Re: [PATCH] ARC: update definitions in elf/elf.h

[Vineet Gupta via Libc-alpha <libc-alpha@sourceware.org>]

On 11/18/22 05:15, Shahab Vahedi wrote:
> While porting ARCv2 to elfutils [1], it was brought up that the
> necessary changes to the project's libelf/elf.h must come from
> glibc, because they sync it from glibc [2].  Therefore, this patch
> is to update ARC entries in elf/elf.h.
>
> The majority of the update is about adding new definitions,
> specially for the relocations.  However, there is one rename, one
> deletion, and one change:

For completeness: And some cosmetic changes to uppercase hex digits.

>
> - R_ARC_JUMP_SLOT renamed to R_ARC_JMP_SLOT to match binutils.
> - R_ARC_B26 removed because it is unused and deprecated.
> - R_ARC_TLS_DTPOFF_S9 changed from 0x4a to the correct value 0x49.

Technically this would be an ABI change, but is currently not being used 
in glibc at all (and I doubt anything outside glibc would use it 
anyways) so this should be non-controversial.

> [1]
> https://sourceware.org/pipermail/elfutils-devel/2022q4/005530.html
>
> [2]
> https://sourceware.org/pipermail/elfutils-devel/2022q4/005548.html
>
> Signed-off-by: Shahab Vahedi <shahab@synopsys.com>
> ---
>   elf/elf.h | 30 +++++++++++++++++++++++++-----
>   1 file changed, 25 insertions(+), 5 deletions(-)
>
> diff --git a/elf/elf.h b/elf/elf.h
> index 920e6891e6..dfe5f79036 100644
> --- a/elf/elf.h
> +++ b/elf/elf.h
> @@ -4160,13 +4160,23 @@ enum
>   #define R_LARCH_GNU_VTENTRY  58
>   
>   
> +/* ARC specific declarations.  */
> +
> +/* Processor specific flags for the Ehdr e_flags field.  */
> +#define EF_ARC_MACH_MSK	    0x000000ff
> +#define EF_ARC_OSABI_MSK    0x00000f00
> +#define EF_ARC_ALL_MSK	    (EF_ARC_MACH_MSK | EF_ARC_OSABI_MSK)
> +
> +/* Processor specific values for the Shdr sh_type field.  */
> +#define SHT_ARC_ATTRIBUTES	(SHT_LOPROC + 1) /* ARC attributes section.  */
> +
>   /* ARCompact/ARCv2 specific relocs.  */
>   #define R_ARC_NONE		0x0
>   #define R_ARC_8			0x1
>   #define R_ARC_16		0x2
>   #define R_ARC_24		0x3
>   #define R_ARC_32		0x4
> -#define R_ARC_B26		0x5
> +
>   #define R_ARC_B22_PCREL		0x6
>   #define R_ARC_H30		0x7
>   #define R_ARC_N8		0x8
> @@ -4206,16 +4216,23 @@ enum
>   #define R_ARC_SECTOFF_ME_2	0x2A
>   #define R_ARC_SECTOFF_1		0x2B
>   #define R_ARC_SECTOFF_2		0x2C
> +#define R_ARC_SDA_12		0x2D
> +#define R_ARC_SDA16_ST2		0x30
> +#define R_ARC_32_PCREL		0x31

OK.

>   #define R_ARC_PC32		0x32
>   #define R_ARC_GOTPC32		0x33
>   #define R_ARC_PLT32		0x34
>   #define R_ARC_COPY		0x35
>   #define R_ARC_GLOB_DAT		0x36
> -#define R_ARC_JUMP_SLOT		0x37
> +#define R_ARC_JMP_SLOT		0x37

Did you build glibc with this change ? There are references to old 
definition.

git grep R_ARC_JUMP_SLOT

sysdeps/arc/dl-machine.h:199:  ((((type) == 
R_ARC_JUMP_SLOT                                     \
sysdeps/arc/dl-machine.h:206:#define ELF_MACHINE_JMP_SLOT R_ARC_JUMP_SLOT
sysdeps/arc/dl-machine.h:277:        case R_ARC_JUMP_SLOT:
sysdeps/arc/dl-machine.h:337:  if (r_type == R_ARC_JUMP_SLOT)



>   #define R_ARC_RELATIVE		0x38
>   #define R_ARC_GOTOFF		0x39
>   #define R_ARC_GOTPC		0x3A
>   #define R_ARC_GOT32		0x3B
> +#define R_ARC_S21W_PCREL_PLT	0x3C
> +#define R_ARC_S25H_PCREL_PLT	0x3D
> +
> +#define R_ARC_JLI_SECTOFF	0x3F

OK.

>   #define R_ARC_TLS_DTPMOD	0x42
>   #define R_ARC_TLS_DTPOFF	0x43
> @@ -4224,9 +4241,12 @@ enum
>   #define R_ARC_TLS_GD_LD	        0x46
>   #define R_ARC_TLS_GD_CALL	0x47
>   #define R_ARC_TLS_IE_GOT	0x48
> -#define R_ARC_TLS_DTPOFF_S9	0x4a
> -#define R_ARC_TLS_LE_S9		0x4a
> -#define R_ARC_TLS_LE_32		0x4b
> +#define R_ARC_TLS_DTPOFF_S9	0x49

Value change, but not used currently so no ABI implications.

> +#define R_ARC_TLS_LE_S9		0x4A

cosmetic. OK

> +#define R_ARC_TLS_LE_32		0x4B

Ditto.

> +#define R_ARC_S25W_PCREL_PLT	0x4C
> +#define R_ARC_S21H_PCREL_PLT	0x4D
> +#define R_ARC_NPS_CMEM16	0x4E

OK.