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

[Sunil V L]

On Tue, Jul 13, 2021 at 05:27:30PM +0800, Daniel Schaefer wrote:
> Looks good. I compared it with existing R_RISCV_PCREL_LO12_I and looked at
> the differences.
> 
Thanks Daniel.

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

GOT fixup is required only for load to avoid the indirection for symbol
resolution.

Thanks
Sunil
> 
> 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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