linux-kernel - [PATCH 3/4] arm64/mm: make tramp_pg_dir and swapper_pg

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Message-Id: <20180601080903.11868-1-yaojun8558363@gmail.com>
Date:   Fri,  1 Jun 2018 16:09:03 +0800
From:   Jun Yao <yaojun8558363@...il.com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     catalin.marinas@....com, will.deacon@....com,
        linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com,
        greg@...ah.com
Subject: [PATCH 3/4] arm64/mm: make tramp_pg_dir and swapper_pg_dir adjacent

To defense KSMA, we need to migrate tramp_pg_dir and swapper_pg_dir
together. Make them adjacent to avoid modifying tramp_(un)map_kernel.

Signed-off-by: Jun Yao <yaojun8558363@...il.com>
---
 arch/arm64/kernel/entry.S       | 4 ++--
 arch/arm64/kernel/vmlinux.lds.S | 9 +++++----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index ec2ee720e33e..b35425feaf56 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -1004,7 +1004,7 @@ __ni_sys_trace:
 
 	.macro tramp_map_kernel, tmp
 	mrs	\tmp, ttbr1_el1
-	add	\tmp, \tmp, #(PAGE_SIZE + RESERVED_TTBR0_SIZE)
+	add	\tmp, \tmp, #(PAGE_SIZE)
 	bic	\tmp, \tmp, #USER_ASID_FLAG
 	msr	ttbr1_el1, \tmp
 #ifdef CONFIG_QCOM_FALKOR_ERRATUM_1003
@@ -1023,7 +1023,7 @@ alternative_else_nop_endif
 
 	.macro tramp_unmap_kernel, tmp
 	mrs	\tmp, ttbr1_el1
-	sub	\tmp, \tmp, #(PAGE_SIZE + RESERVED_TTBR0_SIZE)
+	sub	\tmp, \tmp, #(PAGE_SIZE)
 	orr	\tmp, \tmp, #USER_ASID_FLAG
 	msr	ttbr1_el1, \tmp
 	/*
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 605d1b60469c..3c72e6dec890 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -219,15 +219,16 @@ SECTIONS
 	idmap_pg_dir = .;
 	. += IDMAP_DIR_SIZE;
 
+#ifdef CONFIG_ARM64_SW_TTBR0_PAN
+	reserved_ttbr0 = .;
+	. += RESERVED_TTBR0_SIZE;
+#endif
+
 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
 	tramp_pg_dir = .;
 	. += PAGE_SIZE;
 #endif
 
-#ifdef CONFIG_ARM64_SW_TTBR0_PAN
-	reserved_ttbr0 = .;
-	. += RESERVED_TTBR0_SIZE;
-#endif
 	swapper_pg_dir = .;
 	. += SWAPPER_DIR_SIZE;
 	swapper_pg_end = .;
-- 
2.17.0