diff options
Diffstat (limited to 'core/stack.c')
| -rw-r--r-- | core/stack.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/core/stack.c b/core/stack.c new file mode 100644 index 0000000..0d8a7eb --- /dev/null +++ b/core/stack.c @@ -0,0 +1,184 @@ +/* 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> + +#define STACK_BUF_ENTRIES 20 +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 int i = 1; /* Start at level 1 */ + + *count = 0; + while(room) { + unsigned long pc, + fp = (unsigned long)__builtin_frame_address(i); + if (!fp) + break; + pc = (unsigned long)__builtin_return_address(i); + entries->sp = fp; + entries->pc = pc; + entries++; + *count = (*count) + 1; + room--; + } +} + +void __print_backtrace(unsigned int pir, + struct bt_entry *entries, unsigned int count, + char *out_buf, unsigned int *len) +{ + int i, l = 0, max; + char *buf = out_buf; + unsigned long bottom, top, tbot, ttop; + char mark; + + if (len) + max = *len - 1; + else + max = INT_MAX; + + bottom = cpu_stack_bottom(pir); + top = cpu_stack_top(pir); + tbot = (unsigned long)&_stext; + ttop = (unsigned long)&_etext; + + if (buf) + l += snprintf(buf, max, "CPU %04x Backtrace:\n", pir); + else + l += printf("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 (buf) + l += snprintf(buf + l, max - l, + " S: %016lx R: %016lx %c\n", + entries->sp, entries->pc, mark); + else + l += printf(" S: %016lx R: %016lx %c\n", + entries->sp, entries->pc, mark); + entries++; + } + if (buf) + buf[l++] = 0; + else + l++; + 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); +} + +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 + +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) { + c->stack_bot_mark = mark; + c->stack_bot_pc = lr; + c->stack_bot_tok = c->current_token; + } + + /* 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(); +} + +static int64_t lowest_stack_mark = LONG_MAX; +static struct lock stack_check_lock = LOCK_UNLOCKED; + +void check_stacks(void) +{ + struct cpu_thread *c; + uint64_t lmark, lpc, ltok; + int found = -1; + + 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) { + unlock(&stack_check_lock); + continue; + } + lmark = lowest_stack_mark = c->stack_bot_mark; + lpc = c->stack_bot_pc; + ltok = c->stack_bot_tok; + found = c->pir; + unlock(&stack_check_lock); + } + if (found >= 0) + prlog(PR_NOTICE, "CPU %04x lowest stack mark %lld bytes left" + " pc=%08llx token=%lld\n", found, lmark, lpc, ltok); +} + +#endif /* STACK_CHECK_ENABLED */ |