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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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727 lines
18 KiB
C
727 lines
18 KiB
C
/*
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* linux/arch/arm/kernel/signal.c
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*
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* Copyright (C) 1995-2009 Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/errno.h>
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#include <linux/random.h>
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#include <linux/signal.h>
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#include <linux/personality.h>
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#include <linux/uaccess.h>
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#include <linux/tracehook.h>
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#include <linux/uprobes.h>
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#include <linux/syscalls.h>
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#include <asm/elf.h>
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#include <asm/cacheflush.h>
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#include <asm/traps.h>
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#include <asm/unistd.h>
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#include <asm/vfp.h>
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#include "signal.h"
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extern const unsigned long sigreturn_codes[17];
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static unsigned long signal_return_offset;
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#ifdef CONFIG_CRUNCH
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static int preserve_crunch_context(struct crunch_sigframe __user *frame)
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{
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char kbuf[sizeof(*frame) + 8];
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struct crunch_sigframe *kframe;
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/* the crunch context must be 64 bit aligned */
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kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
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kframe->magic = CRUNCH_MAGIC;
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kframe->size = CRUNCH_STORAGE_SIZE;
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crunch_task_copy(current_thread_info(), &kframe->storage);
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return __copy_to_user(frame, kframe, sizeof(*frame));
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}
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static int restore_crunch_context(char __user **auxp)
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{
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struct crunch_sigframe __user *frame =
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(struct crunch_sigframe __user *)*auxp;
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char kbuf[sizeof(*frame) + 8];
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struct crunch_sigframe *kframe;
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/* the crunch context must be 64 bit aligned */
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kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
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if (__copy_from_user(kframe, frame, sizeof(*frame)))
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return -1;
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if (kframe->magic != CRUNCH_MAGIC ||
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kframe->size != CRUNCH_STORAGE_SIZE)
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return -1;
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*auxp += CRUNCH_STORAGE_SIZE;
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crunch_task_restore(current_thread_info(), &kframe->storage);
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return 0;
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}
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#endif
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#ifdef CONFIG_IWMMXT
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static int preserve_iwmmxt_context(struct iwmmxt_sigframe __user *frame)
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{
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char kbuf[sizeof(*frame) + 8];
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struct iwmmxt_sigframe *kframe;
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int err = 0;
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/* the iWMMXt context must be 64 bit aligned */
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kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
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if (test_thread_flag(TIF_USING_IWMMXT)) {
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kframe->magic = IWMMXT_MAGIC;
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kframe->size = IWMMXT_STORAGE_SIZE;
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iwmmxt_task_copy(current_thread_info(), &kframe->storage);
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} else {
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/*
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* For bug-compatibility with older kernels, some space
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* has to be reserved for iWMMXt even if it's not used.
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* Set the magic and size appropriately so that properly
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* written userspace can skip it reliably:
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*/
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*kframe = (struct iwmmxt_sigframe) {
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.magic = DUMMY_MAGIC,
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.size = IWMMXT_STORAGE_SIZE,
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};
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}
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err = __copy_to_user(frame, kframe, sizeof(*kframe));
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return err;
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}
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static int restore_iwmmxt_context(char __user **auxp)
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{
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struct iwmmxt_sigframe __user *frame =
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(struct iwmmxt_sigframe __user *)*auxp;
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char kbuf[sizeof(*frame) + 8];
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struct iwmmxt_sigframe *kframe;
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/* the iWMMXt context must be 64 bit aligned */
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kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
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if (__copy_from_user(kframe, frame, sizeof(*frame)))
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return -1;
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/*
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* For non-iWMMXt threads: a single iwmmxt_sigframe-sized dummy
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* block is discarded for compatibility with setup_sigframe() if
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* present, but we don't mandate its presence. If some other
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* magic is here, it's not for us:
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*/
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if (!test_thread_flag(TIF_USING_IWMMXT) &&
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kframe->magic != DUMMY_MAGIC)
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return 0;
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if (kframe->size != IWMMXT_STORAGE_SIZE)
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return -1;
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if (test_thread_flag(TIF_USING_IWMMXT)) {
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if (kframe->magic != IWMMXT_MAGIC)
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return -1;
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iwmmxt_task_restore(current_thread_info(), &kframe->storage);
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}
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*auxp += IWMMXT_STORAGE_SIZE;
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return 0;
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}
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#endif
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#ifdef CONFIG_VFP
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static int preserve_vfp_context(struct vfp_sigframe __user *frame)
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{
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struct vfp_sigframe kframe;
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int err = 0;
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memset(&kframe, 0, sizeof(kframe));
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kframe.magic = VFP_MAGIC;
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kframe.size = VFP_STORAGE_SIZE;
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err = vfp_preserve_user_clear_hwstate(&kframe.ufp, &kframe.ufp_exc);
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if (err)
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return err;
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return __copy_to_user(frame, &kframe, sizeof(kframe));
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}
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static int restore_vfp_context(char __user **auxp)
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{
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struct vfp_sigframe frame;
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int err;
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err = __copy_from_user(&frame, *auxp, sizeof(frame));
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if (err)
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return err;
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if (frame.magic != VFP_MAGIC || frame.size != VFP_STORAGE_SIZE)
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return -EINVAL;
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*auxp += sizeof(frame);
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return vfp_restore_user_hwstate(&frame.ufp, &frame.ufp_exc);
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}
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#endif
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/*
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* Do a signal return; undo the signal stack. These are aligned to 64-bit.
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*/
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static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
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{
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struct sigcontext context;
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char __user *aux;
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sigset_t set;
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int err;
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err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
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if (err == 0)
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set_current_blocked(&set);
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err |= __copy_from_user(&context, &sf->uc.uc_mcontext, sizeof(context));
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if (err == 0) {
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regs->ARM_r0 = context.arm_r0;
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regs->ARM_r1 = context.arm_r1;
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regs->ARM_r2 = context.arm_r2;
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regs->ARM_r3 = context.arm_r3;
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regs->ARM_r4 = context.arm_r4;
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regs->ARM_r5 = context.arm_r5;
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regs->ARM_r6 = context.arm_r6;
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regs->ARM_r7 = context.arm_r7;
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regs->ARM_r8 = context.arm_r8;
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regs->ARM_r9 = context.arm_r9;
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regs->ARM_r10 = context.arm_r10;
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regs->ARM_fp = context.arm_fp;
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regs->ARM_ip = context.arm_ip;
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regs->ARM_sp = context.arm_sp;
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regs->ARM_lr = context.arm_lr;
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regs->ARM_pc = context.arm_pc;
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regs->ARM_cpsr = context.arm_cpsr;
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}
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err |= !valid_user_regs(regs);
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aux = (char __user *) sf->uc.uc_regspace;
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#ifdef CONFIG_CRUNCH
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if (err == 0)
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err |= restore_crunch_context(&aux);
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#endif
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#ifdef CONFIG_IWMMXT
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if (err == 0)
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err |= restore_iwmmxt_context(&aux);
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#endif
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#ifdef CONFIG_VFP
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if (err == 0)
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err |= restore_vfp_context(&aux);
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#endif
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return err;
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}
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asmlinkage int sys_sigreturn(struct pt_regs *regs)
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{
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struct sigframe __user *frame;
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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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* Since we stacked the signal on a 64-bit boundary,
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* then 'sp' should be word 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 (regs->ARM_sp & 7)
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goto badframe;
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frame = (struct sigframe __user *)regs->ARM_sp;
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if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
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goto badframe;
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if (restore_sigframe(regs, frame))
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goto badframe;
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return regs->ARM_r0;
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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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asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
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{
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struct rt_sigframe __user *frame;
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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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* Since we stacked the signal on a 64-bit boundary,
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* then 'sp' should be word 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 (regs->ARM_sp & 7)
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goto badframe;
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frame = (struct rt_sigframe __user *)regs->ARM_sp;
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if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
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goto badframe;
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if (restore_sigframe(regs, &frame->sig))
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goto badframe;
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if (restore_altstack(&frame->sig.uc.uc_stack))
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goto badframe;
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return regs->ARM_r0;
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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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static int
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setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
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{
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struct aux_sigframe __user *aux;
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struct sigcontext context;
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int err = 0;
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context = (struct sigcontext) {
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.arm_r0 = regs->ARM_r0,
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.arm_r1 = regs->ARM_r1,
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.arm_r2 = regs->ARM_r2,
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.arm_r3 = regs->ARM_r3,
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.arm_r4 = regs->ARM_r4,
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.arm_r5 = regs->ARM_r5,
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.arm_r6 = regs->ARM_r6,
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.arm_r7 = regs->ARM_r7,
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.arm_r8 = regs->ARM_r8,
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.arm_r9 = regs->ARM_r9,
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.arm_r10 = regs->ARM_r10,
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.arm_fp = regs->ARM_fp,
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.arm_ip = regs->ARM_ip,
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.arm_sp = regs->ARM_sp,
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.arm_lr = regs->ARM_lr,
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.arm_pc = regs->ARM_pc,
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.arm_cpsr = regs->ARM_cpsr,
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.trap_no = current->thread.trap_no,
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.error_code = current->thread.error_code,
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.fault_address = current->thread.address,
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.oldmask = set->sig[0],
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};
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err |= __copy_to_user(&sf->uc.uc_mcontext, &context, sizeof(context));
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err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
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aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
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#ifdef CONFIG_CRUNCH
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if (err == 0)
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err |= preserve_crunch_context(&aux->crunch);
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#endif
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#ifdef CONFIG_IWMMXT
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if (err == 0)
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err |= preserve_iwmmxt_context(&aux->iwmmxt);
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#endif
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#ifdef CONFIG_VFP
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if (err == 0)
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err |= preserve_vfp_context(&aux->vfp);
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#endif
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err |= __put_user(0, &aux->end_magic);
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return err;
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}
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static inline void __user *
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get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize)
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{
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unsigned long sp = sigsp(regs->ARM_sp, ksig);
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void __user *frame;
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/*
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* ATPCS B01 mandates 8-byte alignment
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*/
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frame = (void __user *)((sp - framesize) & ~7);
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/*
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* Check that we can actually write to the signal frame.
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*/
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if (!access_ok(VERIFY_WRITE, frame, framesize))
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frame = NULL;
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return frame;
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}
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static int
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setup_return(struct pt_regs *regs, struct ksignal *ksig,
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unsigned long __user *rc, void __user *frame)
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{
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unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler;
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unsigned long handler_fdpic_GOT = 0;
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unsigned long retcode;
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unsigned int idx, thumb = 0;
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unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
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bool fdpic = IS_ENABLED(CONFIG_BINFMT_ELF_FDPIC) &&
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(current->personality & FDPIC_FUNCPTRS);
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if (fdpic) {
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unsigned long __user *fdpic_func_desc =
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(unsigned long __user *)handler;
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if (__get_user(handler, &fdpic_func_desc[0]) ||
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__get_user(handler_fdpic_GOT, &fdpic_func_desc[1]))
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return 1;
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}
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cpsr |= PSR_ENDSTATE;
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/*
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* Maybe we need to deliver a 32-bit signal to a 26-bit task.
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*/
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if (ksig->ka.sa.sa_flags & SA_THIRTYTWO)
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cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
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#ifdef CONFIG_ARM_THUMB
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if (elf_hwcap & HWCAP_THUMB) {
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/*
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* The LSB of the handler determines if we're going to
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* be using THUMB or ARM mode for this signal handler.
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*/
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thumb = handler & 1;
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/*
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* Clear the If-Then Thumb-2 execution state. ARM spec
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* requires this to be all 000s in ARM mode. Snapdragon
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* S4/Krait misbehaves on a Thumb=>ARM signal transition
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* without this.
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*
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* We must do this whenever we are running on a Thumb-2
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* capable CPU, which includes ARMv6T2. However, we elect
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* to always do this to simplify the code; this field is
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* marked UNK/SBZP for older architectures.
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*/
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cpsr &= ~PSR_IT_MASK;
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if (thumb) {
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cpsr |= PSR_T_BIT;
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} else
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cpsr &= ~PSR_T_BIT;
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}
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#endif
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if (ksig->ka.sa.sa_flags & SA_RESTORER) {
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retcode = (unsigned long)ksig->ka.sa.sa_restorer;
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if (fdpic) {
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/*
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* We need code to load the function descriptor.
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* That code follows the standard sigreturn code
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* (6 words), and is made of 3 + 2 words for each
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* variant. The 4th copied word is the actual FD
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* address that the assembly code expects.
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*/
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idx = 6 + thumb * 3;
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if (ksig->ka.sa.sa_flags & SA_SIGINFO)
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idx += 5;
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if (__put_user(sigreturn_codes[idx], rc ) ||
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__put_user(sigreturn_codes[idx+1], rc+1) ||
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__put_user(sigreturn_codes[idx+2], rc+2) ||
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__put_user(retcode, rc+3))
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return 1;
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goto rc_finish;
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}
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} else {
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idx = thumb << 1;
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if (ksig->ka.sa.sa_flags & SA_SIGINFO)
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idx += 3;
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/*
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* Put the sigreturn code on the stack no matter which return
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* mechanism we use in order to remain ABI compliant
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*/
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if (__put_user(sigreturn_codes[idx], rc) ||
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__put_user(sigreturn_codes[idx+1], rc+1))
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return 1;
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rc_finish:
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#ifdef CONFIG_MMU
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if (cpsr & MODE32_BIT) {
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struct mm_struct *mm = current->mm;
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/*
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* 32-bit code can use the signal return page
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* except when the MPU has protected the vectors
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* page from PL0
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*/
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retcode = mm->context.sigpage + signal_return_offset +
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(idx << 2) + thumb;
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} else
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#endif
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{
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/*
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* Ensure that the instruction cache sees
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* the return code written onto the stack.
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*/
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flush_icache_range((unsigned long)rc,
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(unsigned long)(rc + 3));
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retcode = ((unsigned long)rc) + thumb;
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}
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}
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regs->ARM_r0 = ksig->sig;
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regs->ARM_sp = (unsigned long)frame;
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regs->ARM_lr = retcode;
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regs->ARM_pc = handler;
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if (fdpic)
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regs->ARM_r9 = handler_fdpic_GOT;
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regs->ARM_cpsr = cpsr;
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return 0;
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}
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static int
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setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
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{
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struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
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int err = 0;
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if (!frame)
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return 1;
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/*
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* Set uc.uc_flags to a value which sc.trap_no would never have.
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*/
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err = __put_user(0x5ac3c35a, &frame->uc.uc_flags);
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err |= setup_sigframe(frame, regs, set);
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if (err == 0)
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err = setup_return(regs, ksig, frame->retcode, frame);
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return err;
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}
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static int
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setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
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{
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struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
|
|
int err = 0;
|
|
|
|
if (!frame)
|
|
return 1;
|
|
|
|
err |= copy_siginfo_to_user(&frame->info, &ksig->info);
|
|
|
|
err |= __put_user(0, &frame->sig.uc.uc_flags);
|
|
err |= __put_user(NULL, &frame->sig.uc.uc_link);
|
|
|
|
err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp);
|
|
err |= setup_sigframe(&frame->sig, regs, set);
|
|
if (err == 0)
|
|
err = setup_return(regs, ksig, frame->sig.retcode, frame);
|
|
|
|
if (err == 0) {
|
|
/*
|
|
* For realtime signals we must also set the second and third
|
|
* arguments for the signal handler.
|
|
* -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
|
|
*/
|
|
regs->ARM_r1 = (unsigned long)&frame->info;
|
|
regs->ARM_r2 = (unsigned long)&frame->sig.uc;
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* OK, we're invoking a handler
|
|
*/
|
|
static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
|
|
{
|
|
sigset_t *oldset = sigmask_to_save();
|
|
int ret;
|
|
|
|
/*
|
|
* Increment event counter and perform fixup for the pre-signal
|
|
* frame.
|
|
*/
|
|
rseq_signal_deliver(ksig, regs);
|
|
|
|
/*
|
|
* Set up the stack frame
|
|
*/
|
|
if (ksig->ka.sa.sa_flags & SA_SIGINFO)
|
|
ret = setup_rt_frame(ksig, oldset, regs);
|
|
else
|
|
ret = setup_frame(ksig, oldset, regs);
|
|
|
|
/*
|
|
* Check that the resulting registers are actually sane.
|
|
*/
|
|
ret |= !valid_user_regs(regs);
|
|
|
|
signal_setup_done(ret, ksig, 0);
|
|
}
|
|
|
|
/*
|
|
* Note that 'init' is a special process: it doesn't get signals it doesn't
|
|
* want to handle. Thus you cannot kill init even with a SIGKILL even by
|
|
* mistake.
|
|
*
|
|
* Note that we go through the signals twice: once to check the signals that
|
|
* the kernel can handle, and then we build all the user-level signal handling
|
|
* stack-frames in one go after that.
|
|
*/
|
|
static int do_signal(struct pt_regs *regs, int syscall)
|
|
{
|
|
unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
|
|
struct ksignal ksig;
|
|
int restart = 0;
|
|
|
|
/*
|
|
* If we were from a system call, check for system call restarting...
|
|
*/
|
|
if (syscall) {
|
|
continue_addr = regs->ARM_pc;
|
|
restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
|
|
retval = regs->ARM_r0;
|
|
|
|
/*
|
|
* Prepare for system call restart. We do this here so that a
|
|
* debugger will see the already changed PSW.
|
|
*/
|
|
switch (retval) {
|
|
case -ERESTART_RESTARTBLOCK:
|
|
restart -= 2;
|
|
case -ERESTARTNOHAND:
|
|
case -ERESTARTSYS:
|
|
case -ERESTARTNOINTR:
|
|
restart++;
|
|
regs->ARM_r0 = regs->ARM_ORIG_r0;
|
|
regs->ARM_pc = restart_addr;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Get the signal to deliver. When running under ptrace, at this
|
|
* point the debugger may change all our registers ...
|
|
*/
|
|
/*
|
|
* Depending on the signal settings we may need to revert the
|
|
* decision to restart the system call. But skip this if a
|
|
* debugger has chosen to restart at a different PC.
|
|
*/
|
|
if (get_signal(&ksig)) {
|
|
/* handler */
|
|
if (unlikely(restart) && regs->ARM_pc == restart_addr) {
|
|
if (retval == -ERESTARTNOHAND ||
|
|
retval == -ERESTART_RESTARTBLOCK
|
|
|| (retval == -ERESTARTSYS
|
|
&& !(ksig.ka.sa.sa_flags & SA_RESTART))) {
|
|
regs->ARM_r0 = -EINTR;
|
|
regs->ARM_pc = continue_addr;
|
|
}
|
|
}
|
|
handle_signal(&ksig, regs);
|
|
} else {
|
|
/* no handler */
|
|
restore_saved_sigmask();
|
|
if (unlikely(restart) && regs->ARM_pc == restart_addr) {
|
|
regs->ARM_pc = continue_addr;
|
|
return restart;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
asmlinkage int
|
|
do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
|
|
{
|
|
/*
|
|
* The assembly code enters us with IRQs off, but it hasn't
|
|
* informed the tracing code of that for efficiency reasons.
|
|
* Update the trace code with the current status.
|
|
*/
|
|
trace_hardirqs_off();
|
|
do {
|
|
if (likely(thread_flags & _TIF_NEED_RESCHED)) {
|
|
schedule();
|
|
} else {
|
|
if (unlikely(!user_mode(regs)))
|
|
return 0;
|
|
local_irq_enable();
|
|
if (thread_flags & _TIF_SIGPENDING) {
|
|
int restart = do_signal(regs, syscall);
|
|
if (unlikely(restart)) {
|
|
/*
|
|
* Restart without handlers.
|
|
* Deal with it without leaving
|
|
* the kernel space.
|
|
*/
|
|
return restart;
|
|
}
|
|
syscall = 0;
|
|
} else if (thread_flags & _TIF_UPROBE) {
|
|
uprobe_notify_resume(regs);
|
|
} else {
|
|
clear_thread_flag(TIF_NOTIFY_RESUME);
|
|
tracehook_notify_resume(regs);
|
|
rseq_handle_notify_resume(NULL, regs);
|
|
}
|
|
}
|
|
local_irq_disable();
|
|
thread_flags = current_thread_info()->flags;
|
|
} while (thread_flags & _TIF_WORK_MASK);
|
|
return 0;
|
|
}
|
|
|
|
struct page *get_signal_page(void)
|
|
{
|
|
unsigned long ptr;
|
|
unsigned offset;
|
|
struct page *page;
|
|
void *addr;
|
|
|
|
page = alloc_pages(GFP_KERNEL, 0);
|
|
|
|
if (!page)
|
|
return NULL;
|
|
|
|
addr = page_address(page);
|
|
|
|
/* Give the signal return code some randomness */
|
|
offset = 0x200 + (get_random_int() & 0x7fc);
|
|
signal_return_offset = offset;
|
|
|
|
/*
|
|
* Copy signal return handlers into the vector page, and
|
|
* set sigreturn to be a pointer to these.
|
|
*/
|
|
memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
|
|
|
|
ptr = (unsigned long)addr + offset;
|
|
flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));
|
|
|
|
return page;
|
|
}
|
|
|
|
/* Defer to generic check */
|
|
asmlinkage void addr_limit_check_failed(void)
|
|
{
|
|
addr_limit_user_check();
|
|
}
|
|
|
|
#ifdef CONFIG_DEBUG_RSEQ
|
|
asmlinkage void do_rseq_syscall(struct pt_regs *regs)
|
|
{
|
|
rseq_syscall(regs);
|
|
}
|
|
#endif
|