[Mesa-dev] [Intel-gfx] [PATCH 03/11] i965: copy in system routine, reserve extra scratch

Eric Anholt eric at anholt.net
Fri Jun 24 17:37:11 PDT 2011


On Fri, 24 Jun 2011 12:42:48 -0700, Ben Widawsky <ben at bwidawsk.net> wrote:
> The debugger shared memory needs to be a fixed size. Since this is
> scratch memory that is already used by register spilling, add
> appropriate hooks to do the right thing when debugging.
> 
> Also copy in a binary blob system routine based on an environment
> variable. This blob will need to be relocated, and emitted as part of
> the state setup. We do this part now since there is no point debugging
> if that fails.
> 
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>

This patch loads a file from a user-defined path into graphics memory,
which is accessible by any user with DRI permissions.  If the X Server
is setuid, then it seems this patch would allow loading any file on the
system by a user with permission to start the setuid X Server.

> ---
>  src/mesa/drivers/dri/i965/brw_context.c  |   11 +++++
>  src/mesa/drivers/dri/i965/brw_context.h  |    4 ++
>  src/mesa/drivers/dri/i965/brw_wm.c       |   38 +++++++++-------
>  src/mesa/drivers/dri/i965/brw_wm.h       |    2 +
>  src/mesa/drivers/dri/i965/brw_wm_debug.c |   69 ++++++++++++++++++++++++++++++
>  5 files changed, 107 insertions(+), 17 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
> index d6a99ab..b40771b 100644
> --- a/src/mesa/drivers/dri/i965/brw_context.c
> +++ b/src/mesa/drivers/dri/i965/brw_context.c
> @@ -230,6 +230,17 @@ GLboolean brwCreateContext( int api,
>        brw->wm_max_threads = 1;
>     }
>  
> +   if (getenv("INTEL_SHADER_DEBUG") &&
> +      (!strncmp("wm", getenv("INTEL_SHADER_DEBUG"), 2))) {
> +      char *sr_path;
> +      if ((sr_path = getenv("INTEL_SYSTEM_ROUTINE_PATH"))) {
> +         brw_wm_init_debug( brw, (const char *)sr_path );

(you shouldn't need to cast from char * to const char *)

> +      } else {
> +	 fprintf(stderr, "please add INTEL_SYSTEM_ROUTINE_PATH "
> +			 "environment variable\n");
> +      }
> +   }
> +
>     brw_init_state( brw );
>  
>     brw->curbe.last_buf = calloc(1, 4096);
> diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
> index 621b6f8..1557a7a 100644
> --- a/src/mesa/drivers/dri/i965/brw_context.h
> +++ b/src/mesa/drivers/dri/i965/brw_context.h
> @@ -713,6 +713,10 @@ struct brw_context
>         * Pre-gen6, push constants live in the CURBE.
>         */
>        uint32_t push_const_offset;
> +
> +      /** Debug the wm shaders with the system routine */
> +      GLboolean debugging;

We spell this "bool" these days.

> +      drm_intel_bo *system_routine;
>     } wm;


>  
>  
> diff --git a/src/mesa/drivers/dri/i965/brw_wm.c b/src/mesa/drivers/dri/i965/brw_wm.c
> index 1aebd12..8d9976c 100644
> --- a/src/mesa/drivers/dri/i965/brw_wm.c
> +++ b/src/mesa/drivers/dri/i965/brw_wm.c
> @@ -194,6 +194,7 @@ bool do_wm_prog(struct brw_context *brw,
>     struct brw_wm_compile *c;
>     const GLuint *program;
>     GLuint program_size;
> +   uint32_t total_scratch = 0;
>  
>     c = brw->wm.compile_data;
>     if (c == NULL) {
> @@ -239,30 +240,33 @@ bool do_wm_prog(struct brw_context *brw,
>        c->prog_data.dispatch_width = 16;
>     }
>  
> -   /* Scratch space is used for register spilling */
> -   if (c->last_scratch) {
> -      uint32_t total_scratch;
> -
> -      /* Per-thread scratch space is power-of-two sized. */
> -      for (c->prog_data.total_scratch = 1024;
> -	   c->prog_data.total_scratch <= c->last_scratch;
> -	   c->prog_data.total_scratch *= 2) {
> -	 /* empty */
> -      }
> -      total_scratch = c->prog_data.total_scratch * brw->wm_max_threads;
> -
> +   /* Scratch space is used for register spilling and debugger shared memory.
> +    * Since the debugger must know the size in advance, we try for a fixed size,
> +    * and hope it's large enough
> +    */
> +   if (c->last_scratch && !brw->wm.debugging) {
> +	 /* Per-thread scratch space is power-of-two sized. */
> +	 for (c->prog_data.total_scratch = 1024;
> +	    c->prog_data.total_scratch <= c->last_scratch;
> +	    c->prog_data.total_scratch *= 2) {
> +	    /* empty */
> +	 }

Something seems to have gone wrong with your indentation here.  It looks
like there should be no diff here except for the if expression.

>        if (brw->wm.scratch_bo && total_scratch > brw->wm.scratch_bo->size) {

You stopped initializing the local total_scratch variable, though?

> -	 drm_intel_bo_unreference(brw->wm.scratch_bo);
> -	 brw->wm.scratch_bo = NULL;
> +         drm_intel_bo_unreference(brw->wm.scratch_bo);
> +         brw->wm.scratch_bo = NULL;
>        }
>        if (brw->wm.scratch_bo == NULL) {
> -	 brw->wm.scratch_bo = drm_intel_bo_alloc(intel->bufmgr,
> +         brw->wm.scratch_bo = drm_intel_bo_alloc(intel->bufmgr,
>  						 "wm scratch",
>  						 total_scratch,
>  						 4096);

More broken indentation.

>        }
> -   }
> -   else {
> +   } else if (brw->wm.debugging) {
> +      uint32_t thread_scratch = brw->wm.scratch_bo->size / brw->wm_max_threads;
> +      assert(brw->wm.scratch_bo);
> +      assert(thread_scratch / 2 >= c->last_scratch);
> +      c->prog_data.total_scratch = thread_scratch;
> +   } else {
>        c->prog_data.total_scratch = 0;
>     }
>  
> diff --git a/src/mesa/drivers/dri/i965/brw_wm.h b/src/mesa/drivers/dri/i965/brw_wm.h
> index e244b55..9e94928 100644
> --- a/src/mesa/drivers/dri/i965/brw_wm.h
> +++ b/src/mesa/drivers/dri/i965/brw_wm.h
> @@ -309,6 +309,8 @@ void brw_wm_print_insn( struct brw_wm_compile *c,
>  void brw_wm_print_program( struct brw_wm_compile *c,
>  			   const char *stage );
>  
> +void brw_wm_init_debug( struct brw_context *brw, const char *sr_path );
> +
>  void brw_wm_lookup_iz(struct intel_context *intel,
>  		      struct brw_wm_compile *c);
>  
> diff --git a/src/mesa/drivers/dri/i965/brw_wm_debug.c b/src/mesa/drivers/dri/i965/brw_wm_debug.c
> index 6a91251..41ee926 100644
> --- a/src/mesa/drivers/dri/i965/brw_wm_debug.c
> +++ b/src/mesa/drivers/dri/i965/brw_wm_debug.c
> @@ -172,3 +172,72 @@ void brw_wm_print_program( struct brw_wm_compile *c,
>     printf("\n");
>  }
>  
> +/* This define should be shared with the debugger. Not sure of the best place
> + * for it */
> +#define SCRATCH_SIZE (512 * 1024)
> +void brw_wm_init_debug( struct brw_context *brw,
> +			const char *sr_path )
> +{
> +   struct intel_context *intel = &brw->intel;
> +   struct drm_i915_gem_set_domain domain;
> +   struct brw_instruction *insn;
> +   int sr_insns, i;
> +   FILE *stream;
> +   size_t size;
> +   uint32_t name;
> +   int ret;
> +
> +   stream = fopen(sr_path, "rb");
> +   if (stream == NULL) {
> +      fprintf(stderr, "Couldn't find the system routine in %s, shader debugging"
> +	      " will be disabled\n", sr_path);
> +      brw->wm.debugging = GL_FALSE;
> +      return;
> +   }
> +
> +   /* can we use sys headers? */
> +   fseek(stream, 0, SEEK_END);
> +   sr_insns = ftell(stream) / sizeof(*insn);
> +   insn = calloc(sr_insns, sizeof(*insn));
> +   fseek(stream, 0, SEEK_SET);
> +
> +   for (i = 0; i < sr_insns; i++) {
> +      size = fread(&insn[i], sizeof(*insn), 1, stream);
> +      if (size != 1)
> +	 break;
> +   }
> +
> +   if (i != sr_insns) {
> +      fprintf(stderr, "Not all system routine bytes absorbed (%d/%d)\n",
> +		      i, sr_insns);
> +      goto done;
> +   }
> +
> +   brw->wm.system_routine = drm_intel_bo_alloc(intel->bufmgr, "system routine",
> +					       i * sizeof(*insn), 4096);
> +   drm_intel_bo_subdata(brw->wm.system_routine, 0, i * sizeof(*insn), insn);
> +
> +   /* In the debug case, we allocate the buffer now because we'll need to attach
> +    * with the debugger at a later time when flink will not work (the ring /
> +    * struct_mutex are likely to be frozen). If we make the buffer visible early
> +    * enough, the debugger can map it before the first breakpoint.
> +    */
> +   brw->wm.scratch_bo = drm_intel_bo_alloc(intel->bufmgr,
> +					   "wm scratch",
> +					   SCRATCH_SIZE * brw->wm_max_threads,
> +					   4096);
> +   assert(brw->wm.scratch_bo);
> +
> +   drm_intel_bo_map(brw->wm.scratch_bo, 0);
> +   memset(brw->wm.scratch_bo->virtual, 0xa5, SCRATCH_SIZE * brw->wm_max_threads);
> +   drm_intel_bo_unmap(brw->wm.scratch_bo);
> +
> +   ret = drm_intel_bo_flink(brw->wm.scratch_bo, &name);
> +   assert(ret == 0);
> +
> +   brw->wm.debugging = GL_TRUE;
> +
> +done:
> +   free(insn);
> +   fclose(stream);
> +}
> -- 
> 1.7.5.2
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
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