Great commit message, thanks Sunil!
Maintainers, please take a look and let us know if there's any other concern.
This patch lets us build the RISC-V platforms using modern toolchains that are provided directly by the distributions, rather than building your own from source.
Thanks,
Daniel
------------------------------------------------------------------------
*From:* Sunil V L <sunilvl@ventanamicro.com>
*Sent:* Friday, June 11, 2021 22:08
*To:* devel@edk2.groups.io <devel@edk2.groups.io>
*Cc:* Chang, Abner (HPS SW/FW Technologist) <abner.chang@hpe.com>; Schaefer, Daniel <daniel.schaefer@hpe.com>; Bob Feng <bob.c.feng@intel.com>; Liming Gao <gaoliming@byosoft.com.cn>; Yuwei Chen <yuwei.chen@intel.com>; Heinrich Schuchardt <xypron.glpk@gmx.de>
*Subject:* Re: [RESEND PATCH v2] BaseTools: Add support for RISCV GOT/PLT relocations
Hi,
    I just edited the commit message to indicate the module and CC the
    maintainers. Could I get the feedback please?
Thanks
Sunil
On Fri, Jun 11, 2021 at 07:35:03PM +0530, Sunil V L wrote:

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

<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

<https://github.com/riscv/riscv-gnu-toolchain/issues/905#issuecomment-846682710>

Changes in v2:
   - Addressed Daniel's comment on formatting
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: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Yuwei Chen <yuwei.chen@intel.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