mcp->mc_ownedfp = fpugetregs(td, (struct savefpu *)&mcp->mc_fpstate);
mcp->mc_fpformat = fpuformat();
}
static int
ia32_set_fpcontext(struct thread *td, const struct ia32_mcontext *mcp)
{
if (mcp->mc_fpformat == _MC_FPFMT_NODEV)
return (0);
else if (mcp->mc_fpformat != _MC_FPFMT_XMM)
return (EINVAL);
else if (mcp->mc_ownedfp == _MC_FPOWNED_NONE)
/* We don't care what state is left in the FPU or PCB. */
fpstate_drop(td);
else if (mcp->mc_ownedfp == _MC_FPOWNED_FPU ||
mcp->mc_ownedfp == _MC_FPOWNED_PCB) {
/*
* XXX we violate the dubious requirement that fpusetregs()
* be called with interrupts disabled.
*/
fpusetregs(td, (struct savefpu *)&mcp->mc_fpstate);
} else
return (EINVAL);
return (0);
}
/*
* Get machine context.
*/
static int
ia32_get_mcontext(struct thread *td, struct ia32_mcontext *mcp, int flags)
{
struct trapframe *tp;
tp = td->td_frame;
PROC_LOCK(curthread->td_proc);
mcp->mc_onstack = sigonstack(tp->tf_rsp);
PROC_UNLOCK(curthread->td_proc);
/* Entry into kernel always sets TF_HASSEGS */
mcp->mc_gs = tp->tf_gs;
mcp->mc_fs = tp->tf_fs;
mcp->mc_es = tp->tf_es;
mcp->mc_ds = tp->tf_ds;
mcp->mc_edi = tp->tf_rdi;
mcp->mc_esi = tp->tf_rsi;
mcp->mc_ebp = tp->tf_rbp;
mcp->mc_isp = tp->tf_rsp;
if (flags & GET_MC_CLEAR_RET) {
mcp->mc_eax = 0;
mcp->mc_edx = 0;
} else {
mcp->mc_eax = tp->tf_rax;
mcp->mc_edx = tp->tf_rdx;
}
mcp->mc_ebx = tp->tf_rbx;
mcp->mc_ecx = tp->tf_rcx;
mcp->mc_eip = tp->tf_rip;
mcp->mc_cs = tp->tf_cs;
mcp->mc_eflags = tp->tf_rflags;
mcp->mc_esp = tp->tf_rsp;
mcp->mc_ss = tp->tf_ss;
mcp->mc_len = sizeof(*mcp);
ia32_get_fpcontext(td, mcp);
mcp->mc_fsbase = td->td_pcb->pcb_fsbase;
mcp->mc_gsbase = td->td_pcb->pcb_gsbase;
td->td_pcb->pcb_full_iret = 1;
return (0);
}
/*
* Set machine context.
*
* However, we don't set any but the user modifiable flags, and we won't
* touch the cs selector.
*/
static int
ia32_set_mcontext(struct thread *td, const struct ia32_mcontext *mcp)
{
struct trapframe *tp;
long rflags;
int ret;
tp = td->td_frame;
if (mcp->mc_len != sizeof(*mcp))
return (EINVAL);
rflags = (mcp->mc_eflags & PSL_USERCHANGE) |
(tp->tf_rflags & ~PSL_USERCHANGE);
ret = ia32_set_fpcontext(td, mcp);
if (ret != 0)
return (ret);
tp->tf_gs = mcp->mc_gs;
tp->tf_fs = mcp->mc_fs;
tp->tf_es = mcp->mc_es;
tp->tf_ds = mcp->mc_ds;
tp->tf_flags = TF_HASSEGS;
tp->tf_rdi = mcp->mc_edi;
tp->tf_rsi = mcp->mc_esi;
tp->tf_rbp = mcp->mc_ebp;
tp->tf_rbx = mcp->mc_ebx;
tp->tf_rdx = mcp->mc_edx;
tp->tf_rcx = mcp->mc_ecx;
tp->tf_rax = mcp->mc_eax;
/* trapno, err */
tp->tf_rip = mcp->mc_eip;
tp->tf_rflags = rflags;
tp->tf_rsp = mcp->mc_esp;
tp->tf_ss = mcp->mc_ss;
td->td_pcb->pcb_flags |= PCB_FULLCTX;
td->td_pcb->pcb_full_iret = 1;
return (0);
}
/*
* The first two fields of a ucontext_t are the signal mask and
* the machine context. The next field is uc_link; we want to
* avoid destroying the link when copying out contexts.
*/
#define UC_COPY_SIZE offsetof(struct ia32_ucontext, uc_link)
int
freebsd32_getcontext(struct thread *td, struct freebsd32_getcontext_args *uap)
{
struct ia32_ucontext uc;
int ret;
if (uap->ucp == NULL)
ret = EINVAL;
else {
ia32_get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
PROC_LOCK(td->td_proc);
uc.uc_sigmask = td->td_sigmask;
PROC_UNLOCK(td->td_proc);
ret = copyout(&uc, uap->ucp, UC_COPY_SIZE);
}
return (ret);
}
int
freebsd32_setcontext(struct thread *td, struct freebsd32_setcontext_args *uap)
{
struct ia32_ucontext uc;
int ret;
if (uap->ucp == NULL)
ret = EINVAL;
else {
ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
if (ret == 0) {
ret = ia32_set_mcontext(td, &uc.uc_mcontext);
if (ret == 0) {
kern_sigprocmask(td, SIG_SETMASK,
&uc.uc_sigmask, NULL, 0);
}
}
}
return (ret == 0 ? EJUSTRETURN : ret);
}
int
freebsd32_swapcontext(struct thread *td, struct freebsd32_swapcontext_args *uap)
{
struct ia32_ucontext uc;
int ret;
if (uap->oucp == NULL || uap->ucp == NULL)
ret = EINVAL;
else {
ia32_get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
PROC_LOCK(td->td_proc);
uc.uc_sigmask = td->td_sigmask;
PROC_UNLOCK(td->td_proc);
ret = copyout(&uc, uap->oucp, UC_COPY_SIZE);
if (ret == 0) {
ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
if (ret == 0) {
ret = ia32_set_mcontext(td, &uc.uc_mcontext);
if (ret == 0) {
kern_sigprocmask(td, SIG_SETMASK,
&uc.uc_sigmask, NULL, 0);
}
}
}
}
return (ret == 0 ? EJUSTRETURN : ret);
}
/*
* Send an interrupt to process.
*
* Stack is set up to allow sigcode stored
* at top to call routine, followed by kcall
* to sigreturn routine below. After sigreturn
* resets the signal mask, the stack, and the
* frame pointer, it returns to the user
* specified pc, psl.
*/
#ifdef COMPAT_FREEBSD4
static void
freebsd4_ia32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
{
struct ia32_sigframe4 sf, *sfp;
struct siginfo32 siginfo;
struct proc *p;
struct thread *td;
struct sigacts *psp;
struct trapframe *regs;
int oonstack;
int sig;
td = curthread;
p = td->td_proc;
siginfo_to_siginfo32(&ksi->ksi_info, &siginfo);
PROC_LOCK_ASSERT(p, MA_OWNED);
sig = siginfo.si_signo;
psp = p->p_sigacts;
mtx_assert(&psp->ps_mtx, MA_OWNED);
regs = td->td_frame;
oonstack = sigonstack(regs->tf_rsp);
/* Save user context. */
bzero(&sf, sizeof(sf));
sf.sf_uc.uc_sigmask = *mask;
sf.sf_uc.uc_stack.ss_sp = (uintptr_t)td->td_sigstk.ss_sp;
sf.sf_uc.uc_stack.ss_size = td->td_sigstk.ss_size;
sf.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK)
? ((oonstack) ? SS_ONSTACK : 0) : SS_DISABLE;
sf.sf_uc.uc_mcontext.mc_onstack = (oonstack) ? 1 : 0;
sf.sf_uc.uc_mcontext.mc_edi = regs->tf_rdi;
sf.sf_uc.uc_mcontext.mc_esi = regs->tf_rsi;
sf.sf_uc.uc_mcontext.mc_ebp = regs->tf_rbp;
sf.sf_uc.uc_mcontext.mc_isp = regs->tf_rsp; /* XXX */
sf.sf_uc.uc_mcontext.mc_ebx = regs->tf_rbx;
sf.sf_uc.uc_mcontext.mc_edx = regs->tf_rdx;
sf.sf_uc.uc_mcontext.mc_ecx = regs->tf_rcx;
sf.sf_uc.uc_mcontext.mc_eax = regs->tf_rax;
sf.sf_uc.uc_mcontext.mc_trapno = regs->tf_trapno;
sf.sf_uc.uc_mcontext.mc_err = regs->tf_err;
sf.sf_uc.uc_mcontext.mc_eip = regs->tf_rip;
sf.sf_uc.uc_mcontext.mc_cs = regs->tf_cs;
sf.sf_uc.uc_mcontext.mc_eflags = regs->tf_rflags;
sf.sf_uc.uc_mcontext.mc_esp = regs->tf_rsp;
sf.sf_uc.uc_mcontext.mc_ss = regs->tf_ss;
sf.sf_uc.uc_mcontext.mc_ds = regs->tf_ds;
sf.sf_uc.uc_mcontext.mc_es = regs->tf_es;
sf.sf_uc.uc_mcontext.mc_fs = regs->tf_fs;
sf.sf_uc.uc_mcontext.mc_gs = regs->tf_gs;
/* Allocate space for the signal handler context. */
if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
SIGISMEMBER(psp->ps_sigonstack, sig)) {
sfp = (struct ia32_sigframe4 *)(td->td_sigstk.ss_sp +
td->td_sigstk.ss_size - sizeof(sf));
} else
sfp = (struct ia32_sigframe4 *)regs->tf_rsp - 1;
PROC_UNLOCK(p);
/* Translate the signal if appropriate. */
if (p->p_sysent->sv_sigtbl && sig <= p->p_sysent->sv_sigsize)
sig = p->p_sysent->sv_sigtbl[_SIG_IDX(sig)];
/* Build the argument list for the signal handler. */
sf.sf_signum = sig;
sf.sf_ucontext = (register_t)&sfp->sf_uc;
if (SIGISMEMBER(psp->ps_siginfo, sig)) {
/* Signal handler installed with SA_SIGINFO. */
sf.sf_siginfo = (u_int32_t)(uintptr_t)&sfp->sf_si;
sf.sf_ah = (u_int32_t)(uintptr_t)catcher;
/* Fill in POSIX parts */
sf.sf_si = siginfo;
sf.sf_si.si_signo = sig;
} else {
/* Old FreeBSD-style arguments. */
sf.sf_siginfo = siginfo.si_code;
sf.sf_addr = (u_int32_t)siginfo.si_addr;
sf.sf_ah = (u_int32_t)(uintptr_t)catcher;
}
mtx_unlock(&psp->ps_mtx);
/*
* Copy the sigframe out to the user's stack.
*/
if (copyout(&sf, sfp, sizeof(*sfp)) != 0) {
#ifdef DEBUG
printf("process %ld has trashed its stack\n", (long)p->p_pid);
#endif
PROC_LOCK(p);
sigexit(td, SIGILL);
}
regs->tf_rsp = (uintptr_t)sfp;
regs->tf_rip = FREEBSD32_PS_STRINGS - sz_freebsd4_ia32_sigcode;
regs->tf_rflags &= ~(PSL_T | PSL_D);
regs->tf_cs = _ucode32sel;
regs->tf_ss = _udatasel;
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;
td->td_pcb->pcb_full_iret = 1;
/* leave user %fs and %gs untouched */
PROC_LOCK(p);
mtx_lock(&psp->ps_mtx);
}
#endif /* COMPAT_FREEBSD4 */
void
ia32_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
{
struct ia32_sigframe sf, *sfp;
struct siginfo32 siginfo;
struct proc *p;
struct thread *td;
struct sigacts *psp;
char *sp;
struct trapframe *regs;
int oonstack;
int sig;
siginfo_to_siginfo32(&ksi->ksi_info, &siginfo);
td = curthread;
p = td->td_proc;
PROC_LOCK_ASSERT(p, MA_OWNED);
sig = siginfo.si_signo;
psp = p->p_sigacts;
#ifdef COMPAT_FREEBSD4
if (SIGISMEMBER(psp->ps_freebsd4, sig)) {
freebsd4_ia32_sendsig(catcher, ksi, mask);
return;
}
#endif
mtx_assert(&psp->ps_mtx, MA_OWNED);
regs = td->td_frame;
oonstack = sigonstack(regs->tf_rsp);
/* Save user context. */
bzero(&sf, sizeof(sf));
sf.sf_uc.uc_sigmask = *mask;
sf.sf_uc.uc_stack.ss_sp = (uintptr_t)td->td_sigstk.ss_sp;
sf.sf_uc.uc_stack.ss_size = td->td_sigstk.ss_size;
sf.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK)
? ((oonstack) ? SS_ONSTACK : 0) : SS_DISABLE;
sf.sf_uc.uc_mcontext.mc_onstack = (oonstack) ? 1 : 0;
sf.sf_uc.uc_mcontext.mc_edi = regs->tf_rdi;
sf.sf_uc.uc_mcontext.mc_esi = regs->tf_rsi;
sf.sf_uc.uc_mcontext.mc_ebp = regs->tf_rbp;
sf.sf_uc.uc_mcontext.mc_isp = regs->tf_rsp; /* XXX */
sf.sf_uc.uc_mcontext.mc_ebx = regs->tf_rbx;
sf.sf_uc.uc_mcontext.mc_edx = regs->tf_rdx;
sf.sf_uc.uc_mcontext.mc_ecx = regs->tf_rcx;
sf.sf_uc.uc_mcontext.mc_eax = regs->tf_rax;
sf.sf_uc.uc_mcontext.mc_trapno = regs->tf_trapno;
sf.sf_uc.uc_mcontext.mc_err = regs->tf_err;
sf.sf_uc.uc_mcontext.mc_eip = regs->tf_rip;
sf.sf_uc.uc_mcontext.mc_cs = regs->tf_cs;
sf.sf_uc.uc_mcontext.mc_eflags = regs->tf_rflags;
sf.sf_uc.uc_mcontext.mc_esp = regs->tf_rsp;
sf.sf_uc.uc_mcontext.mc_ss = regs->tf_ss;
sf.sf_uc.uc_mcontext.mc_ds = regs->tf_ds;
sf.sf_uc.uc_mcontext.mc_es = regs->tf_es;
sf.sf_uc.uc_mcontext.mc_fs = regs->tf_fs;
sf.sf_uc.uc_mcontext.mc_gs = regs->tf_gs;
sf.sf_uc.uc_mcontext.mc_len = sizeof(sf.sf_uc.uc_mcontext); /* magic */
ia32_get_fpcontext(td, &sf.sf_uc.uc_mcontext);
fpstate_drop(td);
sf.sf_uc.uc_mcontext.mc_fsbase = td->td_pcb->pcb_fsbase;
sf.sf_uc.uc_mcontext.mc_gsbase = td->td_pcb->pcb_gsbase;
/* Allocate space for the signal handler context. */
if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
SIGISMEMBER(psp->ps_sigonstack, sig)) {
sp = td->td_sigstk.ss_sp +
td->td_sigstk.ss_size - sizeof(sf);
} else
sp = (char *)regs->tf_rsp - sizeof(sf);
/* Align to 16 bytes. */
sfp = (struct ia32_sigframe *)((uintptr_t)sp & ~0xF);
PROC_UNLOCK(p);
/* Translate the signal if appropriate. */
if (p->p_sysent->sv_sigtbl && sig <= p->p_sysent->sv_sigsize)
sig = p->p_sysent->sv_sigtbl[_SIG_IDX(sig)];
/* Build the argument list for the signal handler. */
sf.sf_signum = sig;
sf.sf_ucontext = (register_t)&sfp->sf_uc;
if (SIGISMEMBER(psp->ps_siginfo, sig)) {
/* Signal handler installed with SA_SIGINFO. */
sf.sf_siginfo = (u_int32_t)(uintptr_t)&sfp->sf_si;
sf.sf_ah = (u_int32_t)(uintptr_t)catcher;
/* Fill in POSIX parts */
sf.sf_si = siginfo;
sf.sf_si.si_signo = sig;
} else {
/* Old FreeBSD-style arguments. */
sf.sf_siginfo = siginfo.si_code;
sf.sf_addr = (u_int32_t)siginfo.si_addr;
sf.sf_ah = (u_int32_t)(uintptr_t)catcher;
}
mtx_unlock(&psp->ps_mtx);
/*
* Copy the sigframe out to the user's stack.
*/
if (copyout(&sf, sfp, sizeof(*sfp)) != 0) {
#ifdef DEBUG
printf("process %ld has trashed its stack\n", (long)p->p_pid);
#endif
PROC_LOCK(p);
sigexit(td, SIGILL);
}
regs->tf_rsp = (uintptr_t)sfp;
regs->tf_rip = FREEBSD32_PS_STRINGS - *(p->p_sysent->sv_szsigcode);
regs->tf_rflags &= ~(PSL_T | PSL_D);
regs->tf_cs = _ucode32sel;
regs->tf_ss = _udatasel;
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;
td->td_pcb->pcb_full_iret = 1;
/* XXXKIB leave user %fs and %gs untouched */
PROC_LOCK(p);
mtx_lock(&psp->ps_mtx);
}
/*
* System call to cleanup state after a signal
* has been taken. Reset signal mask and
* stack state from context left by sendsig (above).
* Return to previous pc and psl as specified by
* context left by sendsig. Check carefully to
* make sure that the user has not modified the
* state to gain improper privileges.
*/
#ifdef COMPAT_FREEBSD4
/*
* MPSAFE
*/
int
freebsd4_freebsd32_sigreturn(td, uap)
struct thread *td;
struct freebsd4_freebsd32_sigreturn_args /* {
const struct freebsd4_freebsd32_ucontext *sigcntxp;
} */ *uap;
{
struct ia32_ucontext4 uc;
struct trapframe *regs;
struct ia32_ucontext4 *ucp;
int cs, eflags, error;
ksiginfo_t ksi;
error = copyin(uap->sigcntxp, &uc, sizeof(uc));
if (error != 0)
return (error);
ucp = &uc;
regs = td->td_frame;
eflags = ucp->uc_mcontext.mc_eflags;
/*
* Don't allow users to change privileged or reserved flags.
*/
/*
* XXX do allow users to change the privileged flag PSL_RF.
* The cpu sets PSL_RF in tf_eflags for faults. Debuggers
* should sometimes set it there too. tf_eflags is kept in
* the signal context during signal handling and there is no
* other place to remember it, so the PSL_RF bit may be
* corrupted by the signal handler without us knowing.
* Corruption of the PSL_RF bit at worst causes one more or
* one less debugger trap, so allowing it is fairly harmless.
*/
if (!EFL_SECURE(eflags & ~PSL_RF, regs->tf_rflags & ~PSL_RF)) {
printf("freebsd4_freebsd32_sigreturn: eflags = 0x%x\n", eflags);
return (EINVAL);
}
/*
* Don't allow users to load a valid privileged %cs. Let the
* hardware check for invalid selectors, excess privilege in
* other selectors, invalid %eip's and invalid %esp's.
*/
cs = ucp->uc_mcontext.mc_cs;
if (!CS_SECURE(cs)) {
printf("freebsd4_sigreturn: cs = 0x%x\n", cs);
ksiginfo_init_trap(&ksi);
ksi.ksi_signo = SIGBUS;
ksi.ksi_code = BUS_OBJERR;
ksi.ksi_trapno = T_PROTFLT;
ksi.ksi_addr = (void *)regs->tf_rip;
trapsignal(td, &ksi);
return (EINVAL);
}
regs->tf_rdi = ucp->uc_mcontext.mc_edi;
regs->tf_rsi = ucp->uc_mcontext.mc_esi;
regs->tf_rbp = ucp->uc_mcontext.mc_ebp;
regs->tf_rbx = ucp->uc_mcontext.mc_ebx;
regs->tf_rdx = ucp->uc_mcontext.mc_edx;
regs->tf_rcx = ucp->uc_mcontext.mc_ecx;
regs->tf_rax = ucp->uc_mcontext.mc_eax;
regs->tf_trapno = ucp->uc_mcontext.mc_trapno;
regs->tf_err = ucp->uc_mcontext.mc_err;
regs->tf_rip = ucp->uc_mcontext.mc_eip;
regs->tf_cs = cs;
regs->tf_rflags = ucp->uc_mcontext.mc_eflags;
regs->tf_rsp = ucp->uc_mcontext.mc_esp;
regs->tf_ss = ucp->uc_mcontext.mc_ss;
regs->tf_ds = ucp->uc_mcontext.mc_ds;
regs->tf_es = ucp->uc_mcontext.mc_es;
regs->tf_fs = ucp->uc_mcontext.mc_fs;
regs->tf_gs = ucp->uc_mcontext.mc_gs;
kern_sigprocmask(td, SIG_SETMASK, &ucp->uc_sigmask, NULL, 0);
td->td_pcb->pcb_full_iret = 1;
return (EJUSTRETURN);
}
#endif /* COMPAT_FREEBSD4 */
/*
* MPSAFE
*/
int
freebsd32_sigreturn(td, uap)
struct thread *td;
struct freebsd32_sigreturn_args /* {
const struct freebsd32_ucontext *sigcntxp;
} */ *uap;
{
struct ia32_ucontext uc;
struct trapframe *regs;
struct ia32_ucontext *ucp;
int cs, eflags, error, ret;
ksiginfo_t ksi;
error = copyin(uap->sigcntxp, &uc, sizeof(uc));
if (error != 0)
return (error);
ucp = &uc;
regs = td->td_frame;
eflags = ucp->uc_mcontext.mc_eflags;
/*
* Don't allow users to change privileged or reserved flags.
*/
/*
* XXX do allow users to change the privileged flag PSL_RF.
* The cpu sets PSL_RF in tf_eflags for faults. Debuggers
* should sometimes set it there too. tf_eflags is kept in
* the signal context during signal handling and there is no
* other place to remember it, so the PSL_RF bit may be
* corrupted by the signal handler without us knowing.
* Corruption of the PSL_RF bit at worst causes one more or
* one less debugger trap, so allowing it is fairly harmless.
*/
if (!EFL_SECURE(eflags & ~PSL_RF, regs->tf_rflags & ~PSL_RF)) {
printf("freebsd32_sigreturn: eflags = 0x%x\n", eflags);
return (EINVAL);
}
/*
* Don't allow users to load a valid privileged %cs. Let the
* hardware check for invalid selectors, excess privilege in
* other selectors, invalid %eip's and invalid %esp's.
*/
cs = ucp->uc_mcontext.mc_cs;
if (!CS_SECURE(cs)) {
printf("sigreturn: cs = 0x%x\n", cs);
ksiginfo_init_trap(&ksi);
ksi.ksi_signo = SIGBUS;
ksi.ksi_code = BUS_OBJERR;
ksi.ksi_trapno = T_PROTFLT;
ksi.ksi_addr = (void *)regs->tf_rip;
trapsignal(td, &ksi);
return (EINVAL);
}
ret = ia32_set_fpcontext(td, &ucp->uc_mcontext);
if (ret != 0)
return (ret);
regs->tf_rdi = ucp->uc_mcontext.mc_edi;
regs->tf_rsi = ucp->uc_mcontext.mc_esi;
regs->tf_rbp = ucp->uc_mcontext.mc_ebp;
regs->tf_rbx = ucp->uc_mcontext.mc_ebx;
regs->tf_rdx = ucp->uc_mcontext.mc_edx;
regs->tf_rcx = ucp->uc_mcontext.mc_ecx;
regs->tf_rax = ucp->uc_mcontext.mc_eax;
regs->tf_trapno = ucp->uc_mcontext.mc_trapno;
regs->tf_err = ucp->uc_mcontext.mc_err;
regs->tf_rip = ucp->uc_mcontext.mc_eip;
regs->tf_cs = cs;
regs->tf_rflags = ucp->uc_mcontext.mc_eflags;
regs->tf_rsp = ucp->uc_mcontext.mc_esp;
regs->tf_ss = ucp->uc_mcontext.mc_ss;
regs->tf_ds = ucp->uc_mcontext.mc_ds;
regs->tf_es = ucp->uc_mcontext.mc_es;
regs->tf_fs = ucp->uc_mcontext.mc_fs;
regs->tf_gs = ucp->uc_mcontext.mc_gs;
regs->tf_flags = TF_HASSEGS;
kern_sigprocmask(td, SIG_SETMASK, &ucp->uc_sigmask, NULL, 0);
td->td_pcb->pcb_full_iret = 1;
return (EJUSTRETURN);
}
/*
* Clear registers on exec
*/
void
ia32_setregs(td, entry, stack, ps_strings)
struct thread *td;
u_long entry;
u_long stack;
u_long ps_strings;
{
struct trapframe *regs = td->td_frame;
struct pcb *pcb = td->td_pcb;
mtx_lock(&dt_lock);
if (td->td_proc->p_md.md_ldt != NULL)
user_ldt_free(td);
else
mtx_unlock(&dt_lock);
pcb->pcb_fsbase = 0;
pcb->pcb_gsbase = 0;
pcb->pcb_initial_fpucw = __INITIAL_FPUCW_I386__;
bzero((char *)regs, sizeof(struct trapframe));
regs->tf_rip = entry;
regs->tf_rsp = stack;
regs->tf_rflags = PSL_USER | (regs->tf_rflags & PSL_T);
regs->tf_ss = _udatasel;
regs->tf_cs = _ucode32sel;
regs->tf_rbx = ps_strings;
regs->tf_ds = _udatasel;
regs->tf_es = _udatasel;
regs->tf_fs = _ufssel;
regs->tf_gs = _ugssel;
regs->tf_flags = TF_HASSEGS;
load_cr0(rcr0() | CR0_MP | CR0_TS);
fpstate_drop(td);
/* Return via doreti so that we can change to a different %cs */
pcb->pcb_flags |= PCB_FULLCTX | PCB_32BIT;
pcb->pcb_flags &= ~PCB_GS32BIT;
td->td_pcb->pcb_full_iret = 1;
td->td_retval[1] = 0;
}
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