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    Subject[PATCH mm] kfence: fix reports if constant function prefixes exist
    From
    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.

    Link: https://lkml.kernel.org/r/f036c53d-7e81-763c-47f4-6024c6c5f058@csgroup.eu
    Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
    Tested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
    Signed-off-by: Marco Elver <elver@google.com>
    ---
    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)
    --
    2.30.1.766.gb4fecdf3b7-goog
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