core/stack.c - skiboot - Git at Google

 // SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 /*
  * Create/Print backtraces, check stack usage etc.
  *
  * Copyright 2013-2019 IBM Corp.
  */

 #include <skiboot.h>
 #include <processor.h>
 #include <cpu.h>
 #include <stack.h>
 #include <mem_region.h>
 #include <unistd.h>
 #include <lock.h>

 #define STACK_BUF_ENTRIES	60
 static struct bt_entry bt_buf[STACK_BUF_ENTRIES];

 /* Dumps backtrace to buffer */
 static void __nomcount __backtrace_create(struct bt_entry *entries,
 				 unsigned int max_ents,
 				 struct bt_metadata *metadata,
 				 struct stack_frame *eframe)
 {
 	unsigned long *fp = (unsigned long *)eframe;
 	unsigned long top_adj = top_of_ram;

 	/* Assume one stack for early backtraces */
 	if (top_of_ram == SKIBOOT_BASE + SKIBOOT_SIZE)
 		top_adj = top_of_ram + STACK_SIZE;

 	metadata->ents = 0;
 	while (max_ents) {
 		fp = (unsigned long *)fp[0];
 		if (!fp || (unsigned long)fp > top_adj)
 			break;
 		eframe = (struct stack_frame *)fp;
 		if (eframe->magic == STACK_INT_MAGIC) {
 			entries->exception_type = eframe->type;
 			entries->exception_pc = eframe->pc;
 		} else {
 			entries->exception_type = 0;
 		}
 		entries->sp = (unsigned long)fp;
 		entries->pc = fp[2];
 		entries++;
 		metadata->ents++;
 		max_ents--;
 	}

 	metadata->r1_caller = eframe->gpr[1];

 	if (fp)
 		metadata->token = eframe->gpr[0];
 	else
 		metadata->token = -1UL;

 	metadata->pir = mfspr(SPR_PIR);
 }

 void __nomcount backtrace_create(struct bt_entry *entries,
 				 unsigned int max_ents,
 				 struct bt_metadata *metadata)
 {
 	unsigned long *fp = __builtin_frame_address(0);
 	struct stack_frame *eframe = (struct stack_frame *)fp;

 	__backtrace_create(entries, max_ents, metadata, eframe);
 }

 void backtrace_print(struct bt_entry *entries, struct bt_metadata *metadata,
 		     char *out_buf, unsigned int *len, bool symbols)
 {
 	static char bt_text_buf[4096];
 	int i, l = 0, max;
 	char *buf = out_buf;
 	unsigned long bottom, top, normal_top, tbot, ttop;
 	char mark;

 	if (!out_buf) {
 		buf = bt_text_buf;
 		max = sizeof(bt_text_buf) - 16;
 	} else
 		max = *len - 1;

 	bottom = cpu_stack_bottom(metadata->pir);
 	normal_top = cpu_stack_top(metadata->pir);
 	top = cpu_emergency_stack_top(metadata->pir);
 	tbot = SKIBOOT_BASE;
 	ttop = (unsigned long)&_etext;

 	l += snprintf(buf, max, "CPU %04lx Backtrace:\n", metadata->pir);
 	for (i = 0; i < metadata->ents && l < max; i++) {
 		if (entries->sp < bottom || entries->sp > top)
 			mark = '!';
 		else if (entries->sp > normal_top)
 			mark = 'E';
 		else if (entries->pc < tbot || entries->pc > ttop)
 			mark = '*';
 		else
 			mark = ' ';
 		l += snprintf(buf + l, max - l,
 			      " S: %016lx R: %016lx %c ",
 			      entries->sp, entries->pc, mark);
 		if (symbols)
 			l += snprintf_symbol(buf + l, max - l, entries->pc);
 		l += snprintf(buf + l, max - l, "\n");
 		if (entries->exception_type) {
 			l += snprintf(buf + l, max - l,
 				      " --- Interrupt 0x%lx at %016lx ---\n",
 				      entries->exception_type, entries->exception_pc);
 		}
 		entries++;
 	}
 	if (metadata->token <= OPAL_LAST)
 		l += snprintf(buf + l, max - l,
 			      " --- OPAL call token: 0x%lx caller R1: 0x%016lx ---\n",
 			      metadata->token, metadata->r1_caller);
 	else if (metadata->token == -1UL)
 		l += snprintf(buf + l, max - l, " --- OPAL boot ---\n");
 	if (!out_buf)
 		write(stdout->fd, bt_text_buf, l);
 	buf[l++] = 0;
 	if (len)
 		*len = l;
 }

 /*
  * To ensure that we always get backtrace output we bypass the usual console
  * locking paths. The downside is that when multiple threads need to print
  * a backtrace they garble each other. To prevent this we use a seperate
  * lock to serialise printing of the dumps.
  */
 static struct lock bt_lock = LOCK_UNLOCKED;

 void backtrace(void)
 {
 	struct bt_metadata metadata;

 	lock(&bt_lock);

 	backtrace_create(bt_buf, STACK_BUF_ENTRIES, &metadata);
 	backtrace_print(bt_buf, &metadata, NULL, NULL, true);

 	unlock(&bt_lock);
 }

 void backtrace_r1(uint64_t r1)
 {
 	struct bt_metadata metadata;

 	lock(&bt_lock);

 	__backtrace_create(bt_buf, STACK_BUF_ENTRIES, &metadata, (struct stack_frame *)r1);
 	backtrace_print(bt_buf, &metadata, NULL, NULL, true);

 	unlock(&bt_lock);
 }

 void __nomcount __stack_chk_fail(void);
 void __nomcount __stack_chk_fail(void)
 {
 	static bool failed_once;

 	if (failed_once)
 		return;
 	failed_once = true;
 	prlog(PR_EMERG, "Stack corruption detected !\n");
 	abort();
 }

 #ifdef STACK_CHECK_ENABLED

 static int64_t lowest_stack_mark = LONG_MAX;
 static struct lock stack_check_lock = LOCK_UNLOCKED;

 void __nomcount __mcount_stack_check(uint64_t sp, uint64_t lr);
 void __nomcount __mcount_stack_check(uint64_t sp, uint64_t lr)
 {
 	struct cpu_thread *c = this_cpu();
 	uint64_t base = (uint64_t)c;
 	uint64_t bot = base + sizeof(struct cpu_thread);
 	int64_t mark = sp - bot;
 	uint64_t top = base + NORMAL_STACK_SIZE;

 	/*
 	 * Don't check the emergency stack just yet.
 	 */
 	if (c->in_opal_call > 1)
 		return;

 	/*
 	 * Don't re-enter on this CPU or don't enter at all if somebody
 	 * has spotted an overflow
 	 */
 	if (c->in_mcount)
 		return;
 	c->in_mcount = true;

 	/* Capture lowest stack for this thread */
 	if (mark < c->stack_bot_mark) {
 		lock(&stack_check_lock);
 		c->stack_bot_mark = mark;
 		c->stack_bot_pc = lr;
 		c->stack_bot_tok = c->current_token;
 		backtrace_create(c->stack_bot_bt, CPU_BACKTRACE_SIZE,
 				 &c->stack_bot_bt_metadata);
 		unlock(&stack_check_lock);

 		if (mark < STACK_WARNING_GAP) {
 			prlog(PR_EMERG, "CPU %04x Stack usage danger !"
 			      " pc=%08llx sp=%08llx (gap=%lld) token=%lld\n",
 			      c->pir, lr, sp, mark, c->current_token);
 		}
 	}

 	/* Stack is within bounds? */
 	if (sp >= (bot + STACK_SAFETY_GAP) && sp < top) {
 		c->in_mcount = false;
 		return;
 	}

 	prlog(PR_EMERG, "CPU %04x Stack overflow detected !"
 	      " pc=%08llx sp=%08llx (gap=%lld) token=%lld\n",
 	      c->pir, lr, sp, mark, c->current_token);
 	abort();
 }

 void check_stacks(void)
 {
 	struct cpu_thread *c, *lowest = NULL;

 	/* We should never call that from mcount */
 	assert(!this_cpu()->in_mcount);

 	/* Mark ourselves "in_mcount" to avoid deadlock on stack
 	 * check lock
 	 */
 	this_cpu()->in_mcount = true;

 	for_each_cpu(c) {
 		if (!c->stack_bot_mark ||
 		    c->stack_bot_mark >= lowest_stack_mark)
 			continue;
 		lock(&stack_check_lock);
 		if (c->stack_bot_mark < lowest_stack_mark) {
 			lowest = c;
 			lowest_stack_mark = c->stack_bot_mark;
 		}
 		unlock(&stack_check_lock);
 	}
 	if (lowest) {
 		lock(&bt_lock);
 		prlog(PR_NOTICE, "CPU %04x lowest stack mark %lld bytes left"
 		      " pc=%08llx token=%lld\n",
 		      lowest->pir, lowest->stack_bot_mark, lowest->stack_bot_pc,
 		      lowest->stack_bot_tok);
 		backtrace_print(lowest->stack_bot_bt,
 				&lowest->stack_bot_bt_metadata,
 				NULL, NULL, true);
 		unlock(&bt_lock);
 	}

 	this_cpu()->in_mcount = false;
 }
 #endif /* STACK_CHECK_ENABLED */
	// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
	/*
	* Create/Print backtraces, check stack usage etc.
	*
	* Copyright 2013-2019 IBM Corp.
	*/

	#include <skiboot.h>
	#include <processor.h>
	#include <cpu.h>
	#include <stack.h>
	#include <mem_region.h>
	#include <unistd.h>
	#include <lock.h>

	#define STACK_BUF_ENTRIES 60
	static struct bt_entry bt_buf[STACK_BUF_ENTRIES];

	/* Dumps backtrace to buffer */
	static void __nomcount __backtrace_create(struct bt_entry *entries,
	unsigned int max_ents,
	struct bt_metadata *metadata,
	struct stack_frame *eframe)
	{
	unsigned long fp = (unsigned long )eframe;
	unsigned long top_adj = top_of_ram;

	/* Assume one stack for early backtraces */
	if (top_of_ram == SKIBOOT_BASE + SKIBOOT_SIZE)
	top_adj = top_of_ram + STACK_SIZE;

	metadata->ents = 0;
	while (max_ents) {
	fp = (unsigned long *)fp[0];
	if (!fp \|\| (unsigned long)fp > top_adj)
	break;
	eframe = (struct stack_frame *)fp;
	if (eframe->magic == STACK_INT_MAGIC) {
	entries->exception_type = eframe->type;
	entries->exception_pc = eframe->pc;
	} else {
	entries->exception_type = 0;
	}
	entries->sp = (unsigned long)fp;
	entries->pc = fp[2];
	entries++;
	metadata->ents++;
	max_ents--;
	}

	metadata->r1_caller = eframe->gpr[1];

	if (fp)
	metadata->token = eframe->gpr[0];
	else
	metadata->token = -1UL;

	metadata->pir = mfspr(SPR_PIR);
	}

	void __nomcount backtrace_create(struct bt_entry *entries,
	unsigned int max_ents,
	struct bt_metadata *metadata)
	{
	unsigned long *fp = __builtin_frame_address(0);
	struct stack_frame eframe = (struct stack_frame )fp;

	__backtrace_create(entries, max_ents, metadata, eframe);
	}

	void backtrace_print(struct bt_entry entries, struct bt_metadata metadata,
	char out_buf, unsigned int len, bool symbols)
	{
	static char bt_text_buf[4096];
	int i, l = 0, max;
	char *buf = out_buf;
	unsigned long bottom, top, normal_top, tbot, ttop;
	char mark;

	if (!out_buf) {
	buf = bt_text_buf;
	max = sizeof(bt_text_buf) - 16;
	} else
	max = *len - 1;

	bottom = cpu_stack_bottom(metadata->pir);
	normal_top = cpu_stack_top(metadata->pir);
	top = cpu_emergency_stack_top(metadata->pir);
	tbot = SKIBOOT_BASE;
	ttop = (unsigned long)&_etext;

	l += snprintf(buf, max, "CPU %04lx Backtrace:\n", metadata->pir);
	for (i = 0; i < metadata->ents && l < max; i++) {
	if (entries->sp < bottom \|\| entries->sp > top)
	mark = '!';
	else if (entries->sp > normal_top)
	mark = 'E';
	else if (entries->pc < tbot \|\| entries->pc > ttop)
	mark = '*';
	else
	mark = ' ';
	l += snprintf(buf + l, max - l,
	" S: %016lx R: %016lx %c ",
	entries->sp, entries->pc, mark);
	if (symbols)
	l += snprintf_symbol(buf + l, max - l, entries->pc);
	l += snprintf(buf + l, max - l, "\n");
	if (entries->exception_type) {
	l += snprintf(buf + l, max - l,
	" --- Interrupt 0x%lx at %016lx ---\n",
	entries->exception_type, entries->exception_pc);
	}
	entries++;
	}
	if (metadata->token <= OPAL_LAST)
	l += snprintf(buf + l, max - l,
	" --- OPAL call token: 0x%lx caller R1: 0x%016lx ---\n",
	metadata->token, metadata->r1_caller);
	else if (metadata->token == -1UL)
	l += snprintf(buf + l, max - l, " --- OPAL boot ---\n");
	if (!out_buf)
	write(stdout->fd, bt_text_buf, l);
	buf[l++] = 0;
	if (len)
	*len = l;
	}

	/*
	* To ensure that we always get backtrace output we bypass the usual console
	* locking paths. The downside is that when multiple threads need to print
	* a backtrace they garble each other. To prevent this we use a seperate
	* lock to serialise printing of the dumps.
	*/
	static struct lock bt_lock = LOCK_UNLOCKED;

	void backtrace(void)
	{
	struct bt_metadata metadata;

	lock(&bt_lock);

	backtrace_create(bt_buf, STACK_BUF_ENTRIES, &metadata);
	backtrace_print(bt_buf, &metadata, NULL, NULL, true);

	unlock(&bt_lock);
	}

	void backtrace_r1(uint64_t r1)
	{
	struct bt_metadata metadata;

	lock(&bt_lock);

	__backtrace_create(bt_buf, STACK_BUF_ENTRIES, &metadata, (struct stack_frame *)r1);
	backtrace_print(bt_buf, &metadata, NULL, NULL, true);

	unlock(&bt_lock);
	}

	void __nomcount __stack_chk_fail(void);
	void __nomcount __stack_chk_fail(void)
	{
	static bool failed_once;

	if (failed_once)
	return;
	failed_once = true;
	prlog(PR_EMERG, "Stack corruption detected !\n");
	abort();
	}

	#ifdef STACK_CHECK_ENABLED

	static int64_t lowest_stack_mark = LONG_MAX;
	static struct lock stack_check_lock = LOCK_UNLOCKED;

	void __nomcount __mcount_stack_check(uint64_t sp, uint64_t lr);
	void __nomcount __mcount_stack_check(uint64_t sp, uint64_t lr)
	{
	struct cpu_thread *c = this_cpu();
	uint64_t base = (uint64_t)c;
	uint64_t bot = base + sizeof(struct cpu_thread);
	int64_t mark = sp - bot;
	uint64_t top = base + NORMAL_STACK_SIZE;

	/*
	* Don't check the emergency stack just yet.
	*/
	if (c->in_opal_call > 1)
	return;

	/*
	* Don't re-enter on this CPU or don't enter at all if somebody
	* has spotted an overflow
	*/
	if (c->in_mcount)
	return;
	c->in_mcount = true;

	/* Capture lowest stack for this thread */
	if (mark < c->stack_bot_mark) {
	lock(&stack_check_lock);
	c->stack_bot_mark = mark;
	c->stack_bot_pc = lr;
	c->stack_bot_tok = c->current_token;
	backtrace_create(c->stack_bot_bt, CPU_BACKTRACE_SIZE,
	&c->stack_bot_bt_metadata);
	unlock(&stack_check_lock);

	if (mark < STACK_WARNING_GAP) {
	prlog(PR_EMERG, "CPU %04x Stack usage danger !"
	" pc=%08llx sp=%08llx (gap=%lld) token=%lld\n",
	c->pir, lr, sp, mark, c->current_token);
	}
	}

	/* Stack is within bounds? */
	if (sp >= (bot + STACK_SAFETY_GAP) && sp < top) {
	c->in_mcount = false;
	return;
	}

	prlog(PR_EMERG, "CPU %04x Stack overflow detected !"
	" pc=%08llx sp=%08llx (gap=%lld) token=%lld\n",
	c->pir, lr, sp, mark, c->current_token);
	abort();
	}

	void check_stacks(void)
	{
	struct cpu_thread c, lowest = NULL;

	/* We should never call that from mcount */
	assert(!this_cpu()->in_mcount);

	/* Mark ourselves "in_mcount" to avoid deadlock on stack
	* check lock
	*/
	this_cpu()->in_mcount = true;

	for_each_cpu(c) {
	if (!c->stack_bot_mark \|\|
	c->stack_bot_mark >= lowest_stack_mark)
	continue;
	lock(&stack_check_lock);
	if (c->stack_bot_mark < lowest_stack_mark) {
	lowest = c;
	lowest_stack_mark = c->stack_bot_mark;
	}
	unlock(&stack_check_lock);
	}
	if (lowest) {
	lock(&bt_lock);
	prlog(PR_NOTICE, "CPU %04x lowest stack mark %lld bytes left"
	" pc=%08llx token=%lld\n",
	lowest->pir, lowest->stack_bot_mark, lowest->stack_bot_pc,
	lowest->stack_bot_tok);
	backtrace_print(lowest->stack_bot_bt,
	&lowest->stack_bot_bt_metadata,
	NULL, NULL, true);
	unlock(&bt_lock);
	}

	this_cpu()->in_mcount = false;
	}
	#endif /* STACK_CHECK_ENABLED */