linux-kernel - [PATCH] x86: mpx: move bd_addr to mm_context

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Message-Id: <1481892055-24596-1-git-send-email-mark.rutland@arm.com>
Date:   Fri, 16 Dec 2016 12:40:55 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Mark Rutland <mark.rutland@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH] x86: mpx: move bd_addr to mm_context_t

Currently bd_addr lives in mm_struct, which is otherwise architecture
independent. Architecture-specific data is supposed to live within
mm_context_t (itself contained in mm_struct).

Other x86-specific context like the pkey accounting data lives in
mm_context_t, and there's no readon the MPX data can't also live there.
So as to keep the arch-specific data togather, and to set a good example
for others, this patch moves bd_addr into x86's mm_context_t.

Signed-off-by: Mark Rutland <mark.rutland@....com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/include/asm/mmu.h |  4 ++++
 arch/x86/include/asm/mpx.h |  4 ++--
 arch/x86/mm/mpx.c          | 10 +++++-----
 include/linux/mm_types.h   |  4 ----
 4 files changed, 11 insertions(+), 11 deletions(-)

I spotted this while trying to find a place to but some arm64-specific data.
I now know to use mm_context_t, but was almost lead astray by the MPX example.

I've given this a build-test (with CONFIG_X86_INTEL_MPX selected), and all
seems happy.

Mark.

diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h
index 72198c6..f9813b6 100644
--- a/arch/x86/include/asm/mmu.h
+++ b/arch/x86/include/asm/mmu.h
@@ -31,6 +31,10 @@
 	u16 pkey_allocation_map;
 	s16 execute_only_pkey;
 #endif
+#ifdef CONFIG_X86_INTEL_MPX
+	/* address of the bounds directory */
+	void __user *bd_addr;
+#endif
 } mm_context_t;
 
 #ifdef CONFIG_SMP
diff --git a/arch/x86/include/asm/mpx.h b/arch/x86/include/asm/mpx.h
index 7a35495..0b416d4 100644
--- a/arch/x86/include/asm/mpx.h
+++ b/arch/x86/include/asm/mpx.h
@@ -59,7 +59,7 @@
 int mpx_handle_bd_fault(void);
 static inline int kernel_managing_mpx_tables(struct mm_struct *mm)
 {
-	return (mm->bd_addr != MPX_INVALID_BOUNDS_DIR);
+	return (mm->context.bd_addr != MPX_INVALID_BOUNDS_DIR);
 }
 static inline void mpx_mm_init(struct mm_struct *mm)
 {
@@ -67,7 +67,7 @@ static inline void mpx_mm_init(struct mm_struct *mm)
 	 * NULL is theoretically a valid place to put the bounds
 	 * directory, so point this at an invalid address.
 	 */
-	mm->bd_addr = MPX_INVALID_BOUNDS_DIR;
+	mm->context.bd_addr = MPX_INVALID_BOUNDS_DIR;
 }
 void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
 		      unsigned long start, unsigned long end);
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index e4f8009..324e571 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -350,12 +350,12 @@ int mpx_enable_management(void)
 	 * The copy_xregs_to_kernel() beneath get_xsave_field_ptr() is
 	 * expected to be relatively expensive. Storing the bounds
 	 * directory here means that we do not have to do xsave in the
-	 * unmap path; we can just use mm->bd_addr instead.
+	 * unmap path; we can just use mm->context.bd_addr instead.
 	 */
 	bd_base = mpx_get_bounds_dir();
 	down_write(&mm->mmap_sem);
-	mm->bd_addr = bd_base;
-	if (mm->bd_addr == MPX_INVALID_BOUNDS_DIR)
+	mm->context.bd_addr = bd_base;
+	if (mm->context.bd_addr == MPX_INVALID_BOUNDS_DIR)
 		ret = -ENXIO;
 
 	up_write(&mm->mmap_sem);
@@ -370,7 +370,7 @@ int mpx_disable_management(void)
 		return -ENXIO;
 
 	down_write(&mm->mmap_sem);
-	mm->bd_addr = MPX_INVALID_BOUNDS_DIR;
+	mm->context.bd_addr = MPX_INVALID_BOUNDS_DIR;
 	up_write(&mm->mmap_sem);
 	return 0;
 }
@@ -947,7 +947,7 @@ static int try_unmap_single_bt(struct mm_struct *mm,
 		end = bta_end_vaddr;
 	}
 
-	bde_vaddr = mm->bd_addr + mpx_get_bd_entry_offset(mm, start);
+	bde_vaddr = mm->context.bd_addr + mpx_get_bd_entry_offset(mm, start);
 	ret = get_bt_addr(mm, bde_vaddr, &bt_addr);
 	/*
 	 * No bounds table there, so nothing to unmap.
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 4a8aced..ce70ceb 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -508,10 +508,6 @@ struct mm_struct {
 	bool tlb_flush_pending;
 #endif
 	struct uprobes_state uprobes_state;
-#ifdef CONFIG_X86_INTEL_MPX
-	/* address of the bounds directory */
-	void __user *bd_addr;
-#endif
 #ifdef CONFIG_HUGETLB_PAGE
 	atomic_long_t hugetlb_usage;
 #endif
-- 
1.9.1