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From: Rusty Russell <rusty@rustcorp.com.au>
To: Zwane Mwaikambo <zwane@holomorphy.com>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [BUG][2.5.50] kallsyms dies badly with module 
In-reply-to: Your message of "Fri, 29 Nov 2002 11:17:24 CDT."
             <Pine.LNX.4.50.0211291105440.14410-100000@montezuma.mastecende.com> 
Date: Mon, 02 Dec 2002 12:49:35 +1100
Message-Id: <20021202015750.C49922C0B2@lists.samba.org>
Sender: linux-kernel-owner@vger.kernel.org
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In message <Pine.LNX.4.50.0211291105440.14410-100000@montezuma.mastecende.com> 
you write:
> Hi Rusty,
> 	If kallsyms_lookup tries to get a symbol from tiglusb.c loaded as
> a module it oopses.

Yes, see kallsyms fix patch (attached for your convenience).  I was
keeping the wrong module section 8(

Hope this helps,
Rusty.
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.

Name: Kallsyms inside module fix
Author: Rusty Russell
Status: Tested on 2.5.50

D: Two fixes.  Firstly, set ALLOC on the right section so we actually
D: keep the symbol names and don't deref a freed section, and secondly
D: get the symbol size (more) correct.

diff -urNp --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.50/kernel/module.c working-2.5.50-ksymoops/kernel/module.c
--- linux-2.5.50/kernel/module.c	Mon Nov 25 08:44:19 2002
+++ working-2.5.50-ksymoops/kernel/module.c	Thu Nov 28 16:22:56 2002
@@ -892,7 +892,7 @@ static struct module *load_module(void *
 		}
 #ifdef CONFIG_KALLSYMS
 		/* symbol and string tables for decoding later. */
-		if (sechdrs[i].sh_type == SHT_SYMTAB || i == hdr->e_shstrndx)
+		if (sechdrs[i].sh_type == SHT_SYMTAB || i == strindex)
 			sechdrs[i].sh_flags |= SHF_ALLOC;
 #endif
 #ifndef CONFIG_MODULE_UNLOAD
@@ -1165,7 +1165,14 @@ static const char *get_ksymbol(struct mo
 			       unsigned long *size,
 			       unsigned long *offset)
 {
-	unsigned int i, next = 0, best = 0;
+	unsigned int i, best = 0;
+	unsigned long nextval;
+
+	/* At worse, next value is at end of module */
+	if (inside_core(mod, addr))
+		nextval = (unsigned long)mod->module_core+mod->core_size;
+	else 
+		nextval = (unsigned long)mod->module_init+mod->init_size;
 
 	/* Scan for closest preceeding symbol, and next symbol. (ELF
            starts real symbols at 1). */
@@ -1177,22 +1186,14 @@ static const char *get_ksymbol(struct mo
 		    && mod->symtab[i].st_value > mod->symtab[best].st_value)
 			best = i;
 		if (mod->symtab[i].st_value > addr
-		    && mod->symtab[i].st_value < mod->symtab[next].st_value)
-			next = i;
+		    && mod->symtab[i].st_value < nextval)
+			nextval = mod->symtab[i].st_value;
 	}
 
 	if (!best)
 		return NULL;
 
-	if (!next) {
-		/* Last symbol?  It ends at the end of the module then. */
-		if (inside_core(mod, addr))
-			*size = mod->module_core+mod->core_size - (void*)addr;
-		else
-			*size = mod->module_init+mod->init_size - (void*)addr;
-	} else
-		*size = mod->symtab[next].st_value - addr;
-
+	*size = nextval - mod->symtab[best].st_value;
 	*offset = addr - mod->symtab[best].st_value;
 	return mod->strtab + mod->symtab[best].st_name;
 }
-
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