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

Nam Cao
2024-06-07T20:22:18Z

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@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202404211031.J6l2AfJk-lkp@intel.com [1]
Signed-off-by: Nam Cao <namcao@linutronix.de>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.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