kallsyms: Add more debug output for selftest

While debugging a recent kallsyms_selftest failure[1], I needed more
details on what specifically was failing. This adds those details for
each failure state that is checked.

[1] https://lore.kernel.org/all/202308232200.1c932a90-oliver.sang@intel.com/

Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Yonghong Song <yhs@meta.com>
Cc: "Erhard F." <erhard_f@mailbox.org>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Cc: kernel test robot <oliver.sang@intel.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

diff --git a/kernel/kallsyms_selftest.c b/kernel/kallsyms_selftest.c
index a2e3745..232e8fa 100644 (file)
--- a/kernel/kallsyms_selftest.c
+++ b/kernel/kallsyms_selftest.c
@@ -341,6 +341,7 @@ static int test_kallsyms_basic_function(void)
                ret = lookup_symbol_name(addr, namebuf);
                if (unlikely(ret)) {
                        namebuf[0] = 0;
+                       pr_info("%d: lookup_symbol_name(%lx) failed\n", i, addr);
                        goto failed;
                }
 
@@ -388,8 +389,11 @@ static int test_kallsyms_basic_function(void)
                        if (stat->addr != stat2->addr ||
                            stat->real_cnt != stat2->real_cnt ||
                            memcmp(stat->addrs, stat2->addrs,
-                                  stat->save_cnt * sizeof(stat->addrs[0])))
+                                  stat->save_cnt * sizeof(stat->addrs[0]))) {
+                               pr_info("%s: mismatch between kallsyms_on_each_symbol() and kallsyms_on_each_match_symbol()\n",
+                                       namebuf);
                                goto failed;
+                       }
 
                        /*
                         * The average of random increments is 128, that is, one of
@@ -400,15 +404,23 @@ static int test_kallsyms_basic_function(void)
                }
 
                /* Need to be found at least once */
-               if (!stat->real_cnt)
+               if (!stat->real_cnt) {
+                       pr_info("%s: Never found\n", namebuf);
                        goto failed;
+               }
 
                /*
                 * kallsyms_lookup_name() returns the address of the first
                 * symbol found and cannot be NULL.
                 */
-               if (!lookup_addr || lookup_addr != stat->addrs[0])
+               if (!lookup_addr) {
+                       pr_info("%s: NULL lookup_addr?!\n", namebuf);
+                       goto failed;
+               }
+               if (lookup_addr != stat->addrs[0]) {
+                       pr_info("%s: lookup_addr != stat->addrs[0]\n", namebuf);
                        goto failed;
+               }
 
                /*
                 * If the addresses of all matching symbols are recorded, the
@@ -420,8 +432,10 @@ static int test_kallsyms_basic_function(void)
                                        break;
                        }
 
-                       if (j == stat->save_cnt)
+                       if (j == stat->save_cnt) {
+                               pr_info("%s: j == save_cnt?!\n", namebuf);
                                goto failed;
+                       }
                }
        }