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

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

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

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,
};

static int _unwind__prepare_access(struct thread *thread)
{
	if (callchain_param.record_mode != CALLCHAIN_DWARF)
		return 0;

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

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

static void _unwind__flush_access(struct thread *thread)
{
	if (callchain_param.record_mode != CALLCHAIN_DWARF)
		return;

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

static void _unwind__finish_access(struct thread *thread)
{
	if (callchain_param.record_mode != CALLCHAIN_DWARF)
		return;

	unw_destroy_addr_space(thread->addr_space);
}

static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,
		       void *arg, int max_stack)
{
	u64 val;
	unw_word_t ips[max_stack];
	unw_addr_space_t addr_space;
	unw_cursor_t c;
	int ret, i = 0;

	ret = perf_reg_value(&val, &ui->sample->user_regs, 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) {
		WARN_ONCE(!ui->thread, "WARNING: ui->thread is NULL");
		addr_space = ui->thread->addr_space;

		if (addr_space == NULL)
			return -1;

		ret = unw_init_remote(&c, addr_space, ui);
		if (ret)
			display_error(ret);

		while (!ret && (unw_step(&c) > 0) && i < max_stack) {
			unw_get_reg(&c, UNW_REG_IP, &ips[i]);
			++i;
		}

		max_stack = i;
	}

	/*
	 * Display what we got based on the order setup.
	 */
	for (i = 0; i < max_stack && !ret; i++) {
		int j = i;

		if (callchain_param.order == ORDER_CALLER)
			j = max_stack - i - 1;
		ret = ips[j] ? entry(ips[j], ui->thread, cb, arg) : 0;
	}

	return ret;
}

static int _unwind__get_entries(unwind_entry_cb_t cb, void *arg,
			struct thread *thread,
			struct perf_sample *data, int max_stack)
{
	struct unwind_info ui = {
		.sample       = data,
		.thread       = thread,
		.machine      = thread->mg->machine,
	};

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

	if (max_stack <= 0)
		return -EINVAL;

	return get_entries(&ui, cb, arg, max_stack);
}

static struct unwind_libunwind_ops
_unwind_libunwind_ops = {
	.prepare_access = _unwind__prepare_access,
	.flush_access   = _unwind__flush_access,
	.finish_access  = _unwind__finish_access,
	.get_entries    = _unwind__get_entries,
};

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