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Message-ID: <CACT4Y+YcQH2mKv3y15XkWa-tKvyhRQHAw5dLVoAkFRWgFMLq1w@mail.gmail.com>
Date: Wed, 28 Oct 2020 12:05:21 +0100
From: Dmitry Vyukov <dvyukov@...gle.com>
To: Andrey Konovalov <andreyknvl@...gle.com>
Cc: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Vincenzo Frascino <vincenzo.frascino@....com>,
Alexander Potapenko <glider@...gle.com>,
Marco Elver <elver@...gle.com>,
Evgenii Stepanov <eugenis@...gle.com>,
Kostya Serebryany <kcc@...gle.com>,
Peter Collingbourne <pcc@...gle.com>,
Serban Constantinescu <serbanc@...gle.com>,
Andrey Ryabinin <aryabinin@...tuozzo.com>,
Elena Petrova <lenaptr@...gle.com>,
Branislav Rankov <Branislav.Rankov@....com>,
Kevin Brodsky <kevin.brodsky@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
kasan-dev <kasan-dev@...glegroups.com>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
Linux-MM <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC v2 09/21] kasan: inline kasan_reset_tag for tag-based modes
On Thu, Oct 22, 2020 at 3:19 PM Andrey Konovalov <andreyknvl@...gle.com> wrote:
>
> Using kasan_reset_tag() currently results in a function call. As it's
> called quite often from the allocator code this leads to a noticeable
> slowdown. Move it to include/linux/kasan.h and turn it into a static
> inline function.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
> Link: https://linux-review.googlesource.com/id/I4d2061acfe91d480a75df00b07c22d8494ef14b5
> ---
> include/linux/kasan.h | 5 ++++-
> mm/kasan/hw_tags.c | 5 -----
> mm/kasan/kasan.h | 6 ++----
> mm/kasan/sw_tags.c | 5 -----
> 4 files changed, 6 insertions(+), 15 deletions(-)
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 93d9834b7122..6377d7d3a951 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -187,7 +187,10 @@ static inline void kasan_record_aux_stack(void *ptr) {}
>
> void __init kasan_init_tags(void);
>
> -void *kasan_reset_tag(const void *addr);
> +static inline void *kasan_reset_tag(const void *addr)
> +{
> + return (void *)arch_kasan_reset_tag(addr);
It seems that all implementations already return (void *), so the cast
is not needed.
> +}
>
> bool kasan_report(unsigned long addr, size_t size,
> bool is_write, unsigned long ip);
> diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
> index b372421258c8..c3a0e83b5e7a 100644
> --- a/mm/kasan/hw_tags.c
> +++ b/mm/kasan/hw_tags.c
> @@ -24,11 +24,6 @@ void __init kasan_init_tags(void)
> pr_info("KernelAddressSanitizer initialized\n");
> }
>
> -void *kasan_reset_tag(const void *addr)
> -{
> - return reset_tag(addr);
> -}
> -
> void kasan_poison_memory(const void *address, size_t size, u8 value)
> {
> set_mem_tag_range(reset_tag(address),
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 456b264e5124..0ccbb3c4c519 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -246,15 +246,13 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
> return addr;
> }
> #endif
> -#ifndef arch_kasan_reset_tag
> -#define arch_kasan_reset_tag(addr) ((void *)(addr))
> -#endif
> #ifndef arch_kasan_get_tag
> #define arch_kasan_get_tag(addr) 0
> #endif
>
> +/* kasan_reset_tag() defined in include/linux/kasan.h. */
> +#define reset_tag(addr) ((void *)kasan_reset_tag(addr))
The cast is not needed.
I would also now remove reset_tag entirely by replacing it with
kasan_reset_tag. Having 2 names for the same thing does not add
clarity.
> #define set_tag(addr, tag) ((void *)arch_kasan_set_tag((addr), (tag)))
> -#define reset_tag(addr) ((void *)arch_kasan_reset_tag(addr))
> #define get_tag(addr) arch_kasan_get_tag(addr)
>
> #ifndef arch_init_tags
> diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c
> index 099af6dc8f7e..4db41f274702 100644
> --- a/mm/kasan/sw_tags.c
> +++ b/mm/kasan/sw_tags.c
> @@ -67,11 +67,6 @@ u8 random_tag(void)
> return (u8)(state % (KASAN_TAG_MAX + 1));
> }
>
> -void *kasan_reset_tag(const void *addr)
> -{
> - return reset_tag(addr);
> -}
> -
> bool check_memory_region(unsigned long addr, size_t size, bool write,
> unsigned long ret_ip)
> {
> --
> 2.29.0.rc1.297.gfa9743e501-goog
>
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