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