[v2] accel/tcg: Introduce tlb_fill_align hook

[PATCH v2 01/21] accel/tcg: Assert noreturn from write-only page for atomics

Posted by Richard Henderson 1 month, 2 weeks ago

There should be no "just in case"; the page is already
in the tlb, and known to be not readable.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 accel/tcg/cputlb.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index 117b516739..fd6459b695 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -1852,10 +1852,9 @@ static void *atomic_mmu_lookup(CPUState *cpu, vaddr addr, MemOpIdx oi,
         /*
          * Since we don't support reads and writes to different
          * addresses, and we do have the proper page loaded for
-         * write, this shouldn't ever return.  But just in case,
-         * handle via stop-the-world.
+         * write, this shouldn't ever return.
          */
-        goto stop_the_world;
+        g_assert_not_reached();
     }
     /* Collect tlb flags for read. */
     tlb_addr |= tlbe->addr_read;
-- 
2.43.0

Re: [PATCH v2 01/21] accel/tcg: Assert noreturn from write-only page for atomics

Posted by Peter Maydell 1 month, 2 weeks ago

On Sat, 5 Oct 2024 at 21:06, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> There should be no "just in case"; the page is already
> in the tlb, and known to be not readable.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  accel/tcg/cputlb.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
> index 117b516739..fd6459b695 100644
> --- a/accel/tcg/cputlb.c
> +++ b/accel/tcg/cputlb.c
> @@ -1852,10 +1852,9 @@ static void *atomic_mmu_lookup(CPUState *cpu, vaddr addr, MemOpIdx oi,
>          /*
>           * Since we don't support reads and writes to different
>           * addresses, and we do have the proper page loaded for
> -         * write, this shouldn't ever return.  But just in case,
> -         * handle via stop-the-world.
> +         * write, this shouldn't ever return.
>           */
> -        goto stop_the_world;
> +        g_assert_not_reached();
>      }
>      /* Collect tlb flags for read. */
>      tlb_addr |= tlbe->addr_read;

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM

Re: [PATCH v2 01/21] accel/tcg: Assert noreturn from write-only page for atomics

Posted by Helge Deller 1 month, 2 weeks ago

On 10/5/24 22:05, Richard Henderson wrote:
> There should be no "just in case"; the page is already
> in the tlb, and known to be not readable.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Helge Deller <deller@gmx.de>

> ---
>   accel/tcg/cputlb.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
> index 117b516739..fd6459b695 100644
> --- a/accel/tcg/cputlb.c
> +++ b/accel/tcg/cputlb.c
> @@ -1852,10 +1852,9 @@ static void *atomic_mmu_lookup(CPUState *cpu, vaddr addr, MemOpIdx oi,
>           /*
>            * Since we don't support reads and writes to different
>            * addresses, and we do have the proper page loaded for
> -         * write, this shouldn't ever return.  But just in case,
> -         * handle via stop-the-world.
> +         * write, this shouldn't ever return.
>            */
> -        goto stop_the_world;
> +        g_assert_not_reached();
>       }
>       /* Collect tlb flags for read. */
>       tlb_addr |= tlbe->addr_read;