From: Heinrich Schuchardt <xypron.glpk@gmx.de>
Date: Sat, 18 Jul 2020 07:53:01 +0000 (+0200)
Subject: efi_loader: document efi_save_gd(), efi_restore_gd()
X-Git-Url: http://git.dujemihanovic.xyz/img/static/git-favicon.png?a=commitdiff_plain;h=e7d64065cb4b74357e50b54e54adc780e2f44db1;p=u-boot.git

efi_loader: document efi_save_gd(), efi_restore_gd()

Provide function descriptions for efi_save_gd() and efi_restore_gd().

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
---

diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index 0b16554ba2..d49145fc76 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -104,7 +104,15 @@ int __efi_exit_check(void)
 	return ret;
 }
 
-/* Called from do_bootefi_exec() */
+/**
+ * efi_save_gd() - save global data register
+ *
+ * On the ARM architecture gd is mapped to a fixed register (r9 or x18).
+ * As this register may be overwritten by an EFI payload we save it here
+ * and restore it on every callback entered.
+ *
+ * This function is called after relocation from initr_reloc_global_data().
+ */
 void efi_save_gd(void)
 {
 #ifdef CONFIG_ARM
@@ -112,10 +120,12 @@ void efi_save_gd(void)
 #endif
 }
 
-/*
- * Special case handler for error/abort that just forces things back to u-boot
- * world so we can dump out an abort message, without any care about returning
- * back to UEFI world.
+/**
+ * efi_restore_gd() - restore global data register
+ *
+ * On the ARM architecture gd is mapped to a fixed register (r9 or x18).
+ * Restore it after returning from the UEFI world to the value saved via
+ * efi_save_gd().
  */
 void efi_restore_gd(void)
 {