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From: Yordan Karadzhov <y.karadz@gmail.com>
To: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
Cc: rostedt@goodmis.org, linux-trace-devel@vger.kernel.org
Subject: Re: [RFC PATCH v2 1/4] trace-cruncher: Logic for resolving address to function name
Date: Mon, 18 Apr 2022 12:13:16 +0300	[thread overview]
Message-ID: <5276cd27-a3b0-340d-51da-ab959c92de24@gmail.com> (raw)
In-Reply-To: <20220415041012.36151-2-tz.stoyanov@gmail.com>



On 15.04.22 г. 7:10 ч., Tzvetomir Stoyanov (VMware) wrote:
> Resolving virtual address to function name and vise versa is useful
> functionality for a trace application. Trace-cruncher can use it in two
> use cases:
>   - Resolving VMA to function name, when collecting user application
>     performance traces with perf.
>   - Resolving function name to VMA, when using ftarce uprobe dynamic
>     events.
> 
> Proposed implementation uses the bfd library to parse the binary files
> and read the symbol table. This information is available only if the
> files are not stripped.
> 
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>   src/trace-obj-debug.c | 982 ++++++++++++++++++++++++++++++++++++++++++
>   src/trace-obj-debug.h |  54 +++
>   2 files changed, 1036 insertions(+)
>   create mode 100644 src/trace-obj-debug.c
>   create mode 100644 src/trace-obj-debug.h
> 
> diff --git a/src/trace-obj-debug.c b/src/trace-obj-debug.c
> new file mode 100644
> index 0000000..a6da22f
> --- /dev/null
> +++ b/src/trace-obj-debug.c
> @@ -0,0 +1,982 @@
> +// SPDX-License-Identifier: LGPL-2.1
> +/*
> + * Copyright (C) 2020, VMware, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
> + *
> + */

Add here

#ifndef _GNU_SOURCE
/** Use GNU C Library. */
#define _GNU_SOURCE
#endif // _GNU_SOURCE

> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <limits.h>
> +#include <errno.h>
> +#include <bfd.h>
> +#include <unistd.h>
> +#include <dlfcn.h>
> +#include <fnmatch.h>
> +#include <ctype.h>
> +
> +#include "trace-obj-debug.h"
> +
> +//#define DEBUG_INTERNALS
> +
> +/* Got from demangle.h */
> +#define DMGL_AUTO (1 << 8)
> +
> +struct debug_bfd_handle {
> +	bfd *bfd;
> +	unsigned long long addr_offset;
> +};
> +
> +enum match_type {
> +	MATCH_EXACT	= 0,
> +	MATH_WILDCARD	= 1,
> +};
> +
> +struct debug_symbols {
> +	struct debug_symbols		*next;
> +	struct dbg_trace_symbols	symbol;
> +	enum match_type			match;
> +};
> +
> +struct debug_file {
> +	struct debug_file		*next;
> +	char				*file_name;
> +
> +	/* Start and end address, where this file is mapped into the memory of the process. */
> +	unsigned long long		vmem_start;
> +	unsigned long long		vmem_end;
> +
> +	/* bfd library context for this file. */
> +	struct debug_bfd_handle	*dbg;
> +
> +	/* Symbols to resolve, search in this file only. */
> +	int				sym_count;
> +	struct debug_symbols		*sym;
> +};
> +
> +struct dbg_trace_context {
> +	/* PID or name of the process. */
> +	int				pid;
> +	char				*fname;
> +
> +	/* List of all libraries and object files, mapped in the memory of the process. */
> +	struct dbg_trace_pid_maps	*fmaps;
> +
> +	/* Symbols to resolve, search in all files. */
> +	int				sym_count;
> +	struct debug_symbols		*sym;
> +
> +	/* List of all libraries and object files, opened from bfd library for processing. */
> +	struct debug_file		*files;
> +};
> +
> +#define RESOLVE_NAME		(1 << 0)
> +#define RESOLVE_VMA		(1 << 1)
> +#define RESOLVE_FOFFSET		(1 << 2)
> +
> +struct debug_obj_job {
> +	unsigned int flags;
> +	unsigned long long addr_offset;
> +	struct debug_symbols *symbols;
> +};
> +
> +struct debug_dwarf_bfd_context {
> +	asymbol **table;
> +	struct debug_obj_job *job;
> +};
> +
> +/*
> + * A hook, called from bfd library for each section of the file.
> + * The logic is used for symbol name and file offset resolving from given symbol VMA.
> + */
> +static void process_bfd_section(bfd *abfd, asection *section, void *param)
> +{
> +	struct debug_dwarf_bfd_context *context = (struct debug_dwarf_bfd_context *)param;
> +	unsigned int discriminator;
> +	const char *functionname;
> +	struct debug_symbols *s;
> +	unsigned long long vma;
> +	const char *filename;
> +	unsigned int line;
> +	bfd_boolean found;
> +
> +	/* Skip sections that have no code. */
> +	if (!(section->flags & SEC_CODE))
> +		return;
> +
> +	/* Loop through all symbols, that have to be resolved. */
> +	for (s = context->job->symbols; s; s = s->next) {
> +		if (s->symbol.vma_near)
> +			vma = s->symbol.vma_near;
> +		else if (s->symbol.vma_start)
> +			vma = s->symbol.vma_start;
> +		else
> +			continue;
> +
> +		/* Adjust the symbol's VMA, if this section is dynamically loaded. */
> +		if (abfd->flags & DYNAMIC)
> +			vma -=  context->job->addr_offset;
                                ^extra space.

Thanks!
Yordan

> +
> +		/* Check if requested symbol's vma is within the current section. */
> +		if (vma && section->vma <= vma &&
> +		    (section->vma + section->size) > vma) {
> +
> +			/* Found the file, where the symbol is defined. */
> +			if (!s->symbol.fname)
> +				s->symbol.fname = strdup(abfd->filename);
> +
> +			/* Found the offset of the symbol within the file. */
> +			if (context->job->flags & RESOLVE_FOFFSET)
> +				s->symbol.foffset = section->filepos + (vma - section->vma);
> +
> +			/* Look for the nearest function. */
> +			if (!s->symbol.name && (context->job->flags & RESOLVE_NAME)) {
> +				found = bfd_find_nearest_line_discriminator(abfd, section, context->table,
> +									    vma - section->vma, &filename,
> +									    &functionname, &line, &discriminator);
> +#ifdef DEBUG_INTERNALS
> +				printf("Find addr near 0x%X, offset 0x%X - > vma - 0x%X in %s, found %s\n\r",
> +					s->symbol.vma_near, context->job->addr_offset, vma, abfd->filename,
> +					found ? functionname : "NA");
> +#endif
> +				if (found) {
> +					/* Demangle the name of the function. */
> +					s->symbol.name = bfd_demangle(abfd, functionname, DMGL_AUTO);
> +					/* Found the name of the symbol. */
> +					if (!s->symbol.name)
> +						s->symbol.name = strdup(functionname);
> +				}
> +			}
> +		}
> +	}
> +}
> +
> +/* Load the symbol table from the file. */
> +static asymbol **get_sym_table(bfd *handle)
> +{
> +	long size, ssize, dsize;
> +	asymbol **symtable;
> +	long count;
> +
> +	if ((bfd_get_file_flags(handle) & HAS_SYMS) == 0)
> +		return NULL;
> +
> +	dsize = bfd_get_dynamic_symtab_upper_bound(handle);
> +	size = dsize > 0 ? dsize : 0;
> +
> +	ssize = bfd_get_symtab_upper_bound(handle);
> +	size += ssize > 0 ? ssize : 0;
> +
> +	if (size <= 0)
> +		return NULL;
> +
> +	symtable = (asymbol **) calloc(1, size);
> +	if (!symtable)
> +		return NULL;
> +
> +	count = bfd_canonicalize_symtab(handle, symtable);
> +	count += bfd_canonicalize_dynamic_symtab(handle, symtable + count);
> +	if (count <= 0) {
> +		free(symtable);
> +		return NULL;
> +	}
> +
> +	return symtable;
> +}
> +
> +/* Match the requested name to the name of the symbol. Handle a wildcard match. */
> +static bool symbol_match(char *pattern, enum match_type match, const char *symbol)
> +{
> +	bool ret = false;
> +
> +	switch (match) {
> +	case MATCH_EXACT:
> +		if (strlen(pattern) == strlen(symbol) &&
> +		    !strcmp(pattern, symbol))
> +			ret = true;
> +		break;
> +	case MATH_WILDCARD:
> +		if (!fnmatch(pattern, symbol, 0))
> +			ret = true;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +/* Lookup in the file's symbol table.
> + * The logic is used for symbol VMA resolving from given symbol name.
> + */
> +static int lookup_bfd_sym(struct debug_dwarf_bfd_context *context)
> +{
> +	struct debug_symbols *s, *last = NULL;
> +	struct debug_symbols *new, *new_list = NULL;
> +	unsigned long long vma;
> +	asymbol **sp;
> +	int res = 0;
> +
> +	for (sp = context->table; *sp != NULL; sp++) {
> +		/* Skip the symbol, if it is not a function. */
> +		if (!((*sp)->flags & BSF_FUNCTION))
> +			continue;
> +		/* Loop through all symbols that should be resolved. */
> +		for (s = context->job->symbols; s; s = s->next) {
> +			if (!s->symbol.name)
> +				continue;
> +			last = s;
> +			if (!symbol_match(s->symbol.name, s->match, (*sp)->name))
> +				continue;
> +#ifdef DEBUG_INTERNALS
> +			printf("Matched %s, pattern %s\n\r", (*sp)->name, s->symbol.name);
> +#endif
> +			vma = (*sp)->value + (*sp)->section->vma;
> +			/* Adjust the VMA, if the section is dynamically loaded. */
> +			if ((*sp)->the_bfd->flags & DYNAMIC)
> +				vma += context->job->addr_offset;
> +			if (s->match == MATCH_EXACT) {
> +				/* Exact match, update the VMA. */
> +				s->symbol.vma_start = vma;
> +			} else if (s->match == MATH_WILDCARD) {
> +				/* Wildcard pattern match, create a new symbol. */
> +				new = calloc(1, sizeof(struct debug_symbols));
> +				if (!new)
> +					break;
> +				new->symbol.name = strdup((*sp)->name);
> +				new->symbol.vma_start = vma;
> +				new->symbol.vma_near = s->symbol.vma_near;
> +				new->symbol.foffset = s->symbol.foffset;
> +				new->symbol.cookie = s->symbol.cookie;
> +				if (s->symbol.fname)
> +					new->symbol.fname = strdup(s->symbol.fname);
> +				new->next = new_list;
> +				new_list = new;
> +			}
> +			res++;
> +		}
> +	}
> +	if (last && !last->next)
> +		last->next = new_list;
> +
> +	return res;
> +}
> +
> +/* Process a bfd object from the file. */
> +static int process_bfd_object(bfd *abfd, struct debug_obj_job *job)
> +{
> +	struct debug_dwarf_bfd_context context;
> +	int ret = 0;
> +
> +	memset(&context, 0, sizeof(context));
> +	context.job = job;
> +	if (bfd_check_format_matches(abfd, bfd_object, NULL) ||
> +	    bfd_check_format_matches(abfd, bfd_core, NULL)) {
> +		context.table = get_sym_table(abfd);
> +		if (!context.table)
> +			return -1;
> +
> +		/* Resolve VMA from the symbol table. */
> +		if (job->flags & RESOLVE_VMA)
> +			lookup_bfd_sym(&context);
> +
> +		/* Resolve symbol name and file offset from file's sections. */
> +		if ((job->flags & RESOLVE_NAME) || (job->flags & RESOLVE_FOFFSET))
> +			bfd_map_over_sections(abfd, process_bfd_section, &context);
> +
> +		free(context.table);
> +	} else {
> +		ret = -1;
> +	}
> +
> +	return ret;
> +}
> +
> +/* Open a bfd archive file and read all objects. */
> +static int read_all_bfd(bfd *abfd, struct debug_obj_job *job)
> +{
> +	bfd *last_arfile = NULL;
> +	bfd *arfile = NULL;
> +	int ret = 0;
> +
> +	if (bfd_check_format(abfd, bfd_archive)) {
> +		for (;;) {
> +			bfd_set_error(bfd_error_no_error);
> +			arfile = bfd_openr_next_archived_file(abfd, arfile);
> +			if (!arfile) {
> +				if (bfd_get_error() != bfd_error_no_more_archived_files)
> +					break;
> +			}
> +			ret = read_all_bfd(arfile, job);
> +			if (last_arfile)
> +				bfd_close(last_arfile);
> +			last_arfile = arfile;
> +		}
> +		if (last_arfile)
> +			bfd_close(last_arfile);
> +	} else
> +		ret = process_bfd_object(abfd, job);
> +
> +	return ret;
> +}
> +
> +/**
> + * resolve_symbol_vma - name -> (vma, file offset) resolving
> + * @obj - pointer to object, returned by trace_obj_debug_create()
> + * @symbols - link list with desired symbols, with given name
> + *
> + * Get VMA and file offset of the symbols with given name.
> + * Return 0 on success, -1 on error.
> + */
> +static int resolve_symbol_vma(struct debug_bfd_handle *obj,
> +			      struct debug_symbols *symbols)
> +{
> +	struct debug_obj_job job;
> +	int ret;
> +
> +	memset(&job, 0, sizeof(job));
> +	job.flags |= RESOLVE_VMA;
> +	job.flags |= RESOLVE_FOFFSET;
> +	job.symbols = symbols;
> +	job.addr_offset = obj->addr_offset;
> +	ret = read_all_bfd(obj->bfd, &job);
> +
> +	return ret;
> +}
> +
> +/**
> + * resolve_symbol_name - vma -> name resolving
> + * @obj - pointer to object, returned by trace_obj_debug_create()
> + * @symbols - link list with desired symbols, with given VMA
> + *
> + * Get names of the symbols with given VMA, look for nearest symbol to that VMA.
> + * Return 0 on success, -1 on error.
> + */
> +static int resolve_symbol_name(struct debug_bfd_handle *obj,
> +			       struct debug_symbols *symbols)
> +{
> +	struct debug_obj_job job;
> +
> +	if (!obj || !obj->bfd)
> +		return -1;
> +	memset(&job, 0, sizeof(job));
> +	job.flags |= RESOLVE_NAME;
> +	job.addr_offset = obj->addr_offset;
> +	job.symbols = symbols;
> +	return read_all_bfd(obj->bfd, &job);
> +}
> +
> +/**
> + * debug_handle_destroy - Close file opened with trace_obj_debug_create()
> + * @obj - pointer to object, returned by trace_obj_debug_create()
> + *
> + * Close the file and free any allocated resources, related to file's debug
> + * information.
> + */
> +static void debug_handle_destroy(struct debug_bfd_handle *obj)
> +{
> +	if (obj && obj->bfd)
> +		bfd_close(obj->bfd);
> +	free(obj);
> +}
> +
> +/**
> + * debug_handle_create - Open binary file for parsing ELF and DWARF information
> + * @name: Name of the binary ELF file.
> + *
> + * Return pointer to trace_obj_debug structure, that can be passed to other APIs
> + * for extracting debug information from the file. NULL in case of an error.
> + */
> +static struct debug_bfd_handle *debug_handle_create(char *file)
> +{
> +	struct debug_bfd_handle *obj = NULL;
> +
> +	obj = calloc(1, sizeof(*obj));
> +	if (!obj)
> +		return NULL;
> +
> +	bfd_init();
> +	obj->bfd = bfd_openr(file, NULL);
> +	if (!obj->bfd)
> +		goto error;
> +	obj->bfd->flags |= BFD_DECOMPRESS;
> +
> +	return obj;
> +
> +error:
> +	debug_handle_destroy(obj);
> +	return NULL;
> +}
> +
> +/* Get the full path of process's executable, using the /proc fs. */
> +static char *get_full_name(int pid)
> +{
> +	char mapname[PATH_MAX+1];
> +	char fname[PATH_MAX+1];
> +	int ret;
> +
> +	sprintf(fname, "/proc/%d/exe", pid);
> +	ret = readlink(fname, mapname, PATH_MAX);
> +	if (ret >= PATH_MAX || ret < 0)
> +		return NULL;
> +	mapname[ret] = 0;
> +
> +	return strdup(mapname);
> +}
> +
> +/* Get or create a bfd debug context for an object file. */
> +static struct debug_file *get_mapped_file(struct dbg_trace_context *dbg,
> +					  char *fname,
> +					  unsigned long long vmem_start)
> +{
> +	struct debug_file *file = dbg->files;
> +
> +	/* Search if the file is already added. */
> +	while (file) {
> +		if (!strcmp(fname, file->file_name) &&
> +		    vmem_start && file->vmem_end == vmem_start)
> +			return file;
> +		file = file->next;
> +	}
> +
> +	file = calloc(1, sizeof(*file));
> +	if (!file)
> +		return NULL;
> +	file->file_name = strdup(fname);
> +	if (!file->file_name)
> +		goto error;
> +	file->dbg = debug_handle_create(fname);
> +	file->next = dbg->files;
> +	dbg->files = file;
> +	return file;
> +
> +error:
> +	free(file->file_name);
> +	debug_handle_destroy(file->dbg);
> +	free(file);
> +	return NULL;
> +}
> +
> +/* Destroy a bfd debug context. */
> +void dbg_trace_context_destroy(struct dbg_trace_context *dbg)
> +{
> +	struct debug_file *fdel;
> +	struct debug_symbols *sdel;
> +
> +	while (dbg->sym) {
> +		sdel = dbg->sym;
> +		dbg->sym = dbg->sym->next;
> +		free(sdel->symbol.name);
> +		free(sdel->symbol.fname);
> +		free(sdel);
> +	}
> +	while (dbg->files) {
> +		fdel = dbg->files;
> +		dbg->files = dbg->files->next;
> +		debug_handle_destroy(fdel->dbg);
> +		while (fdel->sym) {
> +			sdel = fdel->sym;
> +			fdel->sym = fdel->sym->next;
> +			free(sdel->symbol.name);
> +			free(sdel->symbol.fname);
> +			free(sdel);
> +		}
> +		free(fdel);
> +	}
> +
> +	free(dbg->fname);
> +	dbg_trace_free_filemap(dbg->fmaps);
> +	free(dbg);
> +}
> +
> +/* Add an object file, mapped to specific memory of the process. */
> +int dbg_trace_context_add_file(struct dbg_trace_context *dbg, char *file_name,
> +			       unsigned long long vmem_start,
> +			       unsigned long long vmem_end,
> +			       unsigned long long pgoff)
> +{
> +	struct debug_file *file;
> +
> +	file = get_mapped_file(dbg, file_name, vmem_start);
> +	if (!file)
> +		return -1;
> +	if (file->vmem_end == vmem_start) {
> +		file->vmem_end = vmem_end;
> +	} else {
> +		file->vmem_start = vmem_start;
> +		file->vmem_end = vmem_end;
> +		if (file->dbg)
> +			file->dbg->addr_offset = vmem_start - pgoff;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * dbg_trace_context_create_pid - create debug context for given PID
> + * @pid - ID of running process
> + * @libs - if true: inspect also all libraries, uased by the given process.
> + *
> + * Returns a pointer to allocated debug context, or NULL in case of an error.
> + */
> +struct dbg_trace_context *dbg_trace_context_create_pid(int pid, bool libs)
> +{
> +	struct dbg_trace_context *dbg;
> +	unsigned int i;
> +
> +	dbg = calloc(1, sizeof(*dbg));
> +	if (!dbg)
> +		return NULL;
> +
> +	dbg->pid = pid;
> +	/* Get the full path of the process executable. */
> +	dbg->fname = get_full_name(pid);
> +	if (!dbg->fname) {
> +		free(dbg);
> +		return NULL;
> +	}
> +
> +	/* Get the memory map of all libraries, linked to the process. */
> +	dbg_trace_get_filemap(&dbg->fmaps, pid);
> +
> +	for (i = 0; i < dbg->fmaps->nr_lib_maps; i++) {
> +		if (!libs && strcmp(dbg->fname, dbg->fmaps->lib_maps[i].lib_name))
> +			continue;
> +		/* Create a bfd debug object for each file. */
> +		dbg_trace_context_add_file(dbg, dbg->fmaps->lib_maps[i].lib_name,
> +					   dbg->fmaps->lib_maps[i].start,
> +					   dbg->fmaps->lib_maps[i].end, 0);
> +	}
> +
> +	return dbg;
> +}
> +
> +/* Get the full path of a library. */
> +static char *get_lib_full_path(char *libname)
> +{
> +	void *h = dlmopen(LM_ID_NEWLM, libname, RTLD_LAZY);
> +	char dldir[PATH_MAX+1];
> +	char *fname = NULL;
> +	int ret;
> +
> +	if (!h)
> +		return NULL;
> +
> +	ret = dlinfo(h, RTLD_DI_ORIGIN, dldir);
> +	dlclose(h);
> +
> +	if (ret || asprintf(&fname, "%s/%s", dldir, libname) <= 0)
> +		return NULL;
> +
> +	return fname;
> +}
> +
> +/* Get the memory map of all libraries, linked to an executable file. */
> +static int debug_obj_file_add_libs(struct dbg_trace_context *dbg,
> +				   struct debug_file *file)
> +{
> +	char line[PATH_MAX];
> +	char *libname;
> +	char *trimmed;
> +	char *fullname;
> +	FILE *fp = NULL;
> +	int ret = -1;
> +
> +	setenv("LD_TRACE_LOADED_OBJECTS", "1", 1);
> +	fp = popen(file->file_name, "r");
> +	if (!fp)
> +		goto out;
> +
> +	while (fgets(line, sizeof(line), fp) != NULL) {
> +		libname = strchr(line, ' ');
> +		trimmed = line;
> +		if (libname) {
> +			*libname = '\0';
> +			while (isspace(*trimmed))
> +				trimmed++;
> +			if (*trimmed != '/') {
> +				fullname = get_lib_full_path(trimmed);
> +				if (fullname) {
> +					get_mapped_file(dbg, fullname, 0);
> +					free(fullname);
> +				}
> +			} else {
> +				get_mapped_file(dbg, trimmed, 0);
> +			}
> +		}
> +	}
> +
> +out:
> +	unsetenv("LD_TRACE_LOADED_OBJECTS");
> +	if (fp)
> +		pclose(fp);
> +	return ret;
> +}
> +
> +/**
> + * dbg_trace_context_create_file - create debug context for given executable file
> + * @fname - full path to an executable file
> + * @libs - if true: inspect also all libraries, used by the given file.
> + *
> + * Returns a pointer to allocated debug context, or NULL in case of an error.
> + */
> +struct dbg_trace_context *dbg_trace_context_create_file(char *fname, bool libs)
> +{
> +	struct dbg_trace_context *dbg;
> +	struct debug_file *file;
> +
> +	dbg = calloc(1, sizeof(*dbg));
> +	if (!dbg)
> +		return NULL;
> +
> +	dbg->fname = strdup(fname);
> +	file = get_mapped_file(dbg, fname, 0);
> +	if (!file)
> +		goto error;
> +	if (libs)
> +		debug_obj_file_add_libs(dbg, file);
> +
> +#ifdef DEBUG_INTERNALS
> +	printf("Created debug object for %s:\n\r", dbg->fname);
> +	file = dbg->files;
> +	while (file) {
> +		printf("\t%s\n\r", file->file_name);
> +		file = file->next;
> +	}
> +#endif
> +	return dbg;
> +
> +error:
> +	dbg_trace_context_destroy(dbg);
> +	return NULL;
> +}
> +
> +static void set_unknown(struct debug_symbols *sym, char *file)
> +{
> +	while (sym) {
> +		if (!sym->symbol.fname)
> +			sym->symbol.fname = strdup(file);
> +		sym = sym->next;
> +	}
> +}
> +
> +/* Perform the requested symbols resolving, using the bfd library. */
> +int dbg_trace_resolve_symbols(struct dbg_trace_context *obj)
> +{
> +	struct debug_file *file;
> +
> +	for (file = obj->files; file; file = file->next) {
> +		if (!file->dbg) {
> +			set_unknown(file->sym, file->file_name);
> +			continue;
> +		}
> +		/* Resolve near VMA -> name. */
> +		resolve_symbol_name(file->dbg, file->sym);
> +		/* Resolve name -> exact VMA. */
> +		resolve_symbol_vma(file->dbg, file->sym);
> +		resolve_symbol_vma(file->dbg, obj->sym);
> +	}
> +
> +	return 0;
> +}
> +
> +/* Add VMA -> name resolving request. */
> +static int add_resolve_vma2name(struct dbg_trace_context *obj,
> +				unsigned long long vma, int cookie)
> +{
> +	struct debug_symbols *s = NULL;
> +	struct debug_file *file;
> +
> +	file = obj->files;
> +	while (file) {
> +		/* Find the file, where the requested VMA is. */
> +		if (vma >= file->vmem_start && vma <= file->vmem_end)
> +			break;
> +		file = file->next;
> +	}
> +
> +	if (file) {
> +		s = file->sym;
> +		while (s) {
> +			/* Check if the given VMA is already added for resolving. */
> +			if (s->symbol.vma_near == vma)
> +				break;
> +			s = s->next;
> +		}
> +		if (!s) {
> +			s = calloc(1, sizeof(*s));
> +			if (!s)
> +				return -1;
> +			s->symbol.cookie = cookie;
> +			s->symbol.vma_near = vma;
> +			s->symbol.fname = strdup(file->file_name);
> +			if (!s->symbol.fname)
> +				goto error;
> +			s->next = file->sym;
> +			file->sym = s;
> +			file->sym_count++;
> +		}
> +	}
> +
> +	if (s)
> +		return 0;
> +error:
> +	if (s) {
> +		free(s->symbol.fname);
> +		free(s);
> +	}
> +	return -1;
> +}
> +
> +/* Add name - VMA resolving request, The @name can have wildcards. */
> +static int add_resolve_name2vma(struct dbg_trace_context *obj, char *name, int cookie)
> +{
> +	struct debug_symbols *s = NULL;
> +
> +	s = obj->sym;
> +	while (s) {
> +		/* Check if the given name is already added for resolving. */
> +		if (s->symbol.name && !strcmp(name, s->symbol.name))
> +			break;
> +		s = s->next;
> +	}
> +	if (!s) {
> +		s = calloc(1, sizeof(*s));
> +		if (!s)
> +			return -1;
> +		s->symbol.cookie = cookie;
> +		s->symbol.name = strdup(name);
> +		if (!s->symbol.name)
> +			goto error;
> +		if (strchr(name, '*') || strchr(name, '?'))
> +			s->match = MATH_WILDCARD;
> +
> +		s->next = obj->sym;
> +		obj->sym = s;
> +		obj->sym_count++;
> +	}
> +
> +	return 0;
> +
> +error:
> +	if (s) {
> +		free(s->symbol.name);
> +		free(s);
> +	}
> +	return -1;
> +}
> +
> +/**
> + * dbg_trace_add_resolve_symbol - add new resolving request
> + * @obj - debug object context
> + * @vma - VMA->name resolving, if @vma is not 0
> + * @name - name-VMA resolving, if @name is not NULL
> + * @cookie - a cookie, attached to each successful resolving from this request
> + *
> + * Returns 0 if the request is added successfully, or -1 in case of an error.
> + */
> +int dbg_trace_add_resolve_symbol(struct dbg_trace_context *obj,
> +				 unsigned long long vma, char *name, int cookie)
> +{
> +	int ret = -1;
> +
> +	if (!obj)
> +		return -1;
> +
> +	if (!name && vma) /* vma -> name resolving */
> +		ret = add_resolve_vma2name(obj, vma, cookie);
> +	else if (name) /* name -> vma resolving */
> +		ret = add_resolve_name2vma(obj, name, cookie);
> +
> +	return ret;
> +}
> +
> +static int walk_symbols(struct debug_symbols *sym,
> +			int (*callback)(struct dbg_trace_symbols *, void *),
> +			void *context)
> +{
> +	while (sym) {
> +		if (callback(&sym->symbol, context))
> +			return -1;
> +		sym = sym->next;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * dbg_trace_walk_resolved_symbols - walk through all resolved symbols
> + * @obj - debug object context
> + * @callback - a callback hook, called for each resolved symbol.
> + *		If the callback returns non-zero, the walk stops.
> + * @context - a user specified context, passed to the callback
> + */
> +void dbg_trace_walk_resolved_symbols(struct dbg_trace_context *obj,
> +				     int (*callback)(struct dbg_trace_symbols *, void *),
> +				     void *context)
> +{
> +	struct debug_file *file;
> +
> +	walk_symbols(obj->sym, callback, context);
> +	file = obj->files;
> +	while (file) {
> +		walk_symbols(file->sym, callback, context);
> +		file = file->next;
> +	}
> +}
> +
> +/**
> + * trace_debug_free_symbols - free array of debug symbols
> + * @symbols - array with debug symbols
> + * @count - count of the @symbols array
> + */
> +void trace_debug_free_symbols(struct dbg_trace_symbols *symbols, int count)
> +{
> +	int i;
> +
> +	if (!symbols)
> +		return;
> +
> +	for (i = 0; i < count; i++) {
> +		free(symbols[i].name);
> +		free(symbols[i].fname);
> +	}
> +	free(symbols);
> +
> +}
> +
> +#define _STRINGIFY(x) #x
> +#define STRINGIFY(x) _STRINGIFY(x)
> +/**
> + * dbg_trace_get_filemap - get a memory map of a process, using /proc fs
> + * @pid_maps - return: list of files, mapped into the process memory
> + * @pid - id of a process
> + *
> + * Returns 0 on success, -1 in case of an error.
> + */
> +int dbg_trace_get_filemap(struct dbg_trace_pid_maps **pid_maps, int pid)
> +{
> +	struct dbg_trace_pid_maps *maps = *pid_maps;
> +	struct dbg_trace_proc_addr_map *map;
> +	unsigned long long begin, end;
> +	struct dbg_trace_pid_maps *m;
> +	char mapname[PATH_MAX+1];
> +	char fname[PATH_MAX+1];
> +	char buf[PATH_MAX+100];
> +	unsigned int i;
> +	FILE *f;
> +	int ret;
> +	int res;
> +
> +	sprintf(fname, "/proc/%d/exe", pid);
> +	ret = readlink(fname, mapname, PATH_MAX);
> +	if (ret >= PATH_MAX || ret < 0)
> +		return -ENOENT;
> +	mapname[ret] = 0;
> +
> +	sprintf(fname, "/proc/%d/maps", pid);
> +	f = fopen(fname, "r");
> +	if (!f)
> +		return -ENOENT;
> +
> +	while (maps) {
> +		if (pid == maps->pid)
> +			break;
> +		maps = maps->next;
> +	}
> +
> +	ret = -ENOMEM;
> +	if (!maps) {
> +		maps = calloc(1, sizeof(*maps));
> +		if (!maps)
> +			goto out_fail;
> +		maps->pid = pid;
> +		maps->next = *pid_maps;
> +		*pid_maps = maps;
> +	} else {
> +		for (i = 0; i < maps->nr_lib_maps; i++)
> +			free(maps->lib_maps[i].lib_name);
> +		free(maps->lib_maps);
> +		maps->lib_maps = NULL;
> +		maps->nr_lib_maps = 0;
> +		free(maps->proc_name);
> +	}
> +
> +	maps->proc_name = strdup(mapname);
> +	if (!maps->proc_name)
> +		goto out_fail;
> +
> +	while (fgets(buf, sizeof(buf), f)) {
> +		mapname[0] = '\0';
> +		res = sscanf(buf, "%llx-%llx %*s %*x %*s %*d %"STRINGIFY(PATH_MAX)"s",
> +			     &begin, &end, mapname);
> +		if (res == 3 && mapname[0] != '\0') {
> +			map = realloc(maps->lib_maps,
> +				      (maps->nr_lib_maps + 1) * sizeof(*map));
> +			if (!map)
> +				goto out_fail;
> +			map[maps->nr_lib_maps].end = end;
> +			map[maps->nr_lib_maps].start = begin;
> +			map[maps->nr_lib_maps].lib_name = strdup(mapname);
> +			if (!map[maps->nr_lib_maps].lib_name)
> +				goto out_fail;
> +			maps->lib_maps = map;
> +			maps->nr_lib_maps++;
> +		}
> +	}
> +
> +	fclose(f);
> +	return 0;
> +
> +out_fail:
> +	fclose(f);
> +	if (maps) {
> +		for (i = 0; i < maps->nr_lib_maps; i++)
> +			free(maps->lib_maps[i].lib_name);
> +		if (*pid_maps != maps) {
> +			m = *pid_maps;
> +			while (m) {
> +				if (m->next == maps) {
> +					m->next = maps->next;
> +					break;
> +				}
> +				m = m->next;
> +			}
> +		} else
> +			*pid_maps = maps->next;
> +		free(maps->lib_maps);
> +		maps->lib_maps = NULL;
> +		maps->nr_lib_maps = 0;
> +		free(maps->proc_name);
> +		maps->proc_name = NULL;
> +		free(maps);
> +	}
> +	return ret;
> +}
> +
> +static void procmap_free(struct dbg_trace_pid_maps *maps)
> +{
> +	unsigned int i;
> +
> +	if (!maps)
> +		return;
> +	if (maps->lib_maps) {
> +		for (i = 0; i < maps->nr_lib_maps; i++)
> +			free(maps->lib_maps[i].lib_name);
> +		free(maps->lib_maps);
> +	}
> +	free(maps->proc_name);
> +	free(maps);
> +}
> +
> +/**
> + * dbg_trace_free_filemap - Free list of files, associated with given process
> + * @maps - list of files, returned by dbg_trace_get_filemap()
> + */
> +void dbg_trace_free_filemap(struct dbg_trace_pid_maps *maps)
> +{
> +	struct dbg_trace_pid_maps *del;
> +
> +	while (maps) {
> +		del = maps;
> +		maps = maps->next;
> +		procmap_free(del);
> +	}
> +}
> diff --git a/src/trace-obj-debug.h b/src/trace-obj-debug.h
> new file mode 100644
> index 0000000..19091ad
> --- /dev/null
> +++ b/src/trace-obj-debug.h
> @@ -0,0 +1,54 @@
> +/* SPDX-License-Identifier: LGPL-2.1 */
> +
> +/*
> + * Copyright 2022 VMware Inc, Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> + */
> +
> +#ifndef _TC_TRACE_DEBUG_UTILS_
> +#define _TC_TRACE_DEBUG_UTILS_
> +
> +/* --- Debug symbols--- */
> +struct dbg_trace_pid_maps {
> +	struct dbg_trace_pid_maps	*next;
> +	struct dbg_trace_proc_addr_map	*lib_maps;
> +	unsigned int			nr_lib_maps;
> +	char				*proc_name;
> +	int				pid;
> +};
> +int dbg_trace_get_filemap(struct dbg_trace_pid_maps **file_maps, int pid);
> +void dbg_trace_free_filemap(struct dbg_trace_pid_maps *maps);
> +
> +struct dbg_trace_symbols {
> +	char *name;			/* symbol's name */
> +	char *fname;			/* symbol's file */
> +	int cookie;
> +	unsigned long long vma_start;	/* symbol's start VMA */
> +	unsigned long long vma_near;	/* symbol's requested VMA */
> +	unsigned long long foffset;	/* symbol's offset in the binary file*/
> +};
> +
> +struct dbg_trace_proc_addr_map {
> +	unsigned long long	start;
> +	unsigned long long	end;
> +	char			*lib_name;
> +};
> +
> +struct dbg_trace_context;
> +struct dbg_trace_context *dbg_trace_context_create_file(char *file, bool libs);
> +struct dbg_trace_context *dbg_trace_context_create_pid(int pid, bool libs);
> +
> +void dbg_trace_context_destroy(struct dbg_trace_context *debug);
> +int dbg_trace_context_add_file(struct dbg_trace_context *dbg, char *file_name,
> +			       unsigned long long vmem_start,
> +			       unsigned long long vmem_end,
> +			       unsigned long long pgoff);
> +
> +int dbg_trace_resolve_symbols(struct dbg_trace_context *obj);
> +int dbg_trace_add_resolve_symbol(struct dbg_trace_context *obj,
> +				 unsigned long long vma, char *name, int cookie);
> +
> +void dbg_trace_walk_resolved_symbols(struct dbg_trace_context *obj,
> +				     int (*callback)(struct dbg_trace_symbols *, void *),
> +				     void *context);
> +
> +#endif /* _TC_TRACE_DEBUG_UTILS_ */

  reply	other threads:[~2022-04-18  9:13 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-15  4:10 [RFC PATCH v2 0/4] trace-cruncher: ftrace uprobes support Tzvetomir Stoyanov (VMware)
2022-04-15  4:10 ` [RFC PATCH v2 1/4] trace-cruncher: Logic for resolving address to function name Tzvetomir Stoyanov (VMware)
2022-04-18  9:13   ` Yordan Karadzhov [this message]
2022-04-15  4:10 ` [RFC PATCH v2 2/4] trace-cruncher: ftrace uprobe raw API Tzvetomir Stoyanov (VMware)
2022-04-15  4:10 ` [RFC PATCH v2 3/4] trace-cruncher: High level wrappers for ftrace uprobes Tzvetomir Stoyanov (VMware)
2022-04-18 11:54   ` Yordan Karadzhov
2022-04-19  8:22     ` Tzvetomir Stoyanov
2022-04-15  4:10 ` [RFC PATCH v2 4/4] trace-cruncher: Example script for uprobes high level API Tzvetomir Stoyanov (VMware)
2022-04-18 11:54   ` Yordan Karadzhov

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