1/*
2 * Machine check exception handling.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright 2013 IBM Corporation
19 * Author: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
20 */
21
22#undef DEBUG
23#define pr_fmt(fmt) "mce: " fmt
24
25#include <linux/types.h>
26#include <linux/ptrace.h>
27#include <linux/percpu.h>
28#include <linux/export.h>
29#include <linux/irq_work.h>
30#include <asm/mce.h>
31
32static DEFINE_PER_CPU(int, mce_nest_count);
33static DEFINE_PER_CPU(struct machine_check_event[MAX_MC_EVT], mce_event);
34
35/* Queue for delayed MCE events. */
36static DEFINE_PER_CPU(int, mce_queue_count);
37static DEFINE_PER_CPU(struct machine_check_event[MAX_MC_EVT], mce_event_queue);
38
39static void machine_check_process_queued_event(struct irq_work *work);
40struct irq_work mce_event_process_work = {
41        .func = machine_check_process_queued_event,
42};
43
44static void mce_set_error_info(struct machine_check_event *mce,
45			       struct mce_error_info *mce_err)
46{
47	mce->error_type = mce_err->error_type;
48	switch (mce_err->error_type) {
49	case MCE_ERROR_TYPE_UE:
50		mce->u.ue_error.ue_error_type = mce_err->u.ue_error_type;
51		break;
52	case MCE_ERROR_TYPE_SLB:
53		mce->u.slb_error.slb_error_type = mce_err->u.slb_error_type;
54		break;
55	case MCE_ERROR_TYPE_ERAT:
56		mce->u.erat_error.erat_error_type = mce_err->u.erat_error_type;
57		break;
58	case MCE_ERROR_TYPE_TLB:
59		mce->u.tlb_error.tlb_error_type = mce_err->u.tlb_error_type;
60		break;
61	case MCE_ERROR_TYPE_UNKNOWN:
62	default:
63		break;
64	}
65}
66
67/*
68 * Decode and save high level MCE information into per cpu buffer which
69 * is an array of machine_check_event structure.
70 */
71void save_mce_event(struct pt_regs *regs, long handled,
72		    struct mce_error_info *mce_err,
73		    uint64_t nip, uint64_t addr)
74{
75	uint64_t srr1;
76	int index = __this_cpu_inc_return(mce_nest_count) - 1;
77	struct machine_check_event *mce = this_cpu_ptr(&mce_event[index]);
78
79	/*
80	 * Return if we don't have enough space to log mce event.
81	 * mce_nest_count may go beyond MAX_MC_EVT but that's ok,
82	 * the check below will stop buffer overrun.
83	 */
84	if (index >= MAX_MC_EVT)
85		return;
86
87	/* Populate generic machine check info */
88	mce->version = MCE_V1;
89	mce->srr0 = nip;
90	mce->srr1 = regs->msr;
91	mce->gpr3 = regs->gpr[3];
92	mce->in_use = 1;
93
94	mce->initiator = MCE_INITIATOR_CPU;
95	if (handled)
96		mce->disposition = MCE_DISPOSITION_RECOVERED;
97	else
98		mce->disposition = MCE_DISPOSITION_NOT_RECOVERED;
99	mce->severity = MCE_SEV_ERROR_SYNC;
100
101	srr1 = regs->msr;
102
103	/*
104	 * Populate the mce error_type and type-specific error_type.
105	 */
106	mce_set_error_info(mce, mce_err);
107
108	if (!addr)
109		return;
110
111	if (mce->error_type == MCE_ERROR_TYPE_TLB) {
112		mce->u.tlb_error.effective_address_provided = true;
113		mce->u.tlb_error.effective_address = addr;
114	} else if (mce->error_type == MCE_ERROR_TYPE_SLB) {
115		mce->u.slb_error.effective_address_provided = true;
116		mce->u.slb_error.effective_address = addr;
117	} else if (mce->error_type == MCE_ERROR_TYPE_ERAT) {
118		mce->u.erat_error.effective_address_provided = true;
119		mce->u.erat_error.effective_address = addr;
120	} else if (mce->error_type == MCE_ERROR_TYPE_UE) {
121		mce->u.ue_error.effective_address_provided = true;
122		mce->u.ue_error.effective_address = addr;
123	}
124	return;
125}
126
127/*
128 * get_mce_event:
129 *	mce	Pointer to machine_check_event structure to be filled.
130 *	release Flag to indicate whether to free the event slot or not.
131 *		0 <= do not release the mce event. Caller will invoke
132 *		     release_mce_event() once event has been consumed.
133 *		1 <= release the slot.
134 *
135 *	return	1 = success
136 *		0 = failure
137 *
138 * get_mce_event() will be called by platform specific machine check
139 * handle routine and in KVM.
140 * When we call get_mce_event(), we are still in interrupt context and
141 * preemption will not be scheduled until ret_from_expect() routine
142 * is called.
143 */
144int get_mce_event(struct machine_check_event *mce, bool release)
145{
146	int index = __this_cpu_read(mce_nest_count) - 1;
147	struct machine_check_event *mc_evt;
148	int ret = 0;
149
150	/* Sanity check */
151	if (index < 0)
152		return ret;
153
154	/* Check if we have MCE info to process. */
155	if (index < MAX_MC_EVT) {
156		mc_evt = this_cpu_ptr(&mce_event[index]);
157		/* Copy the event structure and release the original */
158		if (mce)
159			*mce = *mc_evt;
160		if (release)
161			mc_evt->in_use = 0;
162		ret = 1;
163	}
164	/* Decrement the count to free the slot. */
165	if (release)
166		__this_cpu_dec(mce_nest_count);
167
168	return ret;
169}
170
171void release_mce_event(void)
172{
173	get_mce_event(NULL, true);
174}
175
176/*
177 * Queue up the MCE event which then can be handled later.
178 */
179void machine_check_queue_event(void)
180{
181	int index;
182	struct machine_check_event evt;
183
184	if (!get_mce_event(&evt, MCE_EVENT_RELEASE))
185		return;
186
187	index = __this_cpu_inc_return(mce_queue_count) - 1;
188	/* If queue is full, just return for now. */
189	if (index >= MAX_MC_EVT) {
190		__this_cpu_dec(mce_queue_count);
191		return;
192	}
193	memcpy(this_cpu_ptr(&mce_event_queue[index]), &evt, sizeof(evt));
194
195	/* Queue irq work to process this event later. */
196	irq_work_queue(&mce_event_process_work);
197}
198
199/*
200 * process pending MCE event from the mce event queue. This function will be
201 * called during syscall exit.
202 */
203static void machine_check_process_queued_event(struct irq_work *work)
204{
205	int index;
206
207	/*
208	 * For now just print it to console.
209	 * TODO: log this error event to FSP or nvram.
210	 */
211	while (__this_cpu_read(mce_queue_count) > 0) {
212		index = __this_cpu_read(mce_queue_count) - 1;
213		machine_check_print_event_info(
214				this_cpu_ptr(&mce_event_queue[index]));
215		__this_cpu_dec(mce_queue_count);
216	}
217}
218
219void machine_check_print_event_info(struct machine_check_event *evt)
220{
221	const char *level, *sevstr, *subtype;
222	static const char *mc_ue_types[] = {
223		"Indeterminate",
224		"Instruction fetch",
225		"Page table walk ifetch",
226		"Load/Store",
227		"Page table walk Load/Store",
228	};
229	static const char *mc_slb_types[] = {
230		"Indeterminate",
231		"Parity",
232		"Multihit",
233	};
234	static const char *mc_erat_types[] = {
235		"Indeterminate",
236		"Parity",
237		"Multihit",
238	};
239	static const char *mc_tlb_types[] = {
240		"Indeterminate",
241		"Parity",
242		"Multihit",
243	};
244
245	/* Print things out */
246	if (evt->version != MCE_V1) {
247		pr_err("Machine Check Exception, Unknown event version %d !\n",
248		       evt->version);
249		return;
250	}
251	switch (evt->severity) {
252	case MCE_SEV_NO_ERROR:
253		level = KERN_INFO;
254		sevstr = "Harmless";
255		break;
256	case MCE_SEV_WARNING:
257		level = KERN_WARNING;
258		sevstr = "";
259		break;
260	case MCE_SEV_ERROR_SYNC:
261		level = KERN_ERR;
262		sevstr = "Severe";
263		break;
264	case MCE_SEV_FATAL:
265	default:
266		level = KERN_ERR;
267		sevstr = "Fatal";
268		break;
269	}
270
271	printk("%s%s Machine check interrupt [%s]\n", level, sevstr,
272	       evt->disposition == MCE_DISPOSITION_RECOVERED ?
273	       "Recovered" : "[Not recovered");
274	printk("%s  Initiator: %s\n", level,
275	       evt->initiator == MCE_INITIATOR_CPU ? "CPU" : "Unknown");
276	switch (evt->error_type) {
277	case MCE_ERROR_TYPE_UE:
278		subtype = evt->u.ue_error.ue_error_type <
279			ARRAY_SIZE(mc_ue_types) ?
280			mc_ue_types[evt->u.ue_error.ue_error_type]
281			: "Unknown";
282		printk("%s  Error type: UE [%s]\n", level, subtype);
283		if (evt->u.ue_error.effective_address_provided)
284			printk("%s    Effective address: %016llx\n",
285			       level, evt->u.ue_error.effective_address);
286		if (evt->u.ue_error.physical_address_provided)
287			printk("%s      Physial address: %016llx\n",
288			       level, evt->u.ue_error.physical_address);
289		break;
290	case MCE_ERROR_TYPE_SLB:
291		subtype = evt->u.slb_error.slb_error_type <
292			ARRAY_SIZE(mc_slb_types) ?
293			mc_slb_types[evt->u.slb_error.slb_error_type]
294			: "Unknown";
295		printk("%s  Error type: SLB [%s]\n", level, subtype);
296		if (evt->u.slb_error.effective_address_provided)
297			printk("%s    Effective address: %016llx\n",
298			       level, evt->u.slb_error.effective_address);
299		break;
300	case MCE_ERROR_TYPE_ERAT:
301		subtype = evt->u.erat_error.erat_error_type <
302			ARRAY_SIZE(mc_erat_types) ?
303			mc_erat_types[evt->u.erat_error.erat_error_type]
304			: "Unknown";
305		printk("%s  Error type: ERAT [%s]\n", level, subtype);
306		if (evt->u.erat_error.effective_address_provided)
307			printk("%s    Effective address: %016llx\n",
308			       level, evt->u.erat_error.effective_address);
309		break;
310	case MCE_ERROR_TYPE_TLB:
311		subtype = evt->u.tlb_error.tlb_error_type <
312			ARRAY_SIZE(mc_tlb_types) ?
313			mc_tlb_types[evt->u.tlb_error.tlb_error_type]
314			: "Unknown";
315		printk("%s  Error type: TLB [%s]\n", level, subtype);
316		if (evt->u.tlb_error.effective_address_provided)
317			printk("%s    Effective address: %016llx\n",
318			       level, evt->u.tlb_error.effective_address);
319		break;
320	default:
321	case MCE_ERROR_TYPE_UNKNOWN:
322		printk("%s  Error type: Unknown\n", level);
323		break;
324	}
325}
326
327uint64_t get_mce_fault_addr(struct machine_check_event *evt)
328{
329	switch (evt->error_type) {
330	case MCE_ERROR_TYPE_UE:
331		if (evt->u.ue_error.effective_address_provided)
332			return evt->u.ue_error.effective_address;
333		break;
334	case MCE_ERROR_TYPE_SLB:
335		if (evt->u.slb_error.effective_address_provided)
336			return evt->u.slb_error.effective_address;
337		break;
338	case MCE_ERROR_TYPE_ERAT:
339		if (evt->u.erat_error.effective_address_provided)
340			return evt->u.erat_error.effective_address;
341		break;
342	case MCE_ERROR_TYPE_TLB:
343		if (evt->u.tlb_error.effective_address_provided)
344			return evt->u.tlb_error.effective_address;
345		break;
346	default:
347	case MCE_ERROR_TYPE_UNKNOWN:
348		break;
349	}
350	return 0;
351}
352EXPORT_SYMBOL(get_mce_fault_addr);
353