Relying on objcopy to prefix the ELF section names of the nVHE hyp code
is brittle and prevents us from using wildcards to match specific
section names.

Improve the build rules by partially linking all '.nvhe.o' files and
prefixing their ELF section names using a linker script. Continue using
objcopy for prefixing ELF symbol names.

One immediate advantage of this approach is that all subsections
matching a pattern can be merged into a single prefixed section, eg.
.text and .text.* can be linked into a single '.hyp.text'. This removes
the need for -fno-reorder-functions on GCC and will be useful in the
future too: LTO builds use .text subsections, compilers routinely
generate .rodata subsections, etc.

Partially linking all hyp code into a single object file also makes it
easier to analyze.

Signed-off-by: David Brazdil <redacted>
---
 arch/arm64/include/asm/hyp_image.h | 24 ++++++++++++
 arch/arm64/kvm/hyp/nvhe/Makefile   | 60 ++++++++++++++++--------------
 arch/arm64/kvm/hyp/nvhe/hyp.lds.S  | 13 +++++++
 3 files changed, 70 insertions(+), 27 deletions(-)
 create mode 100644 arch/arm64/include/asm/hyp_image.h
 create mode 100644 arch/arm64/kvm/hyp/nvhe/hyp.lds.S

diff --git a/arch/arm64/include/asm/hyp_image.h b/arch/arm64/include/asm/hyp_image.h
new file mode 100644
index 000000000000..5b1e3b9ef376
--- /dev/null
+++ b/arch/arm64/include/asm/hyp_image.h

@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 Google LLC.
+ * Written by David Brazdil <dbrazdil@google.com>
+ */
+
+#ifndef __ARM64_HYP_IMAGE_H__
+#define __ARM64_HYP_IMAGE_H__
+
+#ifdef LINKER_SCRIPT
+
+/*
+ * KVM nVHE ELF section names are prefixed with .hyp, to separate them
+ * from the kernel proper.
+ */
+#define HYP_SECTION_NAME(NAME)	.hyp##NAME
+
+/* Defines an ELF hyp section from input section @NAME and its subsections. */
+#define HYP_SECTION(NAME) \
+	HYP_SECTION_NAME(NAME) : { *(NAME NAME##.[0-9a-zA-Z_]*) }

+
+#endif /* LINKER_SCRIPT */
+
+#endif /* __ARM64_HYP_IMAGE_H__ */

diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index aef76487edc2..2b27b60182f9 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile

@@ -10,40 +10,46 @@ obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o
 obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
 	 ../fpsimd.o ../hyp-entry.o
 
-obj-y := $(patsubst %.o,%.hyp.o,$(obj-y))
-extra-y := $(patsubst %.hyp.o,%.hyp.tmp.o,$(obj-y))
+##
+## Build rules for compiling nVHE hyp code
+## Output of this folder is `kvm_nvhe.o`, a partially linked object
+## file containing all nVHE hyp code and data.
+##
 
-$(obj)/%.hyp.tmp.o: $(src)/%.c FORCE
+hyp-obj := $(patsubst %.o,%.nvhe.o,$(obj-y))
+obj-y := kvm_nvhe.o
+extra-y := $(hyp-obj) kvm_nvhe.tmp.o hyp.lds
+
+# 1) Compile all source files to `.nvhe.o` object files. The file extension
+#    avoids file name clashes for files shared with VHE.
+$(obj)/%.nvhe.o: $(src)/%.c FORCE
 	$(call if_changed_rule,cc_o_c)
-$(obj)/%.hyp.tmp.o: $(src)/%.S FORCE
+$(obj)/%.nvhe.o: $(src)/%.S FORCE
 	$(call if_changed_rule,as_o_S)
-$(obj)/%.hyp.o: $(obj)/%.hyp.tmp.o FORCE
-	$(call if_changed,hypcopy)
 
-# Disable reordering functions by GCC (enabled at -O2).
-# This pass puts functions into '.text.*' sections to aid the linker
-# in optimizing ELF layout. See HYPCOPY comment below for more info.
-ccflags-y += $(call cc-option,-fno-reorder-functions)
+# 2) Compile linker script.
+$(obj)/hyp.lds: $(src)/hyp.lds.S FORCE
+	$(call if_changed_dep,cpp_lds_S)