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/* Copyright 2013-2014 IBM Corp.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <skiboot.h>
#include <processor.h>
#include <cpu.h>
#include <stack.h>
#include <mem_region.h>
#include <unistd.h>
#define STACK_BUF_ENTRIES 60
static struct bt_entry bt_buf[STACK_BUF_ENTRIES];
extern uint32_t _stext, _etext;
/* Dumps backtrace to buffer */
void __nomcount __backtrace(struct bt_entry *entries, unsigned int *count)
{
unsigned int room = *count;
unsigned long *fp = __builtin_frame_address(0);
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;
*count = 0;
while(room) {
fp = (unsigned long *)fp[0];
if (!fp || (unsigned long)fp > top_adj)
break;
entries->sp = (unsigned long)fp;
entries->pc = fp[2];
entries++;
*count = (*count) + 1;
room--;
}
}
void __print_backtrace(unsigned int pir,
struct bt_entry *entries, unsigned int count,
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, tbot, ttop, saddr = 0;
char *sym = NULL, *sym_end = NULL;
char mark;
if (!out_buf) {
buf = bt_text_buf;
max = sizeof(bt_text_buf) - 16;
} else
max = *len - 1;
bottom = cpu_stack_bottom(pir);
top = cpu_stack_top(pir);
tbot = SKIBOOT_BASE;
ttop = (unsigned long)&_etext;
l += snprintf(buf, max, "CPU %04x Backtrace:\n", pir);
for (i = 0; i < count && l < max; i++) {
if (entries->sp < bottom || entries->sp > top)
mark = '!';
else if (entries->pc < tbot || entries->pc > ttop)
mark = '*';
else
mark = ' ';
if (symbols)
saddr = get_symbol(entries->pc, &sym, &sym_end);
else
saddr = 0;
l += snprintf(buf + l, max - l,
" S: %016lx R: %016lx %c ",
entries->sp, entries->pc, mark);
while(saddr && sym < sym_end && l < max)
buf[l++] = *(sym++);
if (sym && l < max)
l += snprintf(buf + l, max - l, "+0x%lx\n",
entries->pc - saddr);
else
l += snprintf(buf + l, max - l, "\n");
entries++;
}
if (!out_buf)
write(stdout->fd, bt_text_buf, l);
buf[l++] = 0;
if (len)
*len = l;
}
void backtrace(void)
{
unsigned int ents = STACK_BUF_ENTRIES;
__backtrace(bt_buf, &ents);
__print_backtrace(mfspr(SPR_PIR), bt_buf, ents, NULL, NULL, true);
}
void __noreturn __nomcount __stack_chk_fail(void);
void __noreturn __nomcount __stack_chk_fail(void)
{
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 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) {
unsigned int count = CPU_BACKTRACE_SIZE;
lock(&stack_check_lock);
c->stack_bot_mark = mark;
c->stack_bot_pc = lr;
c->stack_bot_tok = c->current_token;
__backtrace(c->stack_bot_bt, &count);
c->stack_bot_bt_count = count;
unlock(&stack_check_lock);
}
/* Stack is within bounds ? check for warning and bail */
if (sp >= (bot + STACK_SAFETY_GAP) && sp < top) {
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);
backtrace();
}
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(&stack_check_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);
__print_backtrace(lowest->pir, lowest->stack_bot_bt,
lowest->stack_bot_bt_count, NULL, NULL, true);
unlock(&stack_check_lock);
}
this_cpu()->in_mcount = false;
}
#endif /* STACK_CHECK_ENABLED */
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