Re: [RFC] ARM binutils feature churn causing kernel problems

[Russell King <rmk+lkml@arm.linux.org.uk>]

On Tue, Oct 05, 2004 at 11:10:46AM +0000, Richard Earnshaw wrote:
> Rusty Russell <rusty <at> rustcorp.com.au> writes:
> > Russell, I thought about not including any symbol which is not of form
> > "[A-Za-z0-9_]+" in kallsyms, for all archs: you are not the only one
> > with weird-ass symbols.  Is it that you want these mapping symbols in
> > /proc/kallsyms but ignored in backtraces, or you don't need them in
> > kallsyms altogether?
> > 
> > Thanks,
> > Rusty.
> 
> 
> Mapping symbols will always be encoded with STB_LOCAL and STT_NOTYPE.
> I would have thought it unlikely that the kernel would ever want to
> report against any symbol with those attributes and they could all
> be dropped on that basis.

(Richard - your mailer appears to have dropped people from the CC: list...)

How about this patch?  Is there a better way to parse the 'nm' output
to achieve the same as your suggestion above?

diff -up -x BitKeeper -x ChangeSet -x SCCS -x _xlk -x *.orig -x *.rej orig/kernel/module.c linux/kernel/module.c
--- orig/kernel/module.c	Wed Sep 22 16:07:38 2004
+++ linux/kernel/module.c	Tue Oct  5 12:46:01 2004
@@ -1923,6 +1923,10 @@ static const char *get_ksymbol(struct mo
 		if (mod->symtab[i].st_shndx == SHN_UNDEF)
 			continue;
 
+		if (ELF_ST_BIND(mod->symtab[i].st_info) == STB_LOCAL
+		    && ELF_ST_TYPE(mod->symtab[i].st_info) == STT_NOTYPE)
+			continue;
+
 		/* We ignore unnamed symbols: they're uninformative
 		 * and inserted at a whim. */
 		if (mod->symtab[i].st_value <= addr
diff -up -x BitKeeper -x ChangeSet -x SCCS -x _xlk -x *.orig -x *.rej orig/scripts/kallsyms.c linux/scripts/kallsyms.c
--- orig/scripts/kallsyms.c	Sun Jul 11 22:56:39 2004
+++ linux/scripts/kallsyms.c	Tue Oct  5 12:51:26 2004
@@ -32,6 +32,17 @@ usage(void)
 	exit(1);
 }
 
+/*
+ * This ignores the intensely annoying "mapping symbols" found
+ * in ARM ELF files: $a, $t and $d.
+ */
+static inline int
+is_arm_mapping_symbol(const char *str)
+{
+	return str[0] == '$' && strchr("atd", str[1]) &&
+	       (str[2] == '\0' || str[2] == '.');
+}
+
 static int
 read_symbol(FILE *in, struct sym_entry *s)
 {
@@ -56,7 +67,8 @@ read_symbol(FILE *in, struct sym_entry *
 		_sinittext = s->addr;
 	else if (strcmp(str, "_einittext") == 0)
 		_einittext = s->addr;
-	else if (toupper(s->type) == 'A' || toupper(s->type) == 'U')
+	else if (toupper(s->type) == 'A' || toupper(s->type) == 'U' ||
+		 is_arm_mapping_symbol(str))
 		return -1;
 
 	s->sym = strdup(str);

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core