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Peter Anvin" , , , , , , , Kefeng Wang Subject: [PATCH rfc v2 10/10] loongarch: mm: try VMA lock-based page fault handling first Date: Mon, 21 Aug 2023 20:30:56 +0800 Message-ID: <20230821123056.2109942-11-wangkefeng.wang@huawei.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20230821123056.2109942-1-wangkefeng.wang@huawei.com> References: <20230821123056.2109942-1-wangkefeng.wang@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.112.125] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm100001.china.huawei.com (7.185.36.93) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230821_053128_393953_13A20FA7 X-CRM114-Status: GOOD ( 16.05 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Attempt VMA lock-based page fault handling first, and fall back to the existing mmap_lock-based handling if that fails. Signed-off-by: Kefeng Wang --- arch/loongarch/Kconfig | 1 + arch/loongarch/mm/fault.c | 37 +++++++++++++++++++++++++++++++------ 2 files changed, 32 insertions(+), 6 deletions(-) diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index 2b27b18a63af..6b821f621920 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -56,6 +56,7 @@ config LOONGARCH select ARCH_SUPPORTS_LTO_CLANG select ARCH_SUPPORTS_LTO_CLANG_THIN select ARCH_SUPPORTS_NUMA_BALANCING + select ARCH_SUPPORTS_PER_VMA_LOCK select ARCH_USE_BUILTIN_BSWAP select ARCH_USE_CMPXCHG_LOCKREF select ARCH_USE_QUEUED_RWLOCKS diff --git a/arch/loongarch/mm/fault.c b/arch/loongarch/mm/fault.c index 2a45e9f3a485..f7ac3a14bb06 100644 --- a/arch/loongarch/mm/fault.c +++ b/arch/loongarch/mm/fault.c @@ -142,6 +142,13 @@ static inline bool access_error(unsigned int flags, struct pt_regs *regs, 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->flags, vmf->regs, vmf->real_address, vma); +} +#endif + /* * This routine handles page faults. It determines the address, * and the problem, and then passes it off to one of the appropriate @@ -151,11 +158,15 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write, unsigned long address) { int si_code = SEGV_MAPERR; - unsigned int flags = FAULT_FLAG_DEFAULT; struct task_struct *tsk = current; struct mm_struct *mm = tsk->mm; struct vm_area_struct *vma = NULL; vm_fault_t fault; + struct vm_fault vmf = { + .real_address = address, + .regs = regs, + .flags = FAULT_FLAG_DEFAULT, + }; if (kprobe_page_fault(regs, current->thread.trap_nr)) return; @@ -184,11 +195,24 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, goto bad_area_nosemaphore; if (user_mode(regs)) - flags |= FAULT_FLAG_USER; + vmf.flags |= FAULT_FLAG_USER; if (write) - flags |= FAULT_FLAG_WRITE; + vmf.flags |= FAULT_FLAG_WRITE; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); + + fault = try_vma_locked_page_fault(&vmf); + if (fault == VM_FAULT_NONE) + goto retry; + if (!(fault & VM_FAULT_RETRY)) + goto done; + + if (fault_signal_pending(fault, regs)) { + if (!user_mode(regs)) + no_context(regs, write, address); + return; + } + retry: vma = lock_mm_and_find_vma(mm, address, regs); if (unlikely(!vma)) @@ -196,7 +220,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, si_code = SEGV_ACCERR; - if (access_error(flags, regs, vma)) + if (access_error(vmf.flags, regs, address, vma)) goto bad_area; /* @@ -204,7 +228,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, * make sure we exit gracefully rather than endlessly redo * the fault. */ - fault = handle_mm_fault(vma, address, flags, regs); + fault = handle_mm_fault(vma, address, vmf.flags, regs); if (fault_signal_pending(fault, regs)) { if (!user_mode(regs)) @@ -217,7 +241,7 @@ static void __kprobes __do_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 @@ -229,6 +253,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, mmap_read_unlock(mm); +done: if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) do_out_of_memory(regs, write, address);