[PATCH 2/2] riscv: patch: skip fixmap mapping when kernel text is already writable

[Xiaofeng Yuan]

Currently patch_map() always creates a temporary writable mapping via
fixmap for kernel text addresses, even when CONFIG_STRICT_KERNEL_RWX
is disabled and the kernel text is already mapped with _PAGE_WRITE.

This is unnecessary overhead at best, and on minimal configurations
it can cause page faults.

Skip the fixmap path for kernel text when CONFIG_STRICT_KERNEL_RWX
is not enabled, since the text pages are already writable in this case.

Signed-off-by: Xiaofeng Yuan <xiaofengmian at 163.com>
---
 arch/riscv/kernel/patch.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
index 16b243376..b6e8e1e83 100644
--- a/arch/riscv/kernel/patch.c
+++ b/arch/riscv/kernel/patch.c
@@ -44,7 +44,8 @@ static __always_inline void *patch_map(void *addr, const unsigned int fixmap)
 	uintptr_t uintaddr = (uintptr_t) addr;
 	phys_addr_t phys;
 
-	if (core_kernel_text(uintaddr) || is_kernel_exittext(uintaddr)) {
+	if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX) &&
+	    (core_kernel_text(uintaddr) || is_kernel_exittext(uintaddr))) {
 		phys = __pa_symbol(addr);
 	} else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) {
 		struct page *page = vmalloc_to_page(addr);
-- 
2.43.0