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authorPunit Agrawal <punit.agrawal@arm.com>2017-06-08 18:25:28 +0100
committerWill Deacon <will.deacon@arm.com>2017-06-12 16:04:29 +0100
commit0e3a9026396cd7d0eb5777ba923a8f30a3d9db19 (patch)
treea56b116717c88dc06c80cdd997be2c24efa9462b /arch/arm64/mm
parentarm64: hwpoison: add VM_FAULT_HWPOISON[_LARGE] handling (diff)
downloadlinux-dev-0e3a9026396cd7d0eb5777ba923a8f30a3d9db19.tar.xz
linux-dev-0e3a9026396cd7d0eb5777ba923a8f30a3d9db19.zip
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 Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/mm')
-rw-r--r--arch/arm64/mm/fault.c68
1 files changed, 36 insertions, 32 deletions
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index d73e7f1fe184..ea2ea68d1bd7 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -359,7 +359,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
{
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;
unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
@@ -398,6 +398,8 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
die("Accessing user space memory outside uaccess.h routines", regs, esr);
}
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
+
/*
* As per x86, we may deadlock here. However, since the kernel only
* validly references user space from well defined areas of the code,
@@ -421,24 +423,42 @@ retry:
}
fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk);
+ major |= fault & VM_FAULT_MAJOR;
- /*
- * If we need to retry but a fatal signal is pending, handle the
- * signal first. We do not need to release the mmap_sem because it
- * would already be released in __lock_page_or_retry in mm/filemap.c.
- */
- if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
- return 0;
+ if (fault & VM_FAULT_RETRY) {
+ /*
+ * If we need to retry but a fatal signal is pending,
+ * handle the signal first. We do not need to release
+ * the mmap_sem because it would already be released
+ * in __lock_page_or_retry in mm/filemap.c.
+ */
+ if (fatal_signal_pending(current))
+ return 0;
+
+ /*
+ * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
+ * starvation.
+ */
+ if (mm_flags & FAULT_FLAG_ALLOW_RETRY) {
+ mm_flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ mm_flags |= FAULT_FLAG_TRIED;
+ goto retry;
+ }
+ }
+ up_read(&mm->mmap_sem);
/*
- * 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);
@@ -447,25 +467,9 @@ retry:
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
addr);
}
- if (fault & VM_FAULT_RETRY) {
- /*
- * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
- * starvation.
- */
- mm_flags &= ~FAULT_FLAG_ALLOW_RETRY;
- mm_flags |= FAULT_FLAG_TRIED;
- goto retry;
- }
- }
-
- up_read(&mm->mmap_sem);
- /*
- * 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