linux-kernel - [PATCH 27/39] x86/mm/pti: Make pti_clone_kernel

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Date:   Wed, 11 Jul 2018 13:29:34 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        "H . Peter Anvin" <hpa@...or.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Juergen Gross <jgross@...e.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>, Jiri Kosina <jkosina@...e.cz>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Brian Gerst <brgerst@...il.com>,
        David Laight <David.Laight@...lab.com>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        Eduardo Valentin <eduval@...zon.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Will Deacon <will.deacon@....com>, aliguori@...zon.com,
        daniel.gruss@...k.tugraz.at, hughd@...gle.com, keescook@...gle.com,
        Andrea Arcangeli <aarcange@...hat.com>,
        Waiman Long <llong@...hat.com>, Pavel Machek <pavel@....cz>,
        "David H . Gutteridge" <dhgutteridge@...patico.ca>,
        jroedel@...e.de, joro@...tes.org
Subject: [PATCH 27/39] x86/mm/pti: Make pti_clone_kernel_text() compile on 32 bit

From: Joerg Roedel <jroedel@...e.de>

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 we need a symbol 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@...e.de>
---
 arch/x86/include/asm/sections.h |  1 +
 arch/x86/kernel/vmlinux.lds.S   | 17 ++++++++++-------
 arch/x86/mm/pti.c               |  2 +-
 3 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h
index 5c019d2..4a911a3 100644
--- 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
index 5e1458f..8bde0a4 100644
--- 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
index 2eadab0..4f6e933 100644
--- 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;
-- 
2.7.4