[PATCH v2] Add support for RISCV GOT/PLT relocations

["Sunil V L" <sunilvl@ventanamicro.com>]

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3096

This patch adds support for R_RISCV_CALL_PLT and R_RISCV_GOT_HI20
relocations generated by PIE enabled compiler. This also needed
changes to R_RISCV_32 and R_RISCV_64 relocations as explained in
https://github.com/riscv/riscv-gnu-toolchain/issues/905#issuecomment-846682710

Testing:
1) Debian GCC 8.3.0 and booted sifive_u and QMEU virt models.
2) Debian 10.2.0 and booted QEMU virt model.
3) riscv-gnu-tool chain 9.2 and booted QEMU virt model.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>

Acked-by: Abner Chang <abner.chang@hpe.com>
Reviewed-by: Daniel Schaefer <daniel.schaefer@hpe.com>
Tested-by: <daniel.schaefer@hpe.com>

Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
---
 BaseTools/Source/C/GenFw/Elf64Convert.c | 44 +++++++++++++++++++++----
 1 file changed, 38 insertions(+), 6 deletions(-)

diff --git a/BaseTools/Source/C/GenFw/Elf64Convert.c b/BaseTools/Source/C/GenFw/Elf64Convert.c
index d097db8632..d684318269 100644
--- a/BaseTools/Source/C/GenFw/Elf64Convert.c
+++ b/BaseTools/Source/C/GenFw/Elf64Convert.c
@@ -129,6 +129,8 @@ STATIC UINT32 mDebugOffset;
 STATIC UINT8       *mRiscVPass1Targ = NULL;
 STATIC Elf_Shdr    *mRiscVPass1Sym = NULL;
 STATIC Elf64_Half  mRiscVPass1SymSecIndex = 0;
+STATIC INT32       mRiscVPass1Offset;
+STATIC INT32       mRiscVPass1GotFixup;
 
 //
 // Initialization Function
@@ -479,11 +481,11 @@ WriteSectionRiscV64 (
     break;
 
   case R_RISCV_32:
-    *(UINT32 *)Targ = (UINT32)((UINT64)(*(UINT32 *)Targ) - SymShdr->sh_addr + mCoffSectionsOffset[Sym->st_shndx]);
+    *(UINT64 *)Targ = Sym->st_value + Rel->r_addend;
     break;
 
   case R_RISCV_64:
-    *(UINT64 *)Targ = *(UINT64 *)Targ - SymShdr->sh_addr + mCoffSectionsOffset[Sym->st_shndx];
+    *(UINT64 *)Targ = Sym->st_value + Rel->r_addend;
     break;
 
   case R_RISCV_HI20:
@@ -533,6 +535,18 @@ WriteSectionRiscV64 (
     mRiscVPass1SymSecIndex = 0;
     break;
 
+  case R_RISCV_GOT_HI20:
+    Value = (Sym->st_value - Rel->r_offset);
+    mRiscVPass1Offset = RV_X(Value, 0, 12);
+    Value = RV_X(Value, 12, 20);
+    *(UINT32 *)Targ = (Value << 12) | (RV_X(*(UINT32*)Targ, 0, 12));
+
+    mRiscVPass1Targ = Targ;
+    mRiscVPass1Sym = SymShdr;
+    mRiscVPass1SymSecIndex = Sym->st_shndx;
+    mRiscVPass1GotFixup = 1;
+    break;
+
   case R_RISCV_PCREL_HI20:
     mRiscVPass1Targ = Targ;
     mRiscVPass1Sym = SymShdr;
@@ -545,11 +559,17 @@ WriteSectionRiscV64 (
     if (mRiscVPass1Targ != NULL && mRiscVPass1Sym != NULL && mRiscVPass1SymSecIndex != 0) {
       int i;
       Value2 = (UINT32)(RV_X(*(UINT32 *)mRiscVPass1Targ, 12, 20));
-      Value = (UINT32)(RV_X(*(UINT32 *)Targ, 20, 12));
-      if(Value & (RISCV_IMM_REACH/2)) {
-        Value |= ~(RISCV_IMM_REACH-1);
+
+      if(mRiscVPass1GotFixup) {
+        Value = (UINT32)(mRiscVPass1Offset);
+      } else {
+        Value = (UINT32)(RV_X(*(UINT32 *)Targ, 20, 12));
+        if(Value & (RISCV_IMM_REACH/2)) {
+          Value |= ~(RISCV_IMM_REACH-1);
+        }
       }
       Value = Value - (UINT32)mRiscVPass1Sym->sh_addr + mCoffSectionsOffset[mRiscVPass1SymSecIndex];
+
       if(-2048 > (INT32)Value) {
         i = (((INT32)Value * -1) / 4096);
         Value2 -= i;
@@ -569,12 +589,21 @@ WriteSectionRiscV64 (
         }
       }
 
-      *(UINT32 *)Targ = (RV_X(Value, 0, 12) << 20) | (RV_X(*(UINT32*)Targ, 0, 20));
+      if(mRiscVPass1GotFixup) {
+        *(UINT32 *)Targ = (RV_X((UINT32)Value, 0, 12) << 20)
+                            | (RV_X(*(UINT32*)Targ, 0, 20));
+        /* Convert LD instruction to ADDI */
+        *(UINT32 *)Targ = ((*(UINT32 *)Targ & ~0x707f) | 0x13);
+      } else {
+        *(UINT32 *)Targ = (RV_X(Value, 0, 12) << 20) | (RV_X(*(UINT32*)Targ, 0, 20));
+      }
       *(UINT32 *)mRiscVPass1Targ = (RV_X(Value2, 0, 20)<<12) | (RV_X(*(UINT32 *)mRiscVPass1Targ, 0, 12));
     }
     mRiscVPass1Sym = NULL;
     mRiscVPass1Targ = NULL;
     mRiscVPass1SymSecIndex = 0;
+    mRiscVPass1Offset = 0;
+    mRiscVPass1GotFixup = 0;
     break;
 
   case R_RISCV_ADD64:
@@ -586,6 +615,7 @@ WriteSectionRiscV64 (
   case R_RISCV_GPREL_I:
   case R_RISCV_GPREL_S:
   case R_RISCV_CALL:
+  case R_RISCV_CALL_PLT:
   case R_RISCV_RVC_BRANCH:
   case R_RISCV_RVC_JUMP:
   case R_RISCV_RELAX:
@@ -1528,6 +1558,7 @@ WriteRelocations64 (
             case R_RISCV_GPREL_I:
             case R_RISCV_GPREL_S:
             case R_RISCV_CALL:
+            case R_RISCV_CALL_PLT:
             case R_RISCV_RVC_BRANCH:
             case R_RISCV_RVC_JUMP:
             case R_RISCV_RELAX:
@@ -1537,6 +1568,7 @@ WriteRelocations64 (
             case R_RISCV_SET16:
             case R_RISCV_SET32:
             case R_RISCV_PCREL_HI20:
+            case R_RISCV_GOT_HI20:
             case R_RISCV_PCREL_LO12_I:
               break;
 
-- 
2.25.1