Re: [RESEND PATCH v2] BaseTools: Add support for RISCV GOT/PLT relocations

["Daniel Schaefer" <daniel.schaefer@hpe.com>]

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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
>
> 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
>
> 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
>

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