retpoline: add indirect thunk support

for gcc version > 7.3, enable CONFIG_RETPOLINE

Signed-off-by: Jason Chen CJ <jason.cj.chen@intel.com>

hypervisor/Makefile

@@ -153,6 +153,19 @@ ifeq ($(PLATFORM),uefi)
 C_SRCS += bsp/$(PLATFORM)/cmdline.c
 endif
 
+# retpoline support
+ifeq (true, $(shell [ $(GCC_MAJOR) -eq 7 ] && [ $(GCC_MINOR) -ge 3 ] && echo true))
+CFLAGS += -mindirect-branch=thunk-extern -mindirect-branch-register
+CFLAGS += -DCONFIG_RETPOLINE
+S_SRCS += arch/x86/retpoline-thunk.S
+else
+ifeq (true, $(shell [ $(GCC_MAJOR) -ge 8 ] && echo true))
+CFLAGS += -mindirect-branch=thunk-extern -mindirect-branch-register
+CFLAGS += -DCONFIG_RETPOLINE
+S_SRCS += arch/x86/retpoline-thunk.S
+endif
+endif
+
 C_OBJS := $(patsubst %.c,$(HV_OBJDIR)/%.o,$(C_SRCS))
 ifeq ($(RELEASE),0)
 C_OBJS += $(patsubst %.c,$(HV_OBJDIR)/%.o,$(D_SRCS))

hypervisor/arch/x86/retpoline-thunk.S

@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2018 Intel Corporation. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in
+ *     the documentation and/or other materials provided with the
+ *     distribution.
+ *   * Neither the name of Intel Corporation nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+.macro retpoline_thunk reg:req
+
+.align 8
+.global __x86_indirect_thunk_\reg
+__x86_indirect_thunk_\reg:
+    call 22f
+11:
+    pause
+    jmp 11b
+22:
+    mov %\reg, (%rsp)
+    ret
+.endm
+
+.section    .retpoline_thunk, "ax"
+
+    retpoline_thunk rax
+    retpoline_thunk rbx
+    retpoline_thunk rcx
+    retpoline_thunk rdx
+    retpoline_thunk rdi
+    retpoline_thunk rsi
+    retpoline_thunk rbp
+    retpoline_thunk r8
+    retpoline_thunk r9
+    retpoline_thunk r10
+    retpoline_thunk r11
+    retpoline_thunk r12
+    retpoline_thunk r13
+    retpoline_thunk r14
+    retpoline_thunk r15

hypervisor/bsp/ld/link_ram.ld.in

@@ -30,6 +30,7 @@ SECTIONS
         *(.text .text*) ;
         *(.gnu.linkonce.t*)
         *(.note.gnu.build-id)
+        *(.retpoline_thunk)
     } > ram
 
     .rodata :

hypervisor/bsp/sbl/include/bsp/bsp_cfg.h

@@ -45,5 +45,4 @@
 #define	CONFIG_LOW_RAM_SIZE	0x000CF000
 #define	CONFIG_RAM_START	0x6E000000
 #define	CONFIG_RAM_SIZE		0x02000000	/* 32M */
-#define	CONFIG_RETPOLINE
 #endif /* BSP_CFG_H */

hypervisor/bsp/uefi/include/bsp/bsp_cfg.h

@@ -48,5 +48,4 @@
 #define	CONFIG_DMAR_PARSE_ENABLED	1
 #define	CONFIG_GPU_SBDF		0x00000010	/* 0000:00:02.0 */
 #define CONFIG_EFI_STUB       1
-#define	CONFIG_RETPOLINE
 #endif /* BSP_CFG_H */