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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
30int show_unhandled_signals = 1;
31
32/*
33 * Allocate space for the signal frame
34 */
35void __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
52static 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
103static 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
149void 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
172unsigned 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}
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 <linux/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
29int show_unhandled_signals = 1;
30
31/*
32 * Allocate space for the signal frame
33 */
34void __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
51static 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
102static 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
148void 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
168unsigned 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}