EFI: don't call printf after ExitBootServices, since it uses Boot Services

ExitBootServices terminates all boot services including console access.
Attempting to call printf afterwards can result in a crash, depending on the
implementation.

Move any printf statements to before we call bi_load, and remove any that
depend on calling bi_load first.

Reviewed by:	imp, tsoome
Differential Revision:	https://reviews.freebsd.org/D19374

2 files changed, 15 insertions, 7 deletions

diff --git a/stand/efi/loader/arch/arm/exec.c b/stand/efi/loader/arch/arm/exec.c
index 2de99a09849f..5fdf8e3daa39 100644
--- a/stand/efi/loader/arch/arm/exec.c
+++ b/stand/efi/loader/arch/arm/exec.c
@@ -74,16 +74,19 @@ __elfN(arm_exec)(struct preloaded_file *fp)
 	e = (Elf_Ehdr *)&fmp->md_data;
 
 	efi_time_fini();
+
+	entry = efi_translate(e->e_entry);
+
+	printf("Kernel entry at 0x%x...\n", (unsigned)entry);
+	printf("Kernel args: %s\n", fp->f_args);
+
 	if ((error = bi_load(fp->f_args, &modulep, &kernend)) != 0) {
 		efi_time_init();
 		return (error);
 	}
 
-	entry = efi_translate(e->e_entry);
-	printf("Kernel entry at 0x%x...\n", (unsigned)entry);
-	printf("Kernel args: %s\n", fp->f_args);
-	printf("modulep: %#x\n", modulep);
-	printf("relocation_offset %llx\n", __elfN(relocation_offset));
+	/* At this point we've called ExitBootServices, so we can't call
+	 * printf or any other function that uses Boot Services */
 
 	dev_cleanup();
 
diff --git a/stand/efi/loader/arch/i386/elf32_freebsd.c b/stand/efi/loader/arch/i386/elf32_freebsd.c
index 83e370e6f165..847d6eead097 100644
--- a/stand/efi/loader/arch/i386/elf32_freebsd.c
+++ b/stand/efi/loader/arch/i386/elf32_freebsd.c
@@ -75,14 +75,19 @@ elf32_exec(struct preloaded_file *fp)
     ehdr = (Elf_Ehdr *)&(md->md_data);
 
     efi_time_fini();
+
+    entry = ehdr->e_entry & 0xffffff;
+
+    printf("Start @ 0x%x ...\n", entry);
+
     err = bi_load(fp->f_args, &modulep, &kernend);
     if (err != 0) {
 	efi_time_init();
 	return(err);
     }
-    entry = ehdr->e_entry & 0xffffff;
 
-    printf("Start @ 0x%x ...\n", entry);
+    /* At this point we've called ExitBootServices, so we can't call
+     * printf or any other function that uses Boot Services */
 
     dev_cleanup();
     __exec((void *)entry, boothowto, bootdev, 0, 0, 0, bootinfop, modulep, kernend);