Re: [PATCH] Fix ARM kernel build with permitted binutils versions

[Sam Ravnborg <sam@ravnborg.org>]

On Wed, Oct 20, 2004 at 12:38:53PM +0100, Russell King wrote:
> Ok, here's the latest version of the patch, fixing all presently known
> issues with ARM binutils post 2.11.90 by changing the kernel to suit.
> 
> Yes, it sounds like the wrong thing to do, but shrug.
> 
> ---
> 
> All ARM binutils versions post 2.11.90 contains an extra "feature" which
> interferes with the kernel in various ways - extra "mapping symbols"
> in the ELF symbol table '$a', '$t' and '$d'.  This causes two problems:
> 
> 1. Since '$a' symbols have the same value as function names, this
>    causes anything which uses the kallsyms infrastructure to report
>    wrong values.
> 2. programs which parse System.map do not expect symbols to start with
>    '$'.
> 
> Signed-off-by: Russell King <rmk@arm.linux.org.uk>

Applied to my tree. Will send onwards to Linus soon.

	Sam
> 
> ===== kernel/module.c 1.120 vs edited =====
> --- 1.120/kernel/module.c	2004-09-08 07:33:04 +01:00
> +++ edited/kernel/module.c	2004-10-08 16:34:19 +01:00
> @@ -1903,6 +1903,16 @@
>  }
>  
>  #ifdef CONFIG_KALLSYMS
> +/*
> + * 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 const char *get_ksymbol(struct module *mod,
>  			       unsigned long addr,
>  			       unsigned long *size,
> @@ -1927,11 +1937,13 @@
>  		 * and inserted at a whim. */
>  		if (mod->symtab[i].st_value <= addr
>  		    && mod->symtab[i].st_value > mod->symtab[best].st_value
> -		    && *(mod->strtab + mod->symtab[i].st_name) != '\0' )
> +		    && *(mod->strtab + mod->symtab[i].st_name) != '\0'
> +		    && !is_arm_mapping_symbol(mod->strtab + mod->symtab[i].st_name))
>  			best = i;
>  		if (mod->symtab[i].st_value > addr
>  		    && mod->symtab[i].st_value < nextval
> -		    && *(mod->strtab + mod->symtab[i].st_name) != '\0')
> +		    && *(mod->strtab + mod->symtab[i].st_name) != '\0'
> +		    && !is_arm_mapping_symbol(mod->strtab + mod->symtab[i].st_name))
>  			nextval = mod->symtab[i].st_value;
>  	}
>  
> ===== scripts/kallsyms.c 1.12 vs edited =====
> --- 1.12/scripts/kallsyms.c	2004-07-11 10:23:27 +01:00
> +++ edited/scripts/kallsyms.c	2004-10-08 16:34:20 +01:00
> @@ -32,6 +32,17 @@
>  	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 @@
>  		_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);
> ===== scripts/mksysmap 1.4 vs edited =====
> --- 1.4/scripts/mksysmap	2004-08-18 22:05:12 +01:00
> +++ edited/scripts/mksysmap	2004-10-08 16:39:39 +01:00
> @@ -40,5 +40,5 @@
>  # so we just ignore them to let readprofile continue to work.
>  # (At least sparc64 has __crc_ in the middle).
>  
> -$NM -n $1 | grep -v '\( [aUw] \)\|\(__crc_\)' > $2
> +$NM -n $1 | grep -v '\( [aUw] \)\|\(__crc_\)\|\( \$[adt]\)' > $2
>  
> 
> -- 
> 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