Re: [PATCH v1 1/3] riscv/kexec: handle R_RISCV_CALL_PLT relocation type

[Petr Tesařík]

+Cc Torsten (somehow missed from the original Cc list).

Petr T

On Tue, 25 Jul 2023 10:44:25 +0200
Petr Tesarik <petrtesarik@xxxxxxxxxxxxxxx> wrote:

> From: Torsten Duwe <duwe@xxxxxxx>
> 
> R_RISCV_CALL has been deprecated and replaced by R_RISCV_CALL_PLT. See Enum
> 18-19 in Table 3. Relocation types here:
> 
> https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-elf.adoc
> 
> It was deprecated in ("Deprecated R_RISCV_CALL, prefer R_RISCV_CALL_PLT"):
> 
> https://github.com/riscv-non-isa/riscv-elf-psabi-doc/commit/a0dced85018d7a0ec17023c9389cbd70b1dbc1b0
> 
> Recent tools (at least GNU binutils-2.40) already use R_RISCV_CALL_PLT.
> Kernels built with such binutils fail kexec_load_file(2) with:
> 
>  kexec_image: Unknown rela relocation: 19
>  kexec_image: Error loading purgatory ret=-8
> 
> The binary code at the call site remains the same, so tell
> arch_kexec_apply_relocations_add() to handle _PLT alike.
> 
> Fixes: 838b3e28488f ("RISC-V: Load purgatory in kexec_file")
> Signed-off-by: Torsten Duwe <duwe@xxxxxxx>
> Signed-off-by: Petr Tesarik <petr.tesarik.ext@xxxxxxxxxx>
> Cc: Li Zhengyu <lizhengyu3@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
>  arch/riscv/kernel/elf_kexec.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/riscv/kernel/elf_kexec.c b/arch/riscv/kernel/elf_kexec.c
> index 5372b708fae2..38390d3bdcac 100644
> --- a/arch/riscv/kernel/elf_kexec.c
> +++ b/arch/riscv/kernel/elf_kexec.c
> @@ -425,6 +425,7 @@ int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
>  		 * sym, instead of searching the whole relsec.
>  		 */
>  		case R_RISCV_PCREL_HI20:
> +		case R_RISCV_CALL_PLT:
>  		case R_RISCV_CALL:
>  			*(u64 *)loc = CLEAN_IMM(UITYPE, *(u64 *)loc) |
>  				 ENCODE_UJTYPE_IMM(val - addr);