// SPDX-License-Identifier: GPL-2.0
/*
* Copyright IBM Corp. 1999, 2006
* Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
*
* Based on Intel version
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
*/
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/entry-common.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/tty.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <linux/syscalls.h>
#include <linux/compat.h>
#include <asm/ucontext.h>
#include <linux/uaccess.h>
#include <asm/lowcore.h>
#include <asm/switch_to.h>
#include <asm/vdso.h>
#include "entry.h"
/*
* Layout of an old-style signal-frame:
* -----------------------------------------
* | save area (_SIGNAL_FRAMESIZE) |
* -----------------------------------------
* | struct sigcontext |
* | oldmask |
* | _sigregs * |
* -----------------------------------------
* | _sigregs with |
* | _s390_regs_common |
* | _s390_fp_regs |
* -----------------------------------------
* | int signo |
* -----------------------------------------
* | _sigregs_ext with |
* | gprs_high 64 byte (opt) |
* | vxrs_low 128 byte (opt) |
* | vxrs_high 256 byte (opt) |
* | reserved 128 byte (opt) |
* -----------------------------------------
* | __u16 svc_insn |
* -----------------------------------------
* The svc_insn entry with the sigreturn system call opcode does not
* have a fixed position and moves if gprs_high or vxrs exist.
* Future extensions will be added to _sigregs_ext.
*/
struct sigframe
{
__u8 callee_used_stack[__SIGNAL_FRAMESIZE];
struct sigcontext sc;
_sigregs sregs;
int signo;
_sigregs_ext sregs_ext;
__u16 svc_insn; /* Offset of svc_insn is NOT fixed! */
};
/*
* Layout of an rt signal-frame:
* -----------------------------------------
* | save area (_SIGNAL_FRAMESIZE) |
* -----------------------------------------
* | svc __NR_rt_sigreturn 2 byte |
* -----------------------------------------
* | struct siginfo |
* -----------------------------------------
* | struct ucontext_extended with |
* | unsigned long uc_flags |
* | struct ucontext *uc_link |
* | stack_t uc_stack |
* | _sigregs uc_mcontext with |
* | _s390_regs_common |
* | _s390_fp_regs |
* | sigset_t uc_sigmask |
* | _sigregs_ext uc_mcontext_ext |
* | gprs_high 64 byte (opt) |
* | vxrs_low 128 byte (opt) |
* | vxrs_high 256 byte (opt)|
* | reserved 128 byte (opt) |
* -----------------------------------------
* Future extensions will be added to _sigregs_ext.
*/
struct rt_sigframe
{
__u8 callee_used_stack[__SIGNAL_FRAMESIZE];
__u16 svc_insn;
struct siginfo info;
struct ucontext_extended uc;
};
/* Store registers needed to create the signal frame */
static void store_sigregs(void)
{
save_access_regs(current->thread.acrs);
save_fpu_regs();
}
/* Load registers after signal return */
static void load_sigregs(void)
{
restore_access_regs(current->thread.acrs);
}
/* Returns non-zero on fault. */
static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
{
_sigregs user_sregs;
/* Copy a 'clean' PSW mask to the user to avoid leaking
information about whether PER is currently on. */
user_sregs.regs.psw.mask = PSW_USER_BITS |
(regs->psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
user_sregs.regs.psw.addr = regs->psw.addr;
memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs));
memcpy(&user_sregs.regs.acrs, current->thread.acrs,
sizeof(user_sregs.regs.acrs));
fpregs_store(&user_sregs.fpregs, ¤t->thread.fpu);
if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs)))
return -EFAULT;
return 0;
}
static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
{
_sigregs user_sregs;
/* Always make any pending restarted system call return -EINTR */
current->restart_block.fn = do_no_restart_syscall;
if (__copy_from_user(&user_sregs, sregs, sizeof(user_sregs)))
return -EFAULT;
if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW_MASK_RI))
return -EINVAL;
/* Test the floating-point-control word. */
if (test_fp_ctl(user_sregs.fpregs.fpc))
return -EINVAL;
/* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */
regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) |
(user_sregs.regs.psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
/* Check for invalid user address space control. */
if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME)
regs->psw.mask = PSW_ASC_PRIMARY |
(regs->psw.mask & ~PSW_MASK_ASC);
/* Check for invalid amode */
if (regs->psw.mask & PSW_MASK_EA)
regs->psw.mask |= PSW_MASK_BA;
regs->psw.addr = user_sregs.regs.psw.addr;
memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
memcpy(¤t->thread.acrs, &user_sregs.regs.acrs,
sizeof(current->thread.acrs));
fpregs_load(&user_sregs.fpregs, ¤t->thread.fpu);
clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */
return 0;
}
/* Returns non-zero on fault. */
static int save_sigregs_ext(struct pt_regs *regs,
_sigregs_ext __user *sregs_ext)
{
__u64 vxrs[__NUM_VXRS_LOW];
int i;
/* Save vector registers to signal stack */
if (MACHINE_HAS_VX) {
for (i = 0; i < __NUM_VXRS_LOW; i++)
vxrs[i] = current->thread.fpu.vxrs[i].low;
if (__copy_to_user(&sregs_ext->vxrs_low, vxrs,
sizeof(sregs_ext->vxrs_low)) ||
__copy_to_user(&sregs_ext->vxrs_high,
current->thread.fpu.vxrs + __NUM_VXRS_LOW,
sizeof(sregs_ext->vxrs_high)))
return -EFAULT;
}
return 0;
}
static int restore_sigregs_ext(struct pt_regs *regs,
_sigregs_ext __user *sregs_ext)
{
__u64 vxrs[__NUM_VXRS_LOW];
int i;
/* Restore vector registers from signal stack */
if (MACHINE_HAS_VX) {
if (__copy_from_user(vxrs, &sregs_ext->vxrs_low,
sizeof(sregs_ext->vxrs_low)) ||
__copy_from_user(current->thread.fpu.vxrs + __NUM_VXRS_LOW,
&sregs_ext->vxrs_high,
sizeof(sregs_ext->vxrs_high)))
return -EFAULT;
for (i = 0; i < __NUM_VXRS_LOW; i++)
current->thread.fpu.vxrs[i].low = vxrs[i];
}
return 0;
}
SYSCALL_DEFINE0(sigreturn)
{
struct pt_regs *regs = task_pt_regs(current);
struct sigframe __user *frame =
(struct sigframe __user *) regs->gprs[15];
sigset_t set;
if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
goto badframe;
set_current_blocked(&set);
save_fpu_regs();
if (restore_sigregs(regs, &frame->sregs))
goto badframe;
if (restore_sigregs_ext(regs, &frame->sregs_ext))
goto badframe;
load_sigregs();
return regs->gprs[2];
badframe:
force_sig(SIGSEGV);
return 0;
}
SYSCALL_DEFINE0(rt_sigreturn)
{
struct pt_regs *regs = task_pt_regs(current);
struct rt_sigframe __user *frame =
(struct rt_sigframe __user *)regs->gprs[15];
sigset_t set;
if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
goto badframe;
set_current_blocked(&set);
if (restore_altstack(&frame->uc.uc_stack))
goto badframe;
save_fpu_regs();
if (restore_sigregs(regs, &frame->uc.uc_mcontext))
goto badframe;
if (restore_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
goto badframe;
load_sigregs();
return regs->gprs[2];
badframe:
force_sig(SIGSEGV);
return 0;
}
/*
* Determine which stack to use..
*/
static inline void __user *
get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
{
unsigned long sp;
/* Default to using normal stack */
sp = regs->gprs[15];
/* Overflow on alternate signal stack gives SIGSEGV. */
if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
return (void __user *) -1UL;
/* This is the X/Open sanctioned signal stack switching. */
if (ka->sa.sa_flags & SA_ONSTACK) {
if (! sas_ss_flags(sp))
sp = current->sas_ss_sp + current->sas_ss_size;
}
return (void __user *)((sp - frame_size) & -8ul);
}
static int setup_frame(int sig, struct k_sigaction *ka,
sigset_t *set, struct pt_regs * regs)
{
struct sigframe __user *frame;
struct sigcontext sc;
unsigned long restorer;
size_t frame_size;
/*
* gprs_high are only present for a 31-bit task running on
* a 64-bit kernel (see compat_signal.c) but the space for
* gprs_high need to be allocated if vector registers are
* included in the signal frame on a 31-bit system.
*/
frame_size = sizeof(*frame) - sizeof(frame->sregs_ext);
if (MACHINE_HAS_VX)
frame_size += sizeof(frame->sregs_ext);
frame = get_sigframe(ka, regs, frame_size);
if (frame == (void __user *) -1UL)
return -EFAULT;
/* Set up backchain. */
if (__put_user(regs->gprs[15], (addr_t __user *) frame))
return -EFAULT;
/* Create struct sigcontext on the signal stack */
memcpy(&sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE);
sc.sregs = (_sigregs __user __force *) &frame->sregs;
if (__copy_to_user(&frame->sc, &sc, sizeof(frame->sc)))
return -EFAULT;
/* Store registers needed to create the signal frame */
store_sigregs();
/* Create _sigregs on the signal stack */
if (save_sigregs(regs, &frame->sregs))
return -EFAULT;
/* Place signal number on stack to allow backtrace from handler. */
if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
return -EFAULT;
/* Create _sigregs_ext on the signal stack */
if (save_sigregs_ext(regs, &frame->sregs_ext))
return -EFAULT;
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
if (ka->sa.sa_flags & SA_RESTORER)
restorer = (unsigned long) ka->sa.sa_restorer;
else
restorer = VDSO64_SYMBOL(current, sigreturn);
/* Set up registers for signal handler */
regs->gprs[14] = restorer;
regs->gprs[15] = (unsigned long) frame;
/* Force default amode and default user address space control. */
regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
(PSW_USER_BITS & PSW_MASK_ASC) |
(regs->psw.mask & ~PSW_MASK_ASC);
regs->psw.addr = (unsigned long) ka->sa.sa_handler;
regs->gprs[2] = sig;
regs->gprs[3] = (unsigned long) &frame->sc;
/* We forgot to include these in the sigcontext.
To avoid breaking binary compatibility, they are passed as args. */
if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
sig == SIGTRAP || sig == SIGFPE) {
/* set extra registers only for synchronous signals */
regs->gprs[4] = regs->int_code & 127;
regs->gprs[5] = regs->int_parm_long;
regs->gprs[6] = current->thread.last_break;
}
return 0;
}
static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
struct pt_regs *regs)
{
struct rt_sigframe __user *frame;
unsigned long uc_flags, restorer;
size_t frame_size;
frame_size = sizeof(struct rt_sigframe) - sizeof(_sigregs_ext);
/*
* gprs_high are only present for a 31-bit task running on
* a 64-bit kernel (see compat_signal.c) but the space for
* gprs_high need to be allocated if vector registers are
* included in the signal frame on a 31-bit system.
*/
uc_flags = 0;
if (MACHINE_HAS_VX) {
frame_size += sizeof(_sigregs_ext);
uc_flags |= UC_VXRS;
}
frame = get_sigframe(&ksig->ka, regs, frame_size);
if (frame == (void __user *) -1UL)
return -EFAULT;
/* Set up backchain. */
if (__put_user(regs->gprs[15], (addr_t __user *) frame))
return -EFAULT;
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
if (ksig->ka.sa.sa_flags & SA_RESTORER)
restorer = (unsigned long) ksig->ka.sa.sa_restorer;
else
restorer = VDSO64_SYMBOL(current, rt_sigreturn);
/* Create siginfo on the signal stack */
if (copy_siginfo_to_user(&frame->info, &ksig->info))
return -EFAULT;
/* Store registers needed to create the signal frame */
store_sigregs();
/* Create ucontext on the signal stack. */
if (__put_user(uc_flags, &frame->uc.uc_flags) ||
__put_user(NULL, &frame->uc.uc_link) ||
__save_altstack(&frame->uc.uc_stack, regs->gprs[15]) ||
save_sigregs(regs, &frame->uc.uc_mcontext) ||
__copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)) ||
save_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
return -EFAULT;
/* Set up registers for signal handler */
regs->gprs[14] = restorer;
regs->gprs[15] = (unsigned long) frame;
/* Force default amode and default user address space control. */
regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
(PSW_USER_BITS & PSW_MASK_ASC) |
(regs->psw.mask & ~PSW_MASK_ASC);
regs->psw.addr = (unsigned long) ksig->ka.sa.sa_handler;
regs->gprs[2] = ksig->sig;
regs->gprs[3] = (unsigned long) &frame->info;
regs->gprs[4] = (unsigned long) &frame->uc;
regs->gprs[5] = current->thread.last_break;
return 0;
}
static void handle_signal(struct ksignal *ksig, sigset_t *oldset,
struct pt_regs *regs)
{
int ret;
/* Set up the stack frame */
if (ksig->ka.sa.sa_flags & SA_SIGINFO)
ret = setup_rt_frame(ksig, oldset, regs);
else
ret = setup_frame(ksig->sig, &ksig->ka, oldset, regs);
signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP));
}
/*
* 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.
*/
void arch_do_signal_or_restart(struct pt_regs *regs)
{
struct ksignal ksig;
sigset_t *oldset = sigmask_to_save();
/*
* Get signal to deliver. When running under ptrace, at this point
* the debugger may change all our registers, including the system
* call information.
*/
current->thread.system_call =
test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;
if (get_signal(&ksig)) {
/* Whee! Actually deliver the signal. */
if (current->thread.system_call) {
regs->int_code = current->thread.system_call;
/* Check for system call restarting. */
switch (regs->gprs[2]) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
regs->gprs[2] = -EINTR;
break;
case -ERESTARTSYS:
if (!(ksig.ka.sa.sa_flags & SA_RESTART)) {
regs->gprs[2] = -EINTR;
break;
}
fallthrough;
case -ERESTARTNOINTR:
regs->gprs[2] = regs->orig_gpr2;
regs->psw.addr =
__rewind_psw(regs->psw,
regs->int_code >> 16);
break;
}
}
/* No longer in a system call */
clear_pt_regs_flag(regs, PIF_SYSCALL);
rseq_signal_deliver(&ksig, regs);
if (is_compat_task())
handle_signal32(&ksig, oldset, regs);
else
handle_signal(&ksig, oldset, regs);
return;
}
/* No handlers present - check for system call restart */
clear_pt_regs_flag(regs, PIF_SYSCALL);
if (current->thread.system_call) {
regs->int_code = current->thread.system_call;
switch (regs->gprs[2]) {
case -ERESTART_RESTARTBLOCK:
/* Restart with sys_restart_syscall */
regs->gprs[2] = regs->orig_gpr2;
current->restart_block.arch_data = regs->psw.addr;
if (is_compat_task())
regs->psw.addr = VDSO32_SYMBOL(current, restart_syscall);
else
regs->psw.addr = VDSO64_SYMBOL(current, restart_syscall);
if (test_thread_flag(TIF_SINGLE_STEP))
clear_thread_flag(TIF_PER_TRAP);
break;
case -ERESTARTNOHAND:
case -ERESTARTSYS:
case -ERESTARTNOINTR:
regs->gprs[2] = regs->orig_gpr2;
regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
if (test_thread_flag(TIF_SINGLE_STEP))
clear_thread_flag(TIF_PER_TRAP);
break;
}
}
/*
* If there's no signal to deliver, we just put the saved sigmask back.
*/
restore_saved_sigmask();
}