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

Commit Message

Petr Tesarik July 25, 2023, 8:44 a.m. UTC

From: Torsten Duwe <[e-mail]>

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 <[e-mail]>
Signed-off-by: Petr Tesarik <[e-mail]>
Cc: Li Zhengyu <[e-mail]>
Cc: [e-mail]
---
 arch/riscv/kernel/elf_kexec.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Petr Tesařík July 25, 2023, 10:15 a.m. UTC | #1

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

Petr T

On Tue, 25 Jul 2023 10:44:25 +0200
Petr Tesarik <[e-mail]> wrote:

> From: Torsten Duwe <[e-mail]>
> 
> 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 <[e-mail]>
> Signed-off-by: Petr Tesarik <[e-mail]>
> Cc: Li Zhengyu <[e-mail]>
> Cc: [e-mail]
> ---
>  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);

Patch

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);