74ffe79ae5
Mostly unwind is done with irqs enabled however SLUB may call it with
irqs disabled while creating a new SLUB cache.
I had system freeze while loading a module which called
kmem_cache_create() on init. That means SLUB's __slab_alloc() disabled
interrupts and then
->new_slab_objects()
->new_slab()
->setup_object()
->setup_object_debug()
->init_tracking()
->set_track()
->save_stack_trace()
->save_stack_trace_tsk()
->walk_stackframe()
->unwind_frame()
->unwind_find_idx()
=>spin_lock_irqsave(&unwind_lock);
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
552 lines
14 KiB
C
552 lines
14 KiB
C
/*
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* arch/arm/kernel/unwind.c
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*
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* Copyright (C) 2008 ARM Limited
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*
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* Stack unwinding support for ARM
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*
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* An ARM EABI version of gcc is required to generate the unwind
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* tables. For information about the structure of the unwind tables,
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* see "Exception Handling ABI for the ARM Architecture" at:
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*
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* http://infocenter.arm.com/help/topic/com.arm.doc.subset.swdev.abi/index.html
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*/
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#ifndef __CHECKER__
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#if !defined (__ARM_EABI__)
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#warning Your compiler does not have EABI support.
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#warning ARM unwind is known to compile only with EABI compilers.
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#warning Change compiler or disable ARM_UNWIND option.
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#elif (__GNUC__ == 4 && __GNUC_MINOR__ <= 2) && !defined(__clang__)
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#warning Your compiler is too buggy; it is known to not compile ARM unwind support.
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#warning Change compiler or disable ARM_UNWIND option.
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#endif
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#endif /* __CHECKER__ */
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/export.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/list.h>
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#include <asm/stacktrace.h>
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#include <asm/traps.h>
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#include <asm/unwind.h>
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/* Dummy functions to avoid linker complaints */
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void __aeabi_unwind_cpp_pr0(void)
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{
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};
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EXPORT_SYMBOL(__aeabi_unwind_cpp_pr0);
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void __aeabi_unwind_cpp_pr1(void)
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{
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};
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EXPORT_SYMBOL(__aeabi_unwind_cpp_pr1);
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void __aeabi_unwind_cpp_pr2(void)
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{
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};
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EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2);
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struct unwind_ctrl_block {
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unsigned long vrs[16]; /* virtual register set */
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const unsigned long *insn; /* pointer to the current instructions word */
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unsigned long sp_high; /* highest value of sp allowed */
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/*
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* 1 : check for stack overflow for each register pop.
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* 0 : save overhead if there is plenty of stack remaining.
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*/
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int check_each_pop;
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int entries; /* number of entries left to interpret */
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int byte; /* current byte number in the instructions word */
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};
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enum regs {
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#ifdef CONFIG_THUMB2_KERNEL
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FP = 7,
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#else
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FP = 11,
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#endif
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SP = 13,
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LR = 14,
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PC = 15
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};
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extern const struct unwind_idx __start_unwind_idx[];
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static const struct unwind_idx *__origin_unwind_idx;
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extern const struct unwind_idx __stop_unwind_idx[];
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static DEFINE_RAW_SPINLOCK(unwind_lock);
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static LIST_HEAD(unwind_tables);
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/* Convert a prel31 symbol to an absolute address */
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#define prel31_to_addr(ptr) \
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({ \
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/* sign-extend to 32 bits */ \
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long offset = (((long)*(ptr)) << 1) >> 1; \
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(unsigned long)(ptr) + offset; \
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})
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/*
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* Binary search in the unwind index. The entries are
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* guaranteed to be sorted in ascending order by the linker.
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*
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* start = first entry
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* origin = first entry with positive offset (or stop if there is no such entry)
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* stop - 1 = last entry
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*/
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static const struct unwind_idx *search_index(unsigned long addr,
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const struct unwind_idx *start,
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const struct unwind_idx *origin,
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const struct unwind_idx *stop)
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{
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unsigned long addr_prel31;
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pr_debug("%s(%08lx, %p, %p, %p)\n",
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__func__, addr, start, origin, stop);
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/*
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* only search in the section with the matching sign. This way the
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* prel31 numbers can be compared as unsigned longs.
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*/
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if (addr < (unsigned long)start)
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/* negative offsets: [start; origin) */
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stop = origin;
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else
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/* positive offsets: [origin; stop) */
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start = origin;
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/* prel31 for address relavive to start */
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addr_prel31 = (addr - (unsigned long)start) & 0x7fffffff;
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while (start < stop - 1) {
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const struct unwind_idx *mid = start + ((stop - start) >> 1);
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/*
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* As addr_prel31 is relative to start an offset is needed to
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* make it relative to mid.
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*/
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if (addr_prel31 - ((unsigned long)mid - (unsigned long)start) <
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mid->addr_offset)
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stop = mid;
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else {
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/* keep addr_prel31 relative to start */
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addr_prel31 -= ((unsigned long)mid -
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(unsigned long)start);
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start = mid;
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}
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}
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if (likely(start->addr_offset <= addr_prel31))
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return start;
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else {
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pr_warn("unwind: Unknown symbol address %08lx\n", addr);
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return NULL;
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}
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}
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static const struct unwind_idx *unwind_find_origin(
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const struct unwind_idx *start, const struct unwind_idx *stop)
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{
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pr_debug("%s(%p, %p)\n", __func__, start, stop);
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while (start < stop) {
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const struct unwind_idx *mid = start + ((stop - start) >> 1);
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if (mid->addr_offset >= 0x40000000)
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/* negative offset */
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start = mid + 1;
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else
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/* positive offset */
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stop = mid;
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}
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pr_debug("%s -> %p\n", __func__, stop);
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return stop;
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}
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static const struct unwind_idx *unwind_find_idx(unsigned long addr)
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{
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const struct unwind_idx *idx = NULL;
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unsigned long flags;
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pr_debug("%s(%08lx)\n", __func__, addr);
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if (core_kernel_text(addr)) {
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if (unlikely(!__origin_unwind_idx))
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__origin_unwind_idx =
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unwind_find_origin(__start_unwind_idx,
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__stop_unwind_idx);
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/* main unwind table */
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idx = search_index(addr, __start_unwind_idx,
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__origin_unwind_idx,
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__stop_unwind_idx);
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} else {
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/* module unwind tables */
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struct unwind_table *table;
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raw_spin_lock_irqsave(&unwind_lock, flags);
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list_for_each_entry(table, &unwind_tables, list) {
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if (addr >= table->begin_addr &&
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addr < table->end_addr) {
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idx = search_index(addr, table->start,
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table->origin,
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table->stop);
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/* Move-to-front to exploit common traces */
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list_move(&table->list, &unwind_tables);
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break;
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}
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}
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raw_spin_unlock_irqrestore(&unwind_lock, flags);
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}
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pr_debug("%s: idx = %p\n", __func__, idx);
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return idx;
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}
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static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl)
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{
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unsigned long ret;
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if (ctrl->entries <= 0) {
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pr_warn("unwind: Corrupt unwind table\n");
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return 0;
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}
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ret = (*ctrl->insn >> (ctrl->byte * 8)) & 0xff;
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if (ctrl->byte == 0) {
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ctrl->insn++;
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ctrl->entries--;
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ctrl->byte = 3;
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} else
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ctrl->byte--;
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return ret;
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}
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/* Before poping a register check whether it is feasible or not */
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static int unwind_pop_register(struct unwind_ctrl_block *ctrl,
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unsigned long **vsp, unsigned int reg)
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{
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if (unlikely(ctrl->check_each_pop))
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if (*vsp >= (unsigned long *)ctrl->sp_high)
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return -URC_FAILURE;
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ctrl->vrs[reg] = *(*vsp)++;
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return URC_OK;
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}
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/* Helper functions to execute the instructions */
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static int unwind_exec_pop_subset_r4_to_r13(struct unwind_ctrl_block *ctrl,
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unsigned long mask)
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{
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unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
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int load_sp, reg = 4;
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load_sp = mask & (1 << (13 - 4));
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while (mask) {
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if (mask & 1)
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if (unwind_pop_register(ctrl, &vsp, reg))
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return -URC_FAILURE;
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mask >>= 1;
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reg++;
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}
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if (!load_sp)
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ctrl->vrs[SP] = (unsigned long)vsp;
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return URC_OK;
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}
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static int unwind_exec_pop_r4_to_rN(struct unwind_ctrl_block *ctrl,
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unsigned long insn)
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{
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unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
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int reg;
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/* pop R4-R[4+bbb] */
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for (reg = 4; reg <= 4 + (insn & 7); reg++)
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if (unwind_pop_register(ctrl, &vsp, reg))
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return -URC_FAILURE;
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if (insn & 0x8)
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if (unwind_pop_register(ctrl, &vsp, 14))
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return -URC_FAILURE;
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ctrl->vrs[SP] = (unsigned long)vsp;
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return URC_OK;
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}
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static int unwind_exec_pop_subset_r0_to_r3(struct unwind_ctrl_block *ctrl,
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unsigned long mask)
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{
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unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
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int reg = 0;
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/* pop R0-R3 according to mask */
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while (mask) {
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if (mask & 1)
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if (unwind_pop_register(ctrl, &vsp, reg))
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return -URC_FAILURE;
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mask >>= 1;
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reg++;
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}
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ctrl->vrs[SP] = (unsigned long)vsp;
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return URC_OK;
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}
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/*
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* Execute the current unwind instruction.
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*/
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static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
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{
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unsigned long insn = unwind_get_byte(ctrl);
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int ret = URC_OK;
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pr_debug("%s: insn = %08lx\n", __func__, insn);
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if ((insn & 0xc0) == 0x00)
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ctrl->vrs[SP] += ((insn & 0x3f) << 2) + 4;
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else if ((insn & 0xc0) == 0x40)
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ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4;
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else if ((insn & 0xf0) == 0x80) {
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unsigned long mask;
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insn = (insn << 8) | unwind_get_byte(ctrl);
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mask = insn & 0x0fff;
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if (mask == 0) {
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pr_warn("unwind: 'Refuse to unwind' instruction %04lx\n",
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insn);
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return -URC_FAILURE;
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}
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ret = unwind_exec_pop_subset_r4_to_r13(ctrl, mask);
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if (ret)
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goto error;
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} else if ((insn & 0xf0) == 0x90 &&
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(insn & 0x0d) != 0x0d)
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ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f];
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else if ((insn & 0xf0) == 0xa0) {
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ret = unwind_exec_pop_r4_to_rN(ctrl, insn);
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if (ret)
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goto error;
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} else if (insn == 0xb0) {
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if (ctrl->vrs[PC] == 0)
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ctrl->vrs[PC] = ctrl->vrs[LR];
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/* no further processing */
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ctrl->entries = 0;
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} else if (insn == 0xb1) {
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unsigned long mask = unwind_get_byte(ctrl);
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if (mask == 0 || mask & 0xf0) {
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pr_warn("unwind: Spare encoding %04lx\n",
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(insn << 8) | mask);
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return -URC_FAILURE;
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}
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ret = unwind_exec_pop_subset_r0_to_r3(ctrl, mask);
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if (ret)
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goto error;
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} else if (insn == 0xb2) {
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unsigned long uleb128 = unwind_get_byte(ctrl);
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ctrl->vrs[SP] += 0x204 + (uleb128 << 2);
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} else {
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pr_warn("unwind: Unhandled instruction %02lx\n", insn);
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return -URC_FAILURE;
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}
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pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__,
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ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]);
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error:
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return ret;
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}
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/*
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* Unwind a single frame starting with *sp for the symbol at *pc. It
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* updates the *pc and *sp with the new values.
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*/
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int unwind_frame(struct stackframe *frame)
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{
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unsigned long low;
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const struct unwind_idx *idx;
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struct unwind_ctrl_block ctrl;
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/* store the highest address on the stack to avoid crossing it*/
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low = frame->sp;
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ctrl.sp_high = ALIGN(low, THREAD_SIZE);
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pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__,
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frame->pc, frame->lr, frame->sp);
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if (!kernel_text_address(frame->pc))
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return -URC_FAILURE;
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idx = unwind_find_idx(frame->pc);
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if (!idx) {
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pr_warn("unwind: Index not found %08lx\n", frame->pc);
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return -URC_FAILURE;
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}
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ctrl.vrs[FP] = frame->fp;
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ctrl.vrs[SP] = frame->sp;
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ctrl.vrs[LR] = frame->lr;
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ctrl.vrs[PC] = 0;
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if (idx->insn == 1)
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/* can't unwind */
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return -URC_FAILURE;
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else if ((idx->insn & 0x80000000) == 0)
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/* prel31 to the unwind table */
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ctrl.insn = (unsigned long *)prel31_to_addr(&idx->insn);
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else if ((idx->insn & 0xff000000) == 0x80000000)
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/* only personality routine 0 supported in the index */
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ctrl.insn = &idx->insn;
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else {
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pr_warn("unwind: Unsupported personality routine %08lx in the index at %p\n",
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idx->insn, idx);
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return -URC_FAILURE;
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}
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/* check the personality routine */
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if ((*ctrl.insn & 0xff000000) == 0x80000000) {
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ctrl.byte = 2;
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ctrl.entries = 1;
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} else if ((*ctrl.insn & 0xff000000) == 0x81000000) {
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ctrl.byte = 1;
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ctrl.entries = 1 + ((*ctrl.insn & 0x00ff0000) >> 16);
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} else {
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pr_warn("unwind: Unsupported personality routine %08lx at %p\n",
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*ctrl.insn, ctrl.insn);
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return -URC_FAILURE;
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}
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ctrl.check_each_pop = 0;
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while (ctrl.entries > 0) {
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int urc;
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if ((ctrl.sp_high - ctrl.vrs[SP]) < sizeof(ctrl.vrs))
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ctrl.check_each_pop = 1;
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urc = unwind_exec_insn(&ctrl);
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if (urc < 0)
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return urc;
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if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= ctrl.sp_high)
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return -URC_FAILURE;
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}
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if (ctrl.vrs[PC] == 0)
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ctrl.vrs[PC] = ctrl.vrs[LR];
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/* check for infinite loop */
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if (frame->pc == ctrl.vrs[PC])
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return -URC_FAILURE;
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frame->fp = ctrl.vrs[FP];
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frame->sp = ctrl.vrs[SP];
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frame->lr = ctrl.vrs[LR];
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frame->pc = ctrl.vrs[PC];
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return URC_OK;
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}
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void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk)
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{
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struct stackframe frame;
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pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
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if (!tsk)
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tsk = current;
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if (regs) {
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arm_get_current_stackframe(regs, &frame);
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/* PC might be corrupted, use LR in that case. */
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if (!kernel_text_address(regs->ARM_pc))
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frame.pc = regs->ARM_lr;
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} else if (tsk == current) {
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frame.fp = (unsigned long)__builtin_frame_address(0);
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frame.sp = current_stack_pointer;
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frame.lr = (unsigned long)__builtin_return_address(0);
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frame.pc = (unsigned long)unwind_backtrace;
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} else {
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/* task blocked in __switch_to */
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frame.fp = thread_saved_fp(tsk);
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frame.sp = thread_saved_sp(tsk);
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/*
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* The function calling __switch_to cannot be a leaf function
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* so LR is recovered from the stack.
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*/
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frame.lr = 0;
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frame.pc = thread_saved_pc(tsk);
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}
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while (1) {
|
|
int urc;
|
|
unsigned long where = frame.pc;
|
|
|
|
urc = unwind_frame(&frame);
|
|
if (urc < 0)
|
|
break;
|
|
dump_backtrace_entry(where, frame.pc, frame.sp - 4);
|
|
}
|
|
}
|
|
|
|
struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
|
|
unsigned long text_addr,
|
|
unsigned long text_size)
|
|
{
|
|
unsigned long flags;
|
|
struct unwind_table *tab = kmalloc(sizeof(*tab), GFP_KERNEL);
|
|
|
|
pr_debug("%s(%08lx, %08lx, %08lx, %08lx)\n", __func__, start, size,
|
|
text_addr, text_size);
|
|
|
|
if (!tab)
|
|
return tab;
|
|
|
|
tab->start = (const struct unwind_idx *)start;
|
|
tab->stop = (const struct unwind_idx *)(start + size);
|
|
tab->origin = unwind_find_origin(tab->start, tab->stop);
|
|
tab->begin_addr = text_addr;
|
|
tab->end_addr = text_addr + text_size;
|
|
|
|
raw_spin_lock_irqsave(&unwind_lock, flags);
|
|
list_add_tail(&tab->list, &unwind_tables);
|
|
raw_spin_unlock_irqrestore(&unwind_lock, flags);
|
|
|
|
return tab;
|
|
}
|
|
|
|
void unwind_table_del(struct unwind_table *tab)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (!tab)
|
|
return;
|
|
|
|
raw_spin_lock_irqsave(&unwind_lock, flags);
|
|
list_del(&tab->list);
|
|
raw_spin_unlock_irqrestore(&unwind_lock, flags);
|
|
|
|
kfree(tab);
|
|
}
|