linux-kernel - [PATCH rfc v2 06/10] riscv: mm: use try_vma_locked_page

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Message-ID: <20230821123056.2109942-7-wangkefeng.wang@huawei.com>
Date:   Mon, 21 Aug 2023 20:30:52 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Andrew Morton <akpm@...ux-foundation.org>, <linux-mm@...ck.org>
CC:     <surenb@...gle.com>, <willy@...radead.org>,
        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>, "H . Peter Anvin" <hpa@...or.com>,
        <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 v2 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 | 58 ++++++++++++++++++-------------------------
 1 file changed, 24 insertions(+), 34 deletions(-)

diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index 6115d7514972..b46129b636f2 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -215,6 +215,13 @@ static inline bool access_error(unsigned long cause, struct vm_area_struct *vma)
 	return false;
 }
 
+#ifdef CONFIG_PER_VMA_LOCK
+bool arch_vma_access_error(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	return access_error(vmf->fault_code, vma);
+}
+#endif
+
 /*
  * This routine handles page faults.  It determines the address and the
  * problem, and then passes it off to one of the appropriate routines.
@@ -223,17 +230,16 @@ void handle_page_fault(struct pt_regs *regs)
 {
 	struct task_struct *tsk;
 	struct vm_area_struct *vma;
-	struct mm_struct *mm;
-	unsigned long addr, cause;
-	unsigned int flags = FAULT_FLAG_DEFAULT;
+	struct mm_struct *mm = current->mm;
+	unsigned long addr = regs->badaddr;
+	unsigned long cause = regs->cause;
 	int code = SEGV_MAPERR;
 	vm_fault_t fault;
-
-	cause = regs->cause;
-	addr = regs->badaddr;
-
-	tsk = current;
-	mm = tsk->mm;
+	struct vm_fault vmf = {
+		.real_address = addr,
+		.fault_code = cause,
+		.flags = FAULT_FLAG_DEFAULT,
+	};
 
 	if (kprobe_page_fault(regs, cause))
 		return;
@@ -268,7 +274,7 @@ void handle_page_fault(struct pt_regs *regs)
 	}
 
 	if (user_mode(regs))
-		flags |= FAULT_FLAG_USER;
+		vmf.flags |= FAULT_FLAG_USER;
 
 	if (!user_mode(regs) && addr < TASK_SIZE && unlikely(!(regs->status & SR_SUM))) {
 		if (fixup_exception(regs))
@@ -280,37 +286,21 @@ void handle_page_fault(struct pt_regs *regs)
 	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
 
 	if (cause == EXC_STORE_PAGE_FAULT)
-		flags |= FAULT_FLAG_WRITE;
+		vmf.flags |= FAULT_FLAG_WRITE;
 	else if (cause == EXC_INST_PAGE_FAULT)
-		flags |= FAULT_FLAG_INSTRUCTION;
-	if (!(flags & FAULT_FLAG_USER))
-		goto lock_mmap;
-
-	vma = lock_vma_under_rcu(mm, addr);
-	if (!vma)
-		goto lock_mmap;
+		vmf.flags |= FAULT_FLAG_INSTRUCTION;
 
-	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);
-	if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
-		vma_end_read(vma);
-
-	if (!(fault & VM_FAULT_RETRY)) {
-		count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
+	fault = try_vma_locked_page_fault(&vmf);
+	if (fault == VM_FAULT_NONE)
+		goto retry;
+	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:
 
 retry:
 	vma = lock_mm_and_find_vma(mm, addr, regs);
@@ -337,7 +327,7 @@ void handle_page_fault(struct pt_regs *regs)
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
-	fault = handle_mm_fault(vma, addr, flags, regs);
+	fault = handle_mm_fault(vma, addr, vmf.flags, regs);
 
 	/*
 	 * If we need to retry but a fatal signal is pending, handle the
@@ -355,7 +345,7 @@ void handle_page_fault(struct pt_regs *regs)
 		return;
 
 	if (unlikely(fault & VM_FAULT_RETRY)) {
-		flags |= FAULT_FLAG_TRIED;
+		vmf.flags |= FAULT_FLAG_TRIED;
 
 		/*
 		 * No need to mmap_read_unlock(mm) as we would
-- 
2.27.0