linux-kernel - [PATCH rfc -next 06/10] riscv: mm: use try_vma_locked_page

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Date:   Thu, 13 Jul 2023 17:53:34 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     <linux-mm@...ck.org>, Andrew Morton <akpm@...ux-foundation.org>,
        <surenb@...gle.com>
CC:     Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Huacai Chen <chenhuacai@...nel.org>,
        WANG Xuerui <kernel@...0n.name>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        <x86@...nel.org>, <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <loongarch@...ts.linux.dev>,
        <linuxppc-dev@...ts.ozlabs.org>, <linux-riscv@...ts.infradead.org>,
        <linux-s390@...r.kernel.org>,
        Kefeng Wang <wangkefeng.wang@...wei.com>
Subject: [PATCH rfc -next 06/10] riscv: mm: use try_vma_locked_page_fault()

Use new try_vma_locked_page_fault() helper to simplify code.
No functional change intended.

Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---
 arch/riscv/mm/fault.c | 38 +++++++++++++++-----------------------
 1 file changed, 15 insertions(+), 23 deletions(-)

diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index 6ea2cce4cc17..13bc60370b5c 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -215,6 +215,16 @@ static inline bool access_error(unsigned long cause, struct vm_area_struct *vma)
 	return false;
 }
 
+#ifdef CONFIG_PER_VMA_LOCK
+int arch_vma_check_access(struct vm_area_struct *vma,
+			  struct vm_locked_fault *vmlf)
+{
+	if (unlikely(access_error(vmlf->fault_code, vma)))
+		return -EINVAL;
+	return 0;
+}
+#endif
+
 /*
  * This routine handles page faults.  It determines the address and the
  * problem, and then passes it off to one of the appropriate routines.
@@ -228,6 +238,7 @@ void handle_page_fault(struct pt_regs *regs)
 	unsigned int flags = FAULT_FLAG_DEFAULT;
 	int code = SEGV_MAPERR;
 	vm_fault_t fault;
+	struct vm_locked_fault vmlf;
 
 	cause = regs->cause;
 	addr = regs->badaddr;
@@ -283,35 +294,18 @@ void handle_page_fault(struct pt_regs *regs)
 		flags |= FAULT_FLAG_WRITE;
 	else if (cause == EXC_INST_PAGE_FAULT)
 		flags |= FAULT_FLAG_INSTRUCTION;
-#ifdef CONFIG_PER_VMA_LOCK
-	if (!(flags & FAULT_FLAG_USER))
-		goto lock_mmap;
 
-	vma = lock_vma_under_rcu(mm, addr);
-	if (!vma)
-		goto lock_mmap;
-
-	if (unlikely(access_error(cause, vma))) {
-		vma_end_read(vma);
-		goto lock_mmap;
-	}
-
-	fault = handle_mm_fault(vma, addr, flags | FAULT_FLAG_VMA_LOCK, regs);
-	vma_end_read(vma);
-
-	if (!(fault & VM_FAULT_RETRY)) {
-		count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
+	VM_LOCKED_FAULT_INIT(vmlf, mm, addr, flags, 0, regs, cause);
+	if (try_vma_locked_page_fault(&vmlf, &fault))
+		goto retry;
+	else if (!(fault | VM_FAULT_RETRY))
 		goto done;
-	}
-	count_vm_vma_lock_event(VMA_LOCK_RETRY);
 
 	if (fault_signal_pending(fault, regs)) {
 		if (!user_mode(regs))
 			no_context(regs, addr);
 		return;
 	}
-lock_mmap:
-#endif /* CONFIG_PER_VMA_LOCK */
 
 retry:
 	vma = lock_mm_and_find_vma(mm, addr, regs);
@@ -368,9 +362,7 @@ void handle_page_fault(struct pt_regs *regs)
 
 	mmap_read_unlock(mm);
 
-#ifdef CONFIG_PER_VMA_LOCK
 done:
-#endif
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		tsk->thread.bad_cause = cause;
 		mm_fault_error(regs, addr, fault);
-- 
2.27.0