From 5e6f40bdef10e6fcd89cdf6fc9e1382e22768d16 Mon Sep 17 00:00:00 2001
From: Ryan Libby <rlibby@FreeBSD.org>
Date: Thu, 20 Jul 2017 06:47:06 +0000
Subject: [PATCH] efi: restrict visibility of EFIABI_ATTR-declared functions

In-tree gcc (4.2) doesn't understand __attribute__((ms_abi))
(EFIABI_ATTR).  Avoid declaring functions with that attribute when the
compiler is detected to be gcc < 4.4.

Reviewed by:	kib, imp (previous version)
Approved by:	markj (mentor)
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D11636
---
 sys/amd64/include/efi.h | 6 ++++++
 sys/sys/efi.h           | 5 ++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/sys/amd64/include/efi.h b/sys/amd64/include/efi.h
index 272d5a8f3a83..a0a39b4056e9 100644
--- a/sys/amd64/include/efi.h
+++ b/sys/amd64/include/efi.h
@@ -36,8 +36,14 @@
  * XXX: from gcc 6.2 manual:
  * Note, the ms_abi attribute for Microsoft Windows 64-bit targets
  * currently requires the -maccumulate-outgoing-args option.
+ *
+ * Avoid EFIABI_ATTR declarations for compilers that don't support it.
+ * GCC support began in version 4.4.
  */
+#if defined(__clang__) || defined(__GNUC__) && \
+    (__GNUC__ > 4 || __GNUC__ == 4 && __GNUC_MINOR__ >= 4)
 #define	EFIABI_ATTR	__attribute__((ms_abi))
+#endif
 
 #ifdef _KERNEL
 struct uuid;
diff --git a/sys/sys/efi.h b/sys/sys/efi.h
index 68fc2816e494..05ccfab4908a 100644
--- a/sys/sys/efi.h
+++ b/sys/sys/efi.h
@@ -122,6 +122,9 @@ struct efi_tblhdr {
 	uint32_t	__res;
 };
 
+#ifdef _KERNEL
+
+#ifdef EFIABI_ATTR
 struct efi_rt {
 	struct efi_tblhdr rt_hdr;
 	efi_status	(*rt_gettime)(struct efi_tm *, struct efi_tmcap *)
@@ -144,6 +147,7 @@ struct efi_rt {
 	efi_status	(*rt_reset)(enum efi_reset, efi_status, u_long,
 	    efi_char *) EFIABI_ATTR;
 };
+#endif
 
 struct efi_systbl {
 	struct efi_tblhdr st_hdr;
@@ -163,7 +167,6 @@ struct efi_systbl {
 	uint64_t	st_cfgtbl;
 };
 
-#ifdef _KERNEL
 extern vm_paddr_t efi_systbl_phys;
 #endif	/* _KERNEL */