forked from Minki/linux
f8544ec4f4
Instead of returnin the number of bytes not copied and/or -EFAULT let the signal handler helper functions always return -EFAULT if a user space access failed. This doesn't fix a bug in the current code, but makes is harder to get it wrong in the future. Also "smatch" won't complain anymore about the fact that the number of remaining bytes gets returned instead of -EFAULT. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
420 lines
12 KiB
C
420 lines
12 KiB
C
/*
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* Copyright IBM Corp. 1999, 2006
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* Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
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*
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* Based on Intel version
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
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*/
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/kernel.h>
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#include <linux/signal.h>
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#include <linux/errno.h>
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#include <linux/wait.h>
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#include <linux/ptrace.h>
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#include <linux/unistd.h>
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#include <linux/stddef.h>
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#include <linux/tty.h>
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#include <linux/personality.h>
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#include <linux/binfmts.h>
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#include <linux/tracehook.h>
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#include <linux/syscalls.h>
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#include <linux/compat.h>
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#include <asm/ucontext.h>
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#include <asm/uaccess.h>
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#include <asm/lowcore.h>
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#include <asm/switch_to.h>
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#include "entry.h"
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typedef struct
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{
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__u8 callee_used_stack[__SIGNAL_FRAMESIZE];
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struct sigcontext sc;
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_sigregs sregs;
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int signo;
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__u8 retcode[S390_SYSCALL_SIZE];
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} sigframe;
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typedef struct
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{
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__u8 callee_used_stack[__SIGNAL_FRAMESIZE];
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__u8 retcode[S390_SYSCALL_SIZE];
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struct siginfo info;
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struct ucontext uc;
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} rt_sigframe;
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/* Returns non-zero on fault. */
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static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
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{
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_sigregs user_sregs;
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save_access_regs(current->thread.acrs);
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/* Copy a 'clean' PSW mask to the user to avoid leaking
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information about whether PER is currently on. */
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user_sregs.regs.psw.mask = PSW_USER_BITS |
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(regs->psw.mask & PSW_MASK_USER);
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user_sregs.regs.psw.addr = regs->psw.addr;
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memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs));
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memcpy(&user_sregs.regs.acrs, current->thread.acrs,
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sizeof(sregs->regs.acrs));
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/*
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* We have to store the fp registers to current->thread.fp_regs
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* to merge them with the emulated registers.
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*/
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save_fp_regs(¤t->thread.fp_regs);
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memcpy(&user_sregs.fpregs, ¤t->thread.fp_regs,
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sizeof(s390_fp_regs));
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if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs)))
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return -EFAULT;
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return 0;
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}
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static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
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{
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_sigregs user_sregs;
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/* Alwys make any pending restarted system call return -EINTR */
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current_thread_info()->restart_block.fn = do_no_restart_syscall;
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if (__copy_from_user(&user_sregs, sregs, sizeof(_sigregs)))
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return -EFAULT;
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/* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */
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regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
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(user_sregs.regs.psw.mask & PSW_MASK_USER);
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/* Check for invalid user address space control. */
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if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME)
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regs->psw.mask = PSW_ASC_PRIMARY |
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(regs->psw.mask & ~PSW_MASK_ASC);
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/* Check for invalid amode */
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if (regs->psw.mask & PSW_MASK_EA)
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regs->psw.mask |= PSW_MASK_BA;
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regs->psw.addr = user_sregs.regs.psw.addr;
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memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
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memcpy(¤t->thread.acrs, &user_sregs.regs.acrs,
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sizeof(sregs->regs.acrs));
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restore_access_regs(current->thread.acrs);
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memcpy(¤t->thread.fp_regs, &user_sregs.fpregs,
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sizeof(s390_fp_regs));
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current->thread.fp_regs.fpc &= FPC_VALID_MASK;
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restore_fp_regs(¤t->thread.fp_regs);
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clear_thread_flag(TIF_SYSCALL); /* No longer in a system call */
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return 0;
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}
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SYSCALL_DEFINE0(sigreturn)
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{
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struct pt_regs *regs = task_pt_regs(current);
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sigframe __user *frame = (sigframe __user *)regs->gprs[15];
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sigset_t set;
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if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
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goto badframe;
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set_current_blocked(&set);
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if (restore_sigregs(regs, &frame->sregs))
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goto badframe;
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return regs->gprs[2];
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badframe:
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force_sig(SIGSEGV, current);
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return 0;
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}
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SYSCALL_DEFINE0(rt_sigreturn)
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{
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struct pt_regs *regs = task_pt_regs(current);
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rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
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sigset_t set;
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if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
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goto badframe;
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set_current_blocked(&set);
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if (restore_sigregs(regs, &frame->uc.uc_mcontext))
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goto badframe;
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if (restore_altstack(&frame->uc.uc_stack))
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goto badframe;
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return regs->gprs[2];
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badframe:
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force_sig(SIGSEGV, current);
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return 0;
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}
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/*
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* Set up a signal frame.
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*/
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/*
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* Determine which stack to use..
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*/
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static inline void __user *
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get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
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{
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unsigned long sp;
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/* Default to using normal stack */
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sp = regs->gprs[15];
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/* Overflow on alternate signal stack gives SIGSEGV. */
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if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
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return (void __user *) -1UL;
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/* This is the X/Open sanctioned signal stack switching. */
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if (ka->sa.sa_flags & SA_ONSTACK) {
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if (! sas_ss_flags(sp))
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sp = current->sas_ss_sp + current->sas_ss_size;
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}
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return (void __user *)((sp - frame_size) & -8ul);
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}
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static inline int map_signal(int sig)
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{
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if (current_thread_info()->exec_domain
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&& current_thread_info()->exec_domain->signal_invmap
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&& sig < 32)
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return current_thread_info()->exec_domain->signal_invmap[sig];
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else
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return sig;
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}
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static int setup_frame(int sig, struct k_sigaction *ka,
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sigset_t *set, struct pt_regs * regs)
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{
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sigframe __user *frame;
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frame = get_sigframe(ka, regs, sizeof(sigframe));
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if (frame == (void __user *) -1UL)
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goto give_sigsegv;
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if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
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goto give_sigsegv;
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if (save_sigregs(regs, &frame->sregs))
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goto give_sigsegv;
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if (__put_user(&frame->sregs, &frame->sc.sregs))
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goto give_sigsegv;
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/* Set up to return from userspace. If provided, use a stub
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already in userspace. */
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if (ka->sa.sa_flags & SA_RESTORER) {
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regs->gprs[14] = (unsigned long)
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ka->sa.sa_restorer | PSW_ADDR_AMODE;
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} else {
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regs->gprs[14] = (unsigned long)
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frame->retcode | PSW_ADDR_AMODE;
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if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
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(u16 __user *)(frame->retcode)))
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goto give_sigsegv;
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}
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/* Set up backchain. */
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if (__put_user(regs->gprs[15], (addr_t __user *) frame))
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goto give_sigsegv;
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/* Set up registers for signal handler */
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regs->gprs[15] = (unsigned long) frame;
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/* Force default amode and default user address space control. */
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regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
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(PSW_USER_BITS & PSW_MASK_ASC) |
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(regs->psw.mask & ~PSW_MASK_ASC);
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regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
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regs->gprs[2] = map_signal(sig);
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regs->gprs[3] = (unsigned long) &frame->sc;
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/* We forgot to include these in the sigcontext.
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To avoid breaking binary compatibility, they are passed as args. */
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if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
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sig == SIGTRAP || sig == SIGFPE) {
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/* set extra registers only for synchronous signals */
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regs->gprs[4] = regs->int_code & 127;
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regs->gprs[5] = regs->int_parm_long;
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regs->gprs[6] = task_thread_info(current)->last_break;
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}
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/* Place signal number on stack to allow backtrace from handler. */
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if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
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goto give_sigsegv;
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return 0;
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give_sigsegv:
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force_sigsegv(sig, current);
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return -EFAULT;
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}
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static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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sigset_t *set, struct pt_regs * regs)
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{
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int err = 0;
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rt_sigframe __user *frame;
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frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
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if (frame == (void __user *) -1UL)
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goto give_sigsegv;
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if (copy_siginfo_to_user(&frame->info, info))
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goto give_sigsegv;
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/* Create the ucontext. */
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err |= __put_user(0, &frame->uc.uc_flags);
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err |= __put_user(NULL, &frame->uc.uc_link);
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err |= __save_altstack(&frame->uc.uc_stack, regs->gprs[15]);
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err |= save_sigregs(regs, &frame->uc.uc_mcontext);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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if (err)
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goto give_sigsegv;
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/* Set up to return from userspace. If provided, use a stub
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already in userspace. */
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if (ka->sa.sa_flags & SA_RESTORER) {
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regs->gprs[14] = (unsigned long)
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ka->sa.sa_restorer | PSW_ADDR_AMODE;
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} else {
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regs->gprs[14] = (unsigned long)
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frame->retcode | PSW_ADDR_AMODE;
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if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
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(u16 __user *)(frame->retcode)))
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goto give_sigsegv;
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}
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/* Set up backchain. */
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if (__put_user(regs->gprs[15], (addr_t __user *) frame))
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goto give_sigsegv;
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/* Set up registers for signal handler */
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regs->gprs[15] = (unsigned long) frame;
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/* Force default amode and default user address space control. */
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regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
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(PSW_USER_BITS & PSW_MASK_ASC) |
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(regs->psw.mask & ~PSW_MASK_ASC);
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regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
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regs->gprs[2] = map_signal(sig);
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regs->gprs[3] = (unsigned long) &frame->info;
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regs->gprs[4] = (unsigned long) &frame->uc;
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regs->gprs[5] = task_thread_info(current)->last_break;
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return 0;
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give_sigsegv:
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force_sigsegv(sig, current);
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return -EFAULT;
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}
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static void handle_signal(unsigned long sig, struct k_sigaction *ka,
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siginfo_t *info, sigset_t *oldset,
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struct pt_regs *regs)
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{
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int ret;
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/* Set up the stack frame */
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if (ka->sa.sa_flags & SA_SIGINFO)
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ret = setup_rt_frame(sig, ka, info, oldset, regs);
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else
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ret = setup_frame(sig, ka, oldset, regs);
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if (ret)
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return;
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signal_delivered(sig, info, ka, regs,
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test_thread_flag(TIF_SINGLE_STEP));
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}
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/*
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* Note that 'init' is a special process: it doesn't get signals it doesn't
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* want to handle. Thus you cannot kill init even with a SIGKILL even by
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* mistake.
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*
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* Note that we go through the signals twice: once to check the signals that
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* the kernel can handle, and then we build all the user-level signal handling
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* stack-frames in one go after that.
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*/
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void do_signal(struct pt_regs *regs)
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{
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siginfo_t info;
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int signr;
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struct k_sigaction ka;
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sigset_t *oldset = sigmask_to_save();
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/*
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* Get signal to deliver. When running under ptrace, at this point
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* the debugger may change all our registers, including the system
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* call information.
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*/
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current_thread_info()->system_call =
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test_thread_flag(TIF_SYSCALL) ? regs->int_code : 0;
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signr = get_signal_to_deliver(&info, &ka, regs, NULL);
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if (signr > 0) {
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/* Whee! Actually deliver the signal. */
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if (current_thread_info()->system_call) {
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regs->int_code = current_thread_info()->system_call;
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/* Check for system call restarting. */
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switch (regs->gprs[2]) {
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case -ERESTART_RESTARTBLOCK:
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case -ERESTARTNOHAND:
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regs->gprs[2] = -EINTR;
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break;
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case -ERESTARTSYS:
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if (!(ka.sa.sa_flags & SA_RESTART)) {
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regs->gprs[2] = -EINTR;
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break;
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}
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/* fallthrough */
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case -ERESTARTNOINTR:
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regs->gprs[2] = regs->orig_gpr2;
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regs->psw.addr =
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__rewind_psw(regs->psw,
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regs->int_code >> 16);
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break;
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}
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}
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/* No longer in a system call */
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clear_thread_flag(TIF_SYSCALL);
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if (is_compat_task())
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handle_signal32(signr, &ka, &info, oldset, regs);
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else
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handle_signal(signr, &ka, &info, oldset, regs);
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return;
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}
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/* No handlers present - check for system call restart */
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clear_thread_flag(TIF_SYSCALL);
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if (current_thread_info()->system_call) {
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regs->int_code = current_thread_info()->system_call;
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switch (regs->gprs[2]) {
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case -ERESTART_RESTARTBLOCK:
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/* Restart with sys_restart_syscall */
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regs->int_code = __NR_restart_syscall;
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/* fallthrough */
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case -ERESTARTNOHAND:
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case -ERESTARTSYS:
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case -ERESTARTNOINTR:
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/* Restart system call with magic TIF bit. */
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regs->gprs[2] = regs->orig_gpr2;
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set_thread_flag(TIF_SYSCALL);
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if (test_thread_flag(TIF_SINGLE_STEP))
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set_thread_flag(TIF_PER_TRAP);
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break;
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}
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}
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/*
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* If there's no signal to deliver, we just put the saved sigmask back.
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*/
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restore_saved_sigmask();
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}
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void do_notify_resume(struct pt_regs *regs)
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{
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clear_thread_flag(TIF_NOTIFY_RESUME);
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tracehook_notify_resume(regs);
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}
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