LXR linux/arch/um/kernel/signal.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   4 */
   5
   6#include <linux/module.h>
   7#include <linux/ptrace.h>
   8#include <linux/sched.h>
   9#include <linux/ftrace.h>
  10#include <asm/siginfo.h>
  11#include <asm/signal.h>
  12#include <asm/unistd.h>
  13#include <frame_kern.h>
  14#include <kern_util.h>
  15#include <os.h>
  16
  17EXPORT_SYMBOL(block_signals);
  18EXPORT_SYMBOL(unblock_signals);
  19
  20void block_signals_trace(void)
  21{
  22        block_signals();
  23        if (current_thread_info())
  24                trace_hardirqs_off();
  25}
  26
  27void unblock_signals_trace(void)
  28{
  29        if (current_thread_info())
  30                trace_hardirqs_on();
  31        unblock_signals();
  32}
  33
  34void um_trace_signals_on(void)
  35{
  36        if (current_thread_info())
  37                trace_hardirqs_on();
  38}
  39
  40void um_trace_signals_off(void)
  41{
  42        if (current_thread_info())
  43                trace_hardirqs_off();
  44}
  45
  46/*
  47 * OK, we're invoking a handler
  48 */
  49static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
  50{
  51        sigset_t *oldset = sigmask_to_save();
  52        int singlestep = 0;
  53        unsigned long sp;
  54        int err;
  55
  56        if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
  57                singlestep = 1;
  58
  59        /* Did we come from a system call? */
  60        if (PT_REGS_SYSCALL_NR(regs) >= 0) {
  61                /* If so, check system call restarting.. */
  62                switch (PT_REGS_SYSCALL_RET(regs)) {
  63                case -ERESTART_RESTARTBLOCK:
  64                case -ERESTARTNOHAND:
  65                        PT_REGS_SYSCALL_RET(regs) = -EINTR;
  66                        break;
  67
  68                case -ERESTARTSYS:
  69                        if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
  70                                PT_REGS_SYSCALL_RET(regs) = -EINTR;
  71                                break;
  72                        }
  73                        fallthrough;
  74                case -ERESTARTNOINTR:
  75                        PT_REGS_RESTART_SYSCALL(regs);
  76                        PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  77                        break;
  78                }
  79        }
  80
  81        sp = PT_REGS_SP(regs);
  82        if ((ksig->ka.sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
  83                sp = current->sas_ss_sp + current->sas_ss_size;
  84
  85#ifdef CONFIG_ARCH_HAS_SC_SIGNALS
  86        if (!(ksig->ka.sa.sa_flags & SA_SIGINFO))
  87                err = setup_signal_stack_sc(sp, ksig, regs, oldset);
  88        else
  89#endif
  90                err = setup_signal_stack_si(sp, ksig, regs, oldset);
  91
  92        signal_setup_done(err, ksig, singlestep);
  93}
  94
  95void do_signal(struct pt_regs *regs)
  96{
  97        struct ksignal ksig;
  98        int handled_sig = 0;
  99
 100        while (get_signal(&ksig)) {
 101                handled_sig = 1;
 102                /* Whee!  Actually deliver the signal.  */
 103                handle_signal(&ksig, regs);
 104        }
 105
 106        /* Did we come from a system call? */
 107        if (!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)) {
 108                /* Restart the system call - no handlers present */
 109                switch (PT_REGS_SYSCALL_RET(regs)) {
 110                case -ERESTARTNOHAND:
 111                case -ERESTARTSYS:
 112                case -ERESTARTNOINTR:
 113                        PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
 114                        PT_REGS_RESTART_SYSCALL(regs);
 115                        break;
 116                case -ERESTART_RESTARTBLOCK:
 117                        PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
 118                        PT_REGS_RESTART_SYSCALL(regs);
 119                        break;
 120                }
 121        }
 122
 123        /*
 124         * This closes a way to execute a system call on the host.  If
 125         * you set a breakpoint on a system call instruction and singlestep
 126         * from it, the tracing thread used to PTRACE_SINGLESTEP the process
 127         * rather than PTRACE_SYSCALL it, allowing the system call to execute
 128         * on the host.  The tracing thread will check this flag and
 129         * PTRACE_SYSCALL if necessary.
 130         */
 131        if (current->ptrace & PT_DTRACE)
 132                current->thread.singlestep_syscall =
 133                        is_syscall(PT_REGS_IP(&current->thread.regs));
 134
 135        /*
 136         * if there's no signal to deliver, we just put the saved sigmask
 137         * back
 138         */
 139        if (!handled_sig)
 140                restore_saved_sigmask();
 141}
 142