[edk2-devel] [PATCH] BaseTools GenFw: Add support for R_RISCV_PCREL_LO12_S relocation

[Daniel Schaefer]

Looks good. I compared it with existing R_RISCV_PCREL_LO12_I and looked 
at the differences.

This one doesn't do use mRiscVPass1GotFixup.
I assume this is an optimization that's not possible here?

Haven't tested that it works but since it works for Pete:

Reviewed-by: Daniel Schaefer <daniel.schaefer at hpe.com>

Thanks!

On 7/10/21 2:31 PM, Sunil V L wrote:
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3459
> 
> This patch adds support for R_RISCV_PCREL_LO12_S relocation type.
> The logic is same as existing R_RISCV_PCREL_LO12_I relocation
> except the difference between load vs store instruction formats.
> 
> Signed-off-by: Sunil V L <sunilvl at ventanamicro.com>
> 
> Cc: Liming Gao <gaoliming at byosoft.com.cn>
> Cc: Bob Feng <bob.c.feng at intel.com>
> Cc: Yuwei Chen <yuwei.chen at intel.com>
> Cc: Pete Batard <pete at akeo.ie>
> Cc: Abner Chang <abner.chang at hpe.com>
> Cc: Daniel Schaefer <daniel.schaefer at hpe.com>
> ---
>   BaseTools/Source/C/GenFw/Elf64Convert.c | 55 +++++++++++++++++++++++++
>   1 file changed, 55 insertions(+)
> 
> diff --git a/BaseTools/Source/C/GenFw/Elf64Convert.c b/BaseTools/Source/C/GenFw/Elf64Convert.c
> index 3d7e20aaff..0bb3ead228 100644
> --- a/BaseTools/Source/C/GenFw/Elf64Convert.c
> +++ b/BaseTools/Source/C/GenFw/Elf64Convert.c
> @@ -557,6 +557,60 @@ WriteSectionRiscV64 (
>       Value = (UINT32)(RV_X(*(UINT32 *)mRiscVPass1Targ, 12, 20));
>       break;
>   
> +  case R_RISCV_PCREL_LO12_S:
> +    if (mRiscVPass1Targ != NULL && mRiscVPass1Sym != NULL && mRiscVPass1SymSecIndex != 0) {
> +      int i;
> +      Value2 = (UINT32)(RV_X(*(UINT32 *)mRiscVPass1Targ, 12, 20));
> +
> +      Value = ((UINT32)(RV_X(*(UINT32 *)Targ, 25, 7)) << 5);
> +      Value = (Value | (UINT32)(RV_X(*(UINT32 *)Targ, 7, 5)));
> +
> +      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;
> +        Value += 4096 * i;
> +        if(-2048 > (INT32)Value) {
> +          Value2 -= 1;
> +          Value += 4096;
> +        }
> +      }
> +      else if( 2047 < (INT32)Value) {
> +        i = (Value / 4096);
> +        Value2 += i;
> +        Value -= 4096 * i;
> +        if(2047 < (INT32)Value) {
> +          Value2 += 1;
> +          Value -= 4096;
> +        }
> +      }
> +
> +      // Update the IMM of SD instruction
> +      //
> +      // |31      25|24  20|19  15|14   12 |11      7|6     0|
> +      // |-------------------------------------------|-------|
> +      // |imm[11:5] | rs2  | rs1  | funct3 |imm[4:0] | opcode|
> +      //  ---------------------------------------------------
> +
> +      // First Zero out current IMM
> +      *(UINT32 *)Targ &= ~0xfe000f80;
> +
> +      // Update with new IMM
> +      *(UINT32 *)Targ |= (RV_X(Value, 5, 7) << 25);
> +      *(UINT32 *)Targ |= (RV_X(Value, 0, 5) << 7);
> +
> +      // Update previous instruction
> +      *(UINT32 *)mRiscVPass1Targ = (RV_X(Value2, 0, 20)<<12) | (RV_X(*(UINT32 *)mRiscVPass1Targ, 0, 12));
> +    }
> +    mRiscVPass1Sym = NULL;
> +    mRiscVPass1Targ = NULL;
> +    mRiscVPass1SymSecIndex = 0;
> +    break;
> +
>     case R_RISCV_PCREL_LO12_I:
>       if (mRiscVPass1Targ != NULL && mRiscVPass1Sym != NULL && mRiscVPass1SymSecIndex != 0) {
>         int i;
> @@ -1587,6 +1641,7 @@ WriteRelocations64 (
>               case R_RISCV_PCREL_HI20:
>               case R_RISCV_GOT_HI20:
>               case R_RISCV_PCREL_LO12_I:
> +            case R_RISCV_PCREL_LO12_S:
>                 break;
>   
>               default:
> 


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