x86/alternatives: Move temporary_mm helpers into C

The only user of these inlines is the text poke code and this must not be
exposed to the world.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200421092559.139069561@linutronix.de

1 files changed, 0 insertions, 55 deletions

diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 2985d06660aa..47562147e70b 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -215,59 +215,4 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
 
 unsigned long __get_current_cr3_fast(void);
 
-typedef struct {
-	struct mm_struct *mm;
-} temp_mm_state_t;
-
-/*
- * Using a temporary mm allows to set temporary mappings that are not accessible
- * by other CPUs. Such mappings are needed to perform sensitive memory writes
- * that override the kernel memory protections (e.g., W^X), without exposing the
- * temporary page-table mappings that are required for these write operations to
- * other CPUs. Using a temporary mm also allows to avoid TLB shootdowns when the
- * mapping is torn down.
- *
- * Context: The temporary mm needs to be used exclusively by a single core. To
- *          harden security IRQs must be disabled while the temporary mm is
- *          loaded, thereby preventing interrupt handler bugs from overriding
- *          the kernel memory protection.
- */
-static inline temp_mm_state_t use_temporary_mm(struct mm_struct *mm)
-{
-	temp_mm_state_t temp_state;
-
-	lockdep_assert_irqs_disabled();
-	temp_state.mm = this_cpu_read(cpu_tlbstate.loaded_mm);
-	switch_mm_irqs_off(NULL, mm, current);
-
-	/*
-	 * If breakpoints are enabled, disable them while the temporary mm is
-	 * used. Userspace might set up watchpoints on addresses that are used
-	 * in the temporary mm, which would lead to wrong signals being sent or
-	 * crashes.
-	 *
-	 * Note that breakpoints are not disabled selectively, which also causes
-	 * kernel breakpoints (e.g., perf's) to be disabled. This might be
-	 * undesirable, but still seems reasonable as the code that runs in the
-	 * temporary mm should be short.
-	 */
-	if (hw_breakpoint_active())
-		hw_breakpoint_disable();
-
-	return temp_state;
-}
-
-static inline void unuse_temporary_mm(temp_mm_state_t prev_state)
-{
-	lockdep_assert_irqs_disabled();
-	switch_mm_irqs_off(NULL, prev_state.mm, current);
-
-	/*
-	 * Restore the breakpoints if they were disabled before the temporary mm
-	 * was loaded.
-	 */
-	if (hw_breakpoint_active())
-		hw_breakpoint_restore();
-}
-
 #endif /* _ASM_X86_MMU_CONTEXT_H */