x86/mm/pti: Make pti_clone_kernel_text() compile on 32 bit

joergroedel · KAGA-KOKO · commit 39d668e04eda · 2018-07-20T01:11:44.000+02:00
The pti_clone_kernel_text() function references __end_rodata_hpage_align, which is only present on x86-64. This makes sense as the end of the rodata section is not huge-page aligned on 32 bit. Nevertheless a symbol is required for the function that points at the right address for both 32 and 64 bit. Introduce __end_rodata_aligned for that purpose and use it in pti_clone_kernel_text(). Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Pavel Machek <pavel@ucw.cz> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Waiman Long <llong@redhat.com> Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca> Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1531906876-13451-28-git-send-email-joro@8bytes.org
diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h
@@ -7,6 +7,7 @@
 
 extern char __brk_base[], __brk_limit[];
 extern struct exception_table_entry __stop___ex_table[];
+extern char __end_rodata_aligned[];
 
 #if defined(CONFIG_X86_64)
 extern char __end_rodata_hpage_align[];
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
@@ -55,19 +55,22 @@ jiffies_64 = jiffies;
  * so we can enable protection checks as well as retain 2MB large page
  * mappings for kernel text.
  */
-#define X64_ALIGN_RODATA_BEGIN	. = ALIGN(HPAGE_SIZE);
+#define X86_ALIGN_RODATA_BEGIN	. = ALIGN(HPAGE_SIZE);
 
-#define X64_ALIGN_RODATA_END					\
+#define X86_ALIGN_RODATA_END					\
 		. = ALIGN(HPAGE_SIZE);				\
-		__end_rodata_hpage_align = .;
+		__end_rodata_hpage_align = .;			\
+		__end_rodata_aligned = .;
 
 #define ALIGN_ENTRY_TEXT_BEGIN	. = ALIGN(PMD_SIZE);
 #define ALIGN_ENTRY_TEXT_END	. = ALIGN(PMD_SIZE);
 
 #else
 
-#define X64_ALIGN_RODATA_BEGIN
-#define X64_ALIGN_RODATA_END
+#define X86_ALIGN_RODATA_BEGIN
+#define X86_ALIGN_RODATA_END					\
+		. = ALIGN(PAGE_SIZE);				\
+		__end_rodata_aligned = .;
 
 #define ALIGN_ENTRY_TEXT_BEGIN
 #define ALIGN_ENTRY_TEXT_END
@@ -141,9 +144,9 @@ SECTIONS
 
 	/* .text should occupy whole number of pages */
 	. = ALIGN(PAGE_SIZE);
-	X64_ALIGN_RODATA_BEGIN
+	X86_ALIGN_RODATA_BEGIN
 	RO_DATA(PAGE_SIZE)
-	X64_ALIGN_RODATA_END
+	X86_ALIGN_RODATA_END
 
 	/* Data */
 	.data : AT(ADDR(.data) - LOAD_OFFSET) {
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
@@ -470,7 +470,7 @@ void pti_clone_kernel_text(void)
 	 * clone the areas past rodata, they might contain secrets.
 	 */
 	unsigned long start = PFN_ALIGN(_text);
-	unsigned long end = (unsigned long)__end_rodata_hpage_align;
+	unsigned long end = (unsigned long)__end_rodata_aligned;
 
 	if (!pti_kernel_image_global_ok())
 		return;
