327 lines
8.6 KiB
C
327 lines
8.6 KiB
C
/*
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* OpenRISC signal.c
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*
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* Linux architectural port borrowing liberally from similar works of
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* others. All original copyrights apply as per the original source
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* declaration.
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*
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* Modifications for the OpenRISC architecture:
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* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
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* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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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/tracehook.h>
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#include <asm/processor.h>
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#include <asm/syscall.h>
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#include <asm/ucontext.h>
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#include <linux/uaccess.h>
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#define DEBUG_SIG 0
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struct rt_sigframe {
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struct siginfo info;
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struct ucontext uc;
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unsigned char retcode[16]; /* trampoline code */
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};
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static int restore_sigcontext(struct pt_regs *regs,
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struct sigcontext __user *sc)
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{
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int err = 0;
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/* Always make any pending restarted system calls return -EINTR */
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current->restart_block.fn = do_no_restart_syscall;
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/*
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* Restore the regs from &sc->regs.
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* (sc is already checked for VERIFY_READ since the sigframe was
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* checked in sys_sigreturn previously)
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*/
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err |= __copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long));
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err |= __copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long));
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err |= __copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long));
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/* make sure the SM-bit is cleared so user-mode cannot fool us */
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regs->sr &= ~SPR_SR_SM;
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regs->orig_gpr11 = -1; /* Avoid syscall restart checks */
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/* TODO: the other ports use regs->orig_XX to disable syscall checks
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* after this completes, but we don't use that mechanism. maybe we can
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* use it now ?
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*/
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return err;
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}
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asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs)
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{
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struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp;
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sigset_t set;
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/*
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* Since we stacked the signal on a dword boundary,
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* then frame should be dword aligned here. If it's
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* not, then the user is trying to mess with us.
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*/
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if (((long)frame) & 3)
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goto badframe;
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if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
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goto badframe;
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if (__copy_from_user(&set, &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_sigcontext(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->gpr[11];
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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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static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
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{
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int err = 0;
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/* copy the regs */
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/* There should be no need to save callee-saved registers here...
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* ...but we save them anyway. Revisit this
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*/
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err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long));
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err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long));
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err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long));
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return err;
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}
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static inline unsigned long align_sigframe(unsigned long sp)
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{
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return sp & ~3UL;
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}
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/*
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* Work out where the signal frame should go. It's either on the user stack
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* or the alternate stack.
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*/
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static inline void __user *get_sigframe(struct ksignal *ksig,
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struct pt_regs *regs, size_t frame_size)
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{
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unsigned long sp = regs->sp;
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/* redzone */
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sp -= STACK_FRAME_OVERHEAD;
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sp = sigsp(sp, ksig);
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sp = align_sigframe(sp - frame_size);
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return (void __user *)sp;
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}
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/* grab and setup a signal frame.
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*
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* basically we stack a lot of state info, and arrange for the
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* user-mode program to return to the kernel using either a
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* trampoline which performs the syscall sigreturn, or a provided
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* user-mode trampoline.
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*/
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static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
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struct pt_regs *regs)
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{
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struct rt_sigframe *frame;
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unsigned long return_ip;
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int err = 0;
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frame = get_sigframe(ksig, regs, sizeof(*frame));
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if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
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return -EFAULT;
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/* Create siginfo. */
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if (ksig->ka.sa.sa_flags & SA_SIGINFO)
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err |= copy_siginfo_to_user(&frame->info, &ksig->info);
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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->sp);
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err |= setup_sigcontext(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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return -EFAULT;
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/* trampoline - the desired return ip is the retcode itself */
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return_ip = (unsigned long)&frame->retcode;
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/* This is:
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l.ori r11,r0,__NR_sigreturn
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l.sys 1
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*/
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err |= __put_user(0xa960, (short *)(frame->retcode + 0));
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err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2));
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err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4));
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err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8));
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if (err)
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return -EFAULT;
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/* Set up registers for signal handler */
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regs->pc = (unsigned long)ksig->ka.sa.sa_handler; /* what we enter NOW */
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regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */
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regs->gpr[3] = (unsigned long)ksig->sig; /* arg 1: signo */
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regs->gpr[4] = (unsigned long)&frame->info; /* arg 2: (siginfo_t*) */
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regs->gpr[5] = (unsigned long)&frame->uc; /* arg 3: ucontext */
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/* actually move the usp to reflect the stacked frame */
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regs->sp = (unsigned long)frame;
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return 0;
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}
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static inline void
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handle_signal(struct ksignal *ksig, struct pt_regs *regs)
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{
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int ret;
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ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
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signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
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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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* Also note that the regs structure given here as an argument, is the latest
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* pushed pt_regs. It may or may not be the same as the first pushed registers
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* when the initial usermode->kernelmode transition took place. Therefore
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* we can use user_mode(regs) to see if we came directly from kernel or user
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* mode below.
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*/
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int do_signal(struct pt_regs *regs, int syscall)
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{
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struct ksignal ksig;
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unsigned long continue_addr = 0;
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unsigned long restart_addr = 0;
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unsigned long retval = 0;
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int restart = 0;
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if (syscall) {
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continue_addr = regs->pc;
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restart_addr = continue_addr - 4;
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retval = regs->gpr[11];
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/*
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* Setup syscall restart here so that a debugger will
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* see the already changed PC.
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*/
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switch (retval) {
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case -ERESTART_RESTARTBLOCK:
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restart = -2;
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/* Fall through */
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case -ERESTARTNOHAND:
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case -ERESTARTSYS:
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case -ERESTARTNOINTR:
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restart++;
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regs->gpr[11] = regs->orig_gpr11;
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regs->pc = restart_addr;
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break;
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}
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}
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/*
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* Get the signal to deliver. During the call to get_signal the
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* debugger may change all our registers so we may need to revert
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* the decision to restart the syscall; specifically, if the PC is
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* changed, don't restart the syscall.
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*/
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if (get_signal(&ksig)) {
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if (unlikely(restart) && regs->pc == restart_addr) {
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if (retval == -ERESTARTNOHAND ||
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retval == -ERESTART_RESTARTBLOCK
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|| (retval == -ERESTARTSYS
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&& !(ksig.ka.sa.sa_flags & SA_RESTART))) {
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/* No automatic restart */
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regs->gpr[11] = -EINTR;
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regs->pc = continue_addr;
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}
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}
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handle_signal(&ksig, regs);
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} else {
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/* no handler */
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restore_saved_sigmask();
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/*
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* Restore pt_regs PC as syscall restart will be handled by
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* kernel without return to userspace
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*/
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if (unlikely(restart) && regs->pc == restart_addr) {
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regs->pc = continue_addr;
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return restart;
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}
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}
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return 0;
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}
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asmlinkage int
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do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
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{
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do {
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if (likely(thread_flags & _TIF_NEED_RESCHED)) {
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schedule();
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} else {
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if (unlikely(!user_mode(regs)))
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return 0;
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local_irq_enable();
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if (thread_flags & _TIF_SIGPENDING) {
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int restart = do_signal(regs, syscall);
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if (unlikely(restart)) {
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/*
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* Restart without handlers.
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* Deal with it without leaving
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* the kernel space.
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*/
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return restart;
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}
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syscall = 0;
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} else {
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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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}
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local_irq_disable();
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thread_flags = current_thread_info()->flags;
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} while (thread_flags & _TIF_WORK_MASK);
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return 0;
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}
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