Re: [PATCH] Update RISC-V specific ELF definitions

[Fangrui Song <maskray@google.com>]

On 2022-05-03, Andreas Schwab wrote:
>The definitions are taken from the 1.0-rc2 version of the ELF psABI.
>---
> elf/elf.h | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
>diff --git a/elf/elf.h b/elf/elf.h
>index 0195029188..648bf66c7d 100644
>--- a/elf/elf.h
>+++ b/elf/elf.h
>@@ -3927,6 +3927,8 @@ enum
> #define EF_RISCV_FLOAT_ABI_SINGLE 	0x0002
> #define EF_RISCV_FLOAT_ABI_DOUBLE 	0x0004
> #define EF_RISCV_FLOAT_ABI_QUAD 	0x0006
>+#define EF_RISCV_RVE			0x0008
>+#define EF_RISCV_TSO			0x0010
>
> /* RISC-V relocations.  */
> #define R_RISCV_NONE		 0
>@@ -3987,6 +3989,18 @@ enum
>
> #define R_RISCV_NUM		59
>
>+/* RISC-V specific values for the st_other field.  */
>+#define STO_RISCV_VARIANT_CC	0x80

I see that there is a precedent that STO_AARCH64_VARIANT_PCS calls this
"AArch64 specific values for the st_other field", but a descriptive
comment may be more useful, e.g. "Mark functions that do not follow the
standard calling convention for the ABI in use."

"RISC-V specific" can probably be removed as "RISCV" in the macro name
self explains.

>+/* RISC-V specific values for the sh_type field.  */
>+#define SHT_RISCV_ATTRIBUTES	(SHT_LOPROC + 3)
>+
>+/* RISC-V specific values for the p_type field.  */
>+#define PT_RISCV_ATTRIBUTES	(PT_LOPROC + 3)
>+
>+/* RISC-V specific values for the d_tag field.  */
>+#define DT_RISCV_VARIANT_CC	(DT_LOPROC + 1)
>+
> /* BPF specific declarations.  */
>
> #define R_BPF_NONE		0	/* No reloc */
>-- 
>2.35.2

I have verified these values match
https://github.com/riscv-non-isa/riscv-elf-psabi-doc/releases/download/v1.0-rc2/riscv-abi.pdf

Reviewed-by: Fangrui Song <maskray@google.com>