[linux-2.6-block.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;
}

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;

	fd = dso__data_fd(dso, machine);
	if (fd < 0)
		return -EINVAL;

	/* Check the .eh_frame section for unwinding info */
	offset = elf_section_offset(fd, ".eh_frame_hdr");

	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 = dso__data_fd(dso, machine);

	if (fd < 0)
		return -EINVAL;

	/* Check the .debug_frame section for unwinding info */
	*offset = elf_section_offset(fd, ".debug_frame");

	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, ui->machine, PERF_RECORD_MISC_USER,
			      MAP__FUNCTION, 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;

	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);
		return 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 (!read_unwind_spec_debug_frame(map->dso, ui->machine, &segbase)) {
		memset(&di, 0, sizeof(di));
		if (dwarf_find_debug_frame(0, &di, ip, 0, map->dso->name,
					   map->start, map->end))
			return dwarf_search_unwind_table(as, ip, &di, pi,
							 need_unwind_info, arg);
	}
#endif

	return -EINVAL;
}

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 addr_location al;
	ssize_t size;

	thread__find_addr_map(ui->thread, ui->machine, PERF_RECORD_MISC_USER,
			      MAP__FUNCTION, addr, &al);
	if (!al.map) {
		pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
		return -1;
	}

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

	size = dso__data_read_addr(al.map->dso, al.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 *) 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 *) 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, struct machine *machine,
		 unwind_entry_cb_t cb, void *arg)
{
	struct unwind_entry e;
	struct addr_location al;

	thread__find_addr_location(thread, machine,
				   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;
	}

	thread__set_priv(thread, addr_space);

	return 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)
{
	unw_addr_space_t addr_space;
	unw_cursor_t c;
	int ret;

	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) && max_stack--) {
		unw_word_t ip;

		unw_get_reg(&c, UNW_REG_IP, &ip);
		ret = ip ? entry(ip, ui->thread, ui->machine, cb, arg) : 0;
	}

	return ret;
}

int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
			struct machine *machine, struct thread *thread,
			struct perf_sample *data, int max_stack)
{
	u64 ip;
	struct unwind_info ui = {
		.sample       = data,
		.thread       = thread,
		.machine      = machine,
	};
	int ret;

	if (!data->user_regs.regs)
		return -EINVAL;

	ret = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
	if (ret)
		return ret;

	ret = entry(ip, thread, machine, cb, arg);
	if (ret)
		return -ENOMEM;

	return --max_stack > 0 ? get_entries(&ui, cb, arg, max_stack) : 0;
}
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
	188	struct table_entry {
	189	u32 start_ip_offset;
	190	u32 fde_offset;
	191	};
	192
	193	struct eh_frame_hdr {
	194	unsigned char version;
	195	unsigned char eh_frame_ptr_enc;
	196	unsigned char fde_count_enc;
	197	unsigned char table_enc;
	198
	199	/*
	200	* The rest of the header is variable-length and consists of the
	201	* following members:
	202	*
	203	* encoded_t eh_frame_ptr;
	204	* encoded_t fde_count;
	205	*/
	206
	207	/* A single encoded pointer should not be more than 8 bytes. */
	208	u64 enc[2];
	209
	210	/*
	211	* struct {
	212	* encoded_t start_ip;
	213	* encoded_t fde_addr;
	214	* } binary_search_table[fde_count];
	215	*/
	216	char data[0];
	217	} __packed;
	218
	219	static int unwind_spec_ehframe(struct dso dso, struct machine machine,
	220	u64 offset, u64 table_data, u64 segbase,
	221	u64 *fde_count)
	222	{
	223	struct eh_frame_hdr hdr;
	224	u8 enc = (u8 ) &hdr.enc;
	225	u8 end = (u8 ) &hdr.data;
	226	ssize_t r;
	227
	228	r = dso__data_read_offset(dso, machine, offset,
	229	(u8 *) &hdr, sizeof(hdr));
	230	if (r != sizeof(hdr))
	231	return -EINVAL;
	232
	233	/* We dont need eh_frame_ptr, just skip it. */
	234	dw_read_encoded_value(enc, end, hdr.eh_frame_ptr_enc);
	235
	236	*fde_count = dw_read_encoded_value(enc, end, hdr.fde_count_enc);
	237	*segbase = offset;
	238	table_data = (enc - (u8 ) &hdr) + offset;
	239	return 0;
	240	}
	241
ab255e72 JP	242	static int read_unwind_spec_eh_frame(struct dso dso, struct machine machine,
	243	u64 table_data, u64 segbase,
	244	u64 *fde_count)
71ad0f5e JO	245	{
	246	int ret = -EINVAL, fd;
	247	u64 offset;
	248
	249	fd = dso__data_fd(dso, machine);
	250	if (fd < 0)
	251	return -EINVAL;
	252
ab255e72	253	/* Check the .eh_frame section for unwinding info */
71ad0f5e	254	offset = elf_section_offset(fd, ".eh_frame_hdr");
71ad0f5e JO	255
	256	if (offset)
	257	ret = unwind_spec_ehframe(dso, machine, offset,
	258	table_data, segbase,
	259	fde_count);
	260
71ad0f5e JO	261	return ret;
	262	}
	263
ab255e72 JP	264	#ifndef NO_LIBUNWIND_DEBUG_FRAME
	265	static int read_unwind_spec_debug_frame(struct dso *dso,
	266	struct machine machine, u64 offset)
	267	{
	268	int fd = dso__data_fd(dso, machine);
	269
	270	if (fd < 0)
	271	return -EINVAL;
	272
	273	/* Check the .debug_frame section for unwinding info */
	274	*offset = elf_section_offset(fd, ".debug_frame");
ab255e72 JP	275
	276	if (*offset)
	277	return 0;
	278
	279	return -EINVAL;
	280	}
	281	#endif
	282
71ad0f5e JO	283	static struct map find_map(unw_word_t ip, struct unwind_info ui)
	284	{
	285	struct addr_location al;
	286
	287	thread__find_addr_map(ui->thread, ui->machine, PERF_RECORD_MISC_USER,
326f59bf	288	MAP__FUNCTION, ip, &al);
71ad0f5e JO	289	return al.map;
	290	}
	291
	292	static int
	293	find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi,
	294	int need_unwind_info, void *arg)
	295	{
	296	struct unwind_info *ui = arg;
	297	struct map *map;
	298	unw_dyn_info_t di;
	299	u64 table_data, segbase, fde_count;
	300
	301	map = find_map(ip, ui);
	302	if (!map \|\| !map->dso)
	303	return -EINVAL;
	304
	305	pr_debug("unwind: find_proc_info dso %s\n", map->dso->name);
	306
ab255e72 JP	307	/* Check the .eh_frame section for unwinding info */
	308	if (!read_unwind_spec_eh_frame(map->dso, ui->machine,
	309	&table_data, &segbase, &fde_count)) {
	310	memset(&di, 0, sizeof(di));
	311	di.format = UNW_INFO_FORMAT_REMOTE_TABLE;
	312	di.start_ip = map->start;
	313	di.end_ip = map->end;
	314	di.u.rti.segbase = map->start + segbase;
	315	di.u.rti.table_data = map->start + table_data;
	316	di.u.rti.table_len = fde_count * sizeof(struct table_entry)
	317	/ sizeof(unw_word_t);
	318	return dwarf_search_unwind_table(as, ip, &di, pi,
	319	need_unwind_info, arg);
	320	}
	321
	322	#ifndef NO_LIBUNWIND_DEBUG_FRAME
	323	/* Check the .debug_frame section for unwinding info */
	324	if (!read_unwind_spec_debug_frame(map->dso, ui->machine, &segbase)) {
	325	memset(&di, 0, sizeof(di));
d11416e7 JP	326	if (dwarf_find_debug_frame(0, &di, ip, 0, map->dso->name,
	327	map->start, map->end))
	328	return dwarf_search_unwind_table(as, ip, &di, pi,
	329	need_unwind_info, arg);
ab255e72 JP	330	}
ab255e72 JP	331	#endif
71ad0f5e	332
ab255e72	333	return -EINVAL;
71ad0f5e JO	334	}
71ad0f5e JO	335
1d037ca1 IT	336	static int access_fpreg(unw_addr_space_t __maybe_unused as,
	337	unw_regnum_t __maybe_unused num,
	338	unw_fpreg_t __maybe_unused *val,
	339	int __maybe_unused __write,
	340	void __maybe_unused *arg)
71ad0f5e JO	341	{
	342	pr_err("unwind: access_fpreg unsupported\n");
	343	return -UNW_EINVAL;
	344	}
	345
1d037ca1 IT	346	static int get_dyn_info_list_addr(unw_addr_space_t __maybe_unused as,
	347	unw_word_t __maybe_unused *dil_addr,
	348	void __maybe_unused *arg)
71ad0f5e JO	349	{
	350	return -UNW_ENOINFO;
	351	}
	352
1d037ca1 IT	353	static int resume(unw_addr_space_t __maybe_unused as,
	354	unw_cursor_t __maybe_unused *cu,
	355	void __maybe_unused *arg)
71ad0f5e JO	356	{
	357	pr_err("unwind: resume unsupported\n");
	358	return -UNW_EINVAL;
	359	}
	360
	361	static int
1d037ca1 IT	362	get_proc_name(unw_addr_space_t __maybe_unused as,
	363	unw_word_t __maybe_unused addr,
	364	char __maybe_unused *bufp, size_t __maybe_unused buf_len,
	365	unw_word_t __maybe_unused offp, void __maybe_unused arg)
71ad0f5e JO	366	{
	367	pr_err("unwind: get_proc_name unsupported\n");
	368	return -UNW_EINVAL;
	369	}
	370
	371	static int access_dso_mem(struct unwind_info *ui, unw_word_t addr,
	372	unw_word_t *data)
	373	{
	374	struct addr_location al;
	375	ssize_t size;
	376
	377	thread__find_addr_map(ui->thread, ui->machine, PERF_RECORD_MISC_USER,
326f59bf	378	MAP__FUNCTION, addr, &al);
71ad0f5e JO	379	if (!al.map) {
	380	pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
	381	return -1;
	382	}
	383
	384	if (!al.map->dso)
	385	return -1;
	386
	387	size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
	388	addr, (u8 ) data, sizeof(data));
	389
	390	return !(size == sizeof(*data));
	391	}
	392
1d037ca1	393	static int access_mem(unw_addr_space_t __maybe_unused as,
71ad0f5e JO	394	unw_word_t addr, unw_word_t *valp,
	395	int __write, void *arg)
	396	{
	397	struct unwind_info *ui = arg;
	398	struct stack_dump *stack = &ui->sample->user_stack;
c9b951c4	399	u64 start, end;
71ad0f5e JO	400	int offset;
	401	int ret;
	402
	403	/* Don't support write, probably not needed. */
	404	if (__write \|\| !stack \|\| !ui->sample->user_regs.regs) {
	405	*valp = 0;
	406	return 0;
	407	}
	408
c9b951c4	409	ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
71ad0f5e JO	410	if (ret)
	411	return ret;
	412
	413	end = start + stack->size;
	414
	415	/* Check overflow. */
	416	if (addr + sizeof(unw_word_t) < addr)
	417	return -EINVAL;
	418
	419	if (addr < start \|\| addr + sizeof(unw_word_t) >= end) {
	420	ret = access_dso_mem(ui, addr, valp);
	421	if (ret) {
c9b951c4 JO	422	pr_debug("unwind: access_mem %p not inside range"
	423	" 0x%" PRIx64 "-0x%" PRIx64 "\n",
	424	(void *) addr, start, end);
71ad0f5e JO	425	*valp = 0;
	426	return ret;
	427	}
	428	return 0;
	429	}
	430
	431	offset = addr - start;
	432	valp = (unw_word_t *)&stack->data[offset];
c9b951c4 JO	433	pr_debug("unwind: access_mem addr %p val %lx, offset %d\n",
c9b951c4 JO	434	(void ) addr, (unsigned long)valp, offset);
71ad0f5e JO	435	return 0;
	436	}
	437
1d037ca1	438	static int access_reg(unw_addr_space_t __maybe_unused as,
71ad0f5e JO	439	unw_regnum_t regnum, unw_word_t *valp,
	440	int __write, void *arg)
	441	{
	442	struct unwind_info *ui = arg;
	443	int id, ret;
c9b951c4	444	u64 val;
71ad0f5e JO	445
	446	/* Don't support write, I suspect we don't need it. */
	447	if (__write) {
	448	pr_err("unwind: access_reg w %d\n", regnum);
	449	return 0;
	450	}
	451
	452	if (!ui->sample->user_regs.regs) {
	453	*valp = 0;
	454	return 0;
	455	}
	456
ea3da69d	457	id = libunwind__arch_reg_id(regnum);
71ad0f5e JO	458	if (id < 0)
	459	return -EINVAL;
	460
c9b951c4	461	ret = perf_reg_value(&val, &ui->sample->user_regs, id);
71ad0f5e JO	462	if (ret) {
	463	pr_err("unwind: can't read reg %d\n", regnum);
	464	return ret;
	465	}
	466
c9b951c4	467	*valp = (unw_word_t) val;
71ad0f5e JO	468	pr_debug("unwind: reg %d, val %lx\n", regnum, (unsigned long)*valp);
	469	return 0;
	470	}
	471
1d037ca1 IT	472	static void put_unwind_info(unw_addr_space_t __maybe_unused as,
	473	unw_proc_info_t *pi __maybe_unused,
	474	void *arg __maybe_unused)
71ad0f5e JO	475	{
	476	pr_debug("unwind: put_unwind_info called\n");
	477	}
	478
	479	static int entry(u64 ip, struct thread thread, struct machine machine,
	480	unwind_entry_cb_t cb, void *arg)
	481	{
	482	struct unwind_entry e;
	483	struct addr_location al;
	484
	485	thread__find_addr_location(thread, machine,
	486	PERF_RECORD_MISC_USER,
61710bde	487	MAP__FUNCTION, ip, &al);
71ad0f5e JO	488
	489	e.ip = ip;
	490	e.map = al.map;
	491	e.sym = al.sym;
	492
	493	pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
	494	al.sym ? al.sym->name : "''",
	495	ip,
	496	al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
	497
	498	return cb(&e, arg);
	499	}
	500
	501	static void display_error(int err)
	502	{
	503	switch (err) {
	504	case UNW_EINVAL:
	505	pr_err("unwind: Only supports local.\n");
	506	break;
	507	case UNW_EUNSPEC:
	508	pr_err("unwind: Unspecified error.\n");
	509	break;
	510	case UNW_EBADREG:
	511	pr_err("unwind: Register unavailable.\n");
	512	break;
	513	default:
	514	break;
	515	}
	516	}
	517
	518	static unw_accessors_t accessors = {
	519	.find_proc_info = find_proc_info,
	520	.put_unwind_info = put_unwind_info,
	521	.get_dyn_info_list_addr = get_dyn_info_list_addr,
	522	.access_mem = access_mem,
	523	.access_reg = access_reg,
	524	.access_fpreg = access_fpreg,
	525	.resume = resume,
	526	.get_proc_name = get_proc_name,
	527	};
	528
66f066d8	529	int unwind__prepare_access(struct thread *thread)
71ad0f5e JO	530	{
71ad0f5e JO	531	unw_addr_space_t addr_space;
66f066d8 NK	532
	533	if (callchain_param.record_mode != CALLCHAIN_DWARF)
	534	return 0;
71ad0f5e JO	535
	536	addr_space = unw_create_addr_space(&accessors, 0);
	537	if (!addr_space) {
	538	pr_err("unwind: Can't create unwind address space.\n");
	539	return -ENOMEM;
	540	}
	541
66f066d8 NK	542	thread__set_priv(thread, addr_space);
	543
	544	return 0;
	545	}
	546
	547	void unwind__finish_access(struct thread *thread)
	548	{
	549	unw_addr_space_t addr_space;
	550
	551	if (callchain_param.record_mode != CALLCHAIN_DWARF)
	552	return;
	553
	554	addr_space = thread__priv(thread);
	555	unw_destroy_addr_space(addr_space);
	556	}
	557
	558	static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,
	559	void *arg, int max_stack)
	560	{
	561	unw_addr_space_t addr_space;
	562	unw_cursor_t c;
	563	int ret;
	564
	565	addr_space = thread__priv(ui->thread);
	566	if (addr_space == NULL)
	567	return -1;
	568
71ad0f5e JO	569	ret = unw_init_remote(&c, addr_space, ui);
	570	if (ret)
	571	display_error(ret);
	572
37676af1	573	while (!ret && (unw_step(&c) > 0) && max_stack--) {
71ad0f5e JO	574	unw_word_t ip;
	575
	576	unw_get_reg(&c, UNW_REG_IP, &ip);
1cf0382a	577	ret = ip ? entry(ip, ui->thread, ui->machine, cb, arg) : 0;
71ad0f5e JO	578	}
71ad0f5e JO	579
71ad0f5e JO	580	return ret;
	581	}
	582
	583	int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
	584	struct machine machine, struct thread thread,
352ea45a	585	struct perf_sample *data, int max_stack)
71ad0f5e	586	{
c9b951c4	587	u64 ip;
71ad0f5e JO	588	struct unwind_info ui = {
71ad0f5e JO	589	.sample = data,
71ad0f5e JO	590	.thread = thread,
	591	.machine = machine,
	592	};
	593	int ret;
	594
	595	if (!data->user_regs.regs)
	596	return -EINVAL;
	597
c9b951c4	598	ret = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
71ad0f5e JO	599	if (ret)
	600	return ret;
	601
	602	ret = entry(ip, thread, machine, cb, arg);
	603	if (ret)
	604	return -ENOMEM;
	605
b42dc32d	606	return --max_stack > 0 ? get_entries(&ui, cb, arg, max_stack) : 0;
71ad0f5e	607	}