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 <linux/livepatch.h> 18 #include <asm/hw_breakpoint.h> 19 #include <linux/uaccess.h> 20 #include <asm/unistd.h> 21 #include <asm/debug.h> 22 #include <asm/tm.h> 23 24 #include "signal.h" 25 26 /* Log an error when sending an unhandled signal to a process. Controlled 27 * through debug.exception-trace sysctl. 28 */ 29 30 int show_unhandled_signals = 1; 31 32 /* 33 * Allocate space for the signal frame 34 */ 35 void __user *get_sigframe(struct ksignal *ksig, unsigned long sp, 36 size_t frame_size, int is_32) 37 { 38 unsigned long oldsp, newsp; 39 40 /* Default to using normal stack */ 41 oldsp = get_clean_sp(sp, is_32); 42 oldsp = sigsp(oldsp, ksig); 43 newsp = (oldsp - frame_size) & ~0xFUL; 44 45 /* Check access */ 46 if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp)) 47 return NULL; 48 49 return (void __user *)newsp; 50 } 51 52 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka, 53 int has_handler) 54 { 55 unsigned long ret = regs->gpr[3]; 56 int restart = 1; 57 58 /* syscall ? */ 59 if (TRAP(regs) != 0x0C00) 60 return; 61 62 /* error signalled ? */ 63 if (!(regs->ccr & 0x10000000)) 64 return; 65 66 switch (ret) { 67 case ERESTART_RESTARTBLOCK: 68 case ERESTARTNOHAND: 69 /* ERESTARTNOHAND means that the syscall should only be 70 * restarted if there was no handler for the signal, and since 71 * we only get here if there is a handler, we dont restart. 72 */ 73 restart = !has_handler; 74 break; 75 case ERESTARTSYS: 76 /* ERESTARTSYS means to restart the syscall if there is no 77 * handler or the handler was registered with SA_RESTART 78 */ 79 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0; 80 break; 81 case ERESTARTNOINTR: 82 /* ERESTARTNOINTR means that the syscall should be 83 * called again after the signal handler returns. 84 */ 85 break; 86 default: 87 return; 88 } 89 if (restart) { 90 if (ret == ERESTART_RESTARTBLOCK) 91 regs->gpr[0] = __NR_restart_syscall; 92 else 93 regs->gpr[3] = regs->orig_gpr3; 94 regs->nip -= 4; 95 regs->result = 0; 96 } else { 97 regs->result = -EINTR; 98 regs->gpr[3] = EINTR; 99 regs->ccr |= 0x10000000; 100 } 101 } 102 103 static void do_signal(struct task_struct *tsk) 104 { 105 sigset_t *oldset = sigmask_to_save(); 106 struct ksignal ksig = { .sig = 0 }; 107 int ret; 108 int is32 = is_32bit_task(); 109 110 BUG_ON(tsk != current); 111 112 get_signal(&ksig); 113 114 /* Is there any syscall restart business here ? */ 115 check_syscall_restart(tsk->thread.regs, &ksig.ka, ksig.sig > 0); 116 117 if (ksig.sig <= 0) { 118 /* No signal to deliver -- put the saved sigmask back */ 119 restore_saved_sigmask(); 120 tsk->thread.regs->trap = 0; 121 return; /* no signals delivered */ 122 } 123 124 #ifndef CONFIG_PPC_ADV_DEBUG_REGS 125 /* 126 * Reenable the DABR before delivering the signal to 127 * user space. The DABR will have been cleared if it 128 * triggered inside the kernel. 129 */ 130 if (tsk->thread.hw_brk.address && tsk->thread.hw_brk.type) 131 __set_breakpoint(&tsk->thread.hw_brk); 132 #endif 133 /* Re-enable the breakpoints for the signal stack */ 134 thread_change_pc(tsk, tsk->thread.regs); 135 136 if (is32) { 137 if (ksig.ka.sa.sa_flags & SA_SIGINFO) 138 ret = handle_rt_signal32(&ksig, oldset, tsk); 139 else 140 ret = handle_signal32(&ksig, oldset, tsk); 141 } else { 142 ret = handle_rt_signal64(&ksig, oldset, tsk); 143 } 144 145 tsk->thread.regs->trap = 0; 146 signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP)); 147 } 148 149 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) 150 { 151 user_exit(); 152 153 if (thread_info_flags & _TIF_UPROBE) 154 uprobe_notify_resume(regs); 155 156 if (thread_info_flags & _TIF_PATCH_PENDING) 157 klp_update_patch_state(current); 158 159 if (thread_info_flags & _TIF_SIGPENDING) { 160 BUG_ON(regs != current->thread.regs); 161 do_signal(current); 162 } 163 164 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 165 clear_thread_flag(TIF_NOTIFY_RESUME); 166 tracehook_notify_resume(regs); 167 } 168 169 user_enter(); 170 } 171 172 unsigned long get_tm_stackpointer(struct task_struct *tsk) 173 { 174 /* When in an active transaction that takes a signal, we need to be 175 * careful with the stack. It's possible that the stack has moved back 176 * up after the tbegin. The obvious case here is when the tbegin is 177 * called inside a function that returns before a tend. In this case, 178 * the stack is part of the checkpointed transactional memory state. 179 * If we write over this non transactionally or in suspend, we are in 180 * trouble because if we get a tm abort, the program counter and stack 181 * pointer will be back at the tbegin but our in memory stack won't be 182 * valid anymore. 183 * 184 * To avoid this, when taking a signal in an active transaction, we 185 * need to use the stack pointer from the checkpointed state, rather 186 * than the speculated state. This ensures that the signal context 187 * (written tm suspended) will be written below the stack required for 188 * the rollback. The transaction is aborted because of the treclaim, 189 * so any memory written between the tbegin and the signal will be 190 * rolled back anyway. 191 * 192 * For signals taken in non-TM or suspended mode, we use the 193 * normal/non-checkpointed stack pointer. 194 */ 195 196 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM 197 BUG_ON(tsk != current); 198 199 if (MSR_TM_ACTIVE(tsk->thread.regs->msr)) { 200 tm_reclaim_current(TM_CAUSE_SIGNAL); 201 if (MSR_TM_TRANSACTIONAL(tsk->thread.regs->msr)) 202 return tsk->thread.ckpt_regs.gpr[1]; 203 } 204 #endif 205 return tsk->thread.regs->gpr[1]; 206 } 207