sandbox: use sections instead of symbols for getopt array boundaries

In style of linked lists, instead of declaring symbols for boundaries
of getopt options array in the linker script, declare corresponding
sections and retrieve the boundaries via static inline functions.

Without this clang's LTO produces binary without any getopt options,
because for some reason it thinks that array is empty (start and end
symbols are at the same address).

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Simon Glass <sjg@chromium.org>

arch/sandbox/cpu/os.c

@@ -375,7 +375,8 @@ static struct option *long_opts;
 
 int os_parse_args(struct sandbox_state *state, int argc, char *argv[])
 {
-	struct sandbox_cmdline_option **sb_opt = __u_boot_sandbox_option_start;
+	struct sandbox_cmdline_option **sb_opt =
+		__u_boot_sandbox_option_start();
 	size_t num_options = __u_boot_sandbox_option_count();
 	size_t i;
 

arch/sandbox/cpu/start.c

@@ -58,7 +58,8 @@ static int h_compare_opt(const void *p1, const void *p2)
 int sandbox_early_getopt_check(void)
 {
 	struct sandbox_state *state = state_get_current();
-	struct sandbox_cmdline_option **sb_opt = __u_boot_sandbox_option_start;
+	struct sandbox_cmdline_option **sb_opt =
+		__u_boot_sandbox_option_start();
 	size_t num_options = __u_boot_sandbox_option_count();
 	size_t i;
 	int max_arg_len, max_noarg_len;

arch/sandbox/cpu/u-boot-spl.lds

@@ -21,9 +21,11 @@ SECTIONS
 		__priv_data_end = .;
 	}
 
-	__u_boot_sandbox_option_start = .;
-	_u_boot_sandbox_getopt : { KEEP(*(.u_boot_sandbox_getopt)) }
-	__u_boot_sandbox_option_end = .;
+	_u_boot_sandbox_getopt : {
+		*(.u_boot_sandbox_getopt_start)
+		KEEP(*(.u_boot_sandbox_getopt))
+		*(.u_boot_sandbox_getopt_end)
+	}
 }
 
 INSERT AFTER .data;

arch/sandbox/cpu/u-boot.lds

@@ -13,9 +13,11 @@ SECTIONS
 		KEEP(*(SORT(.u_boot_list*)));
 	}
 
-	__u_boot_sandbox_option_start = .;
-	_u_boot_sandbox_getopt : { *(.u_boot_sandbox_getopt) }
-	__u_boot_sandbox_option_end = .;
+	_u_boot_sandbox_getopt : {
+		*(.u_boot_sandbox_getopt_start)
+		*(.u_boot_sandbox_getopt)
+		*(.u_boot_sandbox_getopt_end)
+	}
 
 	.__efi_runtime_start : {
 		*(.__efi_runtime_start)

arch/sandbox/include/asm/sections.h

@@ -13,12 +13,27 @@
 
 struct sandbox_cmdline_option;
 
-extern struct sandbox_cmdline_option *__u_boot_sandbox_option_start[],
-	*__u_boot_sandbox_option_end[];
+static inline struct sandbox_cmdline_option **
+__u_boot_sandbox_option_start(void)
+{
+	static char start[0] __aligned(4) __attribute__((unused))
+		__section(".u_boot_sandbox_getopt_start");
+
+	return (struct sandbox_cmdline_option **)&start;
+}
+
+static inline struct sandbox_cmdline_option **
+__u_boot_sandbox_option_end(void)
+{
+	static char end[0] __aligned(4) __attribute__((unused))
+		__section(".u_boot_sandbox_getopt_end");
+
+	return (struct sandbox_cmdline_option **)&end;
+}
 
 static inline size_t __u_boot_sandbox_option_count(void)
 {
-	return __u_boot_sandbox_option_end - __u_boot_sandbox_option_start;
+	return __u_boot_sandbox_option_end() - __u_boot_sandbox_option_start();
 }
 
 #endif