KVM: arm64: Support PREL/PLT relocs in EL2 code

gen-hyprel tool parses object files of the EL2 portion of KVM
and generates runtime relocation data. While only filtering for
R_AARCH64_ABS64 relocations in the input object files, it has an
allow-list of relocation types that are used for relative
addressing. Other, unexpected, relocation types are rejected and
cause the build to fail.

This allow-list did not include the position-relative relocation
types R_AARCH64_PREL64/32/16 and the recently introduced _PLT32.
While not seen used by toolchains in the wild, add them to the
allow-list for completeness.

Fixes: 8c49b5d4 ("KVM: arm64: Generate hyp relocation data")
Cc: <stable@vger.kernel.org>
Reported-by: Will Deacon <will@kernel.org>
Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210331133048.63311-1-dbrazdil@google.com

arch/arm64/kvm/hyp/nvhe/gen-hyprel.c

@@ -50,6 +50,18 @@
 #ifndef R_AARCH64_ABS64
 #define R_AARCH64_ABS64			257
 #endif
+#ifndef R_AARCH64_PREL64
+#define R_AARCH64_PREL64		260
+#endif
+#ifndef R_AARCH64_PREL32
+#define R_AARCH64_PREL32		261
+#endif
+#ifndef R_AARCH64_PREL16
+#define R_AARCH64_PREL16		262
+#endif
+#ifndef R_AARCH64_PLT32
+#define R_AARCH64_PLT32			314
+#endif
 #ifndef R_AARCH64_LD_PREL_LO19
 #define R_AARCH64_LD_PREL_LO19		273
 #endif
@@ -371,6 +383,12 @@ static void emit_rela_section(Elf64_Shdr *sh_rela)
 		case R_AARCH64_ABS64:
 			emit_rela_abs64(rela, sh_orig_name);
 			break;
+		/* Allow position-relative data relocations. */
+		case R_AARCH64_PREL64:
+		case R_AARCH64_PREL32:
+		case R_AARCH64_PREL16:
+		case R_AARCH64_PLT32:
+			break;
 		/* Allow relocations to generate PC-relative addressing. */
 		case R_AARCH64_LD_PREL_LO19:
 		case R_AARCH64_ADR_PREL_LO21: