linux-kernel - [PATCH 3/5] x86/its: move its_pages array to struct mod_arch

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Message-ID: <20250603111446.2609381-4-rppt@kernel.org>
Date: Tue,  3 Jun 2025 14:14:43 +0300
From: Mike Rapoport <rppt@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Ingo Molnar <mingo@...hat.com>,
	Jürgen Groß <jgross@...e.com>,
	Mike Rapoport <rppt@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Xin Li <xin@...or.com>,
	linux-kernel@...r.kernel.org,
	stable@...r.kernel.org,
	x86@...nel.org
Subject: [PATCH 3/5] x86/its: move its_pages array to struct mod_arch_specific

From: "Mike Rapoport (Microsoft)" <rppt@...nel.org>

The of pages with ITS thunks allocated for modules are tracked by an
array in 'struct module'.

Since this is very architecture specific data structure, move it to
'struct mod_arch_specific'.

No functional changes.

Fixes: 872df34d7c51 ("x86/its: Use dynamic thunks for indirect branches")
Suggested-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
---
 arch/x86/include/asm/module.h |  8 ++++++++
 arch/x86/kernel/alternative.c | 19 ++++++++++---------
 include/linux/module.h        |  5 -----
 3 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/arch/x86/include/asm/module.h b/arch/x86/include/asm/module.h
index e988bac0a4a1..3c2de4ce3b10 100644
--- a/arch/x86/include/asm/module.h
+++ b/arch/x86/include/asm/module.h
@@ -5,12 +5,20 @@
 #include <asm-generic/module.h>
 #include <asm/orc_types.h>
 
+struct its_array {
+#ifdef CONFIG_MITIGATION_ITS
+	void **pages;
+	int num;
+#endif
+};
+
 struct mod_arch_specific {
 #ifdef CONFIG_UNWINDER_ORC
 	unsigned int num_orcs;
 	int *orc_unwind_ip;
 	struct orc_entry *orc_unwind;
 #endif
+	struct its_array its_pages;
 };
 
 #endif /* _ASM_X86_MODULE_H */
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 45bcff181cba..372ef5dff631 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -195,8 +195,8 @@ void its_fini_mod(struct module *mod)
 	its_page = NULL;
 	mutex_unlock(&text_mutex);
 
-	for (int i = 0; i < mod->its_num_pages; i++) {
-		void *page = mod->its_page_array[i];
+	for (int i = 0; i < mod->arch.its_pages.num; i++) {
+		void *page = mod->arch.its_pages.pages[i];
 		execmem_restore_rox(page, PAGE_SIZE);
 	}
 }
@@ -206,11 +206,11 @@ void its_free_mod(struct module *mod)
 	if (!cpu_feature_enabled(X86_FEATURE_INDIRECT_THUNK_ITS))
 		return;
 
-	for (int i = 0; i < mod->its_num_pages; i++) {
-		void *page = mod->its_page_array[i];
+	for (int i = 0; i < mod->arch.its_pages.num; i++) {
+		void *page = mod->arch.its_pages.pages[i];
 		execmem_free(page);
 	}
-	kfree(mod->its_page_array);
+	kfree(mod->arch.its_pages.pages);
 }
 #endif /* CONFIG_MODULES */
 
@@ -223,14 +223,15 @@ static void *its_alloc(void)
 
 #ifdef CONFIG_MODULES
 	if (its_mod) {
-		void *tmp = krealloc(its_mod->its_page_array,
-				     (its_mod->its_num_pages+1) * sizeof(void *),
+		struct its_array *pages = &its_mod->arch.its_pages;
+		void *tmp = krealloc(pages->pages,
+				     (pages->num+1) * sizeof(void *),
 				     GFP_KERNEL);
 		if (!tmp)
 			return NULL;
 
-		its_mod->its_page_array = tmp;
-		its_mod->its_page_array[its_mod->its_num_pages++] = page;
+		pages->pages = tmp;
+		pages->pages[pages->num++] = page;
 
 		execmem_make_temp_rw(page, PAGE_SIZE);
 	}
diff --git a/include/linux/module.h b/include/linux/module.h
index 8050f77c3b64..b3329110d668 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -586,11 +586,6 @@ struct module {
 	atomic_t refcnt;
 #endif
 
-#ifdef CONFIG_MITIGATION_ITS
-	int its_num_pages;
-	void **its_page_array;
-#endif
-
 #ifdef CONFIG_CONSTRUCTORS
 	/* Constructor functions. */
 	ctor_fn_t *ctors;
-- 
2.47.2