[mirror_ubuntu-artful-kernel.git] / tools / perf / util / unwind-libunwind-local.c

/*
 * Post mortem Dwarf CFI based unwinding on top of regs and stack dumps.
 *
 * Lots of this code have been borrowed or heavily inspired from parts of
 * the libunwind 0.99 code which are (amongst other contributors I may have
 * forgotten):
 *
 * Copyright (C) 2002-2007 Hewlett-Packard Co
 *	Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
 *
 * And the bugs have been added by:
 *
 * Copyright (C) 2010, Frederic Weisbecker <fweisbec@gmail.com>
 * Copyright (C) 2012, Jiri Olsa <jolsa@redhat.com>
 *
 */

#include <elf.h>
#include <errno.h>
#include <gelf.h>
#include <fcntl.h>
#include <inttypes.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <linux/list.h>
#ifndef REMOTE_UNWIND_LIBUNWIND
#include <libunwind.h>
#include <libunwind-ptrace.h>
#endif
#include "callchain.h"
#include "thread.h"
#include "session.h"
#include "perf_regs.h"
#include "unwind.h"
#include "symbol.h"
#include "util.h"
#include "debug.h"
#include "asm/bug.h"
#include "dso.h"

extern int
UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as,
				    unw_word_t ip,
				    unw_dyn_info_t *di,
				    unw_proc_info_t *pi,
				    int need_unwind_info, void *arg);

#define dwarf_search_unwind_table UNW_OBJ(dwarf_search_unwind_table)

extern int
UNW_OBJ(dwarf_find_debug_frame) (int found, unw_dyn_info_t *di_debug,
				 unw_word_t ip,
				 unw_word_t segbase,
				 const char *obj_name, unw_word_t start,
				 unw_word_t end);

#define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame)

#define DW_EH_PE_FORMAT_MASK	0x0f	/* format of the encoded value */
#define DW_EH_PE_APPL_MASK	0x70	/* how the value is to be applied */

/* Pointer-encoding formats: */
#define DW_EH_PE_omit		0xff
#define DW_EH_PE_ptr		0x00	/* pointer-sized unsigned value */
#define DW_EH_PE_udata4		0x03	/* unsigned 32-bit value */
#define DW_EH_PE_udata8		0x04	/* unsigned 64-bit value */
#define DW_EH_PE_sdata4		0x0b	/* signed 32-bit value */
#define DW_EH_PE_sdata8		0x0c	/* signed 64-bit value */

/* Pointer-encoding application: */
#define DW_EH_PE_absptr		0x00	/* absolute value */
#define DW_EH_PE_pcrel		0x10	/* rel. to addr. of encoded value */

/*
 * The following are not documented by LSB v1.3, yet they are used by
 * GCC, presumably they aren't documented by LSB since they aren't
 * used on Linux:
 */
#define DW_EH_PE_funcrel	0x40	/* start-of-procedure-relative */
#define DW_EH_PE_aligned	0x50	/* aligned pointer */

/* Flags intentionaly not handled, since they're not needed:
 * #define DW_EH_PE_indirect      0x80
 * #define DW_EH_PE_uleb128       0x01
 * #define DW_EH_PE_udata2        0x02
 * #define DW_EH_PE_sleb128       0x09
 * #define DW_EH_PE_sdata2        0x0a
 * #define DW_EH_PE_textrel       0x20
 * #define DW_EH_PE_datarel       0x30
 */

struct unwind_info {
	struct perf_sample	*sample;
	struct machine		*machine;
	struct thread		*thread;
};

#define dw_read(ptr, type, end) ({	\
	type *__p = (type *) ptr;	\
	type  __v;			\
	if ((__p + 1) > (type *) end)	\
		return -EINVAL;		\
	__v = *__p++;			\
	ptr = (typeof(ptr)) __p;	\
	__v;				\
	})

static int __dw_read_encoded_value(u8 **p, u8 *end, u64 *val,
				   u8 encoding)
{
	u8 *cur = *p;
	*val = 0;

	switch (encoding) {
	case DW_EH_PE_omit:
		*val = 0;
		goto out;
	case DW_EH_PE_ptr:
		*val = dw_read(cur, unsigned long, end);
		goto out;
	default:
		break;
	}

	switch (encoding & DW_EH_PE_APPL_MASK) {
	case DW_EH_PE_absptr:
		break;
	case DW_EH_PE_pcrel:
		*val = (unsigned long) cur;
		break;
	default:
		return -EINVAL;
	}

	if ((encoding & 0x07) == 0x00)
		encoding |= DW_EH_PE_udata4;

	switch (encoding & DW_EH_PE_FORMAT_MASK) {
	case DW_EH_PE_sdata4:
		*val += dw_read(cur, s32, end);
		break;
	case DW_EH_PE_udata4:
		*val += dw_read(cur, u32, end);
		break;
	case DW_EH_PE_sdata8:
		*val += dw_read(cur, s64, end);
		break;
	case DW_EH_PE_udata8:
		*val += dw_read(cur, u64, end);
		break;
	default:
		return -EINVAL;
	}

 out:
	*p = cur;
	return 0;
}

#define dw_read_encoded_value(ptr, end, enc) ({			\
	u64 __v;						\
	if (__dw_read_encoded_value(&ptr, end, &__v, enc)) {	\
		return -EINVAL;                                 \
	}                                                       \
	__v;                                                    \
	})

static u64 elf_section_offset(int fd, const char *name)
{
	Elf *elf;
	GElf_Ehdr ehdr;
	GElf_Shdr shdr;
	u64 offset = 0;

	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
	if (elf == NULL)
		return 0;

	do {
		if (gelf_getehdr(elf, &ehdr) == NULL)
			break;

		if (!elf_section_by_name(elf, &ehdr, &shdr, name, NULL))
			break;

		offset = shdr.sh_offset;
	} while (0);

	elf_end(elf);
	return offset;
}

#ifndef NO_LIBUNWIND_DEBUG_FRAME
static int elf_is_exec(int fd, const char *name)
{
	Elf *elf;
	GElf_Ehdr ehdr;
	int retval = 0;

	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
	if (elf == NULL)
		return 0;
	if (gelf_getehdr(elf, &ehdr) == NULL)
		goto out;

	retval = (ehdr.e_type == ET_EXEC);

out:
	elf_end(elf);
	pr_debug("unwind: elf_is_exec(%s): %d\n", name, retval);
	return retval;
}
#endif

struct table_entry {
	u32 start_ip_offset;
	u32 fde_offset;
};

struct eh_frame_hdr {
	unsigned char version;
	unsigned char eh_frame_ptr_enc;
	unsigned char fde_count_enc;
	unsigned char table_enc;

	/*
	 * The rest of the header is variable-length and consists of the
	 * following members:
	 *
	 *	encoded_t eh_frame_ptr;
	 *	encoded_t fde_count;
	 */

	/* A single encoded pointer should not be more than 8 bytes. */
	u64 enc[2];

	/*
	 * struct {
	 *    encoded_t start_ip;
	 *    encoded_t fde_addr;
	 * } binary_search_table[fde_count];
	 */
	char data[0];
} __packed;

static int unwind_spec_ehframe(struct dso *dso, struct machine *machine,
			       u64 offset, u64 *table_data, u64 *segbase,
			       u64 *fde_count)
{
	struct eh_frame_hdr hdr;
	u8 *enc = (u8 *) &hdr.enc;
	u8 *end = (u8 *) &hdr.data;
	ssize_t r;

	r = dso__data_read_offset(dso, machine, offset,
				  (u8 *) &hdr, sizeof(hdr));
	if (r != sizeof(hdr))
		return -EINVAL;

	/* We dont need eh_frame_ptr, just skip it. */
	dw_read_encoded_value(enc, end, hdr.eh_frame_ptr_enc);

	*fde_count  = dw_read_encoded_value(enc, end, hdr.fde_count_enc);
	*segbase    = offset;
	*table_data = (enc - (u8 *) &hdr) + offset;
	return 0;
}

static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine,
				     u64 *table_data, u64 *segbase,
				     u64 *fde_count)
{
	int ret = -EINVAL, fd;
	u64 offset = dso->data.eh_frame_hdr_offset;

	if (offset == 0) {
		fd = dso__data_get_fd(dso, machine);
		if (fd < 0)
			return -EINVAL;

		/* Check the .eh_frame section for unwinding info */
		offset = elf_section_offset(fd, ".eh_frame_hdr");
		dso->data.eh_frame_hdr_offset = offset;
		dso__data_put_fd(dso);
	}

	if (offset)
		ret = unwind_spec_ehframe(dso, machine, offset,
					  table_data, segbase,
					  fde_count);

	return ret;
}

#ifndef NO_LIBUNWIND_DEBUG_FRAME
static int read_unwind_spec_debug_frame(struct dso *dso,
					struct machine *machine, u64 *offset)
{
	int fd;
	u64 ofs = dso->data.debug_frame_offset;

	/* debug_frame can reside in:
	 *  - dso
	 *  - debug pointed by symsrc_filename
	 *  - gnu_debuglink, which doesn't necessary
	 *    has to be pointed by symsrc_filename
	 */
	if (ofs == 0) {
		fd = dso__data_get_fd(dso, machine);
		if (fd >= 0) {
			ofs = elf_section_offset(fd, ".debug_frame");
			dso__data_put_fd(dso);
		}

		if (ofs <= 0) {
			fd = open(dso->symsrc_filename, O_RDONLY);
			if (fd >= 0) {
				ofs = elf_section_offset(fd, ".debug_frame");
				close(fd);
			}
		}

		if (ofs <= 0) {
			char *debuglink = malloc(PATH_MAX);
			int ret = 0;

			ret = dso__read_binary_type_filename(
				dso, DSO_BINARY_TYPE__DEBUGLINK,
				machine->root_dir, debuglink, PATH_MAX);
			if (!ret) {
				fd = open(debuglink, O_RDONLY);
				if (fd >= 0) {
					ofs = elf_section_offset(fd,
							".debug_frame");
					close(fd);
				}
			}
			if (ofs > 0) {
				if (dso->symsrc_filename != NULL) {
					pr_warning(
						"%s: overwrite symsrc(%s,%s)\n",
							__func__,
							dso->symsrc_filename,
							debuglink);
					free(dso->symsrc_filename);
				}
				dso->symsrc_filename = debuglink;
			} else {
				free(debuglink);
			}
		}

		dso->data.debug_frame_offset = ofs;
	}

	*offset = ofs;
	if (*offset)
		return 0;

	return -EINVAL;
}
#endif

static struct map *find_map(unw_word_t ip, struct unwind_info *ui)
{
	struct addr_location al;

	thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
			      MAP__FUNCTION, ip, &al);
	if (!al.map) {
		/*
		 * We've seen cases (softice) where DWARF unwinder went
		 * through non executable mmaps, which we need to lookup
		 * in MAP__VARIABLE tree.
		 */
		thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
				      MAP__VARIABLE, ip, &al);
	}
	return al.map;
}

static int
find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi,
	       int need_unwind_info, void *arg)
{
	struct unwind_info *ui = arg;
	struct map *map;
	unw_dyn_info_t di;
	u64 table_data, segbase, fde_count;
	int ret = -EINVAL;

	map = find_map(ip, ui);
	if (!map || !map->dso)
		return -EINVAL;

	pr_debug("unwind: find_proc_info dso %s\n", map->dso->name);

	/* Check the .eh_frame section for unwinding info */
	if (!read_unwind_spec_eh_frame(map->dso, ui->machine,
				       &table_data, &segbase, &fde_count)) {
		memset(&di, 0, sizeof(di));
		di.format   = UNW_INFO_FORMAT_REMOTE_TABLE;
		di.start_ip = map->start;
		di.end_ip   = map->end;
		di.u.rti.segbase    = map->start + segbase - map->pgoff;
		di.u.rti.table_data = map->start + table_data - map->pgoff;
		di.u.rti.table_len  = fde_count * sizeof(struct table_entry)
				      / sizeof(unw_word_t);
		ret = dwarf_search_unwind_table(as, ip, &di, pi,
						need_unwind_info, arg);
	}

#ifndef NO_LIBUNWIND_DEBUG_FRAME
	/* Check the .debug_frame section for unwinding info */
	if (ret < 0 &&
	    !read_unwind_spec_debug_frame(map->dso, ui->machine, &segbase)) {
		int fd = dso__data_get_fd(map->dso, ui->machine);
		int is_exec = elf_is_exec(fd, map->dso->name);
		unw_word_t base = is_exec ? 0 : map->start;
		const char *symfile;

		if (fd >= 0)
			dso__data_put_fd(map->dso);

		symfile = map->dso->symsrc_filename ?: map->dso->name;

		memset(&di, 0, sizeof(di));
		if (dwarf_find_debug_frame(0, &di, ip, base, symfile,
					   map->start, map->end))
			return dwarf_search_unwind_table(as, ip, &di, pi,
							 need_unwind_info, arg);
	}
#endif

	return ret;
}

static int access_fpreg(unw_addr_space_t __maybe_unused as,
			unw_regnum_t __maybe_unused num,
			unw_fpreg_t __maybe_unused *val,
			int __maybe_unused __write,
			void __maybe_unused *arg)
{
	pr_err("unwind: access_fpreg unsupported\n");
	return -UNW_EINVAL;
}

static int get_dyn_info_list_addr(unw_addr_space_t __maybe_unused as,
				  unw_word_t __maybe_unused *dil_addr,
				  void __maybe_unused *arg)
{
	return -UNW_ENOINFO;
}

static int resume(unw_addr_space_t __maybe_unused as,
		  unw_cursor_t __maybe_unused *cu,
		  void __maybe_unused *arg)
{
	pr_err("unwind: resume unsupported\n");
	return -UNW_EINVAL;
}

static int
get_proc_name(unw_addr_space_t __maybe_unused as,
	      unw_word_t __maybe_unused addr,
		char __maybe_unused *bufp, size_t __maybe_unused buf_len,
		unw_word_t __maybe_unused *offp, void __maybe_unused *arg)
{
	pr_err("unwind: get_proc_name unsupported\n");
	return -UNW_EINVAL;
}

static int access_dso_mem(struct unwind_info *ui, unw_word_t addr,
			  unw_word_t *data)
{
	struct map *map;
	ssize_t size;

	map = find_map(addr, ui);
	if (!map) {
		pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
		return -1;
	}

	if (!map->dso)
		return -1;

	size = dso__data_read_addr(map->dso, map, ui->machine,
				   addr, (u8 *) data, sizeof(*data));

	return !(size == sizeof(*data));
}

static int access_mem(unw_addr_space_t __maybe_unused as,
		      unw_word_t addr, unw_word_t *valp,
		      int __write, void *arg)
{
	struct unwind_info *ui = arg;
	struct stack_dump *stack = &ui->sample->user_stack;
	u64 start, end;
	int offset;
	int ret;

	/* Don't support write, probably not needed. */
	if (__write || !stack || !ui->sample->user_regs.regs) {
		*valp = 0;
		return 0;
	}

	ret = perf_reg_value(&start, &ui->sample->user_regs,
			     LIBUNWIND__ARCH_REG_SP);
	if (ret)
		return ret;

	end = start + stack->size;

	/* 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 (callchain_param.record_mode != CALLCHAIN_DWARF)
		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 (callchain_param.record_mode != CALLCHAIN_DWARF)
		return;

	unw_flush_cache(thread->addr_space, 0, 0);
}

static void _unwind__finish_access(struct thread *thread)
{
	if (callchain_param.record_mode != CALLCHAIN_DWARF)
		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]);
			++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
Commit	Line	Data
71ad0f5e JO	1	/*
	2	* Post mortem Dwarf CFI based unwinding on top of regs and stack dumps.
	3	*
	4	* Lots of this code have been borrowed or heavily inspired from parts of
	5	* the libunwind 0.99 code which are (amongst other contributors I may have
	6	* forgotten):
	7	*
	8	* Copyright (C) 2002-2007 Hewlett-Packard Co
	9	* Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
	10	*
	11	* And the bugs have been added by:
	12	*
	13	* Copyright (C) 2010, Frederic Weisbecker <fweisbec@gmail.com>
	14	* Copyright (C) 2012, Jiri Olsa <jolsa@redhat.com>
	15	*
	16	*/
	17
	18	#include <elf.h>
a43783ae	19	#include <errno.h>
71ad0f5e JO	20	#include <gelf.h>
71ad0f5e JO	21	#include <fcntl.h>
fd20e811	22	#include <inttypes.h>
71ad0f5e JO	23	#include <string.h>
	24	#include <unistd.h>
	25	#include <sys/mman.h>
	26	#include <linux/list.h>
19473e7b	27	#ifndef REMOTE_UNWIND_LIBUNWIND
71ad0f5e JO	28	#include <libunwind.h>
71ad0f5e JO	29	#include <libunwind-ptrace.h>
19473e7b	30	#endif
66f066d8	31	#include "callchain.h"
71ad0f5e JO	32	#include "thread.h"
	33	#include "session.h"
	34	#include "perf_regs.h"
	35	#include "unwind.h"
99ca4233	36	#include "symbol.h"
71ad0f5e	37	#include "util.h"
84f5d36f	38	#include "debug.h"
e583d70c	39	#include "asm/bug.h"
9343e45b	40	#include "dso.h"
71ad0f5e JO	41
	42	extern int
	43	UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as,
	44	unw_word_t ip,
	45	unw_dyn_info_t *di,
	46	unw_proc_info_t *pi,
	47	int need_unwind_info, void *arg);
	48
	49	#define dwarf_search_unwind_table UNW_OBJ(dwarf_search_unwind_table)
	50
ab255e72 JP	51	extern int
	52	UNW_OBJ(dwarf_find_debug_frame) (int found, unw_dyn_info_t *di_debug,
	53	unw_word_t ip,
	54	unw_word_t segbase,
	55	const char *obj_name, unw_word_t start,
	56	unw_word_t end);
	57
	58	#define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame)
	59
71ad0f5e JO	60	#define DW_EH_PE_FORMAT_MASK 0x0f /* format of the encoded value */
	61	#define DW_EH_PE_APPL_MASK 0x70 /* how the value is to be applied */
	62
	63	/* Pointer-encoding formats: */
	64	#define DW_EH_PE_omit 0xff
	65	#define DW_EH_PE_ptr 0x00 /* pointer-sized unsigned value */
	66	#define DW_EH_PE_udata4 0x03 /* unsigned 32-bit value */
	67	#define DW_EH_PE_udata8 0x04 /* unsigned 64-bit value */
	68	#define DW_EH_PE_sdata4 0x0b /* signed 32-bit value */
	69	#define DW_EH_PE_sdata8 0x0c /* signed 64-bit value */
	70
	71	/* Pointer-encoding application: */
	72	#define DW_EH_PE_absptr 0x00 /* absolute value */
	73	#define DW_EH_PE_pcrel 0x10 /* rel. to addr. of encoded value */
	74
	75	/*
	76	* The following are not documented by LSB v1.3, yet they are used by
	77	* GCC, presumably they aren't documented by LSB since they aren't
	78	* used on Linux:
	79	*/
	80	#define DW_EH_PE_funcrel 0x40 /* start-of-procedure-relative */
	81	#define DW_EH_PE_aligned 0x50 /* aligned pointer */
	82
	83	/* Flags intentionaly not handled, since they're not needed:
	84	* #define DW_EH_PE_indirect 0x80
	85	* #define DW_EH_PE_uleb128 0x01
	86	* #define DW_EH_PE_udata2 0x02
	87	* #define DW_EH_PE_sleb128 0x09
	88	* #define DW_EH_PE_sdata2 0x0a
	89	* #define DW_EH_PE_textrel 0x20
	90	* #define DW_EH_PE_datarel 0x30
	91	*/
	92
	93	struct unwind_info {
	94	struct perf_sample *sample;
	95	struct machine *machine;
	96	struct thread *thread;
71ad0f5e JO	97	};
	98
	99	#define dw_read(ptr, type, end) ({ \
	100	type __p = (type ) ptr; \
	101	type __v; \
	102	if ((__p + 1) > (type *) end) \
	103	return -EINVAL; \
	104	__v = *__p++; \
	105	ptr = (typeof(ptr)) __p; \
	106	__v; \
	107	})
	108
	109	static int __dw_read_encoded_value(u8 *p, u8 end, u64 *val,
	110	u8 encoding)
	111	{
	112	u8 cur = p;
	113	*val = 0;
	114
	115	switch (encoding) {
	116	case DW_EH_PE_omit:
	117	*val = 0;
	118	goto out;
	119	case DW_EH_PE_ptr:
	120	*val = dw_read(cur, unsigned long, end);
	121	goto out;
	122	default:
	123	break;
	124	}
	125
	126	switch (encoding & DW_EH_PE_APPL_MASK) {
	127	case DW_EH_PE_absptr:
	128	break;
	129	case DW_EH_PE_pcrel:
	130	*val = (unsigned long) cur;
	131	break;
	132	default:
	133	return -EINVAL;
	134	}
	135
	136	if ((encoding & 0x07) == 0x00)
	137	encoding \|= DW_EH_PE_udata4;
	138
	139	switch (encoding & DW_EH_PE_FORMAT_MASK) {
	140	case DW_EH_PE_sdata4:
	141	*val += dw_read(cur, s32, end);
	142	break;
	143	case DW_EH_PE_udata4:
	144	*val += dw_read(cur, u32, end);
	145	break;
	146	case DW_EH_PE_sdata8:
	147	*val += dw_read(cur, s64, end);
	148	break;
	149	case DW_EH_PE_udata8:
	150	*val += dw_read(cur, u64, end);
	151	break;
	152	default:
	153	return -EINVAL;
	154	}
	155
	156	out:
	157	*p = cur;
	158	return 0;
	159	}
	160
161	#define dw_read_encoded_value(ptr, end, enc) ({ \
162	u64 __v; \
163	if (__dw_read_encoded_value(&ptr, end, &__v, enc)) { \
164	return -EINVAL; \
165	} \
166	__v; \
167	})
168
71ad0f5e JO	169	static u64 elf_section_offset(int fd, const char *name)
	170	{
	171	Elf *elf;
	172	GElf_Ehdr ehdr;
	173	GElf_Shdr shdr;
	174	u64 offset = 0;
	175
	176	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
	177	if (elf == NULL)
	178	return 0;
	179
	180	do {
	181	if (gelf_getehdr(elf, &ehdr) == NULL)
	182	break;
	183
99ca4233	184	if (!elf_section_by_name(elf, &ehdr, &shdr, name, NULL))
71ad0f5e JO	185	break;
	186
	187	offset = shdr.sh_offset;
	188	} while (0);
	189
	190	elf_end(elf);
	191	return offset;
	192	}
	193
b93b0967 WN	194	#ifndef NO_LIBUNWIND_DEBUG_FRAME
	195	static int elf_is_exec(int fd, const char *name)
	196	{
	197	Elf *elf;
	198	GElf_Ehdr ehdr;
	199	int retval = 0;
	200
	201	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
	202	if (elf == NULL)
	203	return 0;
	204	if (gelf_getehdr(elf, &ehdr) == NULL)
	205	goto out;
	206
	207	retval = (ehdr.e_type == ET_EXEC);
	208
	209	out:
	210	elf_end(elf);
	211	pr_debug("unwind: elf_is_exec(%s): %d\n", name, retval);
	212	return retval;
	213	}
	214	#endif
	215
71ad0f5e JO	216	struct table_entry {
	217	u32 start_ip_offset;
	218	u32 fde_offset;
	219	};
	220
	221	struct eh_frame_hdr {
	222	unsigned char version;
	223	unsigned char eh_frame_ptr_enc;
	224	unsigned char fde_count_enc;
	225	unsigned char table_enc;
	226
	227	/*
	228	* The rest of the header is variable-length and consists of the
	229	* following members:
	230	*
	231	* encoded_t eh_frame_ptr;
	232	* encoded_t fde_count;
	233	*/
	234
	235	/* A single encoded pointer should not be more than 8 bytes. */
	236	u64 enc[2];
	237
	238	/*
	239	* struct {
	240	* encoded_t start_ip;
	241	* encoded_t fde_addr;
	242	* } binary_search_table[fde_count];
	243	*/
	244	char data[0];
	245	} __packed;
	246
	247	static int unwind_spec_ehframe(struct dso dso, struct machine machine,
	248	u64 offset, u64 table_data, u64 segbase,
	249	u64 *fde_count)
	250	{
	251	struct eh_frame_hdr hdr;
	252	u8 enc = (u8 ) &hdr.enc;
	253	u8 end = (u8 ) &hdr.data;
	254	ssize_t r;
	255
	256	r = dso__data_read_offset(dso, machine, offset,
	257	(u8 *) &hdr, sizeof(hdr));
	258	if (r != sizeof(hdr))
	259	return -EINVAL;
	260
	261	/* We dont need eh_frame_ptr, just skip it. */
	262	dw_read_encoded_value(enc, end, hdr.eh_frame_ptr_enc);
	263
	264	*fde_count = dw_read_encoded_value(enc, end, hdr.fde_count_enc);
	265	*segbase = offset;
	266	table_data = (enc - (u8 ) &hdr) + offset;
	267	return 0;
	268	}
	269
ab255e72 JP	270	static int read_unwind_spec_eh_frame(struct dso dso, struct machine machine,
	271	u64 table_data, u64 segbase,
	272	u64 *fde_count)
71ad0f5e JO	273	{
71ad0f5e JO	274	int ret = -EINVAL, fd;
303cb89a	275	u64 offset = dso->data.eh_frame_hdr_offset;
71ad0f5e	276
f1f13af9	277	if (offset == 0) {
4bb11d01	278	fd = dso__data_get_fd(dso, machine);
f1f13af9 NK	279	if (fd < 0)
f1f13af9 NK	280	return -EINVAL;
71ad0f5e	281
f1f13af9 NK	282	/* Check the .eh_frame section for unwinding info */
f1f13af9 NK	283	offset = elf_section_offset(fd, ".eh_frame_hdr");
303cb89a	284	dso->data.eh_frame_hdr_offset = offset;
4bb11d01	285	dso__data_put_fd(dso);
f1f13af9	286	}
71ad0f5e JO	287
	288	if (offset)
	289	ret = unwind_spec_ehframe(dso, machine, offset,
	290	table_data, segbase,
	291	fde_count);
	292
71ad0f5e JO	293	return ret;
	294	}
	295
ab255e72 JP	296	#ifndef NO_LIBUNWIND_DEBUG_FRAME
	297	static int read_unwind_spec_debug_frame(struct dso *dso,
	298	struct machine machine, u64 offset)
	299	{
f1f13af9	300	int fd;
303cb89a	301	u64 ofs = dso->data.debug_frame_offset;
ab255e72	302
9343e45b MGP	303	/* debug_frame can reside in:
	304	* - dso
	305	* - debug pointed by symsrc_filename
	306	* - gnu_debuglink, which doesn't necessary
	307	* has to be pointed by symsrc_filename
	308	*/
f1f13af9	309	if (ofs == 0) {
4bb11d01	310	fd = dso__data_get_fd(dso, machine);
9343e45b MGP	311	if (fd >= 0) {
	312	ofs = elf_section_offset(fd, ".debug_frame");
	313	dso__data_put_fd(dso);
	314	}
	315
	316	if (ofs <= 0) {
	317	fd = open(dso->symsrc_filename, O_RDONLY);
	318	if (fd >= 0) {
	319	ofs = elf_section_offset(fd, ".debug_frame");
	320	close(fd);
	321	}
	322	}
	323
	324	if (ofs <= 0) {
	325	char *debuglink = malloc(PATH_MAX);
	326	int ret = 0;
	327
	328	ret = dso__read_binary_type_filename(
	329	dso, DSO_BINARY_TYPE__DEBUGLINK,
	330	machine->root_dir, debuglink, PATH_MAX);
	331	if (!ret) {
	332	fd = open(debuglink, O_RDONLY);
	333	if (fd >= 0) {
	334	ofs = elf_section_offset(fd,
	335	".debug_frame");
	336	close(fd);
	337	}
	338	}
	339	if (ofs > 0) {
	340	if (dso->symsrc_filename != NULL) {
	341	pr_warning(
	342	"%s: overwrite symsrc(%s,%s)\n",
	343	__func__,
	344	dso->symsrc_filename,
	345	debuglink);
	346	free(dso->symsrc_filename);
	347	}
	348	dso->symsrc_filename = debuglink;
	349	} else {
	350	free(debuglink);
	351	}
	352	}
ab255e72	353
303cb89a	354	dso->data.debug_frame_offset = ofs;
f1f13af9	355	}
ab255e72	356
f1f13af9	357	*offset = ofs;
ab255e72 JP	358	if (*offset)
	359	return 0;
	360
	361	return -EINVAL;
	362	}
	363	#endif
	364
71ad0f5e JO	365	static struct map find_map(unw_word_t ip, struct unwind_info ui)
	366	{
	367	struct addr_location al;
	368
bb871a9c	369	thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
326f59bf	370	MAP__FUNCTION, ip, &al);
0ddf5246 JO	371	if (!al.map) {
	372	/*
	373	* We've seen cases (softice) where DWARF unwinder went
	374	* through non executable mmaps, which we need to lookup
	375	* in MAP__VARIABLE tree.
	376	*/
	377	thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
	378	MAP__VARIABLE, ip, &al);
	379	}
71ad0f5e JO	380	return al.map;
	381	}
	382
	383	static int
	384	find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi,
	385	int need_unwind_info, void *arg)
	386	{
	387	struct unwind_info *ui = arg;
	388	struct map *map;
	389	unw_dyn_info_t di;
	390	u64 table_data, segbase, fde_count;
8eac1d5e	391	int ret = -EINVAL;
71ad0f5e JO	392
	393	map = find_map(ip, ui);
	394	if (!map \|\| !map->dso)
	395	return -EINVAL;
	396
	397	pr_debug("unwind: find_proc_info dso %s\n", map->dso->name);
	398
ab255e72 JP	399	/* Check the .eh_frame section for unwinding info */
	400	if (!read_unwind_spec_eh_frame(map->dso, ui->machine,
	401	&table_data, &segbase, &fde_count)) {
	402	memset(&di, 0, sizeof(di));
	403	di.format = UNW_INFO_FORMAT_REMOTE_TABLE;
	404	di.start_ip = map->start;
	405	di.end_ip = map->end;
eac05af2 SS	406	di.u.rti.segbase = map->start + segbase - map->pgoff;
eac05af2 SS	407	di.u.rti.table_data = map->start + table_data - map->pgoff;
ab255e72 JP	408	di.u.rti.table_len = fde_count * sizeof(struct table_entry)
ab255e72 JP	409	/ sizeof(unw_word_t);
8eac1d5e RV	410	ret = dwarf_search_unwind_table(as, ip, &di, pi,
8eac1d5e RV	411	need_unwind_info, arg);
ab255e72 JP	412	}
	413
	414	#ifndef NO_LIBUNWIND_DEBUG_FRAME
	415	/* Check the .debug_frame section for unwinding info */
8eac1d5e RV	416	if (ret < 0 &&
8eac1d5e RV	417	!read_unwind_spec_debug_frame(map->dso, ui->machine, &segbase)) {
4bb11d01	418	int fd = dso__data_get_fd(map->dso, ui->machine);
b93b0967 WN	419	int is_exec = elf_is_exec(fd, map->dso->name);
b93b0967 WN	420	unw_word_t base = is_exec ? 0 : map->start;
7ed4915a	421	const char *symfile;
b93b0967	422
4bb11d01	423	if (fd >= 0)
f005813a	424	dso__data_put_fd(map->dso);
4bb11d01	425
7ed4915a RV	426	symfile = map->dso->symsrc_filename ?: map->dso->name;
7ed4915a RV	427
ab255e72	428	memset(&di, 0, sizeof(di));
7ed4915a	429	if (dwarf_find_debug_frame(0, &di, ip, base, symfile,
d11416e7 JP	430	map->start, map->end))
	431	return dwarf_search_unwind_table(as, ip, &di, pi,
	432	need_unwind_info, arg);
ab255e72 JP	433	}
ab255e72 JP	434	#endif
71ad0f5e	435
8eac1d5e	436	return ret;
71ad0f5e JO	437	}
71ad0f5e JO	438
1d037ca1 IT	439	static int access_fpreg(unw_addr_space_t __maybe_unused as,
	440	unw_regnum_t __maybe_unused num,
	441	unw_fpreg_t __maybe_unused *val,
	442	int __maybe_unused __write,
	443	void __maybe_unused *arg)
71ad0f5e JO	444	{
	445	pr_err("unwind: access_fpreg unsupported\n");
	446	return -UNW_EINVAL;
	447	}
	448
1d037ca1 IT	449	static int get_dyn_info_list_addr(unw_addr_space_t __maybe_unused as,
	450	unw_word_t __maybe_unused *dil_addr,
	451	void __maybe_unused *arg)
71ad0f5e JO	452	{
	453	return -UNW_ENOINFO;
	454	}
	455
1d037ca1 IT	456	static int resume(unw_addr_space_t __maybe_unused as,
	457	unw_cursor_t __maybe_unused *cu,
	458	void __maybe_unused *arg)
71ad0f5e JO	459	{
	460	pr_err("unwind: resume unsupported\n");
	461	return -UNW_EINVAL;
	462	}
	463
	464	static int
1d037ca1 IT	465	get_proc_name(unw_addr_space_t __maybe_unused as,
	466	unw_word_t __maybe_unused addr,
	467	char __maybe_unused *bufp, size_t __maybe_unused buf_len,
	468	unw_word_t __maybe_unused offp, void __maybe_unused arg)
71ad0f5e JO	469	{
	470	pr_err("unwind: get_proc_name unsupported\n");
	471	return -UNW_EINVAL;
	472	}
	473
	474	static int access_dso_mem(struct unwind_info *ui, unw_word_t addr,
	475	unw_word_t *data)
	476	{
f22ed827	477	struct map *map;
71ad0f5e JO	478	ssize_t size;
71ad0f5e JO	479
f22ed827 JO	480	map = find_map(addr, ui);
f22ed827 JO	481	if (!map) {
71ad0f5e JO	482	pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
	483	return -1;
	484	}
	485
f22ed827	486	if (!map->dso)
71ad0f5e JO	487	return -1;
71ad0f5e JO	488
f22ed827	489	size = dso__data_read_addr(map->dso, map, ui->machine,
71ad0f5e JO	490	addr, (u8 ) data, sizeof(data));
	491
	492	return !(size == sizeof(*data));
	493	}
	494
1d037ca1	495	static int access_mem(unw_addr_space_t __maybe_unused as,
71ad0f5e JO	496	unw_word_t addr, unw_word_t *valp,
	497	int __write, void *arg)
	498	{
	499	struct unwind_info *ui = arg;
	500	struct stack_dump *stack = &ui->sample->user_stack;
c9b951c4	501	u64 start, end;
71ad0f5e JO	502	int offset;
	503	int ret;
	504
	505	/* Don't support write, probably not needed. */
	506	if (__write \|\| !stack \|\| !ui->sample->user_regs.regs) {
	507	*valp = 0;
	508	return 0;
	509	}
	510
78ff1d6d HK	511	ret = perf_reg_value(&start, &ui->sample->user_regs,
78ff1d6d HK	512	LIBUNWIND__ARCH_REG_SP);
71ad0f5e JO	513	if (ret)
	514	return ret;
	515
	516	end = start + stack->size;
	517
	518	/* Check overflow. */
	519	if (addr + sizeof(unw_word_t) < addr)
	520	return -EINVAL;
	521
	522	if (addr < start \|\| addr + sizeof(unw_word_t) >= end) {
	523	ret = access_dso_mem(ui, addr, valp);
	524	if (ret) {
c9b951c4 JO	525	pr_debug("unwind: access_mem %p not inside range"
c9b951c4 JO	526	" 0x%" PRIx64 "-0x%" PRIx64 "\n",
186c6cfb	527	(void *) (uintptr_t) addr, start, end);
71ad0f5e JO	528	*valp = 0;
	529	return ret;
	530	}
	531	return 0;
	532	}
	533
	534	offset = addr - start;
	535	valp = (unw_word_t *)&stack->data[offset];
c9b951c4	536	pr_debug("unwind: access_mem addr %p val %lx, offset %d\n",
186c6cfb	537	(void ) (uintptr_t) addr, (unsigned long)valp, offset);
71ad0f5e JO	538	return 0;
	539	}
	540
1d037ca1	541	static int access_reg(unw_addr_space_t __maybe_unused as,
71ad0f5e JO	542	unw_regnum_t regnum, unw_word_t *valp,
	543	int __write, void *arg)
	544	{
	545	struct unwind_info *ui = arg;
	546	int id, ret;
c9b951c4	547	u64 val;
71ad0f5e JO	548
	549	/* Don't support write, I suspect we don't need it. */
	550	if (__write) {
	551	pr_err("unwind: access_reg w %d\n", regnum);
	552	return 0;
	553	}
	554
	555	if (!ui->sample->user_regs.regs) {
	556	*valp = 0;
	557	return 0;
	558	}
	559
eeb118c5	560	id = LIBUNWIND__ARCH_REG_ID(regnum);
71ad0f5e JO	561	if (id < 0)
	562	return -EINVAL;
	563
c9b951c4	564	ret = perf_reg_value(&val, &ui->sample->user_regs, id);
71ad0f5e JO	565	if (ret) {
	566	pr_err("unwind: can't read reg %d\n", regnum);
	567	return ret;
	568	}
	569
c9b951c4	570	*valp = (unw_word_t) val;
71ad0f5e JO	571	pr_debug("unwind: reg %d, val %lx\n", regnum, (unsigned long)*valp);
	572	return 0;
	573	}
	574
1d037ca1 IT	575	static void put_unwind_info(unw_addr_space_t __maybe_unused as,
	576	unw_proc_info_t *pi __maybe_unused,
	577	void *arg __maybe_unused)
71ad0f5e JO	578	{
	579	pr_debug("unwind: put_unwind_info called\n");
	580	}
	581
bb871a9c	582	static int entry(u64 ip, struct thread *thread,
71ad0f5e JO	583	unwind_entry_cb_t cb, void *arg)
	584	{
	585	struct unwind_entry e;
	586	struct addr_location al;
	587
bb871a9c	588	thread__find_addr_location(thread, PERF_RECORD_MISC_USER,
61710bde	589	MAP__FUNCTION, ip, &al);
71ad0f5e	590
67540759	591	e.ip = al.addr;
71ad0f5e JO	592	e.map = al.map;
	593	e.sym = al.sym;
	594
	595	pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
	596	al.sym ? al.sym->name : "''",
	597	ip,
	598	al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
	599
	600	return cb(&e, arg);
	601	}
	602
	603	static void display_error(int err)
	604	{
	605	switch (err) {
	606	case UNW_EINVAL:
	607	pr_err("unwind: Only supports local.\n");
	608	break;
	609	case UNW_EUNSPEC:
	610	pr_err("unwind: Unspecified error.\n");
	611	break;
	612	case UNW_EBADREG:
	613	pr_err("unwind: Register unavailable.\n");
	614	break;
	615	default:
	616	break;
	617	}
	618	}
	619
	620	static unw_accessors_t accessors = {
	621	.find_proc_info = find_proc_info,
	622	.put_unwind_info = put_unwind_info,
	623	.get_dyn_info_list_addr = get_dyn_info_list_addr,
	624	.access_mem = access_mem,
	625	.access_reg = access_reg,
	626	.access_fpreg = access_fpreg,
	627	.resume = resume,
	628	.get_proc_name = get_proc_name,
	629	};
	630
f83c0415	631	static int _unwind__prepare_access(struct thread *thread)
71ad0f5e	632	{
66f066d8 NK	633	if (callchain_param.record_mode != CALLCHAIN_DWARF)
66f066d8 NK	634	return 0;
71ad0f5e	635
e583d70c JO	636	thread->addr_space = unw_create_addr_space(&accessors, 0);
e583d70c JO	637	if (!thread->addr_space) {
71ad0f5e JO	638	pr_err("unwind: Can't create unwind address space.\n");
	639	return -ENOMEM;
	640	}
	641
e583d70c	642	unw_set_caching_policy(thread->addr_space, UNW_CACHE_GLOBAL);
66f066d8 NK	643	return 0;
	644	}
	645
f83c0415	646	static void _unwind__flush_access(struct thread *thread)
380b5143	647	{
380b5143 NK	648	if (callchain_param.record_mode != CALLCHAIN_DWARF)
	649	return;
	650
e583d70c	651	unw_flush_cache(thread->addr_space, 0, 0);
380b5143 NK	652	}
380b5143 NK	653
f83c0415	654	static void _unwind__finish_access(struct thread *thread)
66f066d8	655	{
66f066d8 NK	656	if (callchain_param.record_mode != CALLCHAIN_DWARF)
	657	return;
	658
e583d70c	659	unw_destroy_addr_space(thread->addr_space);
66f066d8 NK	660	}
	661
	662	static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,
	663	void *arg, int max_stack)
	664	{
b26b218a	665	u64 val;
cb1dc22d	666	unw_word_t ips[max_stack];
66f066d8 NK	667	unw_addr_space_t addr_space;
66f066d8 NK	668	unw_cursor_t c;
cb1dc22d	669	int ret, i = 0;
66f066d8	670
78ff1d6d HK	671	ret = perf_reg_value(&val, &ui->sample->user_regs,
78ff1d6d HK	672	LIBUNWIND__ARCH_REG_IP);
b26b218a JO	673	if (ret)
	674	return ret;
	675
cb1dc22d	676	ips[i++] = (unw_word_t) val;
b26b218a	677
cb1dc22d JO	678	/*
	679	* If we need more than one entry, do the DWARF
	680	* unwind itself.
	681	*/
	682	if (max_stack - 1 > 0) {
e583d70c JO	683	WARN_ONCE(!ui->thread, "WARNING: ui->thread is NULL");
	684	addr_space = ui->thread->addr_space;
	685
cb1dc22d JO	686	if (addr_space == NULL)
	687	return -1;
	688
	689	ret = unw_init_remote(&c, addr_space, ui);
	690	if (ret)
	691	display_error(ret);
	692
	693	while (!ret && (unw_step(&c) > 0) && i < max_stack) {
	694	unw_get_reg(&c, UNW_REG_IP, &ips[i]);
	695	++i;
	696	}
66f066d8	697
cb1dc22d JO	698	max_stack = i;
cb1dc22d JO	699	}
71ad0f5e	700
cb1dc22d JO	701	/*
	702	* Display what we got based on the order setup.
	703	*/
	704	for (i = 0; i < max_stack && !ret; i++) {
	705	int j = i;
71ad0f5e	706
cb1dc22d JO	707	if (callchain_param.order == ORDER_CALLER)
	708	j = max_stack - i - 1;
	709	ret = ips[j] ? entry(ips[j], ui->thread, cb, arg) : 0;
71ad0f5e JO	710	}
71ad0f5e JO	711
71ad0f5e JO	712	return ret;
	713	}
	714
f83c0415	715	static int _unwind__get_entries(unwind_entry_cb_t cb, void *arg,
dd8c17a5	716	struct thread *thread,
352ea45a	717	struct perf_sample *data, int max_stack)
71ad0f5e	718	{
71ad0f5e JO	719	struct unwind_info ui = {
71ad0f5e JO	720	.sample = data,
71ad0f5e	721	.thread = thread,
dd8c17a5	722	.machine = thread->mg->machine,
71ad0f5e	723	};
71ad0f5e JO	724
	725	if (!data->user_regs.regs)
	726	return -EINVAL;
	727
b26b218a JO	728	if (max_stack <= 0)
b26b218a JO	729	return -EINVAL;
71ad0f5e	730
b26b218a	731	return get_entries(&ui, cb, arg, max_stack);
71ad0f5e	732	}
f83c0415 HK	733
	734	static struct unwind_libunwind_ops
	735	_unwind_libunwind_ops = {
	736	.prepare_access = _unwind__prepare_access,
	737	.flush_access = _unwind__flush_access,
	738	.finish_access = _unwind__finish_access,
	739	.get_entries = _unwind__get_entries,
	740	};
	741
19473e7b	742	#ifndef REMOTE_UNWIND_LIBUNWIND
f83c0415 HK	743	struct unwind_libunwind_ops *
f83c0415 HK	744	local_unwind_libunwind_ops = &_unwind_libunwind_ops;
19473e7b	745	#endif