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-rw-r--r--arch/tile/kernel/traps.c317
1 files changed, 317 insertions, 0 deletions
diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c
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1/*
2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation, version 2.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 * NON INFRINGEMENT. See the GNU General Public License for
12 * more details.
13 */
14
15#include <linux/sched.h>
16#include <linux/kernel.h>
17#include <linux/kprobes.h>
18#include <linux/module.h>
19#include <linux/reboot.h>
20#include <linux/uaccess.h>
21#include <linux/ptrace.h>
22#include <asm/opcode-tile.h>
23#include <asm/opcode_constants.h>
24#include <asm/stack.h>
25#include <asm/traps.h>
26
27#include <arch/interrupts.h>
28#include <arch/spr_def.h>
29
30void __init trap_init(void)
31{
32 /* Nothing needed here since we link code at .intrpt1 */
33}
34
35int unaligned_fixup = 1;
36
37static int __init setup_unaligned_fixup(char *str)
38{
39 /*
40 * Say "=-1" to completely disable it. If you just do "=0", we
41 * will still parse the instruction, then fire a SIGBUS with
42 * the correct address from inside the single_step code.
43 */
44 long val;
45 if (strict_strtol(str, 0, &val) != 0)
46 return 0;
47 unaligned_fixup = val;
48 pr_info("Fixups for unaligned data accesses are %s\n",
49 unaligned_fixup >= 0 ?
50 (unaligned_fixup ? "enabled" : "disabled") :
51 "completely disabled");
52 return 1;
53}
54__setup("unaligned_fixup=", setup_unaligned_fixup);
55
56#if CHIP_HAS_TILE_DMA()
57
58static int dma_disabled;
59
60static int __init nodma(char *str)
61{
62 pr_info("User-space DMA is disabled\n");
63 dma_disabled = 1;
64 return 1;
65}
66__setup("nodma", nodma);
67
68/* How to decode SPR_GPV_REASON */
69#define IRET_ERROR (1U << 31)
70#define MT_ERROR (1U << 30)
71#define MF_ERROR (1U << 29)
72#define SPR_INDEX ((1U << 15) - 1)
73#define SPR_MPL_SHIFT 9 /* starting bit position for MPL encoded in SPR */
74
75/*
76 * See if this GPV is just to notify the kernel of SPR use and we can
77 * retry the user instruction after adjusting some MPLs suitably.
78 */
79static int retry_gpv(unsigned int gpv_reason)
80{
81 int mpl;
82
83 if (gpv_reason & IRET_ERROR)
84 return 0;
85
86 BUG_ON((gpv_reason & (MT_ERROR|MF_ERROR)) == 0);
87 mpl = (gpv_reason & SPR_INDEX) >> SPR_MPL_SHIFT;
88 if (mpl == INT_DMA_NOTIFY && !dma_disabled) {
89 /* User is turning on DMA. Allow it and retry. */
90 printk(KERN_DEBUG "Process %d/%s is now enabled for DMA\n",
91 current->pid, current->comm);
92 BUG_ON(current->thread.tile_dma_state.enabled);
93 current->thread.tile_dma_state.enabled = 1;
94 grant_dma_mpls();
95 return 1;
96 }
97
98 return 0;
99}
100
101#endif /* CHIP_HAS_TILE_DMA() */
102
103#ifdef __tilegx__
104#define bundle_bits tilegx_bundle_bits
105#else
106#define bundle_bits tile_bundle_bits
107#endif
108
109extern bundle_bits bpt_code;
110
111asm(".pushsection .rodata.bpt_code,\"a\";"
112 ".align 8;"
113 "bpt_code: bpt;"
114 ".size bpt_code,.-bpt_code;"
115 ".popsection");
116
117static int special_ill(bundle_bits bundle, int *sigp, int *codep)
118{
119 int sig, code, maxcode;
120
121 if (bundle == bpt_code) {
122 *sigp = SIGTRAP;
123 *codep = TRAP_BRKPT;
124 return 1;
125 }
126
127 /* If it's a "raise" bundle, then "ill" must be in pipe X1. */
128#ifdef __tilegx__
129 if ((bundle & TILEGX_BUNDLE_MODE_MASK) != 0)
130 return 0;
131 if (get_Opcode_X1(bundle) != UNARY_OPCODE_X1)
132 return 0;
133 if (get_UnaryOpcodeExtension_X1(bundle) != ILL_UNARY_OPCODE_X1)
134 return 0;
135#else
136 if (bundle & TILE_BUNDLE_Y_ENCODING_MASK)
137 return 0;
138 if (get_Opcode_X1(bundle) != SHUN_0_OPCODE_X1)
139 return 0;
140 if (get_UnShOpcodeExtension_X1(bundle) != UN_0_SHUN_0_OPCODE_X1)
141 return 0;
142 if (get_UnOpcodeExtension_X1(bundle) != ILL_UN_0_SHUN_0_OPCODE_X1)
143 return 0;
144#endif
145
146 /* Check that the magic distinguishers are set to mean "raise". */
147 if (get_Dest_X1(bundle) != 29 || get_SrcA_X1(bundle) != 37)
148 return 0;
149
150 /* There must be an "addli zero, zero, VAL" in X0. */
151 if (get_Opcode_X0(bundle) != ADDLI_OPCODE_X0)
152 return 0;
153 if (get_Dest_X0(bundle) != TREG_ZERO)
154 return 0;
155 if (get_SrcA_X0(bundle) != TREG_ZERO)
156 return 0;
157
158 /*
159 * Validate the proposed signal number and si_code value.
160 * Note that we embed these in the static instruction itself
161 * so that we perturb the register state as little as possible
162 * at the time of the actual fault; it's unlikely you'd ever
163 * need to dynamically choose which kind of fault to raise
164 * from user space.
165 */
166 sig = get_Imm16_X0(bundle) & 0x3f;
167 switch (sig) {
168 case SIGILL:
169 maxcode = NSIGILL;
170 break;
171 case SIGFPE:
172 maxcode = NSIGFPE;
173 break;
174 case SIGSEGV:
175 maxcode = NSIGSEGV;
176 break;
177 case SIGBUS:
178 maxcode = NSIGBUS;
179 break;
180 case SIGTRAP:
181 maxcode = NSIGTRAP;
182 break;
183 default:
184 return 0;
185 }
186 code = (get_Imm16_X0(bundle) >> 6) & 0xf;
187 if (code <= 0 || code > maxcode)
188 return 0;
189
190 /* Make it the requested signal. */
191 *sigp = sig;
192 *codep = code | __SI_FAULT;
193 return 1;
194}
195
196void __kprobes do_trap(struct pt_regs *regs, int fault_num,
197 unsigned long reason)
198{
199 siginfo_t info = { 0 };
200 int signo, code;
201 unsigned long address;
202 bundle_bits instr;
203
204 /* Re-enable interrupts. */
205 local_irq_enable();
206
207 /*
208 * If it hits in kernel mode and we can't fix it up, just exit the
209 * current process and hope for the best.
210 */
211 if (!user_mode(regs)) {
212 if (fixup_exception(regs)) /* only UNALIGN_DATA in practice */
213 return;
214 pr_alert("Kernel took bad trap %d at PC %#lx\n",
215 fault_num, regs->pc);
216 if (fault_num == INT_GPV)
217 pr_alert("GPV_REASON is %#lx\n", reason);
218 show_regs(regs);
219 do_exit(SIGKILL); /* FIXME: implement i386 die() */
220 return;
221 }
222
223 switch (fault_num) {
224 case INT_ILL:
225 if (copy_from_user(&instr, (void __user *)regs->pc,
226 sizeof(instr))) {
227 pr_err("Unreadable instruction for INT_ILL:"
228 " %#lx\n", regs->pc);
229 do_exit(SIGKILL);
230 return;
231 }
232 if (!special_ill(instr, &signo, &code)) {
233 signo = SIGILL;
234 code = ILL_ILLOPC;
235 }
236 address = regs->pc;
237 break;
238 case INT_GPV:
239#if CHIP_HAS_TILE_DMA()
240 if (retry_gpv(reason))
241 return;
242#endif
243 /*FALLTHROUGH*/
244 case INT_UDN_ACCESS:
245 case INT_IDN_ACCESS:
246#if CHIP_HAS_SN()
247 case INT_SN_ACCESS:
248#endif
249 signo = SIGILL;
250 code = ILL_PRVREG;
251 address = regs->pc;
252 break;
253 case INT_SWINT_3:
254 case INT_SWINT_2:
255 case INT_SWINT_0:
256 signo = SIGILL;
257 code = ILL_ILLTRP;
258 address = regs->pc;
259 break;
260 case INT_UNALIGN_DATA:
261#ifndef __tilegx__ /* FIXME: GX: no single-step yet */
262 if (unaligned_fixup >= 0) {
263 struct single_step_state *state =
264 current_thread_info()->step_state;
265 if (!state ||
266 (void __user *)(regs->pc) != state->buffer) {
267 single_step_once(regs);
268 return;
269 }
270 }
271#endif
272 signo = SIGBUS;
273 code = BUS_ADRALN;
274 address = 0;
275 break;
276 case INT_DOUBLE_FAULT:
277 /*
278 * For double fault, "reason" is actually passed as
279 * SYSTEM_SAVE_1_2, the hypervisor's double-fault info, so
280 * we can provide the original fault number rather than
281 * the uninteresting "INT_DOUBLE_FAULT" so the user can
282 * learn what actually struck while PL0 ICS was set.
283 */
284 fault_num = reason;
285 signo = SIGILL;
286 code = ILL_DBLFLT;
287 address = regs->pc;
288 break;
289#ifdef __tilegx__
290 case INT_ILL_TRANS:
291 signo = SIGSEGV;
292 code = SEGV_MAPERR;
293 if (reason & SPR_ILL_TRANS_REASON__I_STREAM_VA_RMASK)
294 address = regs->pc;
295 else
296 address = 0; /* FIXME: GX: single-step for address */
297 break;
298#endif
299 default:
300 panic("Unexpected do_trap interrupt number %d", fault_num);
301 return;
302 }
303
304 info.si_signo = signo;
305 info.si_code = code;
306 info.si_addr = (void __user *)address;
307 if (signo == SIGILL)
308 info.si_trapno = fault_num;
309 force_sig_info(signo, &info, current);
310}
311
312void kernel_double_fault(int dummy, ulong pc, ulong lr, ulong sp, ulong r52)
313{
314 _dump_stack(dummy, pc, lr, sp, r52);
315 pr_emerg("Double fault: exiting\n");
316 machine_halt();
317}
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