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![Jonas Bonn](/assets/img/avatar_default.png)
As it was decided not to export struct pt_regs to userspace, struct sigcontext shouldn't be using it either. The pt_regs struct for OpenRISC is kernel internal and the layout of the registers may change in the future. The struct user_regs_struct is what is guaranteed to remain stable, so struct sigcontext may use that instead. This patch removes the usage of struct pt_regs in struct sigcontext and makes according changes in signal.c to get the register layout right. The usp field is removed from the sigcontext structure as this information is already contained in the user_regs_struct. Signed-off-by: Jonas Bonn <jonas@southpole.se> Reviewed-by: Emilio Cota <cota@braap.org>
389 lines
11 KiB
C
389 lines
11 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/ucontext.h>
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#include <asm/uaccess.h>
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#define DEBUG_SIG 0
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#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
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asmlinkage long
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_sys_sigaltstack(const stack_t *uss, stack_t *uoss, struct pt_regs *regs)
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{
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return do_sigaltstack(uss, uoss, regs->sp);
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}
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struct rt_sigframe {
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struct siginfo *pinfo;
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void *puc;
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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, struct sigcontext *sc)
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{
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unsigned int err = 0;
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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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/*
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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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if (__copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long)))
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goto badframe;
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if (__copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long)))
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goto badframe;
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if (__copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long)))
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goto badframe;
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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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/* 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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badframe:
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return 1;
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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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stack_t st;
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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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sigdelsetmask(&set, ~_BLOCKABLE);
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spin_lock_irq(¤t->sighand->siglock);
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current->blocked = set;
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
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goto badframe;
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if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st)))
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goto badframe;
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/* It is more difficult to avoid calling this function than to
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call it and ignore errors. */
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do_sigaltstack(&st, NULL, regs->sp);
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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 sigcontext *sc, struct pt_regs *regs,
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unsigned long mask)
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{
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int err = 0;
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/* copy the regs */
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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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/* then some other stuff */
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err |= __put_user(mask, &sc->oldmask);
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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 k_sigaction *ka,
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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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int onsigstack = on_sig_stack(sp);
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/* redzone */
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sp -= STACK_FRAME_OVERHEAD;
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/* This is the X/Open sanctioned signal stack switching. */
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if ((ka->sa.sa_flags & SA_ONSTACK) && !onsigstack) {
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if (current->sas_ss_size)
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sp = current->sas_ss_sp + current->sas_ss_size;
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}
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sp = align_sigframe(sp - frame_size);
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/*
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* If we are on the alternate signal stack and would overflow it, don't.
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* Return an always-bogus address instead so we will die with SIGSEGV.
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*/
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if (onsigstack && !likely(on_sig_stack(sp)))
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return (void __user *)-1L;
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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 void 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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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(ka, regs, sizeof(*frame));
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if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
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goto give_sigsegv;
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err |= __put_user(&frame->info, &frame->pinfo);
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err |= __put_user(&frame->uc, &frame->puc);
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if (ka->sa.sa_flags & SA_SIGINFO)
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err |= copy_siginfo_to_user(&frame->info, info);
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if (err)
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goto give_sigsegv;
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/* Clear all the bits of the ucontext we don't use. */
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err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
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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 |= __put_user((void *)current->sas_ss_sp,
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&frame->uc.uc_stack.ss_sp);
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err |= __put_user(sas_ss_flags(regs->sp), &frame->uc.uc_stack.ss_flags);
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err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
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err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
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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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/* 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 l.ori r11,r0,__NR_sigreturn, l.sys 1 */
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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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goto give_sigsegv;
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/* TODO what is the current->exec_domain stuff and invmap ? */
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/* Set up registers for signal handler */
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regs->pc = (unsigned long)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)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;
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give_sigsegv:
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if (sig == SIGSEGV)
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ka->sa.sa_handler = SIG_DFL;
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force_sig(SIGSEGV, current);
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}
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static inline void
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handle_signal(unsigned long sig,
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siginfo_t *info, struct k_sigaction *ka,
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sigset_t *oldset, struct pt_regs *regs)
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{
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setup_rt_frame(sig, ka, info, oldset, regs);
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if (ka->sa.sa_flags & SA_ONESHOT)
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ka->sa.sa_handler = SIG_DFL;
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spin_lock_irq(¤t->sighand->siglock);
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sigorsets(¤t->blocked, ¤t->blocked, &ka->sa.sa_mask);
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if (!(ka->sa.sa_flags & SA_NODEFER))
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sigaddset(¤t->blocked, sig);
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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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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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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/*
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* We want the common case to go fast, which
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* is why we may in certain cases get here from
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* kernel mode. Just return without doing anything
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* if so.
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*/
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if (!user_mode(regs))
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return;
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signr = get_signal_to_deliver(&info, &ka, regs, NULL);
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/* If we are coming out of a syscall then we need
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* to check if the syscall was interrupted and wants to be
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* restarted after handling the signal. If so, the original
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* syscall number is put back into r11 and the PC rewound to
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* point at the l.sys instruction that resulted in the
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* original syscall. Syscall results other than the four
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* below mean that the syscall executed to completion and no
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* restart is necessary.
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*/
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if (regs->syscallno) {
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int restart = 0;
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switch (regs->gpr[11]) {
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case -ERESTART_RESTARTBLOCK:
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case -ERESTARTNOHAND:
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/* Restart if there is no signal handler */
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restart = (signr <= 0);
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break;
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case -ERESTARTSYS:
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/* Restart if there no signal handler or
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* SA_RESTART flag is set */
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restart = (signr <= 0 || (ka.sa.sa_flags & SA_RESTART));
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break;
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case -ERESTARTNOINTR:
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/* Always restart */
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restart = 1;
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break;
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}
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if (restart) {
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if (regs->gpr[11] == -ERESTART_RESTARTBLOCK)
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regs->gpr[11] = __NR_restart_syscall;
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else
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regs->gpr[11] = regs->orig_gpr11;
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regs->pc -= 4;
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} else {
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regs->gpr[11] = -EINTR;
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}
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}
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if (signr <= 0) {
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/* no signal to deliver so we just put the saved sigmask
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* back */
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if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
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clear_thread_flag(TIF_RESTORE_SIGMASK);
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sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL);
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}
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} else { /* signr > 0 */
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sigset_t *oldset;
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if (current_thread_info()->flags & _TIF_RESTORE_SIGMASK)
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oldset = ¤t->saved_sigmask;
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else
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oldset = ¤t->blocked;
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/* Whee! Actually deliver the signal. */
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handle_signal(signr, &info, &ka, oldset, regs);
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/* a signal was successfully delivered; the saved
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* sigmask will have been stored in the signal frame,
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* and will be restored by sigreturn, so we can simply
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* clear the TIF_RESTORE_SIGMASK flag */
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if (test_thread_flag(TIF_RESTORE_SIGMASK))
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clear_thread_flag(TIF_RESTORE_SIGMASK);
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tracehook_signal_handler(signr, &info, &ka, regs,
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test_thread_flag(TIF_SINGLESTEP));
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}
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return;
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}
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asmlinkage void do_notify_resume(struct pt_regs *regs)
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{
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if (current_thread_info()->flags & _TIF_SIGPENDING)
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do_signal(regs);
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if (current_thread_info()->flags & _TIF_NOTIFY_RESUME) {
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clear_thread_flag(TIF_NOTIFY_RESUME);
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tracehook_notify_resume(regs);
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if (current->replacement_session_keyring)
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key_replace_session_keyring();
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}
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}
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