bpftool: Align bpf_load_and_run_opts insns and data

A C string lacks alignment so use aligned arrays to avoid potential
alignment problems. Switch to using sizeof (less 1 for the \0
terminator) rather than a hardcode size constant.

Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20231007044439.25171-2-irogers@google.com

diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index 882bf8e6e70e44c10844bde9cae216da468d39cf..ee3ce2b8000d75d211c700fe395ac67788619f86 100644 (file)
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -708,17 +708,22 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
 
                codegen("\
                \n\
-                       skel->%1$s = skel_prep_map_data((void *)\"\\        \n\
-               ", ident);
+                       {                                                   \n\
+                               static const char data[] __attribute__((__aligned__(8))) = \"\\\n\
+               ");
                mmap_data = bpf_map__initial_value(map, &mmap_size);
                print_hex(mmap_data, mmap_size);
                codegen("\
                \n\
-               \", %1$zd, %2$zd);                                          \n\
-                       if (!skel->%3$s)                                    \n\
-                               goto cleanup;                               \n\
-                       skel->maps.%3$s.initial_value = (__u64) (long) skel->%3$s;\n\
-               ", bpf_map_mmap_sz(map), mmap_size, ident);
+               \";                                                         \n\
+                                                                           \n\
+                               skel->%1$s = skel_prep_map_data((void *)data, %2$zd,\n\
+                                                               sizeof(data) - 1);\n\
+                               if (!skel->%1$s)                            \n\
+                                       goto cleanup;                       \n\
+                               skel->maps.%1$s.initial_value = (__u64) (long) skel->%1$s;\n\
+                       }                                                   \n\
+                       ", ident, bpf_map_mmap_sz(map));
        }
        codegen("\
                \n\
@@ -733,32 +738,30 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
                {                                                           \n\
                        struct bpf_load_and_run_opts opts = {};             \n\
                        int err;                                            \n\
-                                                                           \n\
-                       opts.ctx = (struct bpf_loader_ctx *)skel;           \n\
-                       opts.data_sz = %2$d;                                \n\
-                       opts.data = (void *)\"\\                            \n\
+                       static const char opts_data[] __attribute__((__aligned__(8))) = \"\\\n\
                ",
-               obj_name, opts.data_sz);
+               obj_name);
        print_hex(opts.data, opts.data_sz);
        codegen("\
                \n\
                \";                                                         \n\
+                       static const char opts_insn[] __attribute__((__aligned__(8))) = \"\\\n\
                ");
-
-       codegen("\
-               \n\
-                       opts.insns_sz = %d;                                 \n\
-                       opts.insns = (void *)\"\\                           \n\
-               ",
-               opts.insns_sz);
        print_hex(opts.insns, opts.insns_sz);
        codegen("\
                \n\
                \";                                                         \n\
+                                                                           \n\
+                       opts.ctx = (struct bpf_loader_ctx *)skel;           \n\
+                       opts.data_sz = sizeof(opts_data) - 1;               \n\
+                       opts.data = (void *)opts_data;                      \n\
+                       opts.insns_sz = sizeof(opts_insn) - 1;              \n\
+                       opts.insns = (void *)opts_insn;                     \n\
+                                                                           \n\
                        err = bpf_load_and_run(&opts);                      \n\
                        if (err < 0)                                        \n\
                                return err;                                 \n\
-               ", obj_name);
+               ");
        bpf_object__for_each_map(map, obj) {
                const char *mmap_flags;