diff options
Diffstat (limited to 'arch/s390/kernel/signal.c')
| -rw-r--r-- | arch/s390/kernel/signal.c | 534 |
1 files changed, 534 insertions, 0 deletions
diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c new file mode 100644 index 000000000..d63557d38 --- /dev/null +++ b/arch/s390/kernel/signal.c @@ -0,0 +1,534 @@ +// 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(); +} |