linux-kernel - [PATCH v2 8/8] riscv: remove limit on the size of read-only section for XIP kernel

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Date: Fri,  7 Jun 2024 22:22:13 +0200
From: Nam Cao <namcao@...utronix.de>
To: Alexandre Ghiti <alexghiti@...osinc.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 8/8] riscv: remove limit on the size of read-only section for XIP kernel

XIP_OFFSET is the hard-coded offset of writable data section within the
kernel.

By hard-coding this value, the read-only section of the kernel (which is
placed before the writable data section) is restricted in size. This causes
build failures if the kernel gets too big [1].

Remove this limit.

Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202404211031.J6l2AfJk-lkp@intel.com [1]
Signed-off-by: Nam Cao <namcao@...utronix.de>
Reviewed-by: Alexandre Ghiti <alexghiti@...osinc.com>
---
 arch/riscv/include/asm/pgtable.h    | 7 -------
 arch/riscv/include/asm/set_memory.h | 2 +-
 arch/riscv/kernel/vmlinux-xip.lds.S | 5 +++--
 3 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 1bc103aa9b74..bf4afffe0c53 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -107,13 +107,6 @@
 
 #endif
 
-#ifdef CONFIG_XIP_KERNEL
-#define XIP_OFFSET		SZ_32M
-#define XIP_OFFSET_MASK		(SZ_32M - 1)
-#else
-#define XIP_OFFSET		0
-#endif
-
 #ifndef __ASSEMBLY__
 
 #include <asm/page.h>
diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h
index ec11001c3fe0..ab92fc84e1fc 100644
--- a/arch/riscv/include/asm/set_memory.h
+++ b/arch/riscv/include/asm/set_memory.h
@@ -46,7 +46,7 @@ bool kernel_page_present(struct page *page);
 
 #endif /* __ASSEMBLY__ */
 
-#ifdef CONFIG_STRICT_KERNEL_RWX
+#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_XIP_KERNEL)
 #ifdef CONFIG_64BIT
 #define SECTION_ALIGN (1 << 21)
 #else
diff --git a/arch/riscv/kernel/vmlinux-xip.lds.S b/arch/riscv/kernel/vmlinux-xip.lds.S
index 8c3daa1b0531..a7611789bad5 100644
--- a/arch/riscv/kernel/vmlinux-xip.lds.S
+++ b/arch/riscv/kernel/vmlinux-xip.lds.S
@@ -14,6 +14,7 @@
 #include <asm/page.h>
 #include <asm/cache.h>
 #include <asm/thread_info.h>
+#include <asm/set_memory.h>
 
 OUTPUT_ARCH(riscv)
 ENTRY(_start)
@@ -65,10 +66,10 @@ SECTIONS
  * From this point, stuff is considered writable and will be copied to RAM
  */
 	__data_loc = ALIGN(PAGE_SIZE);		/* location in file */
-	. = KERNEL_LINK_ADDR + XIP_OFFSET;	/* location in memory */
+	. = ALIGN(SECTION_ALIGN);		/* location in memory */
 
 #undef LOAD_OFFSET
-#define LOAD_OFFSET (KERNEL_LINK_ADDR + XIP_OFFSET - (__data_loc & XIP_OFFSET_MASK))
+#define LOAD_OFFSET (KERNEL_LINK_ADDR + _sdata - __data_loc)
 
 	_sdata = .;			/* Start of data section */
 	_data = .;
-- 
2.39.2