From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Daniel Walker <danielwa@cisco.com>,
linuxppc-dev@lists.ozlabs.org, x86@kernel.org,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, xe-linux-external@cisco.com
Subject: Re: [PATCH 1/3] lib: early_string: allow early usage of some string functions
Date: Fri, 30 Apr 2021 10:47:39 +0200 [thread overview]
Message-ID: <dc26a67e-dba0-1b8c-3718-3c75415c61f1@csgroup.eu> (raw)
In-Reply-To: <20210430042217.1198052-1-danielwa@cisco.com>
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
> +
next prev parent reply other threads:[~2021-04-30 8:48 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-30 4:22 [PATCH 1/3] lib: early_string: allow early usage of some string functions Daniel Walker
2021-04-30 4:22 ` [PATCH 2/3] powerpc: prom_init: switch to early " Daniel Walker
2021-04-30 8:51 ` Christophe Leroy
2021-04-30 4:22 ` [PATCH 3/3] x86: switch amd mem encrypt " Daniel Walker
2021-04-30 8:47 ` Christophe Leroy [this message]
2021-04-30 8:50 ` [PATCH 1/3] lib: early_string: allow early usage of some " Christophe Leroy
2021-05-01 7:31 ` Christophe Leroy
2021-05-03 18:01 ` Daniel Walker
2021-05-03 18:06 ` Daniel Walker
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