efivars: Refactor sanity checking code into separate function
[linux/fpc-iii.git] / arch / powerpc / kernel / signal.c
blob8fc4177ed65acb6e9b1873f3614fc0457125c783
1 /*
2 * Common signal handling code for both 32 and 64 bits
4 * Copyright (c) 2007 Benjamin Herrenschmidt, IBM Coproration
5 * Extracted from signal_32.c and signal_64.c
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.
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>
23 #include "signal.h"
25 /* Log an error when sending an unhandled signal to a process. Controlled
26 * through debug.exception-trace sysctl.
29 int show_unhandled_signals = 1;
32 * Allocate space for the signal frame
34 void __user * get_sigframe(struct k_sigaction *ka, unsigned long sp,
35 size_t frame_size, int is_32)
37 unsigned long oldsp, newsp;
39 /* Default to using normal stack */
40 oldsp = get_clean_sp(sp, is_32);
42 /* Check for alt stack */
43 if ((ka->sa.sa_flags & SA_ONSTACK) &&
44 current->sas_ss_size && !on_sig_stack(oldsp))
45 oldsp = (current->sas_ss_sp + current->sas_ss_size);
47 /* Get aligned frame */
48 newsp = (oldsp - frame_size) & ~0xFUL;
50 /* Check access */
51 if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp))
52 return NULL;
54 return (void __user *)newsp;
57 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
58 int has_handler)
60 unsigned long ret = regs->gpr[3];
61 int restart = 1;
63 /* syscall ? */
64 if (TRAP(regs) != 0x0C00)
65 return;
67 /* error signalled ? */
68 if (!(regs->ccr & 0x10000000))
69 return;
71 switch (ret) {
72 case ERESTART_RESTARTBLOCK:
73 case ERESTARTNOHAND:
74 /* ERESTARTNOHAND means that the syscall should only be
75 * restarted if there was no handler for the signal, and since
76 * we only get here if there is a handler, we dont restart.
78 restart = !has_handler;
79 break;
80 case ERESTARTSYS:
81 /* ERESTARTSYS means to restart the syscall if there is no
82 * handler or the handler was registered with SA_RESTART
84 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
85 break;
86 case ERESTARTNOINTR:
87 /* ERESTARTNOINTR means that the syscall should be
88 * called again after the signal handler returns.
90 break;
91 default:
92 return;
94 if (restart) {
95 if (ret == ERESTART_RESTARTBLOCK)
96 regs->gpr[0] = __NR_restart_syscall;
97 else
98 regs->gpr[3] = regs->orig_gpr3;
99 regs->nip -= 4;
100 regs->result = 0;
101 } else {
102 regs->result = -EINTR;
103 regs->gpr[3] = EINTR;
104 regs->ccr |= 0x10000000;
108 static int do_signal(struct pt_regs *regs)
110 sigset_t *oldset = sigmask_to_save();
111 siginfo_t info;
112 int signr;
113 struct k_sigaction ka;
114 int ret;
115 int is32 = is_32bit_task();
117 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
119 /* Is there any syscall restart business here ? */
120 check_syscall_restart(regs, &ka, signr > 0);
122 if (signr <= 0) {
123 /* No signal to deliver -- put the saved sigmask back */
124 restore_saved_sigmask();
125 regs->trap = 0;
126 return 0; /* no signals delivered */
129 #ifndef CONFIG_PPC_ADV_DEBUG_REGS
131 * Reenable the DABR before delivering the signal to
132 * user space. The DABR will have been cleared if it
133 * triggered inside the kernel.
135 if (current->thread.hw_brk.address &&
136 current->thread.hw_brk.type)
137 set_breakpoint(&current->thread.hw_brk);
138 #endif
139 /* Re-enable the breakpoints for the signal stack */
140 thread_change_pc(current, regs);
142 if (is32) {
143 if (ka.sa.sa_flags & SA_SIGINFO)
144 ret = handle_rt_signal32(signr, &ka, &info, oldset,
145 regs);
146 else
147 ret = handle_signal32(signr, &ka, &info, oldset,
148 regs);
149 } else {
150 ret = handle_rt_signal64(signr, &ka, &info, oldset, regs);
153 regs->trap = 0;
154 if (ret) {
155 signal_delivered(signr, &info, &ka, regs,
156 test_thread_flag(TIF_SINGLESTEP));
159 return ret;
162 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
164 user_exit();
166 if (thread_info_flags & _TIF_UPROBE)
167 uprobe_notify_resume(regs);
169 if (thread_info_flags & _TIF_SIGPENDING)
170 do_signal(regs);
172 if (thread_info_flags & _TIF_NOTIFY_RESUME) {
173 clear_thread_flag(TIF_NOTIFY_RESUME);
174 tracehook_notify_resume(regs);
177 user_enter();
180 unsigned long get_tm_stackpointer(struct pt_regs *regs)
182 /* When in an active transaction that takes a signal, we need to be
183 * careful with the stack. It's possible that the stack has moved back
184 * up after the tbegin. The obvious case here is when the tbegin is
185 * called inside a function that returns before a tend. In this case,
186 * the stack is part of the checkpointed transactional memory state.
187 * If we write over this non transactionally or in suspend, we are in
188 * trouble because if we get a tm abort, the program counter and stack
189 * pointer will be back at the tbegin but our in memory stack won't be
190 * valid anymore.
192 * To avoid this, when taking a signal in an active transaction, we
193 * need to use the stack pointer from the checkpointed state, rather
194 * than the speculated state. This ensures that the signal context
195 * (written tm suspended) will be written below the stack required for
196 * the rollback. The transaction is aborted becuase of the treclaim,
197 * so any memory written between the tbegin and the signal will be
198 * rolled back anyway.
200 * For signals taken in non-TM or suspended mode, we use the
201 * normal/non-checkpointed stack pointer.
204 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
205 if (MSR_TM_ACTIVE(regs->msr)) {
206 tm_reclaim_current(TM_CAUSE_SIGNAL);
207 if (MSR_TM_TRANSACTIONAL(regs->msr))
208 return current->thread.ckpt_regs.gpr[1];
210 #endif
211 return regs->gpr[1];