[PATCH 2/3] x86: cleanly separate use of asm-generic/mm_hooks.h

From: Dave Hansen
Date: Tue Nov 18 2014 - 13:24:04 EST



From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>

asm-generic/mm_hooks.h provides some generic fillers for the 90%
of architectures that do not need to hook some mmap-mainipulation
functions. A comment inside says:

> Define generic no-op hooks for arch_dup_mmap and
> arch_exit_mmap, to be included in asm-FOO/mmu_context.h
> for any arch FOO which doesn't need to hook these.

So, does x86 need to hook these? It depends on CONFIG_PARAVIRT.
We *conditionally* include this generic header if we have
CONFIG_PARAVIRT=n. That's madness.

With this patch, x86 stops using asm-generic/mmu_hooks.h entirely.
We use our own copies of the functions. The paravirt code
provides some stubs if it is disabled, and we always call those
stubs in our x86-private versions of arch_exit_mmap() and
arch_dup_mmap().

Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---

b/arch/x86/include/asm/mmu_context.h | 13 +++++++++++--
b/arch/x86/include/asm/paravirt.h | 16 +++++++++++++---
2 files changed, 24 insertions(+), 5 deletions(-)

diff -puN arch/x86/include/asm/mmu_context.h~dmess-x86-mmu_hooks arch/x86/include/asm/mmu_context.h
--- a/arch/x86/include/asm/mmu_context.h~dmess-x86-mmu_hooks 2014-11-18 09:14:18.998070191 -0800
+++ b/arch/x86/include/asm/mmu_context.h 2014-11-18 09:14:19.002070371 -0800
@@ -12,8 +12,6 @@
#include <asm/paravirt.h>
#include <asm/mpx.h>
#ifndef CONFIG_PARAVIRT
-#include <asm-generic/mm_hooks.h>
-
static inline void paravirt_activate_mm(struct mm_struct *prev,
struct mm_struct *next)
{
@@ -103,6 +101,17 @@ do { \
} while (0)
#endif

+static inline void arch_dup_mmap(struct mm_struct *oldmm,
+ struct mm_struct *mm)
+{
+ paravirt_arch_dup_mmap(oldmm, mm);
+}
+
+static inline void arch_exit_mmap(struct mm_struct *mm)
+{
+ paravirt_arch_exit_mmap(mm);
+}
+
static inline void arch_bprm_mm_init(struct mm_struct *mm,
struct vm_area_struct *vma)
{
diff -puN arch/x86/include/asm/paravirt.h~dmess-x86-mmu_hooks arch/x86/include/asm/paravirt.h
--- a/arch/x86/include/asm/paravirt.h~dmess-x86-mmu_hooks 2014-11-18 09:14:18.999070236 -0800
+++ b/arch/x86/include/asm/paravirt.h 2014-11-18 09:14:19.003070416 -0800
@@ -330,13 +330,13 @@ static inline void paravirt_activate_mm(
PVOP_VCALL2(pv_mmu_ops.activate_mm, prev, next);
}

-static inline void arch_dup_mmap(struct mm_struct *oldmm,
- struct mm_struct *mm)
+static inline void paravirt_arch_dup_mmap(struct mm_struct *oldmm,
+ struct mm_struct *mm)
{
PVOP_VCALL2(pv_mmu_ops.dup_mmap, oldmm, mm);
}

-static inline void arch_exit_mmap(struct mm_struct *mm)
+static inline void paravirt_arch_exit_mmap(struct mm_struct *mm)
{
PVOP_VCALL1(pv_mmu_ops.exit_mmap, mm);
}
@@ -986,5 +986,15 @@ extern void default_banner(void);
#endif /* __ASSEMBLY__ */
#else /* CONFIG_PARAVIRT */
# define default_banner x86_init_noop
+#ifndef __ASSEMBLY__
+static inline void paravirt_arch_dup_mmap(struct mm_struct *oldmm,
+ struct mm_struct *mm)
+{
+}
+
+static inline void paravirt_arch_exit_mmap(struct mm_struct *mm)
+{
+}
+#endif /* __ASSEMBLY__ */
#endif /* !CONFIG_PARAVIRT */
#endif /* _ASM_X86_PARAVIRT_H */
_
--
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