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signal.c 13.27 KiB
// SPDX-License-Identifier: GPL-2.0
/*
* Architecture-specific signal handling support.
*
* Copyright (C) 1999-2004 Hewlett-Packard Co
* David Mosberger-Tang <davidm@hpl.hp.com>
*
* Derived from i386 and Alpha versions.
*/
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/ptrace.h>
#include <linux/tracehook.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
#include <linux/unistd.h>
#include <linux/wait.h>
#include <asm/intrinsics.h>
#include <linux/uaccess.h>
#include <asm/rse.h>
#include <asm/sigcontext.h>
#include "sigframe.h"
#define DEBUG_SIG 0
#define STACK_ALIGN 16 /* minimal alignment for stack pointer */
#if _NSIG_WORDS > 1
# define PUT_SIGSET(k,u) __copy_to_user((u)->sig, (k)->sig, sizeof(sigset_t))
# define GET_SIGSET(k,u) __copy_from_user((k)->sig, (u)->sig, sizeof(sigset_t))
#else
# define PUT_SIGSET(k,u) __put_user((k)->sig[0], &(u)->sig[0])
# define GET_SIGSET(k,u) __get_user((k)->sig[0], &(u)->sig[0])
#endif
static long
restore_sigcontext (struct sigcontext __user *sc, struct sigscratch *scr)
{
unsigned long ip, flags, nat, um, cfm, rsc;
long err;
/* Always make any pending restarted system calls return -EINTR */
current->restart_block.fn = do_no_restart_syscall;
/* restore scratch that always needs gets updated during signal delivery: */
err = __get_user(flags, &sc->sc_flags);
err |= __get_user(nat, &sc->sc_nat);
err |= __get_user(ip, &sc->sc_ip); /* instruction pointer */
err |= __get_user(cfm, &sc->sc_cfm);
err |= __get_user(um, &sc->sc_um); /* user mask */
err |= __get_user(rsc, &sc->sc_ar_rsc);
err |= __get_user(scr->pt.ar_unat, &sc->sc_ar_unat);
err |= __get_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);
err |= __get_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
err |= __get_user(scr->pt.pr, &sc->sc_pr); /* predicates */
err |= __get_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */
err |= __get_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */
err |= __copy_from_user(&scr->pt.r1, &sc->sc_gr[1], 8); /* r1 */
err |= __copy_from_user(&scr->pt.r8, &sc->sc_gr[8], 4*8); /* r8-r11 */
err |= __copy_from_user(&scr->pt.r12, &sc->sc_gr[12], 2*8); /* r12-r13 */
err |= __copy_from_user(&scr->pt.r15, &sc->sc_gr[15], 8); /* r15 */
scr->pt.cr_ifs = cfm | (1UL << 63); scr->pt.ar_rsc = rsc | (3 << 2); /* force PL3 */
/* establish new instruction pointer: */
scr->pt.cr_iip = ip & ~0x3UL;
ia64_psr(&scr->pt)->ri = ip & 0x3;
scr->pt.cr_ipsr = (scr->pt.cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM);
scr->scratch_unat = ia64_put_scratch_nat_bits(&scr->pt, nat);
if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
/* Restore most scratch-state only when not in syscall. */
err |= __get_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */
err |= __get_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */
err |= __get_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */
err |= __copy_from_user(&scr->pt.ar_csd, &sc->sc_ar25, 2*8); /* ar.csd & ar.ssd */
err |= __copy_from_user(&scr->pt.r2, &sc->sc_gr[2], 2*8); /* r2-r3 */
err |= __copy_from_user(&scr->pt.r16, &sc->sc_gr[16], 16*8); /* r16-r31 */
}
if ((flags & IA64_SC_FLAG_FPH_VALID) != 0) {
struct ia64_psr *psr = ia64_psr(&scr->pt);
err |= __copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16);
psr->mfh = 0; /* drop signal handler's fph contents... */
preempt_disable();
if (psr->dfh)
ia64_drop_fpu(current);
else {
/* We already own the local fph, otherwise psr->dfh wouldn't be 0. */
__ia64_load_fpu(current->thread.fph);
ia64_set_local_fpu_owner(current);
}
preempt_enable();
}
return err;
}
long
ia64_rt_sigreturn (struct sigscratch *scr)
{
extern char ia64_strace_leave_kernel, ia64_leave_kernel;
struct sigcontext __user *sc;
sigset_t set;
long retval;
sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc;
/*
* When we return to the previously executing context, r8 and r10 have already
* been setup the way we want them. Indeed, if the signal wasn't delivered while
* in a system call, we must not touch r8 or r10 as otherwise user-level state
* could be corrupted.
*/
retval = (long) &ia64_leave_kernel;
if (test_thread_flag(TIF_SYSCALL_TRACE)
|| test_thread_flag(TIF_SYSCALL_AUDIT))
/*
* strace expects to be notified after sigreturn returns even though the
* context to which we return may not be in the middle of a syscall.
* Thus, the return-value that strace displays for sigreturn is
* meaningless.
*/
retval = (long) &ia64_strace_leave_kernel;
if (!access_ok(sc, sizeof(*sc)))
goto give_sigsegv;
if (GET_SIGSET(&set, &sc->sc_mask))
goto give_sigsegv;
set_current_blocked(&set);
if (restore_sigcontext(sc, scr))
goto give_sigsegv;
#if DEBUG_SIG
printk("SIG return (%s:%d): sp=%lx ip=%lx\n",
current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip);
#endif
if (restore_altstack(&sc->sc_stack))
goto give_sigsegv;
return retval;
give_sigsegv:
force_sig(SIGSEGV);
return retval;
}
/*
* This does just the minimum required setup of sigcontext.
* Specifically, it only installs data that is either not knowable at
* the user-level or that gets modified before execution in the
* trampoline starts. Everything else is done at the user-level.
*/
static long
setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr)
{
unsigned long flags = 0, ifs, cfm, nat;
long err = 0;
ifs = scr->pt.cr_ifs;
if (on_sig_stack((unsigned long) sc))
flags |= IA64_SC_FLAG_ONSTACK;
if ((ifs & (1UL << 63)) == 0)
/* if cr_ifs doesn't have the valid bit set, we got here through a syscall */
flags |= IA64_SC_FLAG_IN_SYSCALL;
cfm = ifs & ((1UL << 38) - 1);
ia64_flush_fph(current);
if ((current->thread.flags & IA64_THREAD_FPH_VALID)) {
flags |= IA64_SC_FLAG_FPH_VALID;
err = __copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16);
}
nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat);
err |= __put_user(flags, &sc->sc_flags);
err |= __put_user(nat, &sc->sc_nat);
err |= PUT_SIGSET(mask, &sc->sc_mask);
err |= __put_user(cfm, &sc->sc_cfm);
err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um);
err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat); /* ar.unat */
err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr); /* ar.fpsr */
err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
err |= __put_user(scr->pt.pr, &sc->sc_pr); /* predicates */
err |= __put_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */
err |= __put_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */
err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8); /* r1 */
err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8); /* r8-r11 */
err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8); /* r12-r13 */
err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8); /* r15 */
err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip);
if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
/* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */
err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */
err |= __put_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */
err |= __put_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */
err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */ err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8); /* r2-r3 */
err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8); /* r16-r31 */
}
return err;
}
/*
* Check whether the register-backing store is already on the signal stack.
*/
static inline int
rbs_on_sig_stack (unsigned long bsp)
{
return (bsp - current->sas_ss_sp < current->sas_ss_size);
}
static long
setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr)
{
extern char __kernel_sigtramp[];
unsigned long tramp_addr, new_rbs = 0, new_sp;
struct sigframe __user *frame;
long err;
new_sp = scr->pt.r12;
tramp_addr = (unsigned long) __kernel_sigtramp;
if (ksig->ka.sa.sa_flags & SA_ONSTACK) {
int onstack = sas_ss_flags(new_sp);
if (onstack == 0) {
new_sp = current->sas_ss_sp + current->sas_ss_size;
/*
* We need to check for the register stack being on the
* signal stack separately, because it's switched
* separately (memory stack is switched in the kernel,
* register stack is switched in the signal trampoline).
*/
if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
new_rbs = ALIGN(current->sas_ss_sp,
sizeof(long));
} else if (onstack == SS_ONSTACK) {
unsigned long check_sp;
/*
* If we are on the alternate signal stack and would
* overflow it, don't. Return an always-bogus address
* instead so we will die with SIGSEGV.
*/
check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN;
if (!likely(on_sig_stack(check_sp))) {
force_sigsegv(ksig->sig);
return 1;
}
}
}
frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);
if (!access_ok(frame, sizeof(*frame))) {
force_sigsegv(ksig->sig);
return 1;
}
err = __put_user(ksig->sig, &frame->arg0);
err |= __put_user(&frame->info, &frame->arg1);
err |= __put_user(&frame->sc, &frame->arg2);
err |= __put_user(new_rbs, &frame->sc.sc_rbs_base);
err |= __put_user(0, &frame->sc.sc_loadrs); /* initialize to zero */
err |= __put_user(ksig->ka.sa.sa_handler, &frame->handler);
err |= copy_siginfo_to_user(&frame->info, &ksig->info);
err |= __save_altstack(&frame->sc.sc_stack, scr->pt.r12);
err |= setup_sigcontext(&frame->sc, set, scr);
if (unlikely(err)) {
force_sigsegv(ksig->sig);
return 1;
}
scr->pt.r12 = (unsigned long) frame - 16; /* new stack pointer */
scr->pt.ar_fpsr = FPSR_DEFAULT; /* reset fpsr for signal handler */
scr->pt.cr_iip = tramp_addr;
ia64_psr(&scr->pt)->ri = 0; /* start executing in first slot */
ia64_psr(&scr->pt)->be = 0; /* force little-endian byte-order */
/*
* Force the interruption function mask to zero. This has no effect when a
* system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is
* ignored), but it has the desirable effect of making it possible to deliver a
* signal with an incomplete register frame (which happens when a mandatory RSE
* load faults). Furthermore, it has no negative effect on the getting the user's
* dirty partition preserved, because that's governed by scr->pt.loadrs.
*/
scr->pt.cr_ifs = (1UL << 63);
/*
* Note: this affects only the NaT bits of the scratch regs (the ones saved in
* pt_regs), which is exactly what we want.
*/
scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */
#if DEBUG_SIG
printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n",
current->comm, current->pid, ksig->sig, scr->pt.r12, frame->sc.sc_ip, frame->handler);
#endif
return 0;
}
static long
handle_signal (struct ksignal *ksig, struct sigscratch *scr)
{
int ret = setup_frame(ksig, sigmask_to_save(), scr);
if (!ret)
signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
return ret;
}
/*
* Note that `init' is a special process: it doesn't get signals it doesn't want to
* handle. Thus you cannot kill init even with a SIGKILL even by mistake.
*/
void
ia64_do_signal (struct sigscratch *scr, long in_syscall)
{
long restart = in_syscall;
long errno = scr->pt.r8;
struct ksignal ksig;
/*
* This only loops in the rare cases of handle_signal() failing, in which case we
* need to push through a forced SIGSEGV.
*/
while (1) {
if (!get_signal(&ksig))
break;
/*
* get_signal() may have run a debugger (via notify_parent())
* and the debugger may have modified the state (e.g., to arrange for an
* inferior call), thus it's important to check for restarting _after_ * get_signal().
*/
if ((long) scr->pt.r10 != -1)
/*
* A system calls has to be restarted only if one of the error codes
* ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned. If r10
* isn't -1 then r8 doesn't hold an error code and we don't need to
* restart the syscall, so we can clear the "restart" flag here.
*/
restart = 0;
if (ksig.sig <= 0)
break;
if (unlikely(restart)) {
switch (errno) {
case ERESTART_RESTARTBLOCK:
case ERESTARTNOHAND:
scr->pt.r8 = EINTR;
/* note: scr->pt.r10 is already -1 */
break;
case ERESTARTSYS:
if ((ksig.ka.sa.sa_flags & SA_RESTART) == 0) {
scr->pt.r8 = EINTR;
/* note: scr->pt.r10 is already -1 */
break;
}
fallthrough;
case ERESTARTNOINTR:
ia64_decrement_ip(&scr->pt);
restart = 0; /* don't restart twice if handle_signal() fails... */
}
}
/*
* Whee! Actually deliver the signal. If the delivery failed, we need to
* continue to iterate in this loop so we can deliver the SIGSEGV...
*/
if (handle_signal(&ksig, scr))
return;
}
/* Did we come from a system call? */
if (restart) {
/* Restart the system call - no handlers present */
if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR
|| errno == ERESTART_RESTARTBLOCK)
{
/*
* Note: the syscall number is in r15 which is saved in
* pt_regs so all we need to do here is adjust ip so that
* the "break" instruction gets re-executed.
*/
ia64_decrement_ip(&scr->pt);
if (errno == ERESTART_RESTARTBLOCK)
scr->pt.r15 = __NR_restart_syscall;
}
}
/* if there's no signal to deliver, we just put the saved sigmask
* back */
restore_saved_sigmask();
}