[linux-2.6-block.git] / tools / perf / util / unwind-libunwind-local.c

// SPDX-License-Identifier: GPL-2.0
/*
 * 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>
#include <linux/zalloc.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 "map.h"
#include "symbol.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);
					zfree(&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;
	return thread__find_map(ui->thread, PERF_RECORD_MISC_USER, ip, &al);
}

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;

	e.sym = thread__find_symbol(thread, PERF_RECORD_MISC_USER, ip, &al);
	e.ip  = ip;
	e.map = al.map;

	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 map_groups *mg)
{
	mg->addr_space = unw_create_addr_space(&accessors, 0);
	if (!mg->addr_space) {
		pr_err("unwind: Can't create unwind address space.\n");
		return -ENOMEM;
	}

	unw_set_caching_policy(mg->addr_space, UNW_CACHE_GLOBAL);
	return 0;
}

static void _unwind__flush_access(struct map_groups *mg)
{
	unw_flush_cache(mg->addr_space, 0, 0);
}

static void _unwind__finish_access(struct map_groups *mg)
{
	unw_destroy_addr_space(mg->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->mg->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
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
71ad0f5e JO	2	/*
	3	* Post mortem Dwarf CFI based unwinding on top of regs and stack dumps.
	4	*
	5	* Lots of this code have been borrowed or heavily inspired from parts of
	6	* the libunwind 0.99 code which are (amongst other contributors I may have
	7	* forgotten):
	8	*
	9	* Copyright (C) 2002-2007 Hewlett-Packard Co
	10	* Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
	11	*
	12	* And the bugs have been added by:
	13	*
	14	* Copyright (C) 2010, Frederic Weisbecker <fweisbec@gmail.com>
	15	* Copyright (C) 2012, Jiri Olsa <jolsa@redhat.com>
	16	*
	17	*/
	18
	19	#include <elf.h>
a43783ae	20	#include <errno.h>
71ad0f5e JO	21	#include <gelf.h>
71ad0f5e JO	22	#include <fcntl.h>
fd20e811	23	#include <inttypes.h>
71ad0f5e JO	24	#include <string.h>
	25	#include <unistd.h>
	26	#include <sys/mman.h>
	27	#include <linux/list.h>
d8f9da24	28	#include <linux/zalloc.h>
19473e7b	29	#ifndef REMOTE_UNWIND_LIBUNWIND
71ad0f5e JO	30	#include <libunwind.h>
71ad0f5e JO	31	#include <libunwind-ptrace.h>
19473e7b	32	#endif
66f066d8	33	#include "callchain.h"
71ad0f5e JO	34	#include "thread.h"
	35	#include "session.h"
	36	#include "perf_regs.h"
	37	#include "unwind.h"
1101f69a	38	#include "map.h"
99ca4233	39	#include "symbol.h"
84f5d36f	40	#include "debug.h"
e583d70c	41	#include "asm/bug.h"
9343e45b	42	#include "dso.h"
71ad0f5e JO	43
	44	extern int
	45	UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as,
	46	unw_word_t ip,
	47	unw_dyn_info_t *di,
	48	unw_proc_info_t *pi,
	49	int need_unwind_info, void *arg);
	50
	51	#define dwarf_search_unwind_table UNW_OBJ(dwarf_search_unwind_table)
	52
ab255e72 JP	53	extern int
	54	UNW_OBJ(dwarf_find_debug_frame) (int found, unw_dyn_info_t *di_debug,
	55	unw_word_t ip,
	56	unw_word_t segbase,
	57	const char *obj_name, unw_word_t start,
	58	unw_word_t end);
	59
	60	#define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame)
	61
71ad0f5e JO	62	#define DW_EH_PE_FORMAT_MASK 0x0f /* format of the encoded value */
	63	#define DW_EH_PE_APPL_MASK 0x70 /* how the value is to be applied */
	64
	65	/* Pointer-encoding formats: */
	66	#define DW_EH_PE_omit 0xff
	67	#define DW_EH_PE_ptr 0x00 /* pointer-sized unsigned value */
	68	#define DW_EH_PE_udata4 0x03 /* unsigned 32-bit value */
	69	#define DW_EH_PE_udata8 0x04 /* unsigned 64-bit value */
	70	#define DW_EH_PE_sdata4 0x0b /* signed 32-bit value */
	71	#define DW_EH_PE_sdata8 0x0c /* signed 64-bit value */
	72
	73	/* Pointer-encoding application: */
	74	#define DW_EH_PE_absptr 0x00 /* absolute value */
	75	#define DW_EH_PE_pcrel 0x10 /* rel. to addr. of encoded value */
	76
	77	/*
	78	* The following are not documented by LSB v1.3, yet they are used by
	79	* GCC, presumably they aren't documented by LSB since they aren't
	80	* used on Linux:
	81	*/
	82	#define DW_EH_PE_funcrel 0x40 /* start-of-procedure-relative */
	83	#define DW_EH_PE_aligned 0x50 /* aligned pointer */
	84
	85	/* Flags intentionaly not handled, since they're not needed:
	86	* #define DW_EH_PE_indirect 0x80
	87	* #define DW_EH_PE_uleb128 0x01
	88	* #define DW_EH_PE_udata2 0x02
	89	* #define DW_EH_PE_sleb128 0x09
	90	* #define DW_EH_PE_sdata2 0x0a
	91	* #define DW_EH_PE_textrel 0x20
	92	* #define DW_EH_PE_datarel 0x30
	93	*/
	94
	95	struct unwind_info {
	96	struct perf_sample *sample;
	97	struct machine *machine;
	98	struct thread *thread;
71ad0f5e JO	99	};
	100
	101	#define dw_read(ptr, type, end) ({ \
	102	type __p = (type ) ptr; \
	103	type __v; \
	104	if ((__p + 1) > (type *) end) \
	105	return -EINVAL; \
	106	__v = *__p++; \
	107	ptr = (typeof(ptr)) __p; \
	108	__v; \
	109	})
	110
	111	static int __dw_read_encoded_value(u8 *p, u8 end, u64 *val,
	112	u8 encoding)
	113	{
	114	u8 cur = p;
	115	*val = 0;
	116
	117	switch (encoding) {
	118	case DW_EH_PE_omit:
	119	*val = 0;
	120	goto out;
	121	case DW_EH_PE_ptr:
	122	*val = dw_read(cur, unsigned long, end);
	123	goto out;
	124	default:
	125	break;
	126	}
	127
	128	switch (encoding & DW_EH_PE_APPL_MASK) {
	129	case DW_EH_PE_absptr:
	130	break;
	131	case DW_EH_PE_pcrel:
	132	*val = (unsigned long) cur;
	133	break;
	134	default:
	135	return -EINVAL;
	136	}
	137
	138	if ((encoding & 0x07) == 0x00)
	139	encoding \|= DW_EH_PE_udata4;
	140
	141	switch (encoding & DW_EH_PE_FORMAT_MASK) {
	142	case DW_EH_PE_sdata4:
	143	*val += dw_read(cur, s32, end);
	144	break;
	145	case DW_EH_PE_udata4:
	146	*val += dw_read(cur, u32, end);
	147	break;
	148	case DW_EH_PE_sdata8:
	149	*val += dw_read(cur, s64, end);
	150	break;
	151	case DW_EH_PE_udata8:
	152	*val += dw_read(cur, u64, end);
	153	break;
	154	default:
	155	return -EINVAL;
	156	}
	157
	158	out:
	159	*p = cur;
	160	return 0;
	161	}
	162
163	#define dw_read_encoded_value(ptr, end, enc) ({ \
164	u64 __v; \
165	if (__dw_read_encoded_value(&ptr, end, &__v, enc)) { \
166	return -EINVAL; \
167	} \
168	__v; \
169	})
170
71ad0f5e JO	171	static u64 elf_section_offset(int fd, const char *name)
	172	{
	173	Elf *elf;
	174	GElf_Ehdr ehdr;
	175	GElf_Shdr shdr;
	176	u64 offset = 0;
	177
	178	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
	179	if (elf == NULL)
	180	return 0;
	181
	182	do {
	183	if (gelf_getehdr(elf, &ehdr) == NULL)
	184	break;
	185
99ca4233	186	if (!elf_section_by_name(elf, &ehdr, &shdr, name, NULL))
71ad0f5e JO	187	break;
	188
	189	offset = shdr.sh_offset;
	190	} while (0);
	191
	192	elf_end(elf);
	193	return offset;
	194	}
	195
b93b0967 WN	196	#ifndef NO_LIBUNWIND_DEBUG_FRAME
	197	static int elf_is_exec(int fd, const char *name)
	198	{
	199	Elf *elf;
	200	GElf_Ehdr ehdr;
	201	int retval = 0;
	202
	203	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
	204	if (elf == NULL)
	205	return 0;
	206	if (gelf_getehdr(elf, &ehdr) == NULL)
	207	goto out;
	208
	209	retval = (ehdr.e_type == ET_EXEC);
	210
	211	out:
	212	elf_end(elf);
	213	pr_debug("unwind: elf_is_exec(%s): %d\n", name, retval);
	214	return retval;
	215	}
	216	#endif
	217
71ad0f5e JO	218	struct table_entry {
	219	u32 start_ip_offset;
	220	u32 fde_offset;
	221	};
	222
	223	struct eh_frame_hdr {
	224	unsigned char version;
	225	unsigned char eh_frame_ptr_enc;
	226	unsigned char fde_count_enc;
	227	unsigned char table_enc;
	228
	229	/*
	230	* The rest of the header is variable-length and consists of the
	231	* following members:
	232	*
	233	* encoded_t eh_frame_ptr;
	234	* encoded_t fde_count;
	235	*/
	236
	237	/* A single encoded pointer should not be more than 8 bytes. */
	238	u64 enc[2];
	239
	240	/*
	241	* struct {
	242	* encoded_t start_ip;
	243	* encoded_t fde_addr;
	244	* } binary_search_table[fde_count];
	245	*/
	246	char data[0];
	247	} __packed;
	248
	249	static int unwind_spec_ehframe(struct dso dso, struct machine machine,
	250	u64 offset, u64 table_data, u64 segbase,
	251	u64 *fde_count)
	252	{
	253	struct eh_frame_hdr hdr;
	254	u8 enc = (u8 ) &hdr.enc;
	255	u8 end = (u8 ) &hdr.data;
	256	ssize_t r;
	257
	258	r = dso__data_read_offset(dso, machine, offset,
	259	(u8 *) &hdr, sizeof(hdr));
	260	if (r != sizeof(hdr))
	261	return -EINVAL;
	262
	263	/* We dont need eh_frame_ptr, just skip it. */
	264	dw_read_encoded_value(enc, end, hdr.eh_frame_ptr_enc);
	265
	266	*fde_count = dw_read_encoded_value(enc, end, hdr.fde_count_enc);
	267	*segbase = offset;
	268	table_data = (enc - (u8 ) &hdr) + offset;
	269	return 0;
	270	}
	271
ab255e72 JP	272	static int read_unwind_spec_eh_frame(struct dso dso, struct machine machine,
	273	u64 table_data, u64 segbase,
	274	u64 *fde_count)
71ad0f5e JO	275	{
71ad0f5e JO	276	int ret = -EINVAL, fd;
303cb89a	277	u64 offset = dso->data.eh_frame_hdr_offset;
71ad0f5e	278
f1f13af9	279	if (offset == 0) {
4bb11d01	280	fd = dso__data_get_fd(dso, machine);
f1f13af9 NK	281	if (fd < 0)
f1f13af9 NK	282	return -EINVAL;
71ad0f5e	283
f1f13af9 NK	284	/* Check the .eh_frame section for unwinding info */
f1f13af9 NK	285	offset = elf_section_offset(fd, ".eh_frame_hdr");
303cb89a	286	dso->data.eh_frame_hdr_offset = offset;
4bb11d01	287	dso__data_put_fd(dso);
f1f13af9	288	}
71ad0f5e JO	289
	290	if (offset)
	291	ret = unwind_spec_ehframe(dso, machine, offset,
	292	table_data, segbase,
	293	fde_count);
	294
71ad0f5e JO	295	return ret;
	296	}
	297
ab255e72 JP	298	#ifndef NO_LIBUNWIND_DEBUG_FRAME
	299	static int read_unwind_spec_debug_frame(struct dso *dso,
	300	struct machine machine, u64 offset)
	301	{
f1f13af9	302	int fd;
303cb89a	303	u64 ofs = dso->data.debug_frame_offset;
ab255e72	304
9343e45b MGP	305	/* debug_frame can reside in:
	306	* - dso
	307	* - debug pointed by symsrc_filename
	308	* - gnu_debuglink, which doesn't necessary
	309	* has to be pointed by symsrc_filename
	310	*/
f1f13af9	311	if (ofs == 0) {
4bb11d01	312	fd = dso__data_get_fd(dso, machine);
9343e45b MGP	313	if (fd >= 0) {
	314	ofs = elf_section_offset(fd, ".debug_frame");
	315	dso__data_put_fd(dso);
	316	}
	317
	318	if (ofs <= 0) {
	319	fd = open(dso->symsrc_filename, O_RDONLY);
	320	if (fd >= 0) {
	321	ofs = elf_section_offset(fd, ".debug_frame");
	322	close(fd);
	323	}
	324	}
	325
	326	if (ofs <= 0) {
	327	char *debuglink = malloc(PATH_MAX);
	328	int ret = 0;
	329
	330	ret = dso__read_binary_type_filename(
	331	dso, DSO_BINARY_TYPE__DEBUGLINK,
	332	machine->root_dir, debuglink, PATH_MAX);
	333	if (!ret) {
	334	fd = open(debuglink, O_RDONLY);
	335	if (fd >= 0) {
	336	ofs = elf_section_offset(fd,
	337	".debug_frame");
	338	close(fd);
	339	}
	340	}
	341	if (ofs > 0) {
	342	if (dso->symsrc_filename != NULL) {
	343	pr_warning(
	344	"%s: overwrite symsrc(%s,%s)\n",
	345	__func__,
	346	dso->symsrc_filename,
	347	debuglink);
d8f9da24	348	zfree(&dso->symsrc_filename);
9343e45b MGP	349	}
	350	dso->symsrc_filename = debuglink;
	351	} else {
	352	free(debuglink);
	353	}
	354	}
ab255e72	355
303cb89a	356	dso->data.debug_frame_offset = ofs;
f1f13af9	357	}
ab255e72	358
f1f13af9	359	*offset = ofs;
ab255e72 JP	360	if (*offset)
	361	return 0;
	362
	363	return -EINVAL;
	364	}
	365	#endif
	366
71ad0f5e JO	367	static struct map find_map(unw_word_t ip, struct unwind_info ui)
	368	{
	369	struct addr_location al;
404eb5a4	370	return thread__find_map(ui->thread, PERF_RECORD_MISC_USER, ip, &al);
71ad0f5e JO	371	}
	372
	373	static int
	374	find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi,
	375	int need_unwind_info, void *arg)
	376	{
	377	struct unwind_info *ui = arg;
	378	struct map *map;
	379	unw_dyn_info_t di;
	380	u64 table_data, segbase, fde_count;
8eac1d5e	381	int ret = -EINVAL;
71ad0f5e JO	382
	383	map = find_map(ip, ui);
	384	if (!map \|\| !map->dso)
	385	return -EINVAL;
	386
	387	pr_debug("unwind: find_proc_info dso %s\n", map->dso->name);
	388
ab255e72 JP	389	/* Check the .eh_frame section for unwinding info */
	390	if (!read_unwind_spec_eh_frame(map->dso, ui->machine,
	391	&table_data, &segbase, &fde_count)) {
	392	memset(&di, 0, sizeof(di));
	393	di.format = UNW_INFO_FORMAT_REMOTE_TABLE;
	394	di.start_ip = map->start;
	395	di.end_ip = map->end;
eac05af2 SS	396	di.u.rti.segbase = map->start + segbase - map->pgoff;
eac05af2 SS	397	di.u.rti.table_data = map->start + table_data - map->pgoff;
ab255e72 JP	398	di.u.rti.table_len = fde_count * sizeof(struct table_entry)
ab255e72 JP	399	/ sizeof(unw_word_t);
8eac1d5e RV	400	ret = dwarf_search_unwind_table(as, ip, &di, pi,
8eac1d5e RV	401	need_unwind_info, arg);
ab255e72 JP	402	}
	403
	404	#ifndef NO_LIBUNWIND_DEBUG_FRAME
	405	/* Check the .debug_frame section for unwinding info */
8eac1d5e RV	406	if (ret < 0 &&
8eac1d5e RV	407	!read_unwind_spec_debug_frame(map->dso, ui->machine, &segbase)) {
4bb11d01	408	int fd = dso__data_get_fd(map->dso, ui->machine);
b93b0967 WN	409	int is_exec = elf_is_exec(fd, map->dso->name);
b93b0967 WN	410	unw_word_t base = is_exec ? 0 : map->start;
7ed4915a	411	const char *symfile;
b93b0967	412
4bb11d01	413	if (fd >= 0)
f005813a	414	dso__data_put_fd(map->dso);
4bb11d01	415
7ed4915a RV	416	symfile = map->dso->symsrc_filename ?: map->dso->name;
7ed4915a RV	417
ab255e72	418	memset(&di, 0, sizeof(di));
7ed4915a	419	if (dwarf_find_debug_frame(0, &di, ip, base, symfile,
d11416e7 JP	420	map->start, map->end))
	421	return dwarf_search_unwind_table(as, ip, &di, pi,
	422	need_unwind_info, arg);
ab255e72 JP	423	}
ab255e72 JP	424	#endif
71ad0f5e	425
8eac1d5e	426	return ret;
71ad0f5e JO	427	}
71ad0f5e JO	428
1d037ca1 IT	429	static int access_fpreg(unw_addr_space_t __maybe_unused as,
	430	unw_regnum_t __maybe_unused num,
	431	unw_fpreg_t __maybe_unused *val,
	432	int __maybe_unused __write,
	433	void __maybe_unused *arg)
71ad0f5e JO	434	{
	435	pr_err("unwind: access_fpreg unsupported\n");
	436	return -UNW_EINVAL;
	437	}
	438
1d037ca1 IT	439	static int get_dyn_info_list_addr(unw_addr_space_t __maybe_unused as,
	440	unw_word_t __maybe_unused *dil_addr,
	441	void __maybe_unused *arg)
71ad0f5e JO	442	{
	443	return -UNW_ENOINFO;
	444	}
	445
1d037ca1 IT	446	static int resume(unw_addr_space_t __maybe_unused as,
	447	unw_cursor_t __maybe_unused *cu,
	448	void __maybe_unused *arg)
71ad0f5e JO	449	{
	450	pr_err("unwind: resume unsupported\n");
	451	return -UNW_EINVAL;
	452	}
	453
	454	static int
1d037ca1 IT	455	get_proc_name(unw_addr_space_t __maybe_unused as,
	456	unw_word_t __maybe_unused addr,
	457	char __maybe_unused *bufp, size_t __maybe_unused buf_len,
	458	unw_word_t __maybe_unused offp, void __maybe_unused arg)
71ad0f5e JO	459	{
	460	pr_err("unwind: get_proc_name unsupported\n");
	461	return -UNW_EINVAL;
	462	}
	463
	464	static int access_dso_mem(struct unwind_info *ui, unw_word_t addr,
	465	unw_word_t *data)
	466	{
f22ed827	467	struct map *map;
71ad0f5e JO	468	ssize_t size;
71ad0f5e JO	469
f22ed827 JO	470	map = find_map(addr, ui);
f22ed827 JO	471	if (!map) {
71ad0f5e JO	472	pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
	473	return -1;
	474	}
	475
f22ed827	476	if (!map->dso)
71ad0f5e JO	477	return -1;
71ad0f5e JO	478
f22ed827	479	size = dso__data_read_addr(map->dso, map, ui->machine,
71ad0f5e JO	480	addr, (u8 ) data, sizeof(data));
	481
	482	return !(size == sizeof(*data));
	483	}
	484
1d037ca1	485	static int access_mem(unw_addr_space_t __maybe_unused as,
71ad0f5e JO	486	unw_word_t addr, unw_word_t *valp,
	487	int __write, void *arg)
	488	{
	489	struct unwind_info *ui = arg;
	490	struct stack_dump *stack = &ui->sample->user_stack;
c9b951c4	491	u64 start, end;
71ad0f5e JO	492	int offset;
	493	int ret;
	494
	495	/* Don't support write, probably not needed. */
	496	if (__write \|\| !stack \|\| !ui->sample->user_regs.regs) {
	497	*valp = 0;
	498	return 0;
	499	}
	500
78ff1d6d HK	501	ret = perf_reg_value(&start, &ui->sample->user_regs,
78ff1d6d HK	502	LIBUNWIND__ARCH_REG_SP);
71ad0f5e JO	503	if (ret)
	504	return ret;
	505
	506	end = start + stack->size;
	507
	508	/* Check overflow. */
	509	if (addr + sizeof(unw_word_t) < addr)
	510	return -EINVAL;
	511
	512	if (addr < start \|\| addr + sizeof(unw_word_t) >= end) {
	513	ret = access_dso_mem(ui, addr, valp);
	514	if (ret) {
c9b951c4 JO	515	pr_debug("unwind: access_mem %p not inside range"
c9b951c4 JO	516	" 0x%" PRIx64 "-0x%" PRIx64 "\n",
186c6cfb	517	(void *) (uintptr_t) addr, start, end);
71ad0f5e JO	518	*valp = 0;
	519	return ret;
	520	}
	521	return 0;
	522	}
	523
	524	offset = addr - start;
	525	valp = (unw_word_t *)&stack->data[offset];
c9b951c4	526	pr_debug("unwind: access_mem addr %p val %lx, offset %d\n",
186c6cfb	527	(void ) (uintptr_t) addr, (unsigned long)valp, offset);
71ad0f5e JO	528	return 0;
	529	}
	530
1d037ca1	531	static int access_reg(unw_addr_space_t __maybe_unused as,
71ad0f5e JO	532	unw_regnum_t regnum, unw_word_t *valp,
	533	int __write, void *arg)
	534	{
	535	struct unwind_info *ui = arg;
	536	int id, ret;
c9b951c4	537	u64 val;
71ad0f5e JO	538
	539	/* Don't support write, I suspect we don't need it. */
	540	if (__write) {
	541	pr_err("unwind: access_reg w %d\n", regnum);
	542	return 0;
	543	}
	544
	545	if (!ui->sample->user_regs.regs) {
	546	*valp = 0;
	547	return 0;
	548	}
	549
eeb118c5	550	id = LIBUNWIND__ARCH_REG_ID(regnum);
71ad0f5e JO	551	if (id < 0)
	552	return -EINVAL;
	553
c9b951c4	554	ret = perf_reg_value(&val, &ui->sample->user_regs, id);
71ad0f5e JO	555	if (ret) {
	556	pr_err("unwind: can't read reg %d\n", regnum);
	557	return ret;
	558	}
	559
c9b951c4	560	*valp = (unw_word_t) val;
71ad0f5e JO	561	pr_debug("unwind: reg %d, val %lx\n", regnum, (unsigned long)*valp);
	562	return 0;
	563	}
	564
1d037ca1 IT	565	static void put_unwind_info(unw_addr_space_t __maybe_unused as,
	566	unw_proc_info_t *pi __maybe_unused,
	567	void *arg __maybe_unused)
71ad0f5e JO	568	{
	569	pr_debug("unwind: put_unwind_info called\n");
	570	}
	571
bb871a9c	572	static int entry(u64 ip, struct thread *thread,
71ad0f5e JO	573	unwind_entry_cb_t cb, void *arg)
	574	{
	575	struct unwind_entry e;
	576	struct addr_location al;
	577
d9a5f274	578	e.sym = thread__find_symbol(thread, PERF_RECORD_MISC_USER, ip, &al);
2a9d5050	579	e.ip = ip;
71ad0f5e	580	e.map = al.map;
71ad0f5e JO	581
	582	pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
	583	al.sym ? al.sym->name : "''",
	584	ip,
	585	al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
	586
	587	return cb(&e, arg);
	588	}
	589
	590	static void display_error(int err)
	591	{
	592	switch (err) {
	593	case UNW_EINVAL:
	594	pr_err("unwind: Only supports local.\n");
	595	break;
	596	case UNW_EUNSPEC:
	597	pr_err("unwind: Unspecified error.\n");
	598	break;
	599	case UNW_EBADREG:
	600	pr_err("unwind: Register unavailable.\n");
	601	break;
	602	default:
	603	break;
	604	}
	605	}
	606
	607	static unw_accessors_t accessors = {
	608	.find_proc_info = find_proc_info,
	609	.put_unwind_info = put_unwind_info,
	610	.get_dyn_info_list_addr = get_dyn_info_list_addr,
	611	.access_mem = access_mem,
	612	.access_reg = access_reg,
	613	.access_fpreg = access_fpreg,
	614	.resume = resume,
	615	.get_proc_name = get_proc_name,
	616	};
	617
e8ba2906	618	static int _unwind__prepare_access(struct map_groups *mg)
71ad0f5e	619	{
e8ba2906 JK	620	mg->addr_space = unw_create_addr_space(&accessors, 0);
e8ba2906 JK	621	if (!mg->addr_space) {
71ad0f5e JO	622	pr_err("unwind: Can't create unwind address space.\n");
	623	return -ENOMEM;
	624	}
	625
e8ba2906	626	unw_set_caching_policy(mg->addr_space, UNW_CACHE_GLOBAL);
66f066d8 NK	627	return 0;
	628	}
	629
e8ba2906	630	static void _unwind__flush_access(struct map_groups *mg)
380b5143	631	{
e8ba2906	632	unw_flush_cache(mg->addr_space, 0, 0);
380b5143 NK	633	}
380b5143 NK	634
e8ba2906	635	static void _unwind__finish_access(struct map_groups *mg)
66f066d8	636	{
e8ba2906	637	unw_destroy_addr_space(mg->addr_space);
66f066d8 NK	638	}
	639
	640	static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,
	641	void *arg, int max_stack)
	642	{
b26b218a	643	u64 val;
cb1dc22d	644	unw_word_t ips[max_stack];
66f066d8 NK	645	unw_addr_space_t addr_space;
66f066d8 NK	646	unw_cursor_t c;
cb1dc22d	647	int ret, i = 0;
66f066d8	648
78ff1d6d HK	649	ret = perf_reg_value(&val, &ui->sample->user_regs,
78ff1d6d HK	650	LIBUNWIND__ARCH_REG_IP);
b26b218a JO	651	if (ret)
	652	return ret;
	653
cb1dc22d	654	ips[i++] = (unw_word_t) val;
b26b218a	655
cb1dc22d JO	656	/*
	657	* If we need more than one entry, do the DWARF
	658	* unwind itself.
	659	*/
	660	if (max_stack - 1 > 0) {
e583d70c	661	WARN_ONCE(!ui->thread, "WARNING: ui->thread is NULL");
e8ba2906	662	addr_space = ui->thread->mg->addr_space;
e583d70c	663
cb1dc22d JO	664	if (addr_space == NULL)
	665	return -1;
	666
	667	ret = unw_init_remote(&c, addr_space, ui);
	668	if (ret)
	669	display_error(ret);
	670
	671	while (!ret && (unw_step(&c) > 0) && i < max_stack) {
	672	unw_get_reg(&c, UNW_REG_IP, &ips[i]);
1982ad48 MW	673
	674	/*
	675	* Decrement the IP for any non-activation frames.
	676	* this is required to properly find the srcline
	677	* for caller frames.
	678	* See also the documentation for dwfl_frame_pc(),
	679	* which this code tries to replicate.
	680	*/
	681	if (unw_is_signal_frame(&c) <= 0)
	682	--ips[i];
	683
cb1dc22d JO	684	++i;
cb1dc22d JO	685	}
66f066d8	686
cb1dc22d JO	687	max_stack = i;
cb1dc22d JO	688	}
71ad0f5e	689
cb1dc22d JO	690	/*
	691	* Display what we got based on the order setup.
	692	*/
	693	for (i = 0; i < max_stack && !ret; i++) {
	694	int j = i;
71ad0f5e	695
cb1dc22d JO	696	if (callchain_param.order == ORDER_CALLER)
	697	j = max_stack - i - 1;
	698	ret = ips[j] ? entry(ips[j], ui->thread, cb, arg) : 0;
71ad0f5e JO	699	}
71ad0f5e JO	700
71ad0f5e JO	701	return ret;
	702	}
	703
f83c0415	704	static int _unwind__get_entries(unwind_entry_cb_t cb, void *arg,
dd8c17a5	705	struct thread *thread,
352ea45a	706	struct perf_sample *data, int max_stack)
71ad0f5e	707	{
71ad0f5e JO	708	struct unwind_info ui = {
71ad0f5e JO	709	.sample = data,
71ad0f5e	710	.thread = thread,
dd8c17a5	711	.machine = thread->mg->machine,
71ad0f5e	712	};
71ad0f5e JO	713
	714	if (!data->user_regs.regs)
	715	return -EINVAL;
	716
b26b218a JO	717	if (max_stack <= 0)
b26b218a JO	718	return -EINVAL;
71ad0f5e	719
b26b218a	720	return get_entries(&ui, cb, arg, max_stack);
71ad0f5e	721	}
f83c0415 HK	722
	723	static struct unwind_libunwind_ops
	724	_unwind_libunwind_ops = {
	725	.prepare_access = _unwind__prepare_access,
	726	.flush_access = _unwind__flush_access,
	727	.finish_access = _unwind__finish_access,
	728	.get_entries = _unwind__get_entries,
	729	};
	730
19473e7b	731	#ifndef REMOTE_UNWIND_LIBUNWIND
f83c0415 HK	732	struct unwind_libunwind_ops *
f83c0415 HK	733	local_unwind_libunwind_ops = &_unwind_libunwind_ops;
19473e7b	734	#endif