linux-kernel - [PATCH v1 1/3] riscv/kexec: handle R_RISCV_CALL

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Message-Id: <652f652d571458522a615040f68a885f10b45ca7.1690274483.git.petr.tesarik.ext@huawei.com>
Date:   Tue, 25 Jul 2023 10:44:25 +0200
From:   Petr Tesarik <petrtesarik@...weicloud.com>
To:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Li Huafei <lihuafei1@...wei.com>,
        Liao Chang <liaochang1@...wei.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Alyssa Ross <hi@...ssa.is>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Ricardo Ribalda <ribalda@...omium.org>,
        Kees Cook <keescook@...omium.org>,
        Heiko Stuebner <heiko@...ech.de>,
        Li Zhengyu <lizhengyu3@...wei.com>,
        linux-riscv@...ts.infradead.org (open list:RISC-V ARCHITECTURE),
        linux-kernel@...r.kernel.org (open list)
Cc:     Roberto Sassu <roberto.sassu@...weicloud.com>, petr@...arici.cz
Subject: [PATCH v1 1/3] riscv/kexec: handle R_RISCV_CALL_PLT relocation type

From: Torsten Duwe <duwe@...e.de>

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@...e.de>
Signed-off-by: Petr Tesarik <petr.tesarik.ext@...wei.com>
Cc: Li Zhengyu <lizhengyu3@...wei.com>
Cc: stable@...r.kernel.org
---
 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);
-- 
2.25.1