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From:   Peter Xu <peterx@redhat.com>
To:     linux-kernel@vger.kernel.org, linux-mm@kvack.org
Cc:     Peter Xu <peterx@redhat.com>,
        Gerald Schaefer <gerald.schaefer@de.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Will Deacon <will@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Guan Xuetao <gxt@pku.edu.cn>
Subject: [PATCH 22/26] mm/unicore32: Use general page fault accounting
Date:   Fri, 19 Jun 2020 12:13:51 -0400
Message-Id: <20200619161351.9859-1-peterx@redhat.com>
In-Reply-To: <20200619160538.8641-1-peterx@redhat.com>
References: <20200619160538.8641-1-peterx@redhat.com>
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Use the general page fault accounting by passing regs into handle_mm_fault().
It naturally solve the issue of multiple page fault accounting when page fault
retry happened.

Add the missing PERF_COUNT_SW_PAGE_FAULTS perf events too.  Note, the other two
perf events (PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN]) were done in handle_mm_fault().

CC: Guan Xuetao <gxt@pku.edu.cn>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 arch/unicore32/mm/fault.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/unicore32/mm/fault.c b/arch/unicore32/mm/fault.c
index 847ff24fcc2a..b272a389d977 100644
--- a/arch/unicore32/mm/fault.c
+++ b/arch/unicore32/mm/fault.c
@@ -16,6 +16,7 @@
 #include <linux/page-flags.h>
 #include <linux/sched/signal.h>
 #include <linux/io.h>
+#include <linux/perf_event.h>
 
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
@@ -160,7 +161,8 @@ static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
 }
 
 static vm_fault_t __do_pf(struct mm_struct *mm, unsigned long addr,
-		unsigned int fsr, unsigned int flags, struct task_struct *tsk)
+			  unsigned int fsr, unsigned int flags,
+			  struct task_struct *tsk, struct pt_regs *regs)
 {
 	struct vm_area_struct *vma;
 	vm_fault_t fault;
@@ -186,7 +188,7 @@ static vm_fault_t __do_pf(struct mm_struct *mm, unsigned long addr,
 	 * If for any reason at all we couldn't handle the fault, make
 	 * sure we exit gracefully rather than endlessly redo the fault.
 	 */
-	fault = handle_mm_fault(vma, addr & PAGE_MASK, flags, NULL);
+	fault = handle_mm_fault(vma, addr & PAGE_MASK, flags, regs);
 	return fault;
 
 check_stack:
@@ -219,6 +221,8 @@ static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	if (!(fsr ^ 0x12))
 		flags |= FAULT_FLAG_WRITE;
 
+	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,
@@ -244,7 +248,7 @@ static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 #endif
 	}
 
-	fault = __do_pf(mm, addr, fsr, flags, tsk);
+	fault = __do_pf(mm, addr, fsr, flags, tsk, regs);
 
 	/* 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
@@ -254,10 +258,6 @@ static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 		return 0;
 
 	if (!(fault & VM_FAULT_ERROR) && (flags & FAULT_FLAG_ALLOW_RETRY)) {
-		if (fault & VM_FAULT_MAJOR)
-			tsk->maj_flt++;
-		else
-			tsk->min_flt++;
 		if (fault & VM_FAULT_RETRY) {
 			flags |= FAULT_FLAG_TRIED;
 			goto retry;
-- 
2.26.2