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Subject[PATCH 29/39] x86/mm/pti: Introduce pti_finalize()
Date
From: Joerg Roedel <jroedel@suse.de>

Introduce a new function to finalize the kernel mappings for
the userspace page-table after all ro/nx protections have been
applied to the kernel mappings.

Also move the call to pti_clone_kernel_text() to that
function so that it will run on 32 bit kernels too.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/include/asm/pti.h | 3 +--
arch/x86/mm/init_64.c | 6 ------
arch/x86/mm/pti.c | 14 +++++++++++++-
include/linux/pti.h | 1 +
init/main.c | 7 +++++++
5 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/pti.h b/arch/x86/include/asm/pti.h
index 38a17f1..5df09a0 100644
--- a/arch/x86/include/asm/pti.h
+++ b/arch/x86/include/asm/pti.h
@@ -6,10 +6,9 @@
#ifdef CONFIG_PAGE_TABLE_ISOLATION
extern void pti_init(void);
extern void pti_check_boottime_disable(void);
-extern void pti_clone_kernel_text(void);
+extern void pti_finalize(void);
#else
static inline void pti_check_boottime_disable(void) { }
-static inline void pti_clone_kernel_text(void) { }
#endif

#endif /* __ASSEMBLY__ */
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index a688617..9b19f9a 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1291,12 +1291,6 @@ void mark_rodata_ro(void)
(unsigned long) __va(__pa_symbol(_sdata)));

debug_checkwx();
-
- /*
- * Do this after all of the manipulation of the
- * kernel text page tables are complete.
- */
- pti_clone_kernel_text();
}

int kern_addr_valid(unsigned long addr)
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index fc77054..1825f30 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -462,7 +462,7 @@ static inline bool pti_kernel_image_global_ok(void)
* For some configurations, map all of kernel text into the user page
* tables. This reduces TLB misses, especially on non-PCID systems.
*/
-void pti_clone_kernel_text(void)
+static void pti_clone_kernel_text(void)
{
/*
* rodata is part of the kernel image and is normally
@@ -526,3 +526,15 @@ void __init pti_init(void)
pti_setup_espfix64();
pti_setup_vsyscall();
}
+
+/*
+ * Finalize the kernel mappings in the userspace page-table.
+ */
+void pti_finalize(void)
+{
+ /*
+ * Do this after all of the manipulation of the
+ * kernel text page tables are complete.
+ */
+ pti_clone_kernel_text();
+}
diff --git a/include/linux/pti.h b/include/linux/pti.h
index 0174883..1a941ef 100644
--- a/include/linux/pti.h
+++ b/include/linux/pti.h
@@ -6,6 +6,7 @@
#include <asm/pti.h>
#else
static inline void pti_init(void) { }
+static inline void pti_finalize(void) { }
#endif

#endif
diff --git a/init/main.c b/init/main.c
index 3b4ada1..fcfef46 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1065,6 +1065,13 @@ static int __ref kernel_init(void *unused)
jump_label_invalidate_initmem();
free_initmem();
mark_readonly();
+
+ /*
+ * Kernel mappings are now finalized - update the userspace page-table
+ * to finalize PTI.
+ */
+ pti_finalize();
+
system_state = SYSTEM_RUNNING;
numa_default_policy();

--
2.7.4
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