Add instrument-functions.c to help debugging/learning processes

This is the same code as in tcpdump and tcpslice.

Documentation on how to use it will be added later.

1 files changed, 239 insertions, 0 deletions

diff --git a/instrument-functions.c b/instrument-functions.c
new file mode 100644
index 00000000..fb2314dd
--- /dev/null
+++ b/instrument-functions.c
@@ -0,0 +1,239 @@
+/*
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that: (1) source code
+ * distributions retain the above copyright notice and this paragraph
+ * in its entirety, and (2) distributions including binary code include
+ * the above copyright notice and this paragraph in its entirety in
+ * the documentation or other materials provided with the distribution.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND
+ * WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
+ * LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <bfd.h>
+
+/*
+ * Generate instrumentation calls for entry and exit to functions.
+ * Just after function entry and just before function exit, the
+ * following profiling functions are called with the address of the
+ * current function and its call site (currently not use).
+ *
+ * The attribute 'no_instrument_function' causes this instrumentation is
+ * not done.
+ *
+ * These profiling functions call print_debug(). This function prints the
+ * current function name with indentation and call level.
+ * If entering in a function it prints also the calling function name with
+ * file name and line number.
+ *
+ * To configure the printing of only the global functions names:
+ * $ make instrument_global
+ *
+ * To go back to print all the functions names:
+ * $ make instrument_all
+ *
+ * To print nothing, like with no instrumentation:
+ * $ make instrument_off
+ */
+
+#define ND_NO_INSTRUMENT __attribute__((no_instrument_function))
+
+/* Store the function call level, used also in pretty_print_packet() */
+extern int profile_func_level;
+int profile_func_level = -1;
+
+typedef enum {
+	ENTER,
+	EXIT
+} action_type;
+
+void __cyg_profile_func_enter(void *this_fn, void *call_site) ND_NO_INSTRUMENT;
+
+void __cyg_profile_func_exit(void *this_fn, void *call_site) ND_NO_INSTRUMENT;
+
+static void print_debug(void *this_fn, void *call_site, action_type action)
+	ND_NO_INSTRUMENT;
+
+void
+__cyg_profile_func_enter(void *this_fn, void *call_site)
+{
+	print_debug(this_fn, call_site, ENTER);
+}
+
+void
+__cyg_profile_func_exit(void *this_fn, void *call_site)
+{
+	print_debug(this_fn, call_site, EXIT);
+}
+
+/* If this file exists, print only the global functions */
+#define ND_FILE_FLAG_GLOBAL "instrument_functions_global.devel"
+
+/* If this file exists, print nothing, like with no instrumentation */
+#define ND_FILE_FLAG_OFF "instrument_functions_off.devel"
+
+static void print_debug(void *this_fn, void *call_site, action_type action)
+{
+	static bfd* abfd;
+	static asymbol **symtab;
+	static long symcount;
+	static asection *text;
+	static bfd_vma vma;
+	static int instrument_off;
+	static int print_only_global;
+	symbol_info syminfo;
+	struct stat statbuf;
+	int i;
+
+	if (!instrument_off) {
+		/* one-time test */
+		if (!stat(ND_FILE_FLAG_OFF, &statbuf)) {
+			instrument_off = 1;
+			return;
+		}
+	} else
+		return;
+
+	/* If no errors, this block should be executed one time */
+	if (!abfd) {
+		char pgm_name[1024];
+		long symsize;
+
+		if (!stat(ND_FILE_FLAG_GLOBAL, &statbuf))
+			print_only_global = 1;
+
+		ssize_t ret = readlink("/proc/self/exe", pgm_name, sizeof(pgm_name));
+		if (ret == -1) {
+			perror("failed to find executable\n");
+			return;
+		}
+		pgm_name[ret] = 0;
+
+		bfd_init();
+
+		abfd = bfd_openr(pgm_name, NULL);
+		if (!abfd) {
+			bfd_perror("bfd_openr");
+			return;
+		}
+
+		if (!bfd_check_format(abfd, bfd_object)) {
+			bfd_perror("bfd_check_format");
+			return;
+		}
+
+		if((symsize = bfd_get_symtab_upper_bound(abfd)) == -1) {
+			bfd_perror("bfd_get_symtab_upper_bound");
+			return;
+		}
+
+		symtab = (asymbol **)malloc(symsize);
+		symcount = bfd_canonicalize_symtab(abfd, symtab);
+		if (symcount < 0) {
+			free (symtab);
+			bfd_perror ("bfd_canonicalize_symtab");
+			return;
+		}
+
+		if ((text = bfd_get_section_by_name(abfd, ".text")) == NULL) {
+			bfd_perror("bfd_get_section_by_name");
+			return;
+		}
+		vma = text->vma;
+	}
+
+	if (print_only_global) {
+		int found;
+
+		i = 0;
+		found = 0;
+		while (i < symcount && !found) {
+			bfd_get_symbol_info(abfd, symtab[i], &syminfo);
+			if ((void *)syminfo.value == this_fn) {
+				found = 1;
+			}
+			i++;
+		}
+		/* type == 'T' for a global function */
+		if (found == 1 && syminfo.type != 'T')
+			return;
+	}
+
+	/* Current function */
+	if ((bfd_vma)this_fn < vma) {
+		printf("[ERROR address this_fn]");
+	} else {
+		const char *file;
+		const char *func;
+		unsigned int line;
+
+		if (!bfd_find_nearest_line(abfd, text, symtab, (bfd_vma)this_fn - vma,
+								   &file, &func, &line)) {
+			printf("[ERROR bfd_find_nearest_line this_fn]");
+		} else {
+			if (action == ENTER)
+				profile_func_level += 1;
+			/* Indentation */
+			for (i = 0 ; i < profile_func_level ; i++)
+				putchar(' ');
+			if (action == ENTER)
+				printf("[>> ");
+			else
+				printf("[<< ");
+			/* Function name */
+			if (func == NULL || *func == '\0')
+				printf("???");
+			else
+				printf("%s", func);
+			printf(" (%d)", profile_func_level);
+			/* Print the "from" part except for the main function) */
+			if (action == ENTER && strncmp(func, "main", sizeof("main"))) {
+				/* Calling function */
+				if ((bfd_vma)call_site < vma) {
+					printf("[ERROR address call_site]");
+				} else {
+					if (!bfd_find_nearest_line(abfd, text, symtab,
+											   (bfd_vma)call_site - vma, &file,
+											   &func, &line)) {
+						printf("[ERROR bfd_find_nearest_line call_site]");
+					} else {
+						printf(" from ");
+						/* Function name */
+						if (func == NULL || *func == '\0')
+							printf("???");
+						else
+							printf("%s", func);
+						/* File name */
+						if (file == NULL || *file == '\0')
+							printf(" ??:");
+						else {
+							char *slashp = strrchr(file, '/');
+							if (slashp != NULL)
+								file = slashp + 1;
+							printf(" %s:", file);
+						}
+						/* Line number */
+						if (line == 0)
+							printf("?");
+						else
+							printf("%u", line);
+						printf("]");
+					}
+				}
+			}
+			putchar('\n');
+			if (action == EXIT)
+				profile_func_level -= 1;
+		}
+	}
+	fflush(stdout);
+}
+
+/* vi: set tabstop=4 softtabstop=0 shiftwidth=4 smarttab autoindent : */