Re: [RFC PATCH v1] powerpc: Enable KFENCE for PPC32

Christophe Leroy
2021-03-04T14:10:42Z

Le 04/03/2021 à 13:48, Marco Elver a écrit :
> From d118080eb9552073f5dcf1f86198f3d86d5ea850 Mon Sep 17 00:00:00 2001
> From: Marco Elver <elver@google.com>
> Date: Thu, 4 Mar 2021 13:15:51 +0100
> Subject: [PATCH] kfence: fix reports if constant function prefixes exist
>
> Some architectures prefix all functions with a constant string ('.' on
> ppc64). Add ARCH_FUNC_PREFIX, which may optionally be defined in
> <asm/kfence.h>, so that get_stack_skipnr() can work properly.

It works, thanks.

>
> Link: https://lkml.kernel.org/r/f036c53d-7e81-763c-47f4-6024c6c5f058@csgroup.eu
> Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> Signed-off-by: Marco Elver <elver@google.com>

Tested-by: Christophe Leroy <christophe.leroy@csgroup.eu>

> ---
> mm/kfence/report.c | 18 ++++++++++++------
> 1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/mm/kfence/report.c b/mm/kfence/report.c
> index 519f037720f5..e3f71451ad9e 100644
> --- a/mm/kfence/report.c
> +++ b/mm/kfence/report.c
> @@ -20,6 +20,11 @@
>
> #include "kfence.h"
>
> +/* May be overridden by <asm/kfence.h>. */
> +#ifndef ARCH_FUNC_PREFIX
> +#define ARCH_FUNC_PREFIX ""
> +#endif
> +
> extern bool no_hash_pointers;
>
> /* Helper function to either print to a seq_file or to console. */
> @@ -67,8 +72,9 @@ static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries
> for (skipnr = 0; skipnr < num_entries; skipnr++) {
> int len = scnprintf(buf, sizeof(buf), "%ps", (void *)stack_entries[skipnr]);
>
> - if (str_has_prefix(buf, "kfence_") || str_has_prefix(buf, "__kfence_") ||
> - !strncmp(buf, "__slab_free", len)) {
> + if (str_has_prefix(buf, ARCH_FUNC_PREFIX "kfence_") ||
> + str_has_prefix(buf, ARCH_FUNC_PREFIX "__kfence_") ||
> + !strncmp(buf, ARCH_FUNC_PREFIX "__slab_free", len)) {
> /*
> * In case of tail calls from any of the below
> * to any of the above.
> @@ -77,10 +83,10 @@ static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries
> }
>
> /* Also the *_bulk() variants by only checking prefixes. */
> - if (str_has_prefix(buf, "kfree") ||
> - str_has_prefix(buf, "kmem_cache_free") ||
> - str_has_prefix(buf, "__kmalloc") ||
> - str_has_prefix(buf, "kmem_cache_alloc"))
> + if (str_has_prefix(buf, ARCH_FUNC_PREFIX "kfree") ||
> + str_has_prefix(buf, ARCH_FUNC_PREFIX "kmem_cache_free") ||
> + str_has_prefix(buf, ARCH_FUNC_PREFIX "__kmalloc") ||
> + str_has_prefix(buf, ARCH_FUNC_PREFIX "kmem_cache_alloc"))
> goto found;
> }
> if (fallback < num_entries)
>