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linux/arch/alpha/kernel/signal.c
Eric W. Biederman 5f50245ba7 signal/alpha: Use send_sig_fault where appropriate 
Filling in struct siginfo before calling send_sig_info a tedious and
error prone process, where once in a great while the wrong fields
are filled out, and siginfo has been inconsistently cleared.

Simplify this process by using the helper send_sig_fault.  Which
takes as a parameters all of the information it needs, ensures
all of the fiddly bits of filling in struct siginfo are done properly
and then calls send_sig_info.

In short about a 5 line reduction in code for every time send_sig_info
is called, which makes the calling function clearer.

Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: linux-alpha@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-04-25 10:40:58 -05:00

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// SPDX-License-Identifier: GPL-2.0
/*
* linux/arch/alpha/kernel/signal.c
*
* Copyright (C) 1995 Linus Torvalds
*
* 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
*/
#include <linux/sched/signal.h>
#include <linux/sched/task_stack.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
#include <linux/bitops.h>
#include <linux/syscalls.h>
#include <linux/tracehook.h>
#include <linux/uaccess.h>
#include <asm/sigcontext.h>
#include <asm/ucontext.h>
#include "proto.h"
#define DEBUG_SIG 0
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
asmlinkage void ret_from_sys_call(void);
/*
* The OSF/1 sigprocmask calling sequence is different from the
* C sigprocmask() sequence..
*/
SYSCALL_DEFINE2(osf_sigprocmask, int, how, unsigned long, newmask)
{
sigset_t oldmask;
sigset_t mask;
unsigned long res;
siginitset(&mask, newmask & _BLOCKABLE);
res = sigprocmask(how, &mask, &oldmask);
if (!res) {
force_successful_syscall_return();
res = oldmask.sig[0];
}
return res;
}
SYSCALL_DEFINE3(osf_sigaction, int, sig,
const struct osf_sigaction __user *, act,
struct osf_sigaction __user *, oact)
{
struct k_sigaction new_ka, old_ka;
int ret;
if (act) {
old_sigset_t mask;
if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
__get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
__get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
__get_user(mask, &act->sa_mask))
return -EFAULT;
siginitset(&new_ka.sa.sa_mask, mask);
new_ka.ka_restorer = NULL;
}
ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
if (!ret && oact) {
if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
__put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
__put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
return -EFAULT;
}
return ret;
}
SYSCALL_DEFINE5(rt_sigaction, int, sig, const struct sigaction __user *, act,
struct sigaction __user *, oact,
size_t, sigsetsize, void __user *, restorer)
{
struct k_sigaction new_ka, old_ka;
int ret;
/* XXX: Don't preclude handling different sized sigset_t's. */
if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
if (act) {
new_ka.ka_restorer = restorer;
if (copy_from_user(&new_ka.sa, act, sizeof(*act)))
return -EFAULT;
}
ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
if (!ret && oact) {
if (copy_to_user(oact, &old_ka.sa, sizeof(*oact)))
return -EFAULT;
}
return ret;
}
/*
* Do a signal return; undo the signal stack.
*/
#if _NSIG_WORDS > 1
# error "Non SA_SIGINFO frame needs rearranging"
#endif
struct sigframe
{
struct sigcontext sc;
unsigned int retcode[3];
};
struct rt_sigframe
{
struct siginfo info;
struct ucontext uc;
unsigned int retcode[3];
};
/* If this changes, userland unwinders that Know Things about our signal
frame will break. Do not undertake lightly. It also implies an ABI
change wrt the size of siginfo_t, which may cause some pain. */
extern char compile_time_assert
[offsetof(struct rt_sigframe, uc.uc_mcontext) == 176 ? 1 : -1];
#define INSN_MOV_R30_R16 0x47fe0410
#define INSN_LDI_R0 0x201f0000
#define INSN_CALLSYS 0x00000083
static long
restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
{
unsigned long usp;
struct switch_stack *sw = (struct switch_stack *)regs - 1;
long i, err = __get_user(regs->pc, &sc->sc_pc);
current->restart_block.fn = do_no_restart_syscall;
sw->r26 = (unsigned long) ret_from_sys_call;
err |= __get_user(regs->r0, sc->sc_regs+0);
err |= __get_user(regs->r1, sc->sc_regs+1);
err |= __get_user(regs->r2, sc->sc_regs+2);
err |= __get_user(regs->r3, sc->sc_regs+3);
err |= __get_user(regs->r4, sc->sc_regs+4);
err |= __get_user(regs->r5, sc->sc_regs+5);
err |= __get_user(regs->r6, sc->sc_regs+6);
err |= __get_user(regs->r7, sc->sc_regs+7);
err |= __get_user(regs->r8, sc->sc_regs+8);
err |= __get_user(sw->r9, sc->sc_regs+9);
err |= __get_user(sw->r10, sc->sc_regs+10);
err |= __get_user(sw->r11, sc->sc_regs+11);
err |= __get_user(sw->r12, sc->sc_regs+12);
err |= __get_user(sw->r13, sc->sc_regs+13);
err |= __get_user(sw->r14, sc->sc_regs+14);
err |= __get_user(sw->r15, sc->sc_regs+15);
err |= __get_user(regs->r16, sc->sc_regs+16);
err |= __get_user(regs->r17, sc->sc_regs+17);
err |= __get_user(regs->r18, sc->sc_regs+18);
err |= __get_user(regs->r19, sc->sc_regs+19);
err |= __get_user(regs->r20, sc->sc_regs+20);
err |= __get_user(regs->r21, sc->sc_regs+21);
err |= __get_user(regs->r22, sc->sc_regs+22);
err |= __get_user(regs->r23, sc->sc_regs+23);
err |= __get_user(regs->r24, sc->sc_regs+24);
err |= __get_user(regs->r25, sc->sc_regs+25);
err |= __get_user(regs->r26, sc->sc_regs+26);
err |= __get_user(regs->r27, sc->sc_regs+27);
err |= __get_user(regs->r28, sc->sc_regs+28);
err |= __get_user(regs->gp, sc->sc_regs+29);
err |= __get_user(usp, sc->sc_regs+30);
wrusp(usp);
for (i = 0; i < 31; i++)
err |= __get_user(sw->fp[i], sc->sc_fpregs+i);
err |= __get_user(sw->fp[31], &sc->sc_fpcr);
return err;
}
/* Note that this syscall is also used by setcontext(3) to install
a given sigcontext. This because it's impossible to set *all*
registers and transfer control from userland. */
asmlinkage void
do_sigreturn(struct sigcontext __user *sc)
{
struct pt_regs *regs = current_pt_regs();
sigset_t set;
/* Verify that it's a good sigcontext before using it */
if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
goto give_sigsegv;
if (__get_user(set.sig[0], &sc->sc_mask))
goto give_sigsegv;
set_current_blocked(&set);
if (restore_sigcontext(sc, regs))
goto give_sigsegv;
/* Send SIGTRAP if we're single-stepping: */
if (ptrace_cancel_bpt (current)) {
send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
current);
}
return;
give_sigsegv:
force_sig(SIGSEGV, current);
}
asmlinkage void
do_rt_sigreturn(struct rt_sigframe __user *frame)
{
struct pt_regs *regs = current_pt_regs();
sigset_t set;
/* Verify that it's a good ucontext_t before using it */
if (!access_ok(VERIFY_READ, &frame->uc, sizeof(frame->uc)))
goto give_sigsegv;
if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
goto give_sigsegv;
set_current_blocked(&set);
if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
goto give_sigsegv;
/* Send SIGTRAP if we're single-stepping: */
if (ptrace_cancel_bpt (current)) {
send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
current);
}
return;
give_sigsegv:
force_sig(SIGSEGV, current);
}
/*
* Set up a signal frame.
*/
static inline void __user *
get_sigframe(struct ksignal *ksig, unsigned long sp, size_t frame_size)
{
return (void __user *)((sigsp(sp, ksig) - frame_size) & -32ul);
}
static long
setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
unsigned long mask, unsigned long sp)
{
struct switch_stack *sw = (struct switch_stack *)regs - 1;
long i, err = 0;
err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack);
err |= __put_user(mask, &sc->sc_mask);
err |= __put_user(regs->pc, &sc->sc_pc);
err |= __put_user(8, &sc->sc_ps);
err |= __put_user(regs->r0 , sc->sc_regs+0);
err |= __put_user(regs->r1 , sc->sc_regs+1);
err |= __put_user(regs->r2 , sc->sc_regs+2);
err |= __put_user(regs->r3 , sc->sc_regs+3);
err |= __put_user(regs->r4 , sc->sc_regs+4);
err |= __put_user(regs->r5 , sc->sc_regs+5);
err |= __put_user(regs->r6 , sc->sc_regs+6);
err |= __put_user(regs->r7 , sc->sc_regs+7);
err |= __put_user(regs->r8 , sc->sc_regs+8);
err |= __put_user(sw->r9 , sc->sc_regs+9);
err |= __put_user(sw->r10 , sc->sc_regs+10);
err |= __put_user(sw->r11 , sc->sc_regs+11);
err |= __put_user(sw->r12 , sc->sc_regs+12);
err |= __put_user(sw->r13 , sc->sc_regs+13);
err |= __put_user(sw->r14 , sc->sc_regs+14);
err |= __put_user(sw->r15 , sc->sc_regs+15);
err |= __put_user(regs->r16, sc->sc_regs+16);
err |= __put_user(regs->r17, sc->sc_regs+17);
err |= __put_user(regs->r18, sc->sc_regs+18);
err |= __put_user(regs->r19, sc->sc_regs+19);
err |= __put_user(regs->r20, sc->sc_regs+20);
err |= __put_user(regs->r21, sc->sc_regs+21);
err |= __put_user(regs->r22, sc->sc_regs+22);
err |= __put_user(regs->r23, sc->sc_regs+23);
err |= __put_user(regs->r24, sc->sc_regs+24);
err |= __put_user(regs->r25, sc->sc_regs+25);
err |= __put_user(regs->r26, sc->sc_regs+26);
err |= __put_user(regs->r27, sc->sc_regs+27);
err |= __put_user(regs->r28, sc->sc_regs+28);
err |= __put_user(regs->gp , sc->sc_regs+29);
err |= __put_user(sp, sc->sc_regs+30);
err |= __put_user(0, sc->sc_regs+31);
for (i = 0; i < 31; i++)
err |= __put_user(sw->fp[i], sc->sc_fpregs+i);
err |= __put_user(0, sc->sc_fpregs+31);
err |= __put_user(sw->fp[31], &sc->sc_fpcr);
err |= __put_user(regs->trap_a0, &sc->sc_traparg_a0);
err |= __put_user(regs->trap_a1, &sc->sc_traparg_a1);
err |= __put_user(regs->trap_a2, &sc->sc_traparg_a2);
return err;
}
static int
setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
{
unsigned long oldsp, r26, err = 0;
struct sigframe __user *frame;
oldsp = rdusp();
frame = get_sigframe(ksig, oldsp, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
return -EFAULT;
err |= setup_sigcontext(&frame->sc, regs, set->sig[0], oldsp);
if (err)
return -EFAULT;
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
r26 = (unsigned long) ksig->ka.ka_restorer;
if (!r26) {
err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
err |= __put_user(INSN_LDI_R0+__NR_sigreturn, frame->retcode+1);
err |= __put_user(INSN_CALLSYS, frame->retcode+2);
imb();
r26 = (unsigned long) frame->retcode;
}
/* Check that everything was written properly. */
if (err)
return err;
/* "Return" to the handler */
regs->r26 = r26;
regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
regs->r16 = ksig->sig; /* a0: signal number */
regs->r17 = 0; /* a1: exception code */
regs->r18 = (unsigned long) &frame->sc; /* a2: sigcontext pointer */
wrusp((unsigned long) frame);
#if DEBUG_SIG
printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
current->comm, current->pid, frame, regs->pc, regs->r26);
#endif
return 0;
}
static int
setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
{
unsigned long oldsp, r26, err = 0;
struct rt_sigframe __user *frame;
oldsp = rdusp();
frame = get_sigframe(ksig, oldsp, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
return -EFAULT;
err |= copy_siginfo_to_user(&frame->info, &ksig->info);
/* Create the ucontext. */
err |= __put_user(0, &frame->uc.uc_flags);
err |= __put_user(0, &frame->uc.uc_link);
err |= __put_user(set->sig[0], &frame->uc.uc_osf_sigmask);
err |= __save_altstack(&frame->uc.uc_stack, oldsp);
err |= setup_sigcontext(&frame->uc.uc_mcontext, regs,
set->sig[0], oldsp);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
if (err)
return -EFAULT;
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
r26 = (unsigned long) ksig->ka.ka_restorer;
if (!r26) {
err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
err |= __put_user(INSN_LDI_R0+__NR_rt_sigreturn,
frame->retcode+1);
err |= __put_user(INSN_CALLSYS, frame->retcode+2);
imb();
r26 = (unsigned long) frame->retcode;
}
if (err)
return -EFAULT;
/* "Return" to the handler */
regs->r26 = r26;
regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
regs->r16 = ksig->sig; /* a0: signal number */
regs->r17 = (unsigned long) &frame->info; /* a1: siginfo pointer */
regs->r18 = (unsigned long) &frame->uc; /* a2: ucontext pointer */
wrusp((unsigned long) frame);
#if DEBUG_SIG
printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
current->comm, current->pid, frame, regs->pc, regs->r26);
#endif
return 0;
}
/*
* OK, we're invoking a handler.
*/
static inline void
handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
sigset_t *oldset = sigmask_to_save();
int ret;
if (ksig->ka.sa.sa_flags & SA_SIGINFO)
ret = setup_rt_frame(ksig, oldset, regs);
else
ret = setup_frame(ksig, oldset, regs);
signal_setup_done(ret, ksig, 0);
}
static inline void
syscall_restart(unsigned long r0, unsigned long r19,
struct pt_regs *regs, struct k_sigaction *ka)
{
switch (regs->r0) {
case ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
case ERESTARTNOHAND:
regs->r0 = EINTR;
break;
}
/* fallthrough */
case ERESTARTNOINTR:
regs->r0 = r0; /* reset v0 and a3 and replay syscall */
regs->r19 = r19;
regs->pc -= 4;
break;
case ERESTART_RESTARTBLOCK:
regs->r0 = EINTR;
break;
}
}
/*
* 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.
*
* Note that we go through the signals twice: once to check the signals that
* the kernel can handle, and then we build all the user-level signal handling
* stack-frames in one go after that.
*
* "r0" and "r19" are the registers we need to restore for system call
* restart. "r0" is also used as an indicator whether we can restart at
* all (if we get here from anything but a syscall return, it will be 0)
*/
static void
do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19)
{
unsigned long single_stepping = ptrace_cancel_bpt(current);
struct ksignal ksig;
/* This lets the debugger run, ... */
if (get_signal(&ksig)) {
/* ... so re-check the single stepping. */
single_stepping |= ptrace_cancel_bpt(current);
/* Whee! Actually deliver the signal. */
if (r0)
syscall_restart(r0, r19, regs, &ksig.ka);
handle_signal(&ksig, regs);
} else {
single_stepping |= ptrace_cancel_bpt(current);
if (r0) {
switch (regs->r0) {
case ERESTARTNOHAND:
case ERESTARTSYS:
case ERESTARTNOINTR:
/* Reset v0 and a3 and replay syscall. */
regs->r0 = r0;
regs->r19 = r19;
regs->pc -= 4;
break;
case ERESTART_RESTARTBLOCK:
/* Set v0 to the restart_syscall and replay */
regs->r0 = __NR_restart_syscall;
regs->pc -= 4;
break;
}
}
restore_saved_sigmask();
}
if (single_stepping)
ptrace_set_bpt(current); /* re-set breakpoint */
}
void
do_work_pending(struct pt_regs *regs, unsigned long thread_flags,
unsigned long r0, unsigned long r19)
{
do {
if (thread_flags & _TIF_NEED_RESCHED) {
schedule();
} else {
local_irq_enable();
if (thread_flags & _TIF_SIGPENDING) {
do_signal(regs, r0, r19);
r0 = 0;
} else {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
}
}
local_irq_disable();
thread_flags = current_thread_info()->flags;
} while (thread_flags & _TIF_WORK_MASK);
}
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