mirror of https://gitee.com/openkylin/linux.git
755 lines
17 KiB
C
755 lines
17 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Post mortem Dwarf CFI based unwinding on top of regs and stack dumps.
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*
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* Lots of this code have been borrowed or heavily inspired from parts of
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* the libunwind 0.99 code which are (amongst other contributors I may have
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* forgotten):
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*
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* Copyright (C) 2002-2007 Hewlett-Packard Co
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* Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
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*
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* And the bugs have been added by:
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*
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* Copyright (C) 2010, Frederic Weisbecker <fweisbec@gmail.com>
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* Copyright (C) 2012, Jiri Olsa <jolsa@redhat.com>
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*
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*/
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#include <elf.h>
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#include <errno.h>
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#include <gelf.h>
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#include <fcntl.h>
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#include <inttypes.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include <linux/list.h>
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#ifndef REMOTE_UNWIND_LIBUNWIND
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#include <libunwind.h>
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#include <libunwind-ptrace.h>
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#endif
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#include "callchain.h"
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#include "thread.h"
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#include "session.h"
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#include "perf_regs.h"
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#include "unwind.h"
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#include "symbol.h"
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#include "util.h"
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#include "debug.h"
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#include "asm/bug.h"
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#include "dso.h"
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extern int
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UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as,
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unw_word_t ip,
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unw_dyn_info_t *di,
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unw_proc_info_t *pi,
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int need_unwind_info, void *arg);
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#define dwarf_search_unwind_table UNW_OBJ(dwarf_search_unwind_table)
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extern int
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UNW_OBJ(dwarf_find_debug_frame) (int found, unw_dyn_info_t *di_debug,
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unw_word_t ip,
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unw_word_t segbase,
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const char *obj_name, unw_word_t start,
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unw_word_t end);
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#define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame)
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#define DW_EH_PE_FORMAT_MASK 0x0f /* format of the encoded value */
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#define DW_EH_PE_APPL_MASK 0x70 /* how the value is to be applied */
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/* Pointer-encoding formats: */
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#define DW_EH_PE_omit 0xff
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#define DW_EH_PE_ptr 0x00 /* pointer-sized unsigned value */
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#define DW_EH_PE_udata4 0x03 /* unsigned 32-bit value */
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#define DW_EH_PE_udata8 0x04 /* unsigned 64-bit value */
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#define DW_EH_PE_sdata4 0x0b /* signed 32-bit value */
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#define DW_EH_PE_sdata8 0x0c /* signed 64-bit value */
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/* Pointer-encoding application: */
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#define DW_EH_PE_absptr 0x00 /* absolute value */
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#define DW_EH_PE_pcrel 0x10 /* rel. to addr. of encoded value */
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/*
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* The following are not documented by LSB v1.3, yet they are used by
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* GCC, presumably they aren't documented by LSB since they aren't
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* used on Linux:
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*/
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#define DW_EH_PE_funcrel 0x40 /* start-of-procedure-relative */
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#define DW_EH_PE_aligned 0x50 /* aligned pointer */
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/* Flags intentionaly not handled, since they're not needed:
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* #define DW_EH_PE_indirect 0x80
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* #define DW_EH_PE_uleb128 0x01
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* #define DW_EH_PE_udata2 0x02
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* #define DW_EH_PE_sleb128 0x09
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* #define DW_EH_PE_sdata2 0x0a
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* #define DW_EH_PE_textrel 0x20
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* #define DW_EH_PE_datarel 0x30
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*/
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struct unwind_info {
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struct perf_sample *sample;
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struct machine *machine;
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struct thread *thread;
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};
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#define dw_read(ptr, type, end) ({ \
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type *__p = (type *) ptr; \
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type __v; \
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if ((__p + 1) > (type *) end) \
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return -EINVAL; \
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__v = *__p++; \
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ptr = (typeof(ptr)) __p; \
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__v; \
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})
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static int __dw_read_encoded_value(u8 **p, u8 *end, u64 *val,
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u8 encoding)
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{
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u8 *cur = *p;
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*val = 0;
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switch (encoding) {
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case DW_EH_PE_omit:
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*val = 0;
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goto out;
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case DW_EH_PE_ptr:
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*val = dw_read(cur, unsigned long, end);
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goto out;
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default:
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break;
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}
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switch (encoding & DW_EH_PE_APPL_MASK) {
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case DW_EH_PE_absptr:
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break;
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case DW_EH_PE_pcrel:
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*val = (unsigned long) cur;
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break;
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default:
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return -EINVAL;
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}
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if ((encoding & 0x07) == 0x00)
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encoding |= DW_EH_PE_udata4;
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switch (encoding & DW_EH_PE_FORMAT_MASK) {
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case DW_EH_PE_sdata4:
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*val += dw_read(cur, s32, end);
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break;
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case DW_EH_PE_udata4:
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*val += dw_read(cur, u32, end);
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break;
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case DW_EH_PE_sdata8:
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*val += dw_read(cur, s64, end);
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break;
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case DW_EH_PE_udata8:
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*val += dw_read(cur, u64, end);
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break;
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default:
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return -EINVAL;
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}
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out:
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*p = cur;
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return 0;
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}
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#define dw_read_encoded_value(ptr, end, enc) ({ \
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u64 __v; \
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if (__dw_read_encoded_value(&ptr, end, &__v, enc)) { \
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return -EINVAL; \
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} \
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__v; \
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})
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static u64 elf_section_offset(int fd, const char *name)
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{
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Elf *elf;
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GElf_Ehdr ehdr;
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GElf_Shdr shdr;
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u64 offset = 0;
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elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
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if (elf == NULL)
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return 0;
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do {
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if (gelf_getehdr(elf, &ehdr) == NULL)
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break;
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if (!elf_section_by_name(elf, &ehdr, &shdr, name, NULL))
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break;
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offset = shdr.sh_offset;
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} while (0);
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elf_end(elf);
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return offset;
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}
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#ifndef NO_LIBUNWIND_DEBUG_FRAME
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static int elf_is_exec(int fd, const char *name)
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{
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Elf *elf;
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GElf_Ehdr ehdr;
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int retval = 0;
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elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
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if (elf == NULL)
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return 0;
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if (gelf_getehdr(elf, &ehdr) == NULL)
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goto out;
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retval = (ehdr.e_type == ET_EXEC);
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out:
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elf_end(elf);
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pr_debug("unwind: elf_is_exec(%s): %d\n", name, retval);
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return retval;
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}
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#endif
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struct table_entry {
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u32 start_ip_offset;
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u32 fde_offset;
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};
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struct eh_frame_hdr {
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unsigned char version;
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unsigned char eh_frame_ptr_enc;
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unsigned char fde_count_enc;
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unsigned char table_enc;
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/*
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* The rest of the header is variable-length and consists of the
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* following members:
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*
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* encoded_t eh_frame_ptr;
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* encoded_t fde_count;
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*/
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/* A single encoded pointer should not be more than 8 bytes. */
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u64 enc[2];
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/*
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* struct {
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* encoded_t start_ip;
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* encoded_t fde_addr;
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* } binary_search_table[fde_count];
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*/
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char data[0];
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} __packed;
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static int unwind_spec_ehframe(struct dso *dso, struct machine *machine,
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u64 offset, u64 *table_data, u64 *segbase,
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u64 *fde_count)
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{
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struct eh_frame_hdr hdr;
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u8 *enc = (u8 *) &hdr.enc;
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u8 *end = (u8 *) &hdr.data;
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ssize_t r;
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r = dso__data_read_offset(dso, machine, offset,
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(u8 *) &hdr, sizeof(hdr));
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if (r != sizeof(hdr))
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return -EINVAL;
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/* We dont need eh_frame_ptr, just skip it. */
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dw_read_encoded_value(enc, end, hdr.eh_frame_ptr_enc);
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*fde_count = dw_read_encoded_value(enc, end, hdr.fde_count_enc);
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*segbase = offset;
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*table_data = (enc - (u8 *) &hdr) + offset;
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return 0;
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}
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static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine,
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u64 *table_data, u64 *segbase,
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u64 *fde_count)
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{
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int ret = -EINVAL, fd;
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u64 offset = dso->data.eh_frame_hdr_offset;
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if (offset == 0) {
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fd = dso__data_get_fd(dso, machine);
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if (fd < 0)
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return -EINVAL;
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/* Check the .eh_frame section for unwinding info */
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offset = elf_section_offset(fd, ".eh_frame_hdr");
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dso->data.eh_frame_hdr_offset = offset;
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dso__data_put_fd(dso);
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}
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if (offset)
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ret = unwind_spec_ehframe(dso, machine, offset,
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table_data, segbase,
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fde_count);
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return ret;
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}
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#ifndef NO_LIBUNWIND_DEBUG_FRAME
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static int read_unwind_spec_debug_frame(struct dso *dso,
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struct machine *machine, u64 *offset)
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{
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int fd;
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u64 ofs = dso->data.debug_frame_offset;
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/* debug_frame can reside in:
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* - dso
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* - debug pointed by symsrc_filename
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* - gnu_debuglink, which doesn't necessary
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* has to be pointed by symsrc_filename
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*/
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if (ofs == 0) {
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fd = dso__data_get_fd(dso, machine);
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if (fd >= 0) {
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ofs = elf_section_offset(fd, ".debug_frame");
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dso__data_put_fd(dso);
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}
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if (ofs <= 0) {
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fd = open(dso->symsrc_filename, O_RDONLY);
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if (fd >= 0) {
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ofs = elf_section_offset(fd, ".debug_frame");
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close(fd);
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}
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}
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if (ofs <= 0) {
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char *debuglink = malloc(PATH_MAX);
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int ret = 0;
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ret = dso__read_binary_type_filename(
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dso, DSO_BINARY_TYPE__DEBUGLINK,
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machine->root_dir, debuglink, PATH_MAX);
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if (!ret) {
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fd = open(debuglink, O_RDONLY);
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if (fd >= 0) {
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ofs = elf_section_offset(fd,
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".debug_frame");
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close(fd);
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}
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}
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if (ofs > 0) {
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if (dso->symsrc_filename != NULL) {
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pr_warning(
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"%s: overwrite symsrc(%s,%s)\n",
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__func__,
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dso->symsrc_filename,
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debuglink);
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free(dso->symsrc_filename);
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}
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dso->symsrc_filename = debuglink;
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} else {
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free(debuglink);
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}
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}
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dso->data.debug_frame_offset = ofs;
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}
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*offset = ofs;
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if (*offset)
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return 0;
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return -EINVAL;
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}
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#endif
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static struct map *find_map(unw_word_t ip, struct unwind_info *ui)
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{
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struct addr_location al;
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thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
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MAP__FUNCTION, ip, &al);
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if (!al.map) {
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/*
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* We've seen cases (softice) where DWARF unwinder went
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* through non executable mmaps, which we need to lookup
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* in MAP__VARIABLE tree.
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*/
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thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
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MAP__VARIABLE, ip, &al);
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}
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return al.map;
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}
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static int
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find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi,
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int need_unwind_info, void *arg)
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{
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struct unwind_info *ui = arg;
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struct map *map;
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unw_dyn_info_t di;
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u64 table_data, segbase, fde_count;
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int ret = -EINVAL;
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map = find_map(ip, ui);
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if (!map || !map->dso)
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return -EINVAL;
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pr_debug("unwind: find_proc_info dso %s\n", map->dso->name);
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/* Check the .eh_frame section for unwinding info */
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if (!read_unwind_spec_eh_frame(map->dso, ui->machine,
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&table_data, &segbase, &fde_count)) {
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memset(&di, 0, sizeof(di));
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di.format = UNW_INFO_FORMAT_REMOTE_TABLE;
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di.start_ip = map->start;
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di.end_ip = map->end;
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di.u.rti.segbase = map->start + segbase - map->pgoff;
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di.u.rti.table_data = map->start + table_data - map->pgoff;
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di.u.rti.table_len = fde_count * sizeof(struct table_entry)
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/ sizeof(unw_word_t);
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ret = dwarf_search_unwind_table(as, ip, &di, pi,
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need_unwind_info, arg);
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}
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#ifndef NO_LIBUNWIND_DEBUG_FRAME
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/* Check the .debug_frame section for unwinding info */
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if (ret < 0 &&
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!read_unwind_spec_debug_frame(map->dso, ui->machine, &segbase)) {
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int fd = dso__data_get_fd(map->dso, ui->machine);
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int is_exec = elf_is_exec(fd, map->dso->name);
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unw_word_t base = is_exec ? 0 : map->start;
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const char *symfile;
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if (fd >= 0)
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dso__data_put_fd(map->dso);
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symfile = map->dso->symsrc_filename ?: map->dso->name;
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memset(&di, 0, sizeof(di));
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if (dwarf_find_debug_frame(0, &di, ip, base, symfile,
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map->start, map->end))
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return dwarf_search_unwind_table(as, ip, &di, pi,
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need_unwind_info, arg);
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}
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#endif
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return ret;
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}
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static int access_fpreg(unw_addr_space_t __maybe_unused as,
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unw_regnum_t __maybe_unused num,
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unw_fpreg_t __maybe_unused *val,
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int __maybe_unused __write,
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void __maybe_unused *arg)
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{
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pr_err("unwind: access_fpreg unsupported\n");
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return -UNW_EINVAL;
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}
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static int get_dyn_info_list_addr(unw_addr_space_t __maybe_unused as,
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unw_word_t __maybe_unused *dil_addr,
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void __maybe_unused *arg)
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{
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return -UNW_ENOINFO;
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}
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static int resume(unw_addr_space_t __maybe_unused as,
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unw_cursor_t __maybe_unused *cu,
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void __maybe_unused *arg)
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{
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pr_err("unwind: resume unsupported\n");
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return -UNW_EINVAL;
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}
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static int
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get_proc_name(unw_addr_space_t __maybe_unused as,
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unw_word_t __maybe_unused addr,
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char __maybe_unused *bufp, size_t __maybe_unused buf_len,
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unw_word_t __maybe_unused *offp, void __maybe_unused *arg)
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{
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pr_err("unwind: get_proc_name unsupported\n");
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return -UNW_EINVAL;
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}
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static int access_dso_mem(struct unwind_info *ui, unw_word_t addr,
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unw_word_t *data)
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{
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struct map *map;
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ssize_t size;
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map = find_map(addr, ui);
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if (!map) {
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pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
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return -1;
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}
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if (!map->dso)
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return -1;
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size = dso__data_read_addr(map->dso, map, ui->machine,
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addr, (u8 *) data, sizeof(*data));
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return !(size == sizeof(*data));
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}
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static int access_mem(unw_addr_space_t __maybe_unused as,
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unw_word_t addr, unw_word_t *valp,
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int __write, void *arg)
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{
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struct unwind_info *ui = arg;
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struct stack_dump *stack = &ui->sample->user_stack;
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u64 start, end;
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int offset;
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int ret;
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/* Don't support write, probably not needed. */
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if (__write || !stack || !ui->sample->user_regs.regs) {
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*valp = 0;
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return 0;
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}
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ret = perf_reg_value(&start, &ui->sample->user_regs,
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LIBUNWIND__ARCH_REG_SP);
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if (ret)
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return ret;
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end = start + stack->size;
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|
|
/* Check overflow. */
|
|
if (addr + sizeof(unw_word_t) < addr)
|
|
return -EINVAL;
|
|
|
|
if (addr < start || addr + sizeof(unw_word_t) >= end) {
|
|
ret = access_dso_mem(ui, addr, valp);
|
|
if (ret) {
|
|
pr_debug("unwind: access_mem %p not inside range"
|
|
" 0x%" PRIx64 "-0x%" PRIx64 "\n",
|
|
(void *) (uintptr_t) addr, start, end);
|
|
*valp = 0;
|
|
return ret;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
offset = addr - start;
|
|
*valp = *(unw_word_t *)&stack->data[offset];
|
|
pr_debug("unwind: access_mem addr %p val %lx, offset %d\n",
|
|
(void *) (uintptr_t) addr, (unsigned long)*valp, offset);
|
|
return 0;
|
|
}
|
|
|
|
static int access_reg(unw_addr_space_t __maybe_unused as,
|
|
unw_regnum_t regnum, unw_word_t *valp,
|
|
int __write, void *arg)
|
|
{
|
|
struct unwind_info *ui = arg;
|
|
int id, ret;
|
|
u64 val;
|
|
|
|
/* Don't support write, I suspect we don't need it. */
|
|
if (__write) {
|
|
pr_err("unwind: access_reg w %d\n", regnum);
|
|
return 0;
|
|
}
|
|
|
|
if (!ui->sample->user_regs.regs) {
|
|
*valp = 0;
|
|
return 0;
|
|
}
|
|
|
|
id = LIBUNWIND__ARCH_REG_ID(regnum);
|
|
if (id < 0)
|
|
return -EINVAL;
|
|
|
|
ret = perf_reg_value(&val, &ui->sample->user_regs, id);
|
|
if (ret) {
|
|
pr_err("unwind: can't read reg %d\n", regnum);
|
|
return ret;
|
|
}
|
|
|
|
*valp = (unw_word_t) val;
|
|
pr_debug("unwind: reg %d, val %lx\n", regnum, (unsigned long)*valp);
|
|
return 0;
|
|
}
|
|
|
|
static void put_unwind_info(unw_addr_space_t __maybe_unused as,
|
|
unw_proc_info_t *pi __maybe_unused,
|
|
void *arg __maybe_unused)
|
|
{
|
|
pr_debug("unwind: put_unwind_info called\n");
|
|
}
|
|
|
|
static int entry(u64 ip, struct thread *thread,
|
|
unwind_entry_cb_t cb, void *arg)
|
|
{
|
|
struct unwind_entry e;
|
|
struct addr_location al;
|
|
|
|
thread__find_addr_location(thread, PERF_RECORD_MISC_USER,
|
|
MAP__FUNCTION, ip, &al);
|
|
|
|
e.ip = al.addr;
|
|
e.map = al.map;
|
|
e.sym = al.sym;
|
|
|
|
pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
|
|
al.sym ? al.sym->name : "''",
|
|
ip,
|
|
al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
|
|
|
|
return cb(&e, arg);
|
|
}
|
|
|
|
static void display_error(int err)
|
|
{
|
|
switch (err) {
|
|
case UNW_EINVAL:
|
|
pr_err("unwind: Only supports local.\n");
|
|
break;
|
|
case UNW_EUNSPEC:
|
|
pr_err("unwind: Unspecified error.\n");
|
|
break;
|
|
case UNW_EBADREG:
|
|
pr_err("unwind: Register unavailable.\n");
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
static unw_accessors_t accessors = {
|
|
.find_proc_info = find_proc_info,
|
|
.put_unwind_info = put_unwind_info,
|
|
.get_dyn_info_list_addr = get_dyn_info_list_addr,
|
|
.access_mem = access_mem,
|
|
.access_reg = access_reg,
|
|
.access_fpreg = access_fpreg,
|
|
.resume = resume,
|
|
.get_proc_name = get_proc_name,
|
|
};
|
|
|
|
static int _unwind__prepare_access(struct thread *thread)
|
|
{
|
|
if (!dwarf_callchain_users)
|
|
return 0;
|
|
thread->addr_space = unw_create_addr_space(&accessors, 0);
|
|
if (!thread->addr_space) {
|
|
pr_err("unwind: Can't create unwind address space.\n");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
unw_set_caching_policy(thread->addr_space, UNW_CACHE_GLOBAL);
|
|
return 0;
|
|
}
|
|
|
|
static void _unwind__flush_access(struct thread *thread)
|
|
{
|
|
if (!dwarf_callchain_users)
|
|
return;
|
|
unw_flush_cache(thread->addr_space, 0, 0);
|
|
}
|
|
|
|
static void _unwind__finish_access(struct thread *thread)
|
|
{
|
|
if (!dwarf_callchain_users)
|
|
return;
|
|
unw_destroy_addr_space(thread->addr_space);
|
|
}
|
|
|
|
static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,
|
|
void *arg, int max_stack)
|
|
{
|
|
u64 val;
|
|
unw_word_t ips[max_stack];
|
|
unw_addr_space_t addr_space;
|
|
unw_cursor_t c;
|
|
int ret, i = 0;
|
|
|
|
ret = perf_reg_value(&val, &ui->sample->user_regs,
|
|
LIBUNWIND__ARCH_REG_IP);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ips[i++] = (unw_word_t) val;
|
|
|
|
/*
|
|
* If we need more than one entry, do the DWARF
|
|
* unwind itself.
|
|
*/
|
|
if (max_stack - 1 > 0) {
|
|
WARN_ONCE(!ui->thread, "WARNING: ui->thread is NULL");
|
|
addr_space = ui->thread->addr_space;
|
|
|
|
if (addr_space == NULL)
|
|
return -1;
|
|
|
|
ret = unw_init_remote(&c, addr_space, ui);
|
|
if (ret)
|
|
display_error(ret);
|
|
|
|
while (!ret && (unw_step(&c) > 0) && i < max_stack) {
|
|
unw_get_reg(&c, UNW_REG_IP, &ips[i]);
|
|
|
|
/*
|
|
* Decrement the IP for any non-activation frames.
|
|
* this is required to properly find the srcline
|
|
* for caller frames.
|
|
* See also the documentation for dwfl_frame_pc(),
|
|
* which this code tries to replicate.
|
|
*/
|
|
if (unw_is_signal_frame(&c) <= 0)
|
|
--ips[i];
|
|
|
|
++i;
|
|
}
|
|
|
|
max_stack = i;
|
|
}
|
|
|
|
/*
|
|
* Display what we got based on the order setup.
|
|
*/
|
|
for (i = 0; i < max_stack && !ret; i++) {
|
|
int j = i;
|
|
|
|
if (callchain_param.order == ORDER_CALLER)
|
|
j = max_stack - i - 1;
|
|
ret = ips[j] ? entry(ips[j], ui->thread, cb, arg) : 0;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int _unwind__get_entries(unwind_entry_cb_t cb, void *arg,
|
|
struct thread *thread,
|
|
struct perf_sample *data, int max_stack)
|
|
{
|
|
struct unwind_info ui = {
|
|
.sample = data,
|
|
.thread = thread,
|
|
.machine = thread->mg->machine,
|
|
};
|
|
|
|
if (!data->user_regs.regs)
|
|
return -EINVAL;
|
|
|
|
if (max_stack <= 0)
|
|
return -EINVAL;
|
|
|
|
return get_entries(&ui, cb, arg, max_stack);
|
|
}
|
|
|
|
static struct unwind_libunwind_ops
|
|
_unwind_libunwind_ops = {
|
|
.prepare_access = _unwind__prepare_access,
|
|
.flush_access = _unwind__flush_access,
|
|
.finish_access = _unwind__finish_access,
|
|
.get_entries = _unwind__get_entries,
|
|
};
|
|
|
|
#ifndef REMOTE_UNWIND_LIBUNWIND
|
|
struct unwind_libunwind_ops *
|
|
local_unwind_libunwind_ops = &_unwind_libunwind_ops;
|
|
#endif
|