Re: [PATCH] [PATCH] linux-user/aarch64: Reset target data on MADV_DONTNEED

[Richard Henderson]

On 7/12/22 03:30, Vitaly Buka wrote:
> aarch64 stores MTE tags in target_date, and they should be reset by
> MADV_DONTNEED.
>
> Signed-off-by: Vitaly Buka <vitalybuka@google.com>
> ---
>   accel/tcg/translate-all.c | 24 ++++++++++++++++++++++++
>   include/exec/cpu-all.h    |  1 +
>   linux-user/mmap.c         |  2 ++
>   3 files changed, 27 insertions(+)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

> diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
> index ef62a199c7..d6f2f1a40a 100644
> --- a/accel/tcg/translate-all.c
> +++ b/accel/tcg/translate-all.c
> @@ -2314,6 +2314,30 @@ void page_set_flags(target_ulong start, target_ulong 
> end, int flags)
>       }
>   }
>   
> +void page_reset_target_data(target_ulong start, target_ulong end)
> +{
> +    target_ulong addr, len;
> +
> +    /* This function should never be called with addresses outside the
> +       guest address space.  If this assert fires, it probably indicates
> +       a missing call to h2g_valid.  */
> +    assert(end - 1 <= GUEST_ADDR_MAX);
> +    assert(start < end);
> +    assert_memory_lock();
> +
> +    start = start & TARGET_PAGE_MASK;
> +    end = TARGET_PAGE_ALIGN(end);
> +
> +    for (addr = start, len = end - start;
> +         len != 0;
> +         len -= TARGET_PAGE_SIZE, addr += TARGET_PAGE_SIZE) {
> +        PageDesc *p = page_find_alloc(addr >> TARGET_PAGE_BITS, 1);
> +
> +        g_free(p->target_data);
> +        p->target_data = NULL;
> +    }
> +}
> +
>   void *page_get_target_data(target_ulong address)
>   {
>       PageDesc *p = page_find(address >> TARGET_PAGE_BITS);
> diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
> index f5bda2c3ca..491629b9ba 100644
> --- a/include/exec/cpu-all.h
> +++ b/include/exec/cpu-all.h
> @@ -271,6 +271,7 @@ int walk_memory_regions(void *, walk_memory_regions_fn);
>   
>   int page_get_flags(target_ulong address);
>   void page_set_flags(target_ulong start, target_ulong end, int flags);
> +void page_reset_target_data(target_ulong start, target_ulong end);
>   int page_check_range(target_ulong start, target_ulong len, int flags);
>   
>   /**
> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> index 4e7a6be6ee..c535dfdc7c 100644
> --- a/linux-user/mmap.c
> +++ b/linux-user/mmap.c
> @@ -894,6 +894,8 @@ abi_long target_madvise(abi_ulong start, abi_ulong len_in, 
> int advice)
>       if ((advice & MADV_DONTNEED) &&
>           can_passthrough_madv_dontneed(start, end)) {
>           ret = get_errno(madvise(g2h_untagged(start), len, MADV_DONTNEED));
> +        if (ret == 0)
> +            page_reset_target_data(start, start + len);
>       }
>       mmap_unlock();
>