diff options
Diffstat (limited to 'arch/arm/kernel/signal.c')
| -rw-r--r-- | arch/arm/kernel/signal.c | 624 |
1 files changed, 624 insertions, 0 deletions
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c new file mode 100644 index 000000000..423663e23 --- /dev/null +++ b/arch/arm/kernel/signal.c @@ -0,0 +1,624 @@ +/* + * linux/arch/arm/kernel/signal.c + * + * Copyright (C) 1995-2009 Russell King + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#include <linux/errno.h> +#include <linux/random.h> +#include <linux/signal.h> +#include <linux/personality.h> +#include <linux/uaccess.h> +#include <linux/tracehook.h> +#include <linux/uprobes.h> + +#include <asm/elf.h> +#include <asm/cacheflush.h> +#include <asm/traps.h> +#include <asm/ucontext.h> +#include <asm/unistd.h> +#include <asm/vfp.h> + +extern const unsigned long sigreturn_codes[7]; + +static unsigned long signal_return_offset; + +#ifdef CONFIG_CRUNCH +static int preserve_crunch_context(struct crunch_sigframe __user *frame) +{ + char kbuf[sizeof(*frame) + 8]; + struct crunch_sigframe *kframe; + + /* the crunch context must be 64 bit aligned */ + kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7); + kframe->magic = CRUNCH_MAGIC; + kframe->size = CRUNCH_STORAGE_SIZE; + crunch_task_copy(current_thread_info(), &kframe->storage); + return __copy_to_user(frame, kframe, sizeof(*frame)); +} + +static int restore_crunch_context(struct crunch_sigframe __user *frame) +{ + char kbuf[sizeof(*frame) + 8]; + struct crunch_sigframe *kframe; + + /* the crunch context must be 64 bit aligned */ + kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7); + if (__copy_from_user(kframe, frame, sizeof(*frame))) + return -1; + if (kframe->magic != CRUNCH_MAGIC || + kframe->size != CRUNCH_STORAGE_SIZE) + return -1; + crunch_task_restore(current_thread_info(), &kframe->storage); + return 0; +} +#endif + +#ifdef CONFIG_IWMMXT + +static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame) +{ + char kbuf[sizeof(*frame) + 8]; + struct iwmmxt_sigframe *kframe; + + /* the iWMMXt context must be 64 bit aligned */ + kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); + kframe->magic = IWMMXT_MAGIC; + kframe->size = IWMMXT_STORAGE_SIZE; + iwmmxt_task_copy(current_thread_info(), &kframe->storage); + return __copy_to_user(frame, kframe, sizeof(*frame)); +} + +static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame) +{ + char kbuf[sizeof(*frame) + 8]; + struct iwmmxt_sigframe *kframe; + + /* the iWMMXt context must be 64 bit aligned */ + kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); + if (__copy_from_user(kframe, frame, sizeof(*frame))) + return -1; + if (kframe->magic != IWMMXT_MAGIC || + kframe->size != IWMMXT_STORAGE_SIZE) + return -1; + iwmmxt_task_restore(current_thread_info(), &kframe->storage); + return 0; +} + +#endif + +#ifdef CONFIG_VFP + +static int preserve_vfp_context(struct vfp_sigframe __user *frame) +{ + const unsigned long magic = VFP_MAGIC; + const unsigned long size = VFP_STORAGE_SIZE; + int err = 0; + + __put_user_error(magic, &frame->magic, err); + __put_user_error(size, &frame->size, err); + + if (err) + return -EFAULT; + + return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc); +} + +static int restore_vfp_context(struct vfp_sigframe __user *frame) +{ + unsigned long magic; + unsigned long size; + int err = 0; + + __get_user_error(magic, &frame->magic, err); + __get_user_error(size, &frame->size, err); + + if (err) + return -EFAULT; + if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE) + return -EINVAL; + + return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc); +} + +#endif + +/* + * Do a signal return; undo the signal stack. These are aligned to 64-bit. + */ +struct sigframe { + struct ucontext uc; + unsigned long retcode[2]; +}; + +struct rt_sigframe { + struct siginfo info; + struct sigframe sig; +}; + +static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf) +{ + struct aux_sigframe __user *aux; + sigset_t set; + int err; + + err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); + if (err == 0) + set_current_blocked(&set); + + __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err); + __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err); + __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err); + __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err); + __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err); + __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err); + __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err); + __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err); + __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err); + __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err); + __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err); + __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err); + __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err); + __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err); + __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err); + __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err); + __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err); + + err |= !valid_user_regs(regs); + + aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; +#ifdef CONFIG_CRUNCH + if (err == 0) + err |= restore_crunch_context(&aux->crunch); +#endif +#ifdef CONFIG_IWMMXT + if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) + err |= restore_iwmmxt_context(&aux->iwmmxt); +#endif +#ifdef CONFIG_VFP + if (err == 0) + err |= restore_vfp_context(&aux->vfp); +#endif + + return err; +} + +asmlinkage int sys_sigreturn(struct pt_regs *regs) +{ + struct sigframe __user *frame; + + /* Always make any pending restarted system calls return -EINTR */ + current->restart_block.fn = do_no_restart_syscall; + + /* + * Since we stacked the signal on a 64-bit boundary, + * then 'sp' should be word aligned here. If it's + * not, then the user is trying to mess with us. + */ + if (regs->ARM_sp & 7) + goto badframe; + + frame = (struct sigframe __user *)regs->ARM_sp; + + if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) + goto badframe; + + if (restore_sigframe(regs, frame)) + goto badframe; + + return regs->ARM_r0; + +badframe: + force_sig(SIGSEGV, current); + return 0; +} + +asmlinkage int sys_rt_sigreturn(struct pt_regs *regs) +{ + struct rt_sigframe __user *frame; + + /* Always make any pending restarted system calls return -EINTR */ + current->restart_block.fn = do_no_restart_syscall; + + /* + * Since we stacked the signal on a 64-bit boundary, + * then 'sp' should be word aligned here. If it's + * not, then the user is trying to mess with us. + */ + if (regs->ARM_sp & 7) + goto badframe; + + frame = (struct rt_sigframe __user *)regs->ARM_sp; + + if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) + goto badframe; + + if (restore_sigframe(regs, &frame->sig)) + goto badframe; + + if (restore_altstack(&frame->sig.uc.uc_stack)) + goto badframe; + + return regs->ARM_r0; + +badframe: + force_sig(SIGSEGV, current); + return 0; +} + +static int +setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set) +{ + struct aux_sigframe __user *aux; + int err = 0; + + __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err); + __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err); + __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err); + __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err); + __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err); + __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err); + __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err); + __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err); + __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err); + __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err); + __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err); + __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err); + __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err); + __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err); + __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err); + __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err); + __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err); + + __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err); + __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err); + __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err); + __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err); + + err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set)); + + aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; +#ifdef CONFIG_CRUNCH + if (err == 0) + err |= preserve_crunch_context(&aux->crunch); +#endif +#ifdef CONFIG_IWMMXT + if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) + err |= preserve_iwmmxt_context(&aux->iwmmxt); +#endif +#ifdef CONFIG_VFP + if (err == 0) + err |= preserve_vfp_context(&aux->vfp); +#endif + __put_user_error(0, &aux->end_magic, err); + + return err; +} + +static inline void __user * +get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize) +{ + unsigned long sp = sigsp(regs->ARM_sp, ksig); + void __user *frame; + + /* + * ATPCS B01 mandates 8-byte alignment + */ + frame = (void __user *)((sp - framesize) & ~7); + + /* + * Check that we can actually write to the signal frame. + */ + if (!access_ok(VERIFY_WRITE, frame, framesize)) + frame = NULL; + + return frame; +} + +static int +setup_return(struct pt_regs *regs, struct ksignal *ksig, + unsigned long __user *rc, void __user *frame) +{ + unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler; + unsigned long retcode; + int thumb = 0; + unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT); + + cpsr |= PSR_ENDSTATE; + + /* + * Maybe we need to deliver a 32-bit signal to a 26-bit task. + */ + if (ksig->ka.sa.sa_flags & SA_THIRTYTWO) + cpsr = (cpsr & ~MODE_MASK) | USR_MODE; + +#ifdef CONFIG_ARM_THUMB + if (elf_hwcap & HWCAP_THUMB) { + /* + * The LSB of the handler determines if we're going to + * be using THUMB or ARM mode for this signal handler. + */ + thumb = handler & 1; + +#if __LINUX_ARM_ARCH__ >= 7 + /* + * Clear the If-Then Thumb-2 execution state + * ARM spec requires this to be all 000s in ARM mode + * Snapdragon S4/Krait misbehaves on a Thumb=>ARM + * signal transition without this. + */ + cpsr &= ~PSR_IT_MASK; +#endif + + if (thumb) { + cpsr |= PSR_T_BIT; + } else + cpsr &= ~PSR_T_BIT; + } +#endif + + if (ksig->ka.sa.sa_flags & SA_RESTORER) { + retcode = (unsigned long)ksig->ka.sa.sa_restorer; + } else { + unsigned int idx = thumb << 1; + + if (ksig->ka.sa.sa_flags & SA_SIGINFO) + idx += 3; + + /* + * Put the sigreturn code on the stack no matter which return + * mechanism we use in order to remain ABI compliant + */ + if (__put_user(sigreturn_codes[idx], rc) || + __put_user(sigreturn_codes[idx+1], rc+1)) + return 1; + +#ifdef CONFIG_MMU + if (cpsr & MODE32_BIT) { + struct mm_struct *mm = current->mm; + + /* + * 32-bit code can use the signal return page + * except when the MPU has protected the vectors + * page from PL0 + */ + retcode = mm->context.sigpage + signal_return_offset + + (idx << 2) + thumb; + } else +#endif + { + /* + * Ensure that the instruction cache sees + * the return code written onto the stack. + */ + flush_icache_range((unsigned long)rc, + (unsigned long)(rc + 2)); + + retcode = ((unsigned long)rc) + thumb; + } + } + + regs->ARM_r0 = ksig->sig; + regs->ARM_sp = (unsigned long)frame; + regs->ARM_lr = retcode; + regs->ARM_pc = handler; + regs->ARM_cpsr = cpsr; + + return 0; +} + +static int +setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) +{ + struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); + int err = 0; + + if (!frame) + return 1; + + /* + * Set uc.uc_flags to a value which sc.trap_no would never have. + */ + __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err); + + err |= setup_sigframe(frame, regs, set); + if (err == 0) + err = setup_return(regs, ksig, frame->retcode, frame); + + return err; +} + +static int +setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) +{ + 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); + + __put_user_error(0, &frame->sig.uc.uc_flags, err); + __put_user_error(NULL, &frame->sig.uc.uc_link, err); + + 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; + + /* + * 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) +{ + 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); + } + } + 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; +} |