From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Scott Wood <oss@buserror.net>,
Balbir Singh <bsingharora@gmail.com>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v3 3/5] powerpc/mm: Implement STRICT_KERNEL_RWX on PPC32
Date: Wed, 2 Aug 2017 15:51:05 +0200 (CEST) [thread overview]
Message-ID: <9924769359ceed81eac6938b56e2aa03c990ecba.1501679954.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1501679953.git.christophe.leroy@c-s.fr>
This patch implements STRICT_KERNEL_RWX on PPC32.
As for CONFIG_DEBUG_PAGEALLOC, it deactivates BAT and LTLB mappings
in order to allow page protection setup at the level of each page.
As BAT/LTLB mappings are deactivated, there might be a performance
impact.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v3: no change
arch/powerpc/Kconfig | 2 +-
arch/powerpc/kernel/vmlinux.lds.S | 2 +-
arch/powerpc/mm/init_32.c | 6 ++++++
arch/powerpc/mm/pgtable_32.c | 24 ++++++++++++++++++++++++
4 files changed, 32 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 5e9de178b557..02d91ee1b601 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -165,7 +165,7 @@ config PPC
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
- select ARCH_HAS_STRICT_KERNEL_RWX if (PPC_BOOK3S_64 && !RELOCATABLE && !HIBERNATION)
+ select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 || PPC32) && !RELOCATABLE && !HIBERNATION)
select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
select HAVE_CBPF_JIT if !PPC64
select HAVE_CONTEXT_TRACKING if PPC64
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index b1a250560198..882628fa6987 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -8,7 +8,7 @@
#include <asm/cache.h>
#include <asm/thread_info.h>
-#ifdef CONFIG_STRICT_KERNEL_RWX
+#if defined(CONFIG_STRICT_KERNEL_RWX) && !defined(CONFIG_PPC32)
#define STRICT_ALIGN_SIZE (1 << 24)
#else
#define STRICT_ALIGN_SIZE PAGE_SIZE
diff --git a/arch/powerpc/mm/init_32.c b/arch/powerpc/mm/init_32.c
index 8a7c38b8d335..7d5fee1bb116 100644
--- a/arch/powerpc/mm/init_32.c
+++ b/arch/powerpc/mm/init_32.c
@@ -113,6 +113,12 @@ void __init MMU_setup(void)
__map_without_bats = 1;
__map_without_ltlbs = 1;
}
+#ifdef CONFIG_STRICT_KERNEL_RWX
+ if (rodata_enabled) {
+ __map_without_bats = 1;
+ __map_without_ltlbs = 1;
+ }
+#endif
}
/*
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 85e8f0e0efe6..4a3dd9fc6989 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -34,6 +34,7 @@
#include <asm/fixmap.h>
#include <asm/io.h>
#include <asm/setup.h>
+#include <asm/sections.h>
#include "mmu_decl.h"
@@ -375,6 +376,29 @@ void mark_initmem_nx(void)
change_page_attr(page, numpages, PAGE_KERNEL);
}
+#ifdef CONFIG_STRICT_KERNEL_RWX
+void mark_rodata_ro(void)
+{
+ struct page *page;
+ unsigned long numpages;
+
+ page = virt_to_page(_stext);
+ numpages = PFN_UP((unsigned long)_etext) -
+ PFN_DOWN((unsigned long)_stext);
+
+ change_page_attr(page, numpages, PAGE_KERNEL_ROX);
+ /*
+ * mark .rodata as read only. Use __init_begin rather than __end_rodata
+ * to cover NOTES and EXCEPTION_TABLE.
+ */
+ page = virt_to_page(__start_rodata);
+ numpages = PFN_UP((unsigned long)__init_begin) -
+ PFN_DOWN((unsigned long)__start_rodata);
+
+ change_page_attr(page, numpages, PAGE_KERNEL_RO);
+}
+#endif
+
#ifdef CONFIG_DEBUG_PAGEALLOC
void __kernel_map_pages(struct page *page, int numpages, int enable)
{
--
2.13.3
next prev parent reply other threads:[~2017-08-02 13:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-02 13:50 [PATCH v3 0/5] powerpc/mm: Fix kernel protection and implement STRICT_KERNEL_RWX on PPC32 Christophe Leroy
2017-08-02 13:51 ` [PATCH v3 1/5] powerpc/mm: Ensure change_page_attr() doesn't invalidate pinned TLBs Christophe Leroy
2017-08-16 12:29 ` [v3, " Michael Ellerman
2017-08-02 13:51 ` [PATCH v3 2/5] powerpc/mm: Fix kernel RAM protection after freeing unused memory on PPC32 Christophe Leroy
2017-08-02 13:51 ` Christophe Leroy [this message]
2017-08-02 13:51 ` [PATCH v3 4/5] powerpc/mm: declare some local functions static Christophe Leroy
2017-08-02 13:51 ` [PATCH v3 5/5] powerpc/mm: Simplify __set_fixmap() Christophe Leroy
2017-08-03 7:24 ` [PATCH v3 0/5] powerpc/mm: Fix kernel protection and implement STRICT_KERNEL_RWX on PPC32 Balbir Singh
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