[PATCH v2] RISC-V: Support 32_PCREL relocation type in kernel module

From: Nylon Chen <nylon.chen@sifive.com>
To: linux-kernel@vger.kernel.org
Cc: linux-riscv@lists.infradead.org, jszhang@kernel.org,
	ajones@ventanamicro.com, conor.dooley@microchip.com,
	aou@eecs.berkeley.edu, palmer@dabbelt.com,
	paul.walmsley@sifive.com, greentime.hu@sifive.com,
	zong.li@sifive.com, nylon7717@gmail.com,
	Nylon Chen <nylon.chen@sifive.com>
Subject: [PATCH v2] RISC-V: Support 32_PCREL relocation type in kernel module
Date: Thu, 15 Jun 2023 15:23:02 +0800	[thread overview]
Message-ID: <20230615072302.25638-1-nylon.chen@sifive.com> (raw)

Fix the 'unsupported relocation type' error caused by
enabling the -fasynchronous-unwind-tables flag,
which generates relocation types that are not supported.

Signed-off-by: Nylon Chen <nylon.chen@sifive.com>
Reviewed-by: Zong Li <zong.li@sifive.com>
---
Changed in v2:
- add commit message.

 arch/riscv/kernel/module.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
index 7c651d55fcbd..65be0360a494 100644
--- a/arch/riscv/kernel/module.c
+++ b/arch/riscv/kernel/module.c
@@ -310,6 +310,15 @@ static int apply_r_riscv_sub64_rela(struct module *me, u32 *location,
 	return 0;
 }
 
+static int apply_r_riscv_pcrel_32_rela(struct module *me, u32 *location,
+				       Elf_Addr v)
+{
+	ptrdiff_t offset = (void *)v - (void *)location;
+
+	*location = (*location & 0xffff0000) | (offset & 0xffff);
+	return 0;
+}
+
 static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
 				Elf_Addr v) = {
 	[R_RISCV_32]			= apply_r_riscv_32_rela,
@@ -335,6 +344,7 @@ static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
 	[R_RISCV_SUB16]			= apply_r_riscv_sub16_rela,
 	[R_RISCV_SUB32]			= apply_r_riscv_sub32_rela,
 	[R_RISCV_SUB64]			= apply_r_riscv_sub64_rela,
+	[R_RISCV_32_PCREL]		= apply_r_riscv_pcrel_32_rela,
 };
 
 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
-- 
2.40.1


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