lkml.org 
[lkml]   [2021]   [Apr]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 1/3] lib: early_string: allow early usage of some string functions
From
Date


Le 30/04/2021 à 06:22, Daniel Walker a écrit :
> This systems allows some string functions to be moved into
> lib/early_string.c and they will be prepended with "early_" and compiled
> without debugging like KASAN.
>
> This is already done on x86 for,
> "AMD Secure Memory Encryption (SME) support"
>
> and on powerpc prom_init.c , and EFI's libstub.
>
> The AMD memory feature disabled KASAN for all string functions, and
> prom_init.c and efi libstub implement their own versions of the
> functions.
>
> This implementation allows sharing of the string functions without
> removing the debugging features for the whole system.

This looks good. I prefer that rather than the way you proposed to do it two years ago.

Only one problem, see below.

> +size_t strlcat(char *dest, const char *src, size_t count)
> +{
> + size_t dsize = strlen(dest);
> + size_t len = strlen(src);
> + size_t res = dsize + len;
> +
> + /* This would be a bug */
> + BUG_ON(dsize >= count);

powerpc is not ready to handle BUG_ON() in when in prom_init.

Can you do:

#ifndef __EARLY_STRING_ENABLED
BUG_ON(dsize >= count);
#endif


> +
> + dest += dsize;
> + count -= dsize;
> + if (len >= count)
> + len = count-1;
> + memcpy(dest, src, len);
> + dest[len] = 0;
> + return res;
> +}
> +EXPORT_SYMBOL(strlcat);
> +#endif
> +

\
 
 \ /
  Last update: 2021-04-30 10:48    [W:0.187 / U:0.208 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site