[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 "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,
};

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

	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;
	}

	unw_destroy_addr_space(addr_space);
	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>
	27	#include "thread.h"
	28	#include "session.h"
	29	#include "perf_regs.h"
	30	#include "unwind.h"
99ca4233	31	#include "symbol.h"
71ad0f5e	32	#include "util.h"
84f5d36f	33	#include "debug.h"
71ad0f5e JO	34
	35	extern int
	36	UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as,
	37	unw_word_t ip,
	38	unw_dyn_info_t *di,
	39	unw_proc_info_t *pi,
	40	int need_unwind_info, void *arg);
	41
	42	#define dwarf_search_unwind_table UNW_OBJ(dwarf_search_unwind_table)
	43
ab255e72 JP	44	extern int
	45	UNW_OBJ(dwarf_find_debug_frame) (int found, unw_dyn_info_t *di_debug,
	46	unw_word_t ip,
	47	unw_word_t segbase,
	48	const char *obj_name, unw_word_t start,
	49	unw_word_t end);
	50
	51	#define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame)
	52
71ad0f5e JO	53	#define DW_EH_PE_FORMAT_MASK 0x0f /* format of the encoded value */
	54	#define DW_EH_PE_APPL_MASK 0x70 /* how the value is to be applied */
	55
	56	/* Pointer-encoding formats: */
	57	#define DW_EH_PE_omit 0xff
	58	#define DW_EH_PE_ptr 0x00 /* pointer-sized unsigned value */
	59	#define DW_EH_PE_udata4 0x03 /* unsigned 32-bit value */
	60	#define DW_EH_PE_udata8 0x04 /* unsigned 64-bit value */
	61	#define DW_EH_PE_sdata4 0x0b /* signed 32-bit value */
	62	#define DW_EH_PE_sdata8 0x0c /* signed 64-bit value */
	63
	64	/* Pointer-encoding application: */
	65	#define DW_EH_PE_absptr 0x00 /* absolute value */
	66	#define DW_EH_PE_pcrel 0x10 /* rel. to addr. of encoded value */
	67
	68	/*
	69	* The following are not documented by LSB v1.3, yet they are used by
	70	* GCC, presumably they aren't documented by LSB since they aren't
	71	* used on Linux:
	72	*/
	73	#define DW_EH_PE_funcrel 0x40 /* start-of-procedure-relative */
	74	#define DW_EH_PE_aligned 0x50 /* aligned pointer */
	75
	76	/* Flags intentionaly not handled, since they're not needed:
	77	* #define DW_EH_PE_indirect 0x80
	78	* #define DW_EH_PE_uleb128 0x01
	79	* #define DW_EH_PE_udata2 0x02
	80	* #define DW_EH_PE_sleb128 0x09
	81	* #define DW_EH_PE_sdata2 0x0a
	82	* #define DW_EH_PE_textrel 0x20
	83	* #define DW_EH_PE_datarel 0x30
	84	*/
	85
	86	struct unwind_info {
	87	struct perf_sample *sample;
	88	struct machine *machine;
	89	struct thread *thread;
71ad0f5e JO	90	};
	91
	92	#define dw_read(ptr, type, end) ({ \
	93	type __p = (type ) ptr; \
	94	type __v; \
	95	if ((__p + 1) > (type *) end) \
	96	return -EINVAL; \
	97	__v = *__p++; \
	98	ptr = (typeof(ptr)) __p; \
	99	__v; \
	100	})
	101
	102	static int __dw_read_encoded_value(u8 *p, u8 end, u64 *val,
	103	u8 encoding)
	104	{
	105	u8 cur = p;
	106	*val = 0;
	107
	108	switch (encoding) {
	109	case DW_EH_PE_omit:
	110	*val = 0;
	111	goto out;
	112	case DW_EH_PE_ptr:
	113	*val = dw_read(cur, unsigned long, end);
	114	goto out;
	115	default:
	116	break;
	117	}
	118
	119	switch (encoding & DW_EH_PE_APPL_MASK) {
	120	case DW_EH_PE_absptr:
	121	break;
	122	case DW_EH_PE_pcrel:
	123	*val = (unsigned long) cur;
	124	break;
	125	default:
	126	return -EINVAL;
	127	}
	128
	129	if ((encoding & 0x07) == 0x00)
	130	encoding \|= DW_EH_PE_udata4;
	131
	132	switch (encoding & DW_EH_PE_FORMAT_MASK) {
	133	case DW_EH_PE_sdata4:
	134	*val += dw_read(cur, s32, end);
	135	break;
	136	case DW_EH_PE_udata4:
	137	*val += dw_read(cur, u32, end);
	138	break;
	139	case DW_EH_PE_sdata8:
	140	*val += dw_read(cur, s64, end);
	141	break;
	142	case DW_EH_PE_udata8:
	143	*val += dw_read(cur, u64, end);
	144	break;
	145	default:
	146	return -EINVAL;
	147	}
	148
	149	out:
	150	*p = cur;
	151	return 0;
	152	}
	153
154	#define dw_read_encoded_value(ptr, end, enc) ({ \
155	u64 __v; \
156	if (__dw_read_encoded_value(&ptr, end, &__v, enc)) { \
157	return -EINVAL; \
158	} \
159	__v; \
160	})
161
71ad0f5e JO	162	static u64 elf_section_offset(int fd, const char *name)
	163	{
	164	Elf *elf;
	165	GElf_Ehdr ehdr;
	166	GElf_Shdr shdr;
	167	u64 offset = 0;
	168
	169	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
	170	if (elf == NULL)
	171	return 0;
	172
	173	do {
	174	if (gelf_getehdr(elf, &ehdr) == NULL)
	175	break;
	176
99ca4233	177	if (!elf_section_by_name(elf, &ehdr, &shdr, name, NULL))
71ad0f5e JO	178	break;
	179
	180	offset = shdr.sh_offset;
	181	} while (0);
	182
	183	elf_end(elf);
	184	return offset;
	185	}
	186
	187	struct table_entry {
	188	u32 start_ip_offset;
	189	u32 fde_offset;
	190	};
	191
	192	struct eh_frame_hdr {
	193	unsigned char version;
	194	unsigned char eh_frame_ptr_enc;
	195	unsigned char fde_count_enc;
	196	unsigned char table_enc;
	197
	198	/*
	199	* The rest of the header is variable-length and consists of the
	200	* following members:
	201	*
	202	* encoded_t eh_frame_ptr;
	203	* encoded_t fde_count;
	204	*/
	205
	206	/* A single encoded pointer should not be more than 8 bytes. */
	207	u64 enc[2];
	208
	209	/*
	210	* struct {
	211	* encoded_t start_ip;
	212	* encoded_t fde_addr;
	213	* } binary_search_table[fde_count];
	214	*/
	215	char data[0];
	216	} __packed;
	217
	218	static int unwind_spec_ehframe(struct dso dso, struct machine machine,
	219	u64 offset, u64 table_data, u64 segbase,
	220	u64 *fde_count)
	221	{
	222	struct eh_frame_hdr hdr;
	223	u8 enc = (u8 ) &hdr.enc;
	224	u8 end = (u8 ) &hdr.data;
	225	ssize_t r;
	226
	227	r = dso__data_read_offset(dso, machine, offset,
	228	(u8 *) &hdr, sizeof(hdr));
	229	if (r != sizeof(hdr))
	230	return -EINVAL;
	231
	232	/* We dont need eh_frame_ptr, just skip it. */
	233	dw_read_encoded_value(enc, end, hdr.eh_frame_ptr_enc);
	234
	235	*fde_count = dw_read_encoded_value(enc, end, hdr.fde_count_enc);
	236	*segbase = offset;
	237	table_data = (enc - (u8 ) &hdr) + offset;
	238	return 0;
	239	}
	240
ab255e72 JP	241	static int read_unwind_spec_eh_frame(struct dso dso, struct machine machine,
	242	u64 table_data, u64 segbase,
	243	u64 *fde_count)
71ad0f5e JO	244	{
	245	int ret = -EINVAL, fd;
	246	u64 offset;
	247
	248	fd = dso__data_fd(dso, machine);
	249	if (fd < 0)
	250	return -EINVAL;
	251
ab255e72	252	/* Check the .eh_frame section for unwinding info */
71ad0f5e	253	offset = elf_section_offset(fd, ".eh_frame_hdr");
71ad0f5e JO	254
	255	if (offset)
	256	ret = unwind_spec_ehframe(dso, machine, offset,
	257	table_data, segbase,
	258	fde_count);
	259
71ad0f5e JO	260	return ret;
	261	}
	262
ab255e72 JP	263	#ifndef NO_LIBUNWIND_DEBUG_FRAME
	264	static int read_unwind_spec_debug_frame(struct dso *dso,
	265	struct machine machine, u64 offset)
	266	{
	267	int fd = dso__data_fd(dso, machine);
	268
	269	if (fd < 0)
	270	return -EINVAL;
	271
	272	/* Check the .debug_frame section for unwinding info */
	273	*offset = elf_section_offset(fd, ".debug_frame");
ab255e72 JP	274
	275	if (*offset)
	276	return 0;
	277
	278	return -EINVAL;
	279	}
	280	#endif
	281
71ad0f5e JO	282	static struct map find_map(unw_word_t ip, struct unwind_info ui)
	283	{
	284	struct addr_location al;
	285
	286	thread__find_addr_map(ui->thread, ui->machine, PERF_RECORD_MISC_USER,
326f59bf	287	MAP__FUNCTION, ip, &al);
71ad0f5e JO	288	return al.map;
	289	}
	290
	291	static int
	292	find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi,
	293	int need_unwind_info, void *arg)
	294	{
	295	struct unwind_info *ui = arg;
	296	struct map *map;
	297	unw_dyn_info_t di;
	298	u64 table_data, segbase, fde_count;
	299
	300	map = find_map(ip, ui);
	301	if (!map \|\| !map->dso)
	302	return -EINVAL;
	303
	304	pr_debug("unwind: find_proc_info dso %s\n", map->dso->name);
	305
ab255e72 JP	306	/* Check the .eh_frame section for unwinding info */
	307	if (!read_unwind_spec_eh_frame(map->dso, ui->machine,
	308	&table_data, &segbase, &fde_count)) {
	309	memset(&di, 0, sizeof(di));
	310	di.format = UNW_INFO_FORMAT_REMOTE_TABLE;
	311	di.start_ip = map->start;
	312	di.end_ip = map->end;
	313	di.u.rti.segbase = map->start + segbase;
	314	di.u.rti.table_data = map->start + table_data;
	315	di.u.rti.table_len = fde_count * sizeof(struct table_entry)
	316	/ sizeof(unw_word_t);
	317	return dwarf_search_unwind_table(as, ip, &di, pi,
	318	need_unwind_info, arg);
	319	}
	320
	321	#ifndef NO_LIBUNWIND_DEBUG_FRAME
	322	/* Check the .debug_frame section for unwinding info */
	323	if (!read_unwind_spec_debug_frame(map->dso, ui->machine, &segbase)) {
	324	memset(&di, 0, sizeof(di));
d11416e7 JP	325	if (dwarf_find_debug_frame(0, &di, ip, 0, map->dso->name,
	326	map->start, map->end))
	327	return dwarf_search_unwind_table(as, ip, &di, pi,
	328	need_unwind_info, arg);
ab255e72 JP	329	}
ab255e72 JP	330	#endif
71ad0f5e	331
ab255e72	332	return -EINVAL;
71ad0f5e JO	333	}
71ad0f5e JO	334
1d037ca1 IT	335	static int access_fpreg(unw_addr_space_t __maybe_unused as,
	336	unw_regnum_t __maybe_unused num,
	337	unw_fpreg_t __maybe_unused *val,
	338	int __maybe_unused __write,
	339	void __maybe_unused *arg)
71ad0f5e JO	340	{
	341	pr_err("unwind: access_fpreg unsupported\n");
	342	return -UNW_EINVAL;
	343	}
	344
1d037ca1 IT	345	static int get_dyn_info_list_addr(unw_addr_space_t __maybe_unused as,
	346	unw_word_t __maybe_unused *dil_addr,
	347	void __maybe_unused *arg)
71ad0f5e JO	348	{
	349	return -UNW_ENOINFO;
	350	}
	351
1d037ca1 IT	352	static int resume(unw_addr_space_t __maybe_unused as,
	353	unw_cursor_t __maybe_unused *cu,
	354	void __maybe_unused *arg)
71ad0f5e JO	355	{
	356	pr_err("unwind: resume unsupported\n");
	357	return -UNW_EINVAL;
	358	}
	359
	360	static int
1d037ca1 IT	361	get_proc_name(unw_addr_space_t __maybe_unused as,
	362	unw_word_t __maybe_unused addr,
	363	char __maybe_unused *bufp, size_t __maybe_unused buf_len,
	364	unw_word_t __maybe_unused offp, void __maybe_unused arg)
71ad0f5e JO	365	{
	366	pr_err("unwind: get_proc_name unsupported\n");
	367	return -UNW_EINVAL;
	368	}
	369
	370	static int access_dso_mem(struct unwind_info *ui, unw_word_t addr,
	371	unw_word_t *data)
	372	{
	373	struct addr_location al;
	374	ssize_t size;
	375
	376	thread__find_addr_map(ui->thread, ui->machine, PERF_RECORD_MISC_USER,
326f59bf	377	MAP__FUNCTION, addr, &al);
71ad0f5e JO	378	if (!al.map) {
	379	pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
	380	return -1;
	381	}
	382
	383	if (!al.map->dso)
	384	return -1;
	385
	386	size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
	387	addr, (u8 ) data, sizeof(data));
	388
	389	return !(size == sizeof(*data));
	390	}
	391
1d037ca1	392	static int access_mem(unw_addr_space_t __maybe_unused as,
71ad0f5e JO	393	unw_word_t addr, unw_word_t *valp,
	394	int __write, void *arg)
	395	{
	396	struct unwind_info *ui = arg;
	397	struct stack_dump *stack = &ui->sample->user_stack;
c9b951c4	398	u64 start, end;
71ad0f5e JO	399	int offset;
	400	int ret;
	401
	402	/* Don't support write, probably not needed. */
	403	if (__write \|\| !stack \|\| !ui->sample->user_regs.regs) {
	404	*valp = 0;
	405	return 0;
	406	}
	407
c9b951c4	408	ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
71ad0f5e JO	409	if (ret)
	410	return ret;
	411
	412	end = start + stack->size;
	413
	414	/* Check overflow. */
	415	if (addr + sizeof(unw_word_t) < addr)
	416	return -EINVAL;
	417
	418	if (addr < start \|\| addr + sizeof(unw_word_t) >= end) {
	419	ret = access_dso_mem(ui, addr, valp);
	420	if (ret) {
c9b951c4 JO	421	pr_debug("unwind: access_mem %p not inside range"
	422	" 0x%" PRIx64 "-0x%" PRIx64 "\n",
	423	(void *) addr, start, end);
71ad0f5e JO	424	*valp = 0;
	425	return ret;
	426	}
	427	return 0;
	428	}
	429
	430	offset = addr - start;
	431	valp = (unw_word_t *)&stack->data[offset];
c9b951c4 JO	432	pr_debug("unwind: access_mem addr %p val %lx, offset %d\n",
c9b951c4 JO	433	(void ) addr, (unsigned long)valp, offset);
71ad0f5e JO	434	return 0;
	435	}
	436
1d037ca1	437	static int access_reg(unw_addr_space_t __maybe_unused as,
71ad0f5e JO	438	unw_regnum_t regnum, unw_word_t *valp,
	439	int __write, void *arg)
	440	{
	441	struct unwind_info *ui = arg;
	442	int id, ret;
c9b951c4	443	u64 val;
71ad0f5e JO	444
	445	/* Don't support write, I suspect we don't need it. */
	446	if (__write) {
	447	pr_err("unwind: access_reg w %d\n", regnum);
	448	return 0;
	449	}
	450
	451	if (!ui->sample->user_regs.regs) {
	452	*valp = 0;
	453	return 0;
	454	}
	455
ea3da69d	456	id = libunwind__arch_reg_id(regnum);
71ad0f5e JO	457	if (id < 0)
	458	return -EINVAL;
	459
c9b951c4	460	ret = perf_reg_value(&val, &ui->sample->user_regs, id);
71ad0f5e JO	461	if (ret) {
	462	pr_err("unwind: can't read reg %d\n", regnum);
	463	return ret;
	464	}
	465
c9b951c4	466	*valp = (unw_word_t) val;
71ad0f5e JO	467	pr_debug("unwind: reg %d, val %lx\n", regnum, (unsigned long)*valp);
	468	return 0;
	469	}
	470
1d037ca1 IT	471	static void put_unwind_info(unw_addr_space_t __maybe_unused as,
	472	unw_proc_info_t *pi __maybe_unused,
	473	void *arg __maybe_unused)
71ad0f5e JO	474	{
	475	pr_debug("unwind: put_unwind_info called\n");
	476	}
	477
	478	static int entry(u64 ip, struct thread thread, struct machine machine,
	479	unwind_entry_cb_t cb, void *arg)
	480	{
	481	struct unwind_entry e;
	482	struct addr_location al;
	483
	484	thread__find_addr_location(thread, machine,
	485	PERF_RECORD_MISC_USER,
61710bde	486	MAP__FUNCTION, ip, &al);
71ad0f5e JO	487
	488	e.ip = ip;
	489	e.map = al.map;
	490	e.sym = al.sym;
	491
	492	pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
	493	al.sym ? al.sym->name : "''",
	494	ip,
	495	al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
	496
	497	return cb(&e, arg);
	498	}
	499
	500	static void display_error(int err)
	501	{
	502	switch (err) {
	503	case UNW_EINVAL:
	504	pr_err("unwind: Only supports local.\n");
	505	break;
	506	case UNW_EUNSPEC:
	507	pr_err("unwind: Unspecified error.\n");
	508	break;
	509	case UNW_EBADREG:
	510	pr_err("unwind: Register unavailable.\n");
	511	break;
	512	default:
	513	break;
	514	}
	515	}
	516
	517	static unw_accessors_t accessors = {
	518	.find_proc_info = find_proc_info,
	519	.put_unwind_info = put_unwind_info,
	520	.get_dyn_info_list_addr = get_dyn_info_list_addr,
	521	.access_mem = access_mem,
	522	.access_reg = access_reg,
	523	.access_fpreg = access_fpreg,
	524	.resume = resume,
	525	.get_proc_name = get_proc_name,
	526	};
	527
	528	static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,
37676af1	529	void *arg, int max_stack)
71ad0f5e JO	530	{
	531	unw_addr_space_t addr_space;
	532	unw_cursor_t c;
	533	int ret;
	534
	535	addr_space = unw_create_addr_space(&accessors, 0);
	536	if (!addr_space) {
	537	pr_err("unwind: Can't create unwind address space.\n");
	538	return -ENOMEM;
	539	}
	540
	541	ret = unw_init_remote(&c, addr_space, ui);
	542	if (ret)
	543	display_error(ret);
	544
37676af1	545	while (!ret && (unw_step(&c) > 0) && max_stack--) {
71ad0f5e JO	546	unw_word_t ip;
	547
	548	unw_get_reg(&c, UNW_REG_IP, &ip);
1cf0382a	549	ret = ip ? entry(ip, ui->thread, ui->machine, cb, arg) : 0;
71ad0f5e JO	550	}
	551
	552	unw_destroy_addr_space(addr_space);
	553	return ret;
	554	}
	555
	556	int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
	557	struct machine machine, struct thread thread,
352ea45a	558	struct perf_sample *data, int max_stack)
71ad0f5e	559	{
c9b951c4	560	u64 ip;
71ad0f5e JO	561	struct unwind_info ui = {
71ad0f5e JO	562	.sample = data,
71ad0f5e JO	563	.thread = thread,
	564	.machine = machine,
	565	};
	566	int ret;
	567
	568	if (!data->user_regs.regs)
	569	return -EINVAL;
	570
c9b951c4	571	ret = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
71ad0f5e JO	572	if (ret)
	573	return ret;
	574
	575	ret = entry(ip, thread, machine, cb, arg);
	576	if (ret)
	577	return -ENOMEM;
	578
b42dc32d	579	return --max_stack > 0 ? get_entries(&ui, cb, arg, max_stack) : 0;
71ad0f5e	580	}