[tip:x86/mm] x86/mm: Break out user address space handling

tip-bot for Dave Hansen
2018-10-09T15:03:36Z

Commit-ID: aa37c51b9421d66f7931c5fdcb9ce80c450974be
Gitweb: https://git.kernel.org/tip/aa37c51b9421d66f7931c5fdcb9ce80c450974be
Author: Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Fri, 28 Sep 2018 09:02:23 -0700
Committer: Peter Zijlstra <peterz@infradead.org>
CommitDate: Tue, 9 Oct 2018 16:51:15 +0200

x86/mm: Break out user address space handling

The last patch broke out kernel address space handing into its own
helper. Now, do the same for user address space handling.

Cc: x86@kernel.org
Cc: Jann Horn <jannh@google.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180928160223.9C4F6440@viggo.jf.intel.com
---
arch/x86/mm/fault.c | 47 ++++++++++++++++++++++++++++-------------------
1 file changed, 28 insertions(+), 19 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index c7e32f453852..0d1f5d39fc63 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -966,6 +966,7 @@ bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
__bad_area(regs, error_code, address, vma, SEGV_ACCERR);
}

+/* Handle faults in the kernel portion of the address space */
static void
do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address,
u32 *pkey, unsigned int fault)
@@ -1254,14 +1255,11 @@ do_kern_addr_fault(struct pt_regs *regs, unsigned long hw_error_code,
}
NOKPROBE_SYMBOL(do_kern_addr_fault);

-/*
- * This routine handles page faults. It determines the address,
- * and the problem, and then passes it off to one of the appropriate
- * routines.
- */
-static noinline void
-__do_page_fault(struct pt_regs *regs, unsigned long hw_error_code,
- unsigned long address)
+/* Handle faults in the user portion of the address space */
+static inline
+void do_user_addr_fault(struct pt_regs *regs,
+ unsigned long hw_error_code,
+ unsigned long address)
{
unsigned long sw_error_code;
struct vm_area_struct *vma;
@@ -1274,17 +1272,6 @@ __do_page_fault(struct pt_regs *regs, unsigned long hw_error_code,
tsk = current;
mm = tsk->mm;

- prefetchw(&mm->mmap_sem);
-
- if (unlikely(kmmio_fault(regs, address)))
- return;
-
- /* Was the fault on kernel-controlled part of the address space? */
- if (unlikely(fault_in_kernel_space(address))) {
- do_kern_addr_fault(regs, hw_error_code, address);
- return;
- }
-
/* kprobes don't want to hook the spurious faults: */
if (unlikely(kprobes_fault(regs)))
return;
@@ -1488,6 +1475,28 @@ good_area:

check_v8086_mode(regs, address, tsk);
}
+NOKPROBE_SYMBOL(do_user_addr_fault);
+
+/*
+ * This routine handles page faults. It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ */
+static noinline void
+__do_page_fault(struct pt_regs *regs, unsigned long hw_error_code,
+ unsigned long address)
+{
+ prefetchw(&current->mm->mmap_sem);
+
+ if (unlikely(kmmio_fault(regs, address)))
+ return;
+
+ /* Was the fault on kernel-controlled part of the address space? */
+ if (unlikely(fault_in_kernel_space(address)))
+ do_kern_addr_fault(regs, hw_error_code, address);
+ else
+ do_user_addr_fault(regs, hw_error_code, address);
+}
NOKPROBE_SYMBOL(__do_page_fault);

static nokprobe_inline void