From 8718e5a3090bbfd759801d088b700aab21e8e989 Mon Sep 17 00:00:00 2001 From: Xiaofeng Yuan Date: Mon, 31 Aug 2026 19:11:23 -0600 Subject: [PATCH] riscv: patch: skip fixmap mapping when kernel text is already writable 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 that case. The module text path is already gated on CONFIG_STRICT_MODULE_RWX and is kept unchanged. Reported-by: Klara Modin Closes: https://lore.kernel.org/all/ant_8TaBbov_GS4i@soda.int.kasm.eu/ Reported-by: Lad Prabhakar Closes: https://lore.kernel.org/all/CA+V-a8tQK8rih9SGGTyqrEBGpNkx4H0eX2YccCRrgkVAPr+EBg@mail.gmail.com/ Tested-by: Klara Modin Tested-by: Lad Prabhakar Link: https://patch.msgid.link/20260814082742.148403-3-xiaofengmian@163.com Signed-off-by: Paul Walmsley --- arch/riscv/kernel/patch.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c index 16b243376f36..2239c28981bc 100644 --- a/arch/riscv/kernel/patch.c +++ b/arch/riscv/kernel/patch.c @@ -45,6 +45,8 @@ static __always_inline void *patch_map(void *addr, const unsigned int fixmap) phys_addr_t phys; if (core_kernel_text(uintaddr) || is_kernel_exittext(uintaddr)) { + if (!IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) + return addr; phys = __pa_symbol(addr); } else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) { struct page *page = vmalloc_to_page(addr);