linux-kernel - [PATCH] openrisc: Add support for more module relocations

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Message-ID: <20240410205201.1885032-1-shorne@gmail.com>
Date: Wed, 10 Apr 2024 21:51:58 +0100
From: Stafford Horne <shorne@...il.com>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Stafford Horne <shorne@...il.com>,
	Jonas Bonn <jonas@...thpole.se>,
	Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
	Eric Biederman <ebiederm@...ssion.com>,
	Kees Cook <keescook@...omium.org>,
	linux-openrisc@...r.kernel.org,
	linux-mm@...ck.org
Subject: [PATCH] openrisc: Add support for more module relocations

When testing modules in OpenRISC I found R_OR32_AHI16 (signed adjusted
high 16-bit) and R_OR32_SLO16 (split low 16-bit) relocations are used in
modules but not implemented yet.

This patch adds the relocations. Note, we use the old naming R_OR32_*
instead or the new naming R_OR1K_* to avoid change as this header is
exported as a user api.

Signed-off-by: Stafford Horne <shorne@...il.com>
---
 arch/openrisc/include/uapi/asm/elf.h |  2 ++
 arch/openrisc/kernel/module.c        | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/arch/openrisc/include/uapi/asm/elf.h b/arch/openrisc/include/uapi/asm/elf.h
index 6868f81c281e..0c882a388524 100644
--- a/arch/openrisc/include/uapi/asm/elf.h
+++ b/arch/openrisc/include/uapi/asm/elf.h
@@ -43,6 +43,8 @@
 #define R_OR32_JUMPTARG	6
 #define R_OR32_VTINHERIT 7
 #define R_OR32_VTENTRY	8
+#define R_OR32_AHI16	35
+#define R_OR32_SLO16	39
 
 typedef unsigned long elf_greg_t;
 
diff --git a/arch/openrisc/kernel/module.c b/arch/openrisc/kernel/module.c
index 532013f523ac..01bda5616114 100644
--- a/arch/openrisc/kernel/module.c
+++ b/arch/openrisc/kernel/module.c
@@ -55,6 +55,16 @@ int apply_relocate_add(Elf32_Shdr *sechdrs,
 			value |= *location & 0xfc000000;
 			*location = value;
 			break;
+		case R_OR32_AHI16:
+			/* Adjust the operand to match with a signed LO16.  */
+			value += 0x8000;
+			*((uint16_t *)location + 1) = value >> 16;
+			break;
+		case R_OR32_SLO16:
+			/* Split value lower 16-bits.  */
+			value = ((value & 0xf800) << 10) | (value & 0x7ff);
+			*location = (*location & ~0x3e007ff) | value;
+			break;
 		default:
 			pr_err("module %s: Unknown relocation: %u\n",
 			       me->name, ELF32_R_TYPE(rel[i].r_info));
-- 
2.44.0