[PATCH v1] riscv/kexec_file: Fix relocation type R_RISCV_ADD16 and R_RISCV_SUB16 unknown

[Andrew Jones]

On Thu, Jul 11, 2024 at 08:32:36AM GMT, sunying at isrc.iscas.ac.cn wrote:
> From: Ying Sun <sunying at isrc.iscas.ac.cn>
> 
> Runs on the kernel with CONFIG_RISCV_ALTERNATIVE enabled:
>   kexec -sl vmlinux
> 
> Error:
>   kexec_image: Unknown rela relocation: 34
>   kexec_image: Error loading purgatory ret=-8
> and
>   kexec_image: Unknown rela relocation: 38
>   kexec_image: Error loading purgatory ret=-8
> 
> The purgatory code uses the 16-bit addition and subtraction relocation
> type, but not handled, resulting in kexec_file_load failure.
> So add handle to arch_kexec_apply_relocations_add().
> 
> Tested on RISC-V64 Qemu-virt, issue fixed.
> 
> Co-developed-by: Petr Tesarik <petr at tesarici.cz>
> Signed-off-by: Petr Tesarik <petr at tesarici.cz>
> Signed-off-by: Ying Sun <sunying at isrc.iscas.ac.cn>
> ---
>  arch/riscv/kernel/elf_kexec.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/riscv/kernel/elf_kexec.c b/arch/riscv/kernel/elf_kexec.c
> index 11c0d2e0becf..3c37661801f9 100644
> --- a/arch/riscv/kernel/elf_kexec.c
> +++ b/arch/riscv/kernel/elf_kexec.c
> @@ -451,6 +451,12 @@ int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
>  			*(u32 *)loc = CLEAN_IMM(CJTYPE, *(u32 *)loc) |
>  				 ENCODE_CJTYPE_IMM(val - addr);
>  			break;
> +		case R_RISCV_ADD16:
> +			*(u16 *)loc += val;
> +			break;
> +		case R_RISCV_SUB16:
> +			*(u16 *)loc -= val;
> +			break;
>  		case R_RISCV_ADD32:
>  			*(u32 *)loc += val;
>  			break;
> -- 
> 2.34.1
>

Reviewed-by: Andrew Jones <ajones at ventanamicro.com>