/* * Common signal handling code for both 32 and 64 bits * * Copyright (c) 2007 Benjamin Herrenschmidt, IBM Corporation * Extracted from signal_32.c and signal_64.c * * This file is subject to the terms and conditions of the GNU General * Public License. See the file README.legal in the main directory of * this archive for more details. */ #include <linux/tracehook.h> #include <linux/signal.h> #include <linux/uprobes.h> #include <linux/key.h> #include <linux/context_tracking.h> #include <linux/livepatch.h> #include <linux/syscalls.h> #include <asm/hw_breakpoint.h> #include <linux/uaccess.h> #include <asm/unistd.h> #include <asm/debug.h> #include <asm/tm.h> #include "signal.h" /* Log an error when sending an unhandled signal to a process. Controlled * through debug.exception-trace sysctl. */ int show_unhandled_signals = 1; /* * Allocate space for the signal frame */ void __user *get_sigframe(struct ksignal *ksig, unsigned long sp, size_t frame_size, int is_32) { unsigned long oldsp, newsp; /* Default to using normal stack */ oldsp = get_clean_sp(sp, is_32); oldsp = sigsp(oldsp, ksig); newsp = (oldsp - frame_size) & ~0xFUL; /* Check access */ if (!access_ok((void __user *)newsp, oldsp - newsp)) return NULL; return (void __user *)newsp; } static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler) { unsigned long ret = regs->gpr[3]; int restart = 1; /* syscall ? */ if (TRAP(regs) != 0x0C00) return; /* error signalled ? */ if (!(regs->ccr & 0x10000000)) return; switch (ret) { case ERESTART_RESTARTBLOCK: case ERESTARTNOHAND: /* ERESTARTNOHAND means that the syscall should only be * restarted if there was no handler for the signal, and since * we only get here if there is a handler, we dont restart. */ restart = !has_handler; break; case ERESTARTSYS: /* ERESTARTSYS means to restart the syscall if there is no * handler or the handler was registered with SA_RESTART */ restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0; break; case ERESTARTNOINTR: /* ERESTARTNOINTR means that the syscall should be * called again after the signal handler returns. */ break; default: return; } if (restart) { if (ret == ERESTART_RESTARTBLOCK) regs->gpr[0] = __NR_restart_syscall; else regs->gpr[3] = regs->orig_gpr3; regs->nip -= 4; regs->result = 0; } else { regs->result = -EINTR; regs->gpr[3] = EINTR; regs->ccr |= 0x10000000; } } static void do_signal(struct task_struct *tsk) { sigset_t *oldset = sigmask_to_save(); struct ksignal ksig = { .sig = 0 }; int ret; int is32 = is_32bit_task(); BUG_ON(tsk != current); get_signal(&ksig); /* Is there any syscall restart business here ? */ check_syscall_restart(tsk->thread.regs, &ksig.ka, ksig.sig > 0); if (ksig.sig <= 0) { /* No signal to deliver -- put the saved sigmask back */ restore_saved_sigmask(); tsk->thread.regs->trap = 0; return; /* no signals delivered */ } #ifndef CONFIG_PPC_ADV_DEBUG_REGS /* * Reenable the DABR before delivering the signal to * user space. The DABR will have been cleared if it * triggered inside the kernel. */ if (tsk->thread.hw_brk.address && tsk->thread.hw_brk.type) __set_breakpoint(&tsk->thread.hw_brk); #endif /* Re-enable the breakpoints for the signal stack */ thread_change_pc(tsk, tsk->thread.regs); rseq_signal_deliver(&ksig, tsk->thread.regs); if (is32) { if (ksig.ka.sa.sa_flags & SA_SIGINFO) ret = handle_rt_signal32(&ksig, oldset, tsk); else ret = handle_signal32(&ksig, oldset, tsk); } else { ret = handle_rt_signal64(&ksig, oldset, tsk); } tsk->thread.regs->trap = 0; signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP)); } void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) { user_exit(); /* Check valid addr_limit, TIF check is done there */ addr_limit_user_check(); if (thread_info_flags & _TIF_UPROBE) uprobe_notify_resume(regs); if (thread_info_flags & _TIF_PATCH_PENDING) klp_update_patch_state(current); if (thread_info_flags & _TIF_SIGPENDING) { BUG_ON(regs != current->thread.regs); do_signal(current); } if (thread_info_flags & _TIF_NOTIFY_RESUME) { clear_thread_flag(TIF_NOTIFY_RESUME); tracehook_notify_resume(regs); rseq_handle_notify_resume(NULL, regs); } user_enter(); } unsigned long get_tm_stackpointer(struct task_struct *tsk) { /* When in an active transaction that takes a signal, we need to be * careful with the stack. It's possible that the stack has moved back * up after the tbegin. The obvious case here is when the tbegin is * called inside a function that returns before a tend. In this case, * the stack is part of the checkpointed transactional memory state. * If we write over this non transactionally or in suspend, we are in * trouble because if we get a tm abort, the program counter and stack * pointer will be back at the tbegin but our in memory stack won't be * valid anymore. * * To avoid this, when taking a signal in an active transaction, we * need to use the stack pointer from the checkpointed state, rather * than the speculated state. This ensures that the signal context * (written tm suspended) will be written below the stack required for * the rollback. The transaction is aborted because of the treclaim, * so any memory written between the tbegin and the signal will be * rolled back anyway. * * For signals taken in non-TM or suspended mode, we use the * normal/non-checkpointed stack pointer. */ #ifdef CONFIG_PPC_TRANSACTIONAL_MEM BUG_ON(tsk != current); if (MSR_TM_ACTIVE(tsk->thread.regs->msr)) { tm_reclaim_current(TM_CAUSE_SIGNAL); if (MSR_TM_TRANSACTIONAL(tsk->thread.regs->msr)) return tsk->thread.ckpt_regs.gpr[1]; } #endif return tsk->thread.regs->gpr[1]; }