cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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signal.c (3383B)

      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 (test_thread_flag(TIF_SINGLESTEP) && (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 (test_thread_flag(TIF_SINGLESTEP))
    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}