1 /* 2 * Common signal handling code for both 32 and 64 bits 3 * 4 * Copyright (c) 2007 Benjamin Herrenschmidt, IBM Corporation 5 * Extracted from signal_32.c and signal_64.c 6 * 7 * This file is subject to the terms and conditions of the GNU General 8 * Public License. See the file README.legal in the main directory of 9 * this archive for more details. 10 */ 11 12 #include <linux/tracehook.h> 13 #include <linux/signal.h> 14 #include <linux/uprobes.h> 15 #include <linux/key.h> 16 #include <linux/context_tracking.h> 17 #include <asm/hw_breakpoint.h> 18 #include <asm/uaccess.h> 19 #include <asm/unistd.h> 20 #include <asm/debug.h> 21 #include <asm/tm.h> 22 23 #include "signal.h" 24 25 /* Log an error when sending an unhandled signal to a process. Controlled 26 * through debug.exception-trace sysctl. 27 */ 28 29 int show_unhandled_signals = 1; 30 31 /* 32 * Allocate space for the signal frame 33 */ 34 void __user *get_sigframe(struct ksignal *ksig, unsigned long sp, 35 size_t frame_size, int is_32) 36 { 37 unsigned long oldsp, newsp; 38 39 /* Default to using normal stack */ 40 oldsp = get_clean_sp(sp, is_32); 41 oldsp = sigsp(oldsp, ksig); 42 newsp = (oldsp - frame_size) & ~0xFUL; 43 44 /* Check access */ 45 if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp)) 46 return NULL; 47 48 return (void __user *)newsp; 49 } 50 51 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka, 52 int has_handler) 53 { 54 unsigned long ret = regs->gpr[3]; 55 int restart = 1; 56 57 /* syscall ? */ 58 if (TRAP(regs) != 0x0C00) 59 return; 60 61 /* error signalled ? */ 62 if (!(regs->ccr & 0x10000000)) 63 return; 64 65 switch (ret) { 66 case ERESTART_RESTARTBLOCK: 67 case ERESTARTNOHAND: 68 /* ERESTARTNOHAND means that the syscall should only be 69 * restarted if there was no handler for the signal, and since 70 * we only get here if there is a handler, we dont restart. 71 */ 72 restart = !has_handler; 73 break; 74 case ERESTARTSYS: 75 /* ERESTARTSYS means to restart the syscall if there is no 76 * handler or the handler was registered with SA_RESTART 77 */ 78 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0; 79 break; 80 case ERESTARTNOINTR: 81 /* ERESTARTNOINTR means that the syscall should be 82 * called again after the signal handler returns. 83 */ 84 break; 85 default: 86 return; 87 } 88 if (restart) { 89 if (ret == ERESTART_RESTARTBLOCK) 90 regs->gpr[0] = __NR_restart_syscall; 91 else 92 regs->gpr[3] = regs->orig_gpr3; 93 regs->nip -= 4; 94 regs->result = 0; 95 } else { 96 regs->result = -EINTR; 97 regs->gpr[3] = EINTR; 98 regs->ccr |= 0x10000000; 99 } 100 } 101 102 static void do_signal(struct task_struct *tsk) 103 { 104 sigset_t *oldset = sigmask_to_save(); 105 struct ksignal ksig; 106 int ret; 107 int is32 = is_32bit_task(); 108 109 BUG_ON(tsk != current); 110 111 get_signal(&ksig); 112 113 /* Is there any syscall restart business here ? */ 114 check_syscall_restart(tsk->thread.regs, &ksig.ka, ksig.sig > 0); 115 116 if (ksig.sig <= 0) { 117 /* No signal to deliver -- put the saved sigmask back */ 118 restore_saved_sigmask(); 119 tsk->thread.regs->trap = 0; 120 return; /* no signals delivered */ 121 } 122 123 #ifndef CONFIG_PPC_ADV_DEBUG_REGS 124 /* 125 * Reenable the DABR before delivering the signal to 126 * user space. The DABR will have been cleared if it 127 * triggered inside the kernel. 128 */ 129 if (tsk->thread.hw_brk.address && tsk->thread.hw_brk.type) 130 __set_breakpoint(&tsk->thread.hw_brk); 131 #endif 132 /* Re-enable the breakpoints for the signal stack */ 133 thread_change_pc(tsk, tsk->thread.regs); 134 135 if (is32) { 136 if (ksig.ka.sa.sa_flags & SA_SIGINFO) 137 ret = handle_rt_signal32(&ksig, oldset, tsk); 138 else 139 ret = handle_signal32(&ksig, oldset, tsk); 140 } else { 141 ret = handle_rt_signal64(&ksig, oldset, tsk); 142 } 143 144 tsk->thread.regs->trap = 0; 145 signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP)); 146 } 147 148 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) 149 { 150 user_exit(); 151 152 if (thread_info_flags & _TIF_UPROBE) 153 uprobe_notify_resume(regs); 154 155 if (thread_info_flags & _TIF_SIGPENDING) { 156 BUG_ON(regs != current->thread.regs); 157 do_signal(current); 158 } 159 160 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 161 clear_thread_flag(TIF_NOTIFY_RESUME); 162 tracehook_notify_resume(regs); 163 } 164 165 user_enter(); 166 } 167 168 unsigned long get_tm_stackpointer(struct task_struct *tsk) 169 { 170 /* When in an active transaction that takes a signal, we need to be 171 * careful with the stack. It's possible that the stack has moved back 172 * up after the tbegin. The obvious case here is when the tbegin is 173 * called inside a function that returns before a tend. In this case, 174 * the stack is part of the checkpointed transactional memory state. 175 * If we write over this non transactionally or in suspend, we are in 176 * trouble because if we get a tm abort, the program counter and stack 177 * pointer will be back at the tbegin but our in memory stack won't be 178 * valid anymore. 179 * 180 * To avoid this, when taking a signal in an active transaction, we 181 * need to use the stack pointer from the checkpointed state, rather 182 * than the speculated state. This ensures that the signal context 183 * (written tm suspended) will be written below the stack required for 184 * the rollback. The transaction is aborted because of the treclaim, 185 * so any memory written between the tbegin and the signal will be 186 * rolled back anyway. 187 * 188 * For signals taken in non-TM or suspended mode, we use the 189 * normal/non-checkpointed stack pointer. 190 */ 191 192 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM 193 BUG_ON(tsk != current); 194 195 if (MSR_TM_ACTIVE(tsk->thread.regs->msr)) { 196 tm_reclaim_current(TM_CAUSE_SIGNAL); 197 if (MSR_TM_TRANSACTIONAL(tsk->thread.regs->msr)) 198 return tsk->thread.ckpt_regs.gpr[1]; 199 } 200 #endif 201 return tsk->thread.regs->gpr[1]; 202 } 203