Re: [PATCH v2 bpf-next 3/5] bpftool: Generalize light skeleton generation.

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On 2/8/22 11:13 AM, Alexei Starovoitov wrote:
From: Alexei Starovoitov <ast@xxxxxxxxxx>

Generealize light skeleton by hiding mmap details in skel_internal.h
In this form generated lskel.h is usable both by user space and by the kernel.

Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
---
  tools/bpf/bpftool/gen.c | 45 ++++++++++++++++++++++++-----------------
  1 file changed, 27 insertions(+), 18 deletions(-)

diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index eacfc6a2060d..903abbf077ce 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -472,7 +472,7 @@ static void codegen_destroy(struct bpf_object *obj, const char *obj_name)
  			continue;
  		if (bpf_map__is_internal(map) &&
  		    (bpf_map__map_flags(map) & BPF_F_MMAPABLE))
-			printf("\tmunmap(skel->%1$s, %2$zd);\n",
+			printf("\tskel_free_map_data(skel->%1$s, skel->maps.%1$s.initial_value, %2$zd);\n",
  			       ident, bpf_map_mmap_sz(map));
  		codegen("\
  			\n\
@@ -481,7 +481,7 @@ static void codegen_destroy(struct bpf_object *obj, const char *obj_name)
  	}
  	codegen("\
  		\n\
-			free(skel);					    \n\
+			skel_free(skel);				    \n\
  		}							    \n\
  		",
  		obj_name);
@@ -525,7 +525,7 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
  		{							    \n\
  			struct %1$s *skel;				    \n\
  									    \n\
-			skel = calloc(sizeof(*skel), 1);		    \n\
+			skel = skel_alloc(sizeof(*skel));		    \n\
  			if (!skel)					    \n\
  				goto cleanup;				    \n\
  			skel->ctx.sz = (void *)&skel->links - (void *)skel; \n\
@@ -544,18 +544,12 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
codegen("\
  			\n\
-				skel->%1$s =					 \n\
-					mmap(NULL, %2$zd, PROT_READ | PROT_WRITE,\n\
-					     MAP_SHARED | MAP_ANONYMOUS, -1, 0); \n\
-				if (skel->%1$s == (void *) -1)			 \n\
-					goto cleanup;				 \n\
-				memcpy(skel->%1$s, (void *)\"\\			 \n\
-			", ident, bpf_map_mmap_sz(map));
+				skel->%1$s = skel_prep_map_data((void *)\"\\	 \n\
+			", ident);
  		mmap_data = bpf_map__initial_value(map, &mmap_size);
  		print_hex(mmap_data, mmap_size);
-		printf("\", %2$zd);\n"
-		       "\tskel->maps.%1$s.initial_value = (__u64)(long)skel->%1$s;\n",
-		       ident, mmap_size);
+		printf("\", %1$zd, %2$zd);\n",
+		       bpf_map_mmap_sz(map), mmap_size);
  	}
  	codegen("\
  		\n\
@@ -592,6 +586,24 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
  	codegen("\
  		\n\
  		\";							    \n\
+		");
+	bpf_object__for_each_map(map, obj) {
+		size_t mmap_size = 0;
+
+		if (!get_map_ident(map, ident, sizeof(ident)))
+			continue;
+
+		if (!bpf_map__is_internal(map) ||
+		    !(bpf_map__map_flags(map) & BPF_F_MMAPABLE))
+			continue;
+
+		bpf_map__initial_value(map, &mmap_size);
+		printf("\tskel->maps.%1$s.initial_value ="
+		       " skel_prep_init_value((void **)&skel->%1$s, %2$zd, %3$zd);\n",
+		       ident, bpf_map_mmap_sz(map), mmap_size);
+	}
+	codegen("\
+		\n\
  			err = bpf_load_and_run(&opts);			    \n\
  			if (err < 0)					    \n\
  				return err;				    \n\
@@ -611,9 +623,8 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
  		else
  			mmap_flags = "PROT_READ | PROT_WRITE";
- printf("\tskel->%1$s =\n"
-		       "\t\tmmap(skel->%1$s, %2$zd, %3$s, MAP_SHARED | MAP_FIXED,\n"
-		       "\t\t\tskel->maps.%1$s.map_fd, 0);\n",
+		printf("\tskel->%1$s = skel_finalize_map_data(&skel->maps.%1$s.initial_value,\n"
+		       "\t\t\t%2$zd, %3$s, skel->maps.%1$s.map_fd);\n",
  		       ident, bpf_map_mmap_sz(map), mmap_flags);
  	}
  	codegen("\
@@ -751,8 +762,6 @@ static int do_skeleton(int argc, char **argv)
  		#ifndef %2$s						    \n\
  		#define %2$s						    \n\
  									    \n\
-		#include <stdlib.h>					    \n\
-		#include <bpf/bpf.h>					    \n\

I noticed that in patch2, the "bpf.h" is used instead of <bpf/bpf.h>.
Any particular reason for this or it is a bug fix?


  		#include <bpf/skel_internal.h>				    \n\
  									    \n\
  		struct %1$s {						    \n\



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