Re: [Qemu-devel] [Qemu-arm] [PATCH for-4.1] target/arm: Stop using variable length array in dc_zva

[Philippe Mathieu-Daudé]

Le jeu. 28 mars 2019 15:30, Peter Maydell <address@hidden> a
écrit :

> Currently the dc_zva helper function uses a variable length
> array. In fact we know (as the comment above remarks) that
> the length of this array is bounded because the architecture
> limits the block size and QEMU limits the target page size.
> Use a fixed array size and assert that we don't run off it.
>
> Signed-off-by: Peter Maydell <address@hidden>
> ---
> A small move in the direction of "avoid using variable length
> arrays in QEMU"...
>
>  target/arm/helper.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index a36f4b3d699..1b6225cb598 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -1,4 +1,5 @@
>  #include "qemu/osdep.h"
> +#include "qemu/units.h"
>  #include "target/arm/idau.h"
>  #include "trace.h"
>  #include "cpu.h"
> @@ -12412,11 +12413,13 @@ void HELPER(dc_zva)(CPUARMState *env, uint64_t
> vaddr_in)
>           * same QEMU executable.
>           */
>          int maxidx = DIV_ROUND_UP(blocklen, TARGET_PAGE_SIZE);
> -        void *hostaddr[maxidx];
> +        void *hostaddr[DIV_ROUND_UP(2 * KiB, 1 << TARGET_PAGE_BITS_MIN)];
>

Or g_new()... For 2K nowadays that is fine.

Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

         int try, i;
>          unsigned mmu_idx = cpu_mmu_index(env, false);
>          TCGMemOpIdx oi = make_memop_idx(MO_UB, mmu_idx);
>
> +        assert(maxidx <= sizeof(hostaddr));
> +
>          for (try = 0; try < 2; try++) {
>
>              for (i = 0; i < maxidx; i++) {
> --
> 2.20.1
>
>
>