[PATCH 3/8] x86/mm: break out user address space handling

Dave Hansen
2018-09-28T16:06:12Z

From: Dave Hansen <dave.hansen@linux.intel.com>

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

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
---

b/arch/x86/mm/fault.c | 47 ++++++++++++++++++++++++++++-------------------
1 file changed, 28 insertions(+), 19 deletions(-)

diff -puN arch/x86/mm/fault.c~pkeys-fault-warnings-01 arch/x86/mm/fault.c
--- a/arch/x86/mm/fault.c~pkeys-fault-warnings-01 2018-09-27 10:17:22.485343569 -0700
+++ b/arch/x86/mm/fault.c 2018-09-27 10:17:22.489343569 -0700
@@ -968,6 +968,7 @@ bad_area_access_error(struct pt_regs *re
__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)
@@ -1256,14 +1257,11 @@ do_kern_addr_fault(struct pt_regs *regs,
}
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;
@@ -1276,17 +1274,6 @@ __do_page_fault(struct pt_regs *regs, un
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;
@@ -1490,6 +1477,28 @@ 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
_