![Martin Schwidefsky](/assets/img/avatar_default.png)
The oi and ni instructions used in entry[64].S to set and clear bits in the thread-flags are not guaranteed to be atomic in regard to other CPUs. Split the TIF bits into CPU, pt_regs and thread-info specific bits. Updates on the TIF bits are done with atomic instructions, updates on CPU and pt_regs bits are done with non-atomic instructions. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
428 lines
12 KiB
C
428 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 | PSW_MASK_RI));
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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(user_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_ctl(¤t->thread.fp_regs.fpc);
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save_fp_regs(current->thread.fp_regs.fprs);
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memcpy(&user_sregs.fpregs, ¤t->thread.fp_regs,
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sizeof(user_sregs.fpregs));
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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(user_sregs)))
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return -EFAULT;
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if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW_MASK_RI))
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return -EINVAL;
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/* Loading the floating-point-control word can fail. Do that first. */
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if (restore_fp_ctl(&user_sregs.fpregs.fpc))
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return -EINVAL;
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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 | PSW_MASK_RI)) |
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(user_sregs.regs.psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
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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(current->thread.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(current->thread.fp_regs));
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restore_fp_regs(current->thread.fp_regs.fprs);
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clear_pt_regs_flag(regs, PIF_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_pt_regs_flag(regs, PIF_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_pt_regs_flag(regs, PIF_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_pt_regs_flag(regs, PIF_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_pt_regs_flag(regs, PIF_SYSCALL);
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if (test_thread_flag(TIF_SINGLE_STEP))
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clear_pt_regs_flag(regs, PIF_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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