Fix RISC-V trampoline code

tnayuki · Feb 15, 2022 · b80b612 · b80b612
1 parent 07831af
commit b80b612
Showing 1 changed file with 21 additions and 6 deletions.
diff --git a/lib/engine-dylib/src/trampoline.rs b/lib/engine-dylib/src/trampoline.rs
@@ -35,8 +35,9 @@ const AARCH64_TRAMPOLINE: [u8; 12] = [
 const X86_64_TRAMPOLINE: [u8; 6] = [0xff, 0x25, 0x00, 0x00, 0x00, 0x00];
 
 // AUIPC t1, #...     17 03 00 00
-// JALR x0, #...(t1)  67 00 03 00
-const RISCV64_TRAMPOLINE: [u8; 8] = [0x17, 0x03, 0x00, 0x00, 0x67, 0x00, 0x03, 0x00];
+// LD t1, #...(t1)    03 33 03 00
+// JR t1              67 00 03 00
+const RISCV64_TRAMPOLINE: [u8; 12] = [0x17, 0x03, 0x00, 0x00, 0x03, 0x33, 0x03, 0x00, 0x67, 0x00, 0x03, 0x00];
 
 fn emit_trampoline(
     obj: &mut Object,
@@ -120,9 +121,11 @@ fn emit_trampoline(
             .unwrap();
         }
         Architecture::Riscv64(_) => {
-            let reloc = match obj.format() {
-                BinaryFormat::Elf => RelocationKind::Elf(elf::R_RISCV_CALL_PLT),
-
+            let (reloc1, reloc2) = match obj.format() {
+                BinaryFormat::Elf => (
+                    RelocationKind::Elf(elf::R_RISCV_PCREL_HI20),
+                    RelocationKind::Elf(elf::R_RISCV_PCREL_LO12_I),
+                ),
                 _ => panic!("Unsupported binary format on Riscv64"),
             };
             let offset = obj.add_symbol_data(libcall_symbol, text, &RISCV64_TRAMPOLINE, 4);
@@ -131,13 +134,25 @@ fn emit_trampoline(
                 Relocation {
                     offset: offset,
                     size: 32,
-                    kind: reloc,
+                    kind: reloc1,
                     encoding: RelocationEncoding::Generic,
                     symbol: trampoline_table_symbols[libcall as usize],
                     addend: 0,
                 },
             )
             .unwrap();
+            obj.add_relocation(
+                text,
+                Relocation {
+                    offset: offset+4,
+                    size: 32,
+                    kind: reloc2,
+                    encoding: RelocationEncoding::Generic,
+                    symbol: libcall_symbol,
+                    addend: 0,
+                },
+            )
+            .unwrap();
         }
         arch => panic!("Unsupported architecture: {}", arch),
     };