KVM: arm64: Link position-independent string routines into .hyp.text

Pull clear_page(), copy_page(), memcpy() and memset() into the nVHE hyp
code and ensure that we always execute the '__pi_' entry point on the
offchance that it changes in future.

[ qperret: Commit title nits and added linker script alias ]
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-3-qperret@google.com

arch/arm64/include/asm/hyp_image.h

@@ -56,6 +56,9 @@
  */
 #define KVM_NVHE_ALIAS(sym)	kvm_nvhe_sym(sym) = sym;
 
+/* Defines a linker script alias for KVM nVHE hyp symbols */
+#define KVM_NVHE_ALIAS_HYP(first, sec)	kvm_nvhe_sym(first) = kvm_nvhe_sym(sec);
+
 #endif /* LINKER_SCRIPT */
 
 #endif /* __ARM64_HYP_IMAGE_H__ */

arch/arm64/kernel/image-vars.h

@@ -104,6 +104,17 @@ KVM_NVHE_ALIAS(kvm_arm_hyp_percpu_base);
 /* PMU available static key */
 KVM_NVHE_ALIAS(kvm_arm_pmu_available);
 
+/* Position-independent library routines */
+KVM_NVHE_ALIAS_HYP(clear_page, __pi_clear_page);
+KVM_NVHE_ALIAS_HYP(copy_page, __pi_copy_page);
+KVM_NVHE_ALIAS_HYP(memcpy, __pi_memcpy);
+KVM_NVHE_ALIAS_HYP(memset, __pi_memset);
+
+#ifdef CONFIG_KASAN
+KVM_NVHE_ALIAS_HYP(__memcpy, __pi_memcpy);
+KVM_NVHE_ALIAS_HYP(__memset, __pi_memset);
+#endif
+
 #endif /* CONFIG_KVM */
 
 #endif /* __ARM64_KERNEL_IMAGE_VARS_H */

arch/arm64/kvm/hyp/nvhe/Makefile

@@ -9,10 +9,14 @@ ccflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS
 hostprogs := gen-hyprel
 HOST_EXTRACFLAGS += -I$(objtree)/include
 
+lib-objs := clear_page.o copy_page.o memcpy.o memset.o
+lib-objs := $(addprefix ../../../lib/, $(lib-objs))
+
 obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
 	 hyp-main.o hyp-smp.o psci-relay.o
 obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
 	 ../fpsimd.o ../hyp-entry.o ../exception.o
+obj-y += $(lib-objs)
 
 ##
 ## Build rules for compiling nVHE hyp code