[deliverable/linux.git] / tools / perf / util / unwind-libunwind.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 <gelf.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <linux/list.h>
#include <libunwind.h>
#include <libunwind-ptrace.h>
#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"

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;

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

		/* Check the .debug_frame section for unwinding info */
		ofs = elf_section_offset(fd, ".debug_frame");
		dso->data.debug_frame_offset = ofs;
		dso__data_put_fd(dso);
	}

	*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;
		di.u.rti.table_data = map->start + table_data;
		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, PERF_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 = ip;
	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,
};

int unwind__prepare_access(struct thread *thread)
{
	unw_addr_space_t addr_space;

	if (callchain_param.record_mode != CALLCHAIN_DWARF)
		return 0;

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

	unw_set_caching_policy(addr_space, UNW_CACHE_GLOBAL);
	thread__set_priv(thread, addr_space);

	return 0;
}

void unwind__flush_access(struct thread *thread)
{
	unw_addr_space_t addr_space;

	if (callchain_param.record_mode != CALLCHAIN_DWARF)
		return;

	addr_space = thread__priv(thread);
	unw_flush_cache(addr_space, 0, 0);
}

void unwind__finish_access(struct thread *thread)
{
	unw_addr_space_t addr_space;

	if (callchain_param.record_mode != CALLCHAIN_DWARF)
		return;

	addr_space = thread__priv(thread);
	unw_destroy_addr_space(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, PERF_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) {
		addr_space = thread__priv(ui->thread);
		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;
}

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);
}
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>
	19	#include <gelf.h>
	20	#include <fcntl.h>
	21	#include <string.h>
	22	#include <unistd.h>
	23	#include <sys/mman.h>
	24	#include <linux/list.h>
	25	#include <libunwind.h>
	26	#include <libunwind-ptrace.h>
66f066d8	27	#include "callchain.h"
71ad0f5e JO	28	#include "thread.h"
	29	#include "session.h"
	30	#include "perf_regs.h"
	31	#include "unwind.h"
99ca4233	32	#include "symbol.h"
71ad0f5e	33	#include "util.h"
84f5d36f	34	#include "debug.h"
71ad0f5e JO	35
	36	extern int
	37	UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as,
	38	unw_word_t ip,
	39	unw_dyn_info_t *di,
	40	unw_proc_info_t *pi,
	41	int need_unwind_info, void *arg);
	42
	43	#define dwarf_search_unwind_table UNW_OBJ(dwarf_search_unwind_table)
	44
ab255e72 JP	45	extern int
	46	UNW_OBJ(dwarf_find_debug_frame) (int found, unw_dyn_info_t *di_debug,
	47	unw_word_t ip,
	48	unw_word_t segbase,
	49	const char *obj_name, unw_word_t start,
	50	unw_word_t end);
	51
	52	#define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame)
	53
71ad0f5e JO	54	#define DW_EH_PE_FORMAT_MASK 0x0f /* format of the encoded value */
	55	#define DW_EH_PE_APPL_MASK 0x70 /* how the value is to be applied */
	56
	57	/* Pointer-encoding formats: */
	58	#define DW_EH_PE_omit 0xff
	59	#define DW_EH_PE_ptr 0x00 /* pointer-sized unsigned value */
	60	#define DW_EH_PE_udata4 0x03 /* unsigned 32-bit value */
	61	#define DW_EH_PE_udata8 0x04 /* unsigned 64-bit value */
	62	#define DW_EH_PE_sdata4 0x0b /* signed 32-bit value */
	63	#define DW_EH_PE_sdata8 0x0c /* signed 64-bit value */
	64
	65	/* Pointer-encoding application: */
	66	#define DW_EH_PE_absptr 0x00 /* absolute value */
	67	#define DW_EH_PE_pcrel 0x10 /* rel. to addr. of encoded value */
	68
	69	/*
	70	* The following are not documented by LSB v1.3, yet they are used by
	71	* GCC, presumably they aren't documented by LSB since they aren't
	72	* used on Linux:
	73	*/
	74	#define DW_EH_PE_funcrel 0x40 /* start-of-procedure-relative */
	75	#define DW_EH_PE_aligned 0x50 /* aligned pointer */
	76
	77	/* Flags intentionaly not handled, since they're not needed:
	78	* #define DW_EH_PE_indirect 0x80
	79	* #define DW_EH_PE_uleb128 0x01
	80	* #define DW_EH_PE_udata2 0x02
	81	* #define DW_EH_PE_sleb128 0x09
	82	* #define DW_EH_PE_sdata2 0x0a
	83	* #define DW_EH_PE_textrel 0x20
	84	* #define DW_EH_PE_datarel 0x30
	85	*/
	86
	87	struct unwind_info {
	88	struct perf_sample *sample;
	89	struct machine *machine;
	90	struct thread *thread;
71ad0f5e JO	91	};
	92
	93	#define dw_read(ptr, type, end) ({ \
	94	type __p = (type ) ptr; \
	95	type __v; \
	96	if ((__p + 1) > (type *) end) \
	97	return -EINVAL; \
	98	__v = *__p++; \
	99	ptr = (typeof(ptr)) __p; \
	100	__v; \
	101	})
	102
	103	static int __dw_read_encoded_value(u8 *p, u8 end, u64 *val,
	104	u8 encoding)
	105	{
	106	u8 cur = p;
	107	*val = 0;
	108
	109	switch (encoding) {
	110	case DW_EH_PE_omit:
	111	*val = 0;
	112	goto out;
	113	case DW_EH_PE_ptr:
	114	*val = dw_read(cur, unsigned long, end);
	115	goto out;
	116	default:
	117	break;
	118	}
	119
	120	switch (encoding & DW_EH_PE_APPL_MASK) {
	121	case DW_EH_PE_absptr:
	122	break;
	123	case DW_EH_PE_pcrel:
	124	*val = (unsigned long) cur;
	125	break;
	126	default:
	127	return -EINVAL;
	128	}
	129
	130	if ((encoding & 0x07) == 0x00)
	131	encoding \|= DW_EH_PE_udata4;
	132
	133	switch (encoding & DW_EH_PE_FORMAT_MASK) {
	134	case DW_EH_PE_sdata4:
	135	*val += dw_read(cur, s32, end);
	136	break;
	137	case DW_EH_PE_udata4:
	138	*val += dw_read(cur, u32, end);
	139	break;
	140	case DW_EH_PE_sdata8:
	141	*val += dw_read(cur, s64, end);
	142	break;
	143	case DW_EH_PE_udata8:
	144	*val += dw_read(cur, u64, end);
	145	break;
	146	default:
	147	return -EINVAL;
	148	}
	149
	150	out:
	151	*p = cur;
	152	return 0;
	153	}
	154
155	#define dw_read_encoded_value(ptr, end, enc) ({ \
156	u64 __v; \
157	if (__dw_read_encoded_value(&ptr, end, &__v, enc)) { \
158	return -EINVAL; \
159	} \
160	__v; \
161	})
162
71ad0f5e JO	163	static u64 elf_section_offset(int fd, const char *name)
	164	{
	165	Elf *elf;
	166	GElf_Ehdr ehdr;
	167	GElf_Shdr shdr;
	168	u64 offset = 0;
	169
	170	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
	171	if (elf == NULL)
	172	return 0;
	173
	174	do {
	175	if (gelf_getehdr(elf, &ehdr) == NULL)
	176	break;
	177
99ca4233	178	if (!elf_section_by_name(elf, &ehdr, &shdr, name, NULL))
71ad0f5e JO	179	break;
	180
	181	offset = shdr.sh_offset;
	182	} while (0);
	183
	184	elf_end(elf);
	185	return offset;
	186	}
	187
b93b0967 WN	188	#ifndef NO_LIBUNWIND_DEBUG_FRAME
	189	static int elf_is_exec(int fd, const char *name)
	190	{
	191	Elf *elf;
	192	GElf_Ehdr ehdr;
	193	int retval = 0;
	194
	195	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
	196	if (elf == NULL)
	197	return 0;
	198	if (gelf_getehdr(elf, &ehdr) == NULL)
	199	goto out;
	200
	201	retval = (ehdr.e_type == ET_EXEC);
	202
	203	out:
	204	elf_end(elf);
	205	pr_debug("unwind: elf_is_exec(%s): %d\n", name, retval);
	206	return retval;
	207	}
	208	#endif
	209
71ad0f5e JO	210	struct table_entry {
	211	u32 start_ip_offset;
	212	u32 fde_offset;
	213	};
	214
	215	struct eh_frame_hdr {
	216	unsigned char version;
	217	unsigned char eh_frame_ptr_enc;
	218	unsigned char fde_count_enc;
	219	unsigned char table_enc;
	220
	221	/*
	222	* The rest of the header is variable-length and consists of the
	223	* following members:
	224	*
	225	* encoded_t eh_frame_ptr;
	226	* encoded_t fde_count;
	227	*/
	228
	229	/* A single encoded pointer should not be more than 8 bytes. */
	230	u64 enc[2];
	231
	232	/*
	233	* struct {
	234	* encoded_t start_ip;
	235	* encoded_t fde_addr;
	236	* } binary_search_table[fde_count];
	237	*/
	238	char data[0];
	239	} __packed;
	240
	241	static int unwind_spec_ehframe(struct dso dso, struct machine machine,
	242	u64 offset, u64 table_data, u64 segbase,
	243	u64 *fde_count)
	244	{
	245	struct eh_frame_hdr hdr;
	246	u8 enc = (u8 ) &hdr.enc;
	247	u8 end = (u8 ) &hdr.data;
	248	ssize_t r;
	249
	250	r = dso__data_read_offset(dso, machine, offset,
	251	(u8 *) &hdr, sizeof(hdr));
	252	if (r != sizeof(hdr))
	253	return -EINVAL;
	254
	255	/* We dont need eh_frame_ptr, just skip it. */
	256	dw_read_encoded_value(enc, end, hdr.eh_frame_ptr_enc);
	257
	258	*fde_count = dw_read_encoded_value(enc, end, hdr.fde_count_enc);
	259	*segbase = offset;
	260	table_data = (enc - (u8 ) &hdr) + offset;
	261	return 0;
	262	}
	263
ab255e72 JP	264	static int read_unwind_spec_eh_frame(struct dso dso, struct machine machine,
	265	u64 table_data, u64 segbase,
	266	u64 *fde_count)
71ad0f5e JO	267	{
71ad0f5e JO	268	int ret = -EINVAL, fd;
303cb89a	269	u64 offset = dso->data.eh_frame_hdr_offset;
71ad0f5e	270
f1f13af9	271	if (offset == 0) {
4bb11d01	272	fd = dso__data_get_fd(dso, machine);
f1f13af9 NK	273	if (fd < 0)
f1f13af9 NK	274	return -EINVAL;
71ad0f5e	275
f1f13af9 NK	276	/* Check the .eh_frame section for unwinding info */
f1f13af9 NK	277	offset = elf_section_offset(fd, ".eh_frame_hdr");
303cb89a	278	dso->data.eh_frame_hdr_offset = offset;
4bb11d01	279	dso__data_put_fd(dso);
f1f13af9	280	}
71ad0f5e JO	281
	282	if (offset)
	283	ret = unwind_spec_ehframe(dso, machine, offset,
	284	table_data, segbase,
	285	fde_count);
	286
71ad0f5e JO	287	return ret;
	288	}
	289
ab255e72 JP	290	#ifndef NO_LIBUNWIND_DEBUG_FRAME
	291	static int read_unwind_spec_debug_frame(struct dso *dso,
	292	struct machine machine, u64 offset)
	293	{
f1f13af9	294	int fd;
303cb89a	295	u64 ofs = dso->data.debug_frame_offset;
ab255e72	296
f1f13af9	297	if (ofs == 0) {
4bb11d01	298	fd = dso__data_get_fd(dso, machine);
f1f13af9 NK	299	if (fd < 0)
f1f13af9 NK	300	return -EINVAL;
ab255e72	301
f1f13af9 NK	302	/* Check the .debug_frame section for unwinding info */
f1f13af9 NK	303	ofs = elf_section_offset(fd, ".debug_frame");
303cb89a	304	dso->data.debug_frame_offset = ofs;
4bb11d01	305	dso__data_put_fd(dso);
f1f13af9	306	}
ab255e72	307
f1f13af9	308	*offset = ofs;
ab255e72 JP	309	if (*offset)
	310	return 0;
	311
	312	return -EINVAL;
	313	}
	314	#endif
	315
71ad0f5e JO	316	static struct map find_map(unw_word_t ip, struct unwind_info ui)
	317	{
	318	struct addr_location al;
	319
bb871a9c	320	thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
326f59bf	321	MAP__FUNCTION, ip, &al);
0ddf5246 JO	322	if (!al.map) {
	323	/*
	324	* We've seen cases (softice) where DWARF unwinder went
	325	* through non executable mmaps, which we need to lookup
	326	* in MAP__VARIABLE tree.
	327	*/
	328	thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
	329	MAP__VARIABLE, ip, &al);
	330	}
71ad0f5e JO	331	return al.map;
	332	}
	333
	334	static int
	335	find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi,
	336	int need_unwind_info, void *arg)
	337	{
	338	struct unwind_info *ui = arg;
	339	struct map *map;
	340	unw_dyn_info_t di;
	341	u64 table_data, segbase, fde_count;
8eac1d5e	342	int ret = -EINVAL;
71ad0f5e JO	343
	344	map = find_map(ip, ui);
	345	if (!map \|\| !map->dso)
	346	return -EINVAL;
	347
	348	pr_debug("unwind: find_proc_info dso %s\n", map->dso->name);
	349
ab255e72 JP	350	/* Check the .eh_frame section for unwinding info */
	351	if (!read_unwind_spec_eh_frame(map->dso, ui->machine,
	352	&table_data, &segbase, &fde_count)) {
	353	memset(&di, 0, sizeof(di));
	354	di.format = UNW_INFO_FORMAT_REMOTE_TABLE;
	355	di.start_ip = map->start;
	356	di.end_ip = map->end;
	357	di.u.rti.segbase = map->start + segbase;
	358	di.u.rti.table_data = map->start + table_data;
	359	di.u.rti.table_len = fde_count * sizeof(struct table_entry)
	360	/ sizeof(unw_word_t);
8eac1d5e RV	361	ret = dwarf_search_unwind_table(as, ip, &di, pi,
8eac1d5e RV	362	need_unwind_info, arg);
ab255e72 JP	363	}
	364
	365	#ifndef NO_LIBUNWIND_DEBUG_FRAME
	366	/* Check the .debug_frame section for unwinding info */
8eac1d5e RV	367	if (ret < 0 &&
8eac1d5e RV	368	!read_unwind_spec_debug_frame(map->dso, ui->machine, &segbase)) {
4bb11d01	369	int fd = dso__data_get_fd(map->dso, ui->machine);
b93b0967 WN	370	int is_exec = elf_is_exec(fd, map->dso->name);
b93b0967 WN	371	unw_word_t base = is_exec ? 0 : map->start;
7ed4915a	372	const char *symfile;
b93b0967	373
4bb11d01	374	if (fd >= 0)
f005813a	375	dso__data_put_fd(map->dso);
4bb11d01	376
7ed4915a RV	377	symfile = map->dso->symsrc_filename ?: map->dso->name;
7ed4915a RV	378
ab255e72	379	memset(&di, 0, sizeof(di));
7ed4915a	380	if (dwarf_find_debug_frame(0, &di, ip, base, symfile,
d11416e7 JP	381	map->start, map->end))
	382	return dwarf_search_unwind_table(as, ip, &di, pi,
	383	need_unwind_info, arg);
ab255e72 JP	384	}
ab255e72 JP	385	#endif
71ad0f5e	386
8eac1d5e	387	return ret;
71ad0f5e JO	388	}
71ad0f5e JO	389
1d037ca1 IT	390	static int access_fpreg(unw_addr_space_t __maybe_unused as,
	391	unw_regnum_t __maybe_unused num,
	392	unw_fpreg_t __maybe_unused *val,
	393	int __maybe_unused __write,
	394	void __maybe_unused *arg)
71ad0f5e JO	395	{
	396	pr_err("unwind: access_fpreg unsupported\n");
	397	return -UNW_EINVAL;
	398	}
	399
1d037ca1 IT	400	static int get_dyn_info_list_addr(unw_addr_space_t __maybe_unused as,
	401	unw_word_t __maybe_unused *dil_addr,
	402	void __maybe_unused *arg)
71ad0f5e JO	403	{
	404	return -UNW_ENOINFO;
	405	}
	406
1d037ca1 IT	407	static int resume(unw_addr_space_t __maybe_unused as,
	408	unw_cursor_t __maybe_unused *cu,
	409	void __maybe_unused *arg)
71ad0f5e JO	410	{
	411	pr_err("unwind: resume unsupported\n");
	412	return -UNW_EINVAL;
	413	}
	414
	415	static int
1d037ca1 IT	416	get_proc_name(unw_addr_space_t __maybe_unused as,
	417	unw_word_t __maybe_unused addr,
	418	char __maybe_unused *bufp, size_t __maybe_unused buf_len,
	419	unw_word_t __maybe_unused offp, void __maybe_unused arg)
71ad0f5e JO	420	{
	421	pr_err("unwind: get_proc_name unsupported\n");
	422	return -UNW_EINVAL;
	423	}
	424
	425	static int access_dso_mem(struct unwind_info *ui, unw_word_t addr,
	426	unw_word_t *data)
	427	{
f22ed827	428	struct map *map;
71ad0f5e JO	429	ssize_t size;
71ad0f5e JO	430
f22ed827 JO	431	map = find_map(addr, ui);
f22ed827 JO	432	if (!map) {
71ad0f5e JO	433	pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
	434	return -1;
	435	}
	436
f22ed827	437	if (!map->dso)
71ad0f5e JO	438	return -1;
71ad0f5e JO	439
f22ed827	440	size = dso__data_read_addr(map->dso, map, ui->machine,
71ad0f5e JO	441	addr, (u8 ) data, sizeof(data));
	442
	443	return !(size == sizeof(*data));
	444	}
	445
1d037ca1	446	static int access_mem(unw_addr_space_t __maybe_unused as,
71ad0f5e JO	447	unw_word_t addr, unw_word_t *valp,
	448	int __write, void *arg)
	449	{
	450	struct unwind_info *ui = arg;
	451	struct stack_dump *stack = &ui->sample->user_stack;
c9b951c4	452	u64 start, end;
71ad0f5e JO	453	int offset;
	454	int ret;
	455
	456	/* Don't support write, probably not needed. */
	457	if (__write \|\| !stack \|\| !ui->sample->user_regs.regs) {
	458	*valp = 0;
	459	return 0;
	460	}
	461
c9b951c4	462	ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
71ad0f5e JO	463	if (ret)
	464	return ret;
	465
	466	end = start + stack->size;
	467
	468	/* Check overflow. */
	469	if (addr + sizeof(unw_word_t) < addr)
	470	return -EINVAL;
	471
	472	if (addr < start \|\| addr + sizeof(unw_word_t) >= end) {
	473	ret = access_dso_mem(ui, addr, valp);
	474	if (ret) {
c9b951c4 JO	475	pr_debug("unwind: access_mem %p not inside range"
c9b951c4 JO	476	" 0x%" PRIx64 "-0x%" PRIx64 "\n",
186c6cfb	477	(void *) (uintptr_t) addr, start, end);
71ad0f5e JO	478	*valp = 0;
	479	return ret;
	480	}
	481	return 0;
	482	}
	483
	484	offset = addr - start;
	485	valp = (unw_word_t *)&stack->data[offset];
c9b951c4	486	pr_debug("unwind: access_mem addr %p val %lx, offset %d\n",
186c6cfb	487	(void ) (uintptr_t) addr, (unsigned long)valp, offset);
71ad0f5e JO	488	return 0;
	489	}
	490
1d037ca1	491	static int access_reg(unw_addr_space_t __maybe_unused as,
71ad0f5e JO	492	unw_regnum_t regnum, unw_word_t *valp,
	493	int __write, void *arg)
	494	{
	495	struct unwind_info *ui = arg;
	496	int id, ret;
c9b951c4	497	u64 val;
71ad0f5e JO	498
	499	/* Don't support write, I suspect we don't need it. */
	500	if (__write) {
	501	pr_err("unwind: access_reg w %d\n", regnum);
	502	return 0;
	503	}
	504
	505	if (!ui->sample->user_regs.regs) {
	506	*valp = 0;
	507	return 0;
	508	}
	509
ea3da69d	510	id = libunwind__arch_reg_id(regnum);
71ad0f5e JO	511	if (id < 0)
	512	return -EINVAL;
	513
c9b951c4	514	ret = perf_reg_value(&val, &ui->sample->user_regs, id);
71ad0f5e JO	515	if (ret) {
	516	pr_err("unwind: can't read reg %d\n", regnum);
	517	return ret;
	518	}
	519
c9b951c4	520	*valp = (unw_word_t) val;
71ad0f5e JO	521	pr_debug("unwind: reg %d, val %lx\n", regnum, (unsigned long)*valp);
	522	return 0;
	523	}
	524
1d037ca1 IT	525	static void put_unwind_info(unw_addr_space_t __maybe_unused as,
	526	unw_proc_info_t *pi __maybe_unused,
	527	void *arg __maybe_unused)
71ad0f5e JO	528	{
	529	pr_debug("unwind: put_unwind_info called\n");
	530	}
	531
bb871a9c	532	static int entry(u64 ip, struct thread *thread,
71ad0f5e JO	533	unwind_entry_cb_t cb, void *arg)
	534	{
	535	struct unwind_entry e;
	536	struct addr_location al;
	537
bb871a9c	538	thread__find_addr_location(thread, PERF_RECORD_MISC_USER,
61710bde	539	MAP__FUNCTION, ip, &al);
71ad0f5e JO	540
	541	e.ip = ip;
	542	e.map = al.map;
	543	e.sym = al.sym;
	544
	545	pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
	546	al.sym ? al.sym->name : "''",
	547	ip,
	548	al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
	549
	550	return cb(&e, arg);
	551	}
	552
	553	static void display_error(int err)
	554	{
	555	switch (err) {
	556	case UNW_EINVAL:
	557	pr_err("unwind: Only supports local.\n");
	558	break;
	559	case UNW_EUNSPEC:
	560	pr_err("unwind: Unspecified error.\n");
	561	break;
	562	case UNW_EBADREG:
	563	pr_err("unwind: Register unavailable.\n");
	564	break;
	565	default:
	566	break;
	567	}
	568	}
	569
	570	static unw_accessors_t accessors = {
	571	.find_proc_info = find_proc_info,
	572	.put_unwind_info = put_unwind_info,
	573	.get_dyn_info_list_addr = get_dyn_info_list_addr,
	574	.access_mem = access_mem,
	575	.access_reg = access_reg,
	576	.access_fpreg = access_fpreg,
	577	.resume = resume,
	578	.get_proc_name = get_proc_name,
	579	};
	580
66f066d8	581	int unwind__prepare_access(struct thread *thread)
71ad0f5e JO	582	{
71ad0f5e JO	583	unw_addr_space_t addr_space;
66f066d8 NK	584
	585	if (callchain_param.record_mode != CALLCHAIN_DWARF)
	586	return 0;
71ad0f5e JO	587
	588	addr_space = unw_create_addr_space(&accessors, 0);
	589	if (!addr_space) {
	590	pr_err("unwind: Can't create unwind address space.\n");
	591	return -ENOMEM;
	592	}
	593
380b5143	594	unw_set_caching_policy(addr_space, UNW_CACHE_GLOBAL);
66f066d8 NK	595	thread__set_priv(thread, addr_space);
	596
	597	return 0;
	598	}
	599
380b5143 NK	600	void unwind__flush_access(struct thread *thread)
	601	{
	602	unw_addr_space_t addr_space;
	603
	604	if (callchain_param.record_mode != CALLCHAIN_DWARF)
	605	return;
	606
	607	addr_space = thread__priv(thread);
	608	unw_flush_cache(addr_space, 0, 0);
	609	}
	610
66f066d8 NK	611	void unwind__finish_access(struct thread *thread)
	612	{
	613	unw_addr_space_t addr_space;
	614
	615	if (callchain_param.record_mode != CALLCHAIN_DWARF)
	616	return;
	617
	618	addr_space = thread__priv(thread);
	619	unw_destroy_addr_space(addr_space);
	620	}
	621
	622	static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,
	623	void *arg, int max_stack)
	624	{
b26b218a	625	u64 val;
cb1dc22d	626	unw_word_t ips[max_stack];
66f066d8 NK	627	unw_addr_space_t addr_space;
66f066d8 NK	628	unw_cursor_t c;
cb1dc22d	629	int ret, i = 0;
66f066d8	630
b26b218a JO	631	ret = perf_reg_value(&val, &ui->sample->user_regs, PERF_REG_IP);
	632	if (ret)
	633	return ret;
	634
cb1dc22d	635	ips[i++] = (unw_word_t) val;
b26b218a	636
cb1dc22d JO	637	/*
	638	* If we need more than one entry, do the DWARF
	639	* unwind itself.
	640	*/
	641	if (max_stack - 1 > 0) {
	642	addr_space = thread__priv(ui->thread);
	643	if (addr_space == NULL)
	644	return -1;
	645
	646	ret = unw_init_remote(&c, addr_space, ui);
	647	if (ret)
	648	display_error(ret);
	649
	650	while (!ret && (unw_step(&c) > 0) && i < max_stack) {
	651	unw_get_reg(&c, UNW_REG_IP, &ips[i]);
	652	++i;
	653	}
66f066d8	654
cb1dc22d JO	655	max_stack = i;
cb1dc22d JO	656	}
71ad0f5e	657
cb1dc22d JO	658	/*
	659	* Display what we got based on the order setup.
	660	*/
	661	for (i = 0; i < max_stack && !ret; i++) {
	662	int j = i;
71ad0f5e	663
cb1dc22d JO	664	if (callchain_param.order == ORDER_CALLER)
	665	j = max_stack - i - 1;
	666	ret = ips[j] ? entry(ips[j], ui->thread, cb, arg) : 0;
71ad0f5e JO	667	}
71ad0f5e JO	668
71ad0f5e JO	669	return ret;
	670	}
	671
	672	int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
dd8c17a5	673	struct thread *thread,
352ea45a	674	struct perf_sample *data, int max_stack)
71ad0f5e	675	{
71ad0f5e JO	676	struct unwind_info ui = {
71ad0f5e JO	677	.sample = data,
71ad0f5e	678	.thread = thread,
dd8c17a5	679	.machine = thread->mg->machine,
71ad0f5e	680	};
71ad0f5e JO	681
	682	if (!data->user_regs.regs)
	683	return -EINVAL;
	684
b26b218a JO	685	if (max_stack <= 0)
b26b218a JO	686	return -EINVAL;
71ad0f5e	687
b26b218a	688	return get_entries(&ui, cb, arg, max_stack);
71ad0f5e	689	}