linux-kernel - [PATCH] LoongArch: Use correct API to map cmdline in relocate

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Date: Tue,  2 Jul 2024 23:14:15 +0800
From: Huacai Chen <chenhuacai@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: loongarch@...ts.linux.dev,
	Xuefeng Li <lixuefeng@...ngson.cn>,
	Guo Ren <guoren@...nel.org>,
	Xuerui Wang <kernel@...0n.name>,
	Jiaxun Yang <jiaxun.yang@...goat.com>,
	linux-kernel@...r.kernel.org,
	loongson-kernel@...ts.loongnix.cn,
	Huacai Chen <chenhuacai@...ngson.cn>
Subject: [PATCH] LoongArch: Use correct API to map cmdline in relocate_kernel()

fw_arg1 is in memory space rather than I/O space, so we should use
early_memremap_ro() instead of early_ioremap() to map the cmdline.
Moreover, we should unmap it after using.

Suggested-by: Jiaxun Yang <jiaxun.yang@...goat.com>
Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
---
 arch/loongarch/kernel/relocate.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/loongarch/kernel/relocate.c b/arch/loongarch/kernel/relocate.c
index 1acfa704c8d0..0eddd4a66b87 100644
--- a/arch/loongarch/kernel/relocate.c
+++ b/arch/loongarch/kernel/relocate.c
@@ -13,6 +13,7 @@
 #include <asm/bootinfo.h>
 #include <asm/early_ioremap.h>
 #include <asm/inst.h>
+#include <asm/io.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
 
@@ -170,7 +171,7 @@ unsigned long __init relocate_kernel(void)
 	unsigned long kernel_length;
 	unsigned long random_offset = 0;
 	void *location_new = _text; /* Default to original kernel start */
-	char *cmdline = early_ioremap(fw_arg1, COMMAND_LINE_SIZE); /* Boot command line is passed in fw_arg1 */
+	char *cmdline = early_memremap_ro(fw_arg1, COMMAND_LINE_SIZE); /* Boot command line is passed in fw_arg1 */
 
 	strscpy(boot_command_line, cmdline, COMMAND_LINE_SIZE);
 
@@ -182,6 +183,7 @@ unsigned long __init relocate_kernel(void)
 		random_offset = (unsigned long)location_new - (unsigned long)(_text);
 #endif
 	reloc_offset = (unsigned long)_text - VMLINUX_LOAD_ADDRESS;
+	early_memunmap(cmdline, COMMAND_LINE_SIZE);
 
 	if (random_offset) {
 		kernel_length = (long)(_end) - (long)(_text);
-- 
2.43.0