linux-kernel - [PATCH 5/8] riscv: add alignment for text, rodata and data sections

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Date:   Mon, 17 Feb 2020 16:32:20 +0800
From:   Zong Li <zong.li@...ive.com>
To:     paul.walmsley@...ive.com, palmer@...belt.com,
        aou@...s.berkeley.edu, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Cc:     Zong Li <zong.li@...ive.com>
Subject: [PATCH 5/8] riscv: add alignment for text, rodata and data sections

The kernel mapping will tried to optimize its mapping by using bigger
size. In rv64, it tries to use PMD_SIZE, and tryies to use PGDIR_SIZE in
rv32. To ensure that the start address of these sections could fit the
mapping entry size, make them align to the biggest alignment.

Define a macro SECTION_ALIGN because the HPAGE_SIZE or PMD_SIZE, etc.,
are invisible in linker script.

This patch is prepared for STRICT_KERNEL_RWX support.

Signed-off-by: Zong Li <zong.li@...ive.com>
---
 arch/riscv/include/asm/set_memory.h | 13 +++++++++++++
 arch/riscv/kernel/vmlinux.lds.S     |  4 +++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h
index a9783a878dca..a91f192063c2 100644
--- a/arch/riscv/include/asm/set_memory.h
+++ b/arch/riscv/include/asm/set_memory.h
@@ -6,6 +6,7 @@
 #ifndef _ASM_RISCV_SET_MEMORY_H
 #define _ASM_RISCV_SET_MEMORY_H
 
+#ifndef __ASSEMBLY__
 /*
  * Functions to change memory attributes.
  */
@@ -17,4 +18,16 @@ int set_memory_nx(unsigned long addr, int numpages);
 int set_direct_map_invalid_noflush(struct page *page);
 int set_direct_map_default_noflush(struct page *page);
 
+#endif /* __ASSEMBLY__ */
+
+#ifdef CONFIG_ARCH_HAS_STRICT_KERNEL_RWX
+#ifdef CONFIG_64BIT
+#define SECTION_ALIGN (1 << 21)
+#else
+#define SECTION_ALIGN (1 << 22)
+#endif
+#else /* !CONFIG_ARCH_HAS_STRICT_KERNEL_RWX */
+#define SECTION_ALIGN L1_CACHE_BYTES
+#endif /* CONFIG_ARCH_HAS_STRICT_KERNEL_RWX */
+
 #endif /* _ASM_RISCV_SET_MEMORY_H */
diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
index 4ba8a5397e8b..0b145b9c1778 100644
--- a/arch/riscv/kernel/vmlinux.lds.S
+++ b/arch/riscv/kernel/vmlinux.lds.S
@@ -37,6 +37,7 @@ SECTIONS
 	PERCPU_SECTION(L1_CACHE_BYTES)
 	__init_end = .;
 
+	. = ALIGN(SECTION_ALIGN);
 	.text : {
 		_text = .;
 		_stext = .;
@@ -53,13 +54,14 @@ SECTIONS
 	}
 
 	/* Start of data section */
-	RO_DATA(L1_CACHE_BYTES)
+	RO_DATA(SECTION_ALIGN)
 	.srodata : {
 		*(.srodata*)
 	}
 
 	EXCEPTION_TABLE(0x10)
 
+	. = ALIGN(SECTION_ALIGN);
 	_sdata = .;
 
 	RW_DATA(L1_CACHE_BYTES, PAGE_SIZE, THREAD_SIZE)
-- 
2.25.0