Re: [Qemu-devel] [PATCH 4/5] ARM BE32 watchpoint fix.

[Peter Maydell]

On 3 November 2016 at 17:30, Julian Brown <address@hidden> wrote:
> In BE32 mode, sub-word size watchpoints can fail to trigger because the
> address of the access is adjusted in the opcode helpers before being
> compared with the watchpoint registers.  This patch reversed the address
> adjustment before performing the comparison.
>
> Signed-off-by: Julian Brown <address@hidden>
> ---
>  exec.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
> diff --git a/exec.c b/exec.c
> index 4c84389..eadab54 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -2047,6 +2047,19 @@ static void check_watchpoint(int offset, int len, 
> MemTxAttrs attrs, int flags)
>          return;
>      }
>      vaddr = (cpu->mem_io_vaddr & TARGET_PAGE_MASK) + offset;
> +#if defined(TARGET_ARM) && !defined(CONFIG_USER_ONLY)
> +    /* In BE32 system mode, target memory is stored byteswapped (FIXME:
> +       relative to a little-endian host system), and by the time we reach 
> here
> +       (via an opcode helper) the addresses of subword accesses have been
> +       adjusted to account for that, which means that watchpoints will not
> +       match.  Undo the adjustment here.  */
> +    if (arm_sctlr_b(env)) {
> +        if (len == 1)
> +            vaddr ^= 3;
> +        else if (len == 2)
> +            vaddr ^= 2;
> +    }
> +#endif

No target-CPU specific code in exec.c, please...

thanks
-- PMM