[Mesa-dev] [PATCH v2 RFC 1/1] clover: Don't crash on NULL global buffer objects.

[Jan Vesely]

On Wed, 2014-01-15 at 18:41 +0100, Francisco Jerez wrote:
> Jan Vesely <jan.vesely at rutgers.edu> writes:
> 
> > Specs say "If the argument is a buffer object, the arg_value
> > pointer can be NULL or point to a NULL value in which case a NULL
> > value will be used as the value for the argument declared as a
> > pointer to __global or __constant memory in the kernel."
> >
> > So don't crash when somebody does that.
> >
> > v2: Insert NULL into input buffer instead of buffer handle pair
> >     Fix constant_argument too
> >     Drop r600 driver changes
> >
> > Signed-off-by: Jan Vesely <jan.vesely at rutgers.edu>
> > ---
> > Hi Francisco,
> >
> Hi Jan,
> 
> > I could not find much info about how ctx.input is supposed to be used.
> > It looks like it stores begin-end intervals of parameters so NULL, NULL
> > seemed appropriate.
> >
> 
> It's just an array of bytes that is passed to the driver as input for
> the kernel.  Some suggestions more below.

Like an image of stack-passed parameters?
So inserting two NULLs produced two 0 bytes, and the only reason it
worked was because of the alignment for the next argument?

thanks,
Jan

> 
> > Is this closer to what you had in mind? This patch fixes my issue
> > even without the r600 changes.
> >
> > regards,
> > Jan
> >
> >  src/gallium/state_trackers/clover/core/kernel.cpp | 34 +++++++++++++----------
> >  1 file changed, 20 insertions(+), 14 deletions(-)
> >
> > diff --git a/src/gallium/state_trackers/clover/core/kernel.cpp b/src/gallium/state_trackers/clover/core/kernel.cpp
> > index 58780d6..d4942b3 100644
> > --- a/src/gallium/state_trackers/clover/core/kernel.cpp
> > +++ b/src/gallium/state_trackers/clover/core/kernel.cpp
> > @@ -327,16 +327,19 @@ kernel::global_argument::set(size_t size, const void *value) {
> >     if (size != sizeof(cl_mem))
> >        throw error(CL_INVALID_ARG_SIZE);
> >  
> > -   buf = &obj<buffer>(*(cl_mem *)value);
> > +   buf = pobj<buffer>(value ? *(cl_mem *)value : NULL);
> >     _set = true;
> >  }
> >  
> >  void
> >  kernel::global_argument::bind(exec_context &ctx,
> >                                const module::argument &marg) {
> > -   align(ctx.input, marg.target_align);
> 
> As null pointers have the same alignment restrictions as normal pointers,
> you should keep this line here before the 'if (buf)' conditional.
> 
> > -   ctx.g_handles.push_back(allocate(ctx.input, marg.target_size));
> > -   ctx.g_buffers.push_back(buf->resource(*ctx.q).pipe);
> > +   if (buf) {
> > +      align(ctx.input, marg.target_align);
> > +      ctx.g_handles.push_back(allocate(ctx.input, marg.target_size));
> > +      ctx.g_buffers.push_back(buf->resource(*ctx.q).pipe);
> > +   } else
> 
> For consistency use braces around the else block of an if block that
> uses braces.
> 
> > +      insert(ctx.input, {NULL, NULL});
> 
> I don't think this does what you want.  The easiest way to append zeroes
> to the input buffer is:
> 
> |    } else {
> |       // Null global pointer.
> |       allocate(ctx.input, marg.target_size);
> |    }
> 
> >  }
> >  
> >  void
> > @@ -379,22 +382,25 @@ kernel::constant_argument::set(size_t size, const void *value) {
> >     if (size != sizeof(cl_mem))
> >        throw error(CL_INVALID_ARG_SIZE);
> >  
> > -   buf = &obj<buffer>(*(cl_mem *)value);
> > +   buf = pobj<buffer>(value ? *(cl_mem *)value : NULL);
> >     _set = true;
> >  }
> >  
> >  void
> >  kernel::constant_argument::bind(exec_context &ctx,
> >                                  const module::argument &marg) {
> > -   auto v = bytes(ctx.resources.size() << 24);
> > -
> > -   extend(v, module::argument::zero_ext, marg.target_size);
> > -   byteswap(v, ctx.q->dev.endianness());
> > -   align(ctx.input, marg.target_align);
> > -   insert(ctx.input, v);
> > -
> > -   st = buf->resource(*ctx.q).bind_surface(*ctx.q, false);
> > -   ctx.resources.push_back(st);
> > +   if (buf) {
> > +      auto v = bytes(ctx.resources.size() << 24);
> > +
> > +      extend(v, module::argument::zero_ext, marg.target_size);
> > +      byteswap(v, ctx.q->dev.endianness());
> > +      align(ctx.input, marg.target_align);
> 
> This align() call should be kept outside the conditional too.
> 
> > +      insert(ctx.input, v);
> > +
> > +      st = buf->resource(*ctx.q).bind_surface(*ctx.q, false);
> > +      ctx.resources.push_back(st);
> > +   } else
> > +      insert(ctx.input, {NULL, NULL});
> 
> Same comment as before.
> 
> Thank you.
> 
> >  }
> >  
> >  void
> > -- 
> > 1.8.4.2

-- 
Jan Vesely <jan.vesely at rutgers.edu>
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