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727 lines
18 KiB
727 lines
18 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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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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#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(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); |
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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(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); |
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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(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)); |
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int err = 0; |
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if (!frame) |
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return 1; |
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err |= copy_siginfo_to_user(&frame->info, &ksig->info); |
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err |= __put_user(0, &frame->sig.uc.uc_flags); |
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err |= __put_user(NULL, &frame->sig.uc.uc_link); |
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err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp); |
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err |= setup_sigframe(&frame->sig, regs, set); |
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if (err == 0) |
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err = setup_return(regs, ksig, frame->sig.retcode, frame); |
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if (err == 0) { |
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/* |
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* For realtime signals we must also set the second and third |
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* arguments for the signal handler. |
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* -- Peter Maydell <[email protected]> 2000-12-06 |
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*/ |
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regs->ARM_r1 = (unsigned long)&frame->info; |
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regs->ARM_r2 = (unsigned long)&frame->sig.uc; |
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} |
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return err; |
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} |
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/* |
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* OK, we're invoking a handler |
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*/ |
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static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) |
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{ |
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sigset_t *oldset = sigmask_to_save(); |
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int ret; |
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/* |
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* Perform fixup for the pre-signal frame. |
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*/ |
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rseq_signal_deliver(ksig, regs); |
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|
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/* |
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* Set up the stack frame |
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*/ |
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if (ksig->ka.sa.sa_flags & SA_SIGINFO) |
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ret = setup_rt_frame(ksig, oldset, regs); |
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else |
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ret = setup_frame(ksig, oldset, regs); |
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|
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/* |
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* Check that the resulting registers are actually sane. |
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*/ |
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ret |= !valid_user_regs(regs); |
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|
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signal_setup_done(ret, ksig, 0); |
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} |
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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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static int do_signal(struct pt_regs *regs, int syscall) |
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{ |
|
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; |
|
fallthrough; |
|
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 | _TIF_NOTIFY_SIGNAL)) { |
|
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 { |
|
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); |
|
|
|
/* Poison the entire page */ |
|
memset32(addr, __opcode_to_mem_arm(0xe7fddef1), |
|
PAGE_SIZE / sizeof(u32)); |
|
|
|
/* Give the signal return code some randomness */ |
|
offset = 0x200 + (get_random_int() & 0x7fc); |
|
signal_return_offset = offset; |
|
|
|
/* Copy signal return handlers into the page */ |
|
memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes)); |
|
|
|
/* Flush out all instructions in this page */ |
|
ptr = (unsigned long)addr; |
|
flush_icache_range(ptr, ptr + PAGE_SIZE); |
|
|
|
return page; |
|
} |
|
|
|
/* Defer to generic check */ |
|
asmlinkage void addr_limit_check_failed(void) |
|
{ |
|
#ifdef CONFIG_MMU |
|
addr_limit_user_check(); |
|
#endif |
|
} |
|
|
|
#ifdef CONFIG_DEBUG_RSEQ |
|
asmlinkage void do_rseq_syscall(struct pt_regs *regs) |
|
{ |
|
rseq_syscall(regs); |
|
} |
|
#endif
|
|
|