arm64: mm: Update perf accounting to handle poison faults
Re-organise the perf accounting for fault handling in preparation for
enabling handling of hardware poison faults in subsequent commits. The
change updates perf accounting to be inline with the behaviour on
x86.
With this update, the perf fault accounting -
* Always report PERF_COUNT_SW_PAGE_FAULTS
* Doesn't report anything else for VM_FAULT_ERROR (which includes
hwpoison faults)
* Reports PERF_COUNT_SW_PAGE_FAULTS_MAJ if it's a major
fault (indicated by VM_FAULT_MAJOR)
* Otherwise, reports PERF_COUNT_SW_PAGE_FAULTS_MIN
Test: run vts -m drop_caches_test
Change-Id: I4be2180ef9d046fb4f8edcbcc9dc30ce0c6622d2
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
(cherry picked from commit 0e3a9026396cd7d0eb5777ba923a8f30a3d9db19)
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index f840220..36d4bd5 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -339,7 +339,7 @@
{
struct task_struct *tsk;
struct mm_struct *mm;
- int fault, sig, code;
+ int fault, sig, code, major = 0;
unsigned long vm_flags = VM_READ | VM_WRITE | VM_EXEC;
unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
struct vm_area_struct *vma = NULL;
@@ -380,6 +380,8 @@
die("Accessing user space memory outside uaccess.h routines", regs, esr);
}
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
+
/*
* let's try a speculative page fault without grabbing the
* mmap_sem.
@@ -414,6 +416,8 @@
vma = find_vma(mm, addr);
fault = __do_page_fault(vma, addr, mm_flags, vm_flags, tsk);
+ major |= fault & VM_FAULT_MAJOR;
+
if (fault & VM_FAULT_RETRY) {
/*
* If we need to retry but a fatal signal is pending, handle the
@@ -449,14 +453,17 @@
done:
/*
- * Major/minor page fault accounting is only done on the initial
- * attempt. If we go through a retry, it is extremely likely that the
- * page will be found in page cache at that point.
+ * Handle the "normal" (no error) case first.
*/
-
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
- if (mm_flags & FAULT_FLAG_ALLOW_RETRY) {
- if (fault & VM_FAULT_MAJOR) {
+ if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
+ VM_FAULT_BADACCESS)))) {
+ /*
+ * Major/minor page fault accounting is only done
+ * once. If we go through a retry, it is extremely
+ * likely that the page will be found in page cache at
+ * that point.
+ */
+ if (major) {
tsk->maj_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
addr);
@@ -465,14 +472,8 @@
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
addr);
}
- }
-
- /*
- * Handle the "normal" case first - VM_FAULT_MAJOR
- */
- if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
- VM_FAULT_BADACCESS))))
return 0;
+ }
/*
* If we are in kernel mode at this point, we have no context to