selftests: kallsyms: fix and clarify current test boundaries

Provide and clarify the existing ranges and what you should expect.
Fix the gen_test_kallsyms.sh script to accept different ranges.

Fixes: 84b4a51fce ("selftests: add new kallsyms selftests")
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

lib/Kconfig.debug

@@ -3003,9 +3003,39 @@ config TEST_KALLSYMS_D
 	tristate
 	depends on m
 
+choice
+	prompt "Kallsym test range"
+	default TEST_KALLSYMS_LARGE
+	help
+	  Selecting something other than "Fast" will enable tests which slow
+	  down the build and may crash your build.
+
+config TEST_KALLSYMS_FAST
+	bool "Fast builds"
+	help
+	  You won't really be testing kallsysms, so this just helps fast builds
+	  when allmodconfig is used..
+
+config TEST_KALLSYMS_LARGE
+	bool "Enable testing kallsyms with large exports"
+	help
+	  This will enable larger number of symbols. This will slow down
+	  your build considerably.
+
+config TEST_KALLSYMS_MAX
+	bool "Known kallsysms limits"
+	help
+	  This will enable exports to the point we know we'll start crashing
+	  builds.
+
+endchoice
+
 config TEST_KALLSYMS_NUMSYMS
 	int "test kallsyms number of symbols"
-	default 100
+	range 2 10000
+	default 2 if TEST_KALLSYMS_FAST
+	default 100 if TEST_KALLSYMS_LARGE
+	default 10000 if TEST_KALLSYMS_MAX
 	help
 	  The number of symbols to create on TEST_KALLSYMS_A, only one of which
 	  module TEST_KALLSYMS_B will use. This also will be used

lib/tests/module/gen_test_kallsyms.sh

@@ -7,6 +7,11 @@ NUM_SYMS=$2
 SCALE_FACTOR=$3
 TEST_TYPE=$(echo $TARGET | sed -e 's|lib/tests/module/test_kallsyms_||g')
 TEST_TYPE=$(echo $TEST_TYPE | sed -e 's|.c||g')
+FIRST_B_LOOKUP=1
+
+if [[ $NUM_SYMS -gt 2 ]]; then
+	FIRST_B_LOOKUP=$((NUM_SYMS/2))
+fi
 
 gen_template_module_header()
 {
@@ -52,10 +57,10 @@ ____END_MODULE
 
 gen_template_module_data_b()
 {
-	printf "\nextern int auto_test_a_%010d;\n\n" 28
+	printf "\nextern int auto_test_a_%010d;\n\n" $FIRST_B_LOOKUP
 	echo "static int auto_runtime_test(void)"
 	echo "{"
-	printf "\nreturn auto_test_a_%010d;\n" 28
+	printf "\nreturn auto_test_a_%010d;\n" $FIRST_B_LOOKUP
 	echo "}"
 }