Re: [PATCH v4 5/6] hppa: Add emulation of Artist graphics

[Sven Schnelle <svens@stackframe.org>]

Hi,

On Fri, Dec 20, 2019 at 05:36:36PM +0100, Helge Deller wrote:
> On 20.12.19 08:26, Helge Deller wrote:
> > On 19.12.19 01:28, Richard Henderson wrote:
> >> On 11/3/19 10:56 AM, Sven Schnelle wrote:
> >>> This adds emulation of Artist graphics good enough
> >>> to get a Text console on both Linux and HP-UX. The
> >>> X11 server from HP-UX also works.
> >>>
> >>> Signed-off-by: Sven Schnelle <svens@stackframe.org>
> >>> ---
> >>>  hw/display/Kconfig       |    4 +
> >>>  hw/display/Makefile.objs |    1 +
> >>>  hw/display/artist.c      | 1449 ++++++++++++++++++++++++++++++++++++++
> >>>  hw/display/trace-events  |    9 +
> >>>  hw/hppa/Kconfig          |    1 +
> >>>  hw/hppa/hppa_hardware.h  |    1 +
> >>>  hw/hppa/machine.c        |    9 +
> >>>  7 files changed, 1474 insertions(+)
> >>>  create mode 100644 hw/display/artist.c
> >>
> >> Seems to have some problems rebased upon master:
> >>
> >> ...
> >
> > Richard, the attached patch (for seabios-hppa) fixes it for me.
> > Can you test as well?
> > It fixes the sti text column to go out-of-range and thus outside the framebuffer memory.
> 
> The attached patch is even better.
> It always wraps to the next line (or scrolls the screen if necessary) if
> the end of the line has been reached.
> 
> Helge

> diff --git a/src/parisc/sti.c b/src/parisc/sti.c
> index 7935770..61e7002 100644
> --- a/src/parisc/sti.c
> +++ b/src/parisc/sti.c
> @@ -168,5 +168,10 @@ void sti_putc(const char c)
>          }
>          return;
>      }
> +
> +    /* wrap to next line or scroll screen if EOL reached */
> +    if (col >= ((sti_glob_cfg.onscreen_x / font->width) - 1))
> +	sti_putc('\n');
> +
>      sti_putchar(rom, row, col++, c);
>  }

Besides this, the root cause is the out-of-bounds check in vram_bit_write():
This fixes the crash for me. I'll resend an updated version later. Thanks for
helping debugging this issue!

diff --git a/hw/display/artist.c b/hw/display/artist.c
index 1d6c7d5d76..13c770e795 100644
--- a/hw/display/artist.c
+++ b/hw/display/artist.c
@@ -360,7 +360,7 @@ static void vram_bit_write(ARTISTState *s, int posx, int posy, bool incr_x,
         return;
     }

-    if (posy * width + posx > buf->size) {
+    if (posy * width + posx >= buf->size) {
         qemu_log("write outside bounds: wants %dx%d, max size %dx%d\n",
                 posx, posy, width, height);
         return;

Regards
Sven