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[217.140.110.172]) by mx.google.com with ESMTP id b49si1092318edb.204.2019.06.07.03.35.54 for ; Fri, 07 Jun 2019 03:35:54 -0700 (PDT) Received-SPF: pass (google.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) client-ip=217.140.110.172; Authentication-Results: mx.google.com; spf=pass (google.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=anshuman.khandual@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 91C3C707; Fri, 7 Jun 2019 03:35:53 -0700 (PDT) Received: from p8cg001049571a15.blr.arm.com (p8cg001049571a15.blr.arm.com [10.162.42.131]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D70673F246; Fri, 7 Jun 2019 03:37:24 -0700 (PDT) From: Anshuman Khandual To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Anshuman Khandual , linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org, Andrew Morton , Michal Hocko , Matthew Wilcox , Mark Rutland , Christophe Leroy , Stephen Rothwell , Andrey Konovalov , Michael Ellerman , Paul Mackerras , Russell King , Catalin Marinas , Will Deacon , Tony Luck , Fenghua Yu , Martin Schwidefsky , Heiko Carstens , Yoshinori Sato , "David S. Miller" , Thomas Gleixner , Peter Zijlstra , Ingo Molnar , Andy Lutomirski , Dave Hansen Subject: [RFC V3] mm: Generalize and rename notify_page_fault() as kprobe_page_fault() Date: Fri, 7 Jun 2019 16:04:15 +0530 Message-Id: <1559903655-5609-1-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Very similar definitions for notify_page_fault() are being used by multiple architectures duplicating much of the same code. This attempts to unify all of them into a generic implementation, rename it as kprobe_page_fault() and then move it to a common header. kprobes_built_in() can detect CONFIG_KPROBES, hence new kprobe_page_fault() need not be wrapped again within CONFIG_KPROBES. Trap number argument can now contain upto an 'unsigned int' accommodating all possible platforms. kprobe_page_fault() goes the x86 way while dealing with preemption context. As explained in these following commits the invoking context in itself must be non-preemptible for kprobes processing context irrespective of whether kprobe_running() or perhaps smp_processor_id() is safe or not. It does not make much sense to continue when original context is preemptible. Instead just bail out earlier. commit a980c0ef9f6d ("x86/kprobes: Refactor kprobes_fault() like kprobe_exceptions_notify()") commit b506a9d08bae ("x86: code clarification patch to Kprobes arch code") Cc: linux-arm-kernel@lists.infradead.org Cc: linux-ia64@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-s390@vger.kernel.org Cc: linux-sh@vger.kernel.org Cc: sparclinux@vger.kernel.org Cc: x86@kernel.org Cc: Andrew Morton Cc: Michal Hocko Cc: Matthew Wilcox Cc: Mark Rutland Cc: Christophe Leroy Cc: Stephen Rothwell Cc: Andrey Konovalov Cc: Michael Ellerman Cc: Paul Mackerras Cc: Russell King Cc: Catalin Marinas Cc: Will Deacon Cc: Tony Luck Cc: Fenghua Yu Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: Yoshinori Sato Cc: "David S. Miller" Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Andy Lutomirski Cc: Dave Hansen Signed-off-by: Anshuman Khandual Reviewed-by: Dave Hansen --- Testing: - Build and boot tested on arm64 and x86 - Build tested on some other archs (arm, sparc64, alpha, powerpc etc) Changes in RFC V3: - Updated the commit message with an explaination for new preemption behaviour - Moved notify_page_fault() to kprobes.h with 'static nokprobe_inline' per Matthew - Changed notify_page_fault() return type from int to bool per Michael Ellerman - Renamed notify_page_fault() as kprobe_page_fault() per Peterz Changes in RFC V2: (https://patchwork.kernel.org/patch/10974221/) - Changed generic notify_page_fault() per Mathew Wilcox - Changed x86 to use new generic notify_page_fault() - s/must not/need not/ in commit message per Matthew Wilcox Changes in RFC V1: (https://patchwork.kernel.org/patch/10968273/) arch/arm/mm/fault.c | 24 +----------------------- arch/arm64/mm/fault.c | 24 +----------------------- arch/ia64/mm/fault.c | 24 +----------------------- arch/powerpc/mm/fault.c | 23 ++--------------------- arch/s390/mm/fault.c | 16 +--------------- arch/sh/mm/fault.c | 18 ++---------------- arch/sparc/mm/fault_64.c | 16 +--------------- arch/x86/mm/fault.c | 21 ++------------------- include/linux/kprobes.h | 16 ++++++++++++++++ 9 files changed, 27 insertions(+), 155 deletions(-) diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index 58f69fa..94a97a4 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -30,28 +30,6 @@ #ifdef CONFIG_MMU -#ifdef CONFIG_KPROBES -static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr) -{ - int ret = 0; - - if (!user_mode(regs)) { - /* kprobe_running() needs smp_processor_id() */ - preempt_disable(); - if (kprobe_running() && kprobe_fault_handler(regs, fsr)) - ret = 1; - preempt_enable(); - } - - return ret; -} -#else -static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr) -{ - return 0; -} -#endif - /* * This is useful to dump out the page tables associated with * 'addr' in mm 'mm'. @@ -266,7 +244,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) vm_fault_t fault; unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; - if (notify_page_fault(regs, fsr)) + if (kprobe_page_fault(regs, fsr)) return 0; tsk = current; diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index a30818e..8fe4bbc 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -70,28 +70,6 @@ static inline const struct fault_info *esr_to_debug_fault_info(unsigned int esr) return debug_fault_info + DBG_ESR_EVT(esr); } -#ifdef CONFIG_KPROBES -static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr) -{ - int ret = 0; - - /* kprobe_running() needs smp_processor_id() */ - if (!user_mode(regs)) { - preempt_disable(); - if (kprobe_running() && kprobe_fault_handler(regs, esr)) - ret = 1; - preempt_enable(); - } - - return ret; -} -#else -static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr) -{ - return 0; -} -#endif - static void data_abort_decode(unsigned int esr) { pr_alert("Data abort info:\n"); @@ -446,7 +424,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, unsigned long vm_flags = VM_READ | VM_WRITE; unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; - if (notify_page_fault(regs, esr)) + if (kprobe_page_fault(regs, esr)) return 0; tsk = current; diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c index 5baeb02..22582f8 100644 --- a/arch/ia64/mm/fault.c +++ b/arch/ia64/mm/fault.c @@ -21,28 +21,6 @@ extern int die(char *, struct pt_regs *, long); -#ifdef CONFIG_KPROBES -static inline int notify_page_fault(struct pt_regs *regs, int trap) -{ - int ret = 0; - - if (!user_mode(regs)) { - /* kprobe_running() needs smp_processor_id() */ - preempt_disable(); - if (kprobe_running() && kprobe_fault_handler(regs, trap)) - ret = 1; - preempt_enable(); - } - - return ret; -} -#else -static inline int notify_page_fault(struct pt_regs *regs, int trap) -{ - return 0; -} -#endif - /* * Return TRUE if ADDRESS points at a page in the kernel's mapped segment * (inside region 5, on ia64) and that page is present. @@ -116,7 +94,7 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re /* * This is to handle the kprobes on user space access instructions */ - if (notify_page_fault(regs, TRAP_BRKPT)) + if (kprobe_page_fault(regs, TRAP_BRKPT)) return; if (user_mode(regs)) diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index ec6b7ad..f20ee668 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -42,26 +42,6 @@ #include #include -static inline bool notify_page_fault(struct pt_regs *regs) -{ - bool ret = false; - -#ifdef CONFIG_KPROBES - /* kprobe_running() needs smp_processor_id() */ - if (!user_mode(regs)) { - preempt_disable(); - if (kprobe_running() && kprobe_fault_handler(regs, 11)) - ret = true; - preempt_enable(); - } -#endif /* CONFIG_KPROBES */ - - if (unlikely(debugger_fault_handler(regs))) - ret = true; - - return ret; -} - /* * Check whether the instruction inst is a store using * an update addressing form which will update r1. @@ -462,8 +442,9 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, int is_write = page_fault_is_write(error_code); vm_fault_t fault, major = 0; bool must_retry = false; + int kprobe_fault = kprobe_page_fault(regs, 11); - if (notify_page_fault(regs)) + if (unlikely(debugger_fault_handler(regs) || kprobe_fault)) return 0; if (unlikely(page_fault_is_bad(error_code))) { diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index 91ce03f..bb77a2c 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -67,20 +67,6 @@ static int __init fault_init(void) } early_initcall(fault_init); -static inline int notify_page_fault(struct pt_regs *regs) -{ - int ret = 0; - - /* kprobe_running() needs smp_processor_id() */ - if (kprobes_built_in() && !user_mode(regs)) { - preempt_disable(); - if (kprobe_running() && kprobe_fault_handler(regs, 14)) - ret = 1; - preempt_enable(); - } - return ret; -} - /* * Find out which address space caused the exception. * Access register mode is impossible, ignore space == 3. @@ -411,7 +397,7 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access) */ clear_pt_regs_flag(regs, PIF_PER_TRAP); - if (notify_page_fault(regs)) + if (kprobe_page_fault(regs, 14)) return 0; mm = tsk->mm; diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c index 6defd2c6..74cd4ac 100644 --- a/arch/sh/mm/fault.c +++ b/arch/sh/mm/fault.c @@ -24,20 +24,6 @@ #include #include -static inline int notify_page_fault(struct pt_regs *regs, int trap) -{ - int ret = 0; - - if (kprobes_built_in() && !user_mode(regs)) { - preempt_disable(); - if (kprobe_running() && kprobe_fault_handler(regs, trap)) - ret = 1; - preempt_enable(); - } - - return ret; -} - static void force_sig_info_fault(int si_signo, int si_code, unsigned long address, struct task_struct *tsk) @@ -415,14 +401,14 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, if (unlikely(fault_in_kernel_space(address))) { if (vmalloc_fault(address) >= 0) return; - if (notify_page_fault(regs, vec)) + if (kprobe_page_fault(regs, vec)) return; bad_area_nosemaphore(regs, error_code, address); return; } - if (unlikely(notify_page_fault(regs, vec))) + if (unlikely(kprobe_page_fault(regs, vec))) return; /* Only enable interrupts if they were on before the fault */ diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c index 8f8a604..6865f9c 100644 --- a/arch/sparc/mm/fault_64.c +++ b/arch/sparc/mm/fault_64.c @@ -38,20 +38,6 @@ int show_unhandled_signals = 1; -static inline __kprobes int notify_page_fault(struct pt_regs *regs) -{ - int ret = 0; - - /* kprobe_running() needs smp_processor_id() */ - if (kprobes_built_in() && !user_mode(regs)) { - preempt_disable(); - if (kprobe_running() && kprobe_fault_handler(regs, 0)) - ret = 1; - preempt_enable(); - } - return ret; -} - static void __kprobes unhandled_fault(unsigned long address, struct task_struct *tsk, struct pt_regs *regs) @@ -285,7 +271,7 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs) fault_code = get_thread_fault_code(); - if (notify_page_fault(regs)) + if (kprobe_page_fault(regs, 0)) goto exit_exception; si_code = SEGV_MAPERR; diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 46df4c6..5400f4e 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -46,23 +46,6 @@ kmmio_fault(struct pt_regs *regs, unsigned long addr) return 0; } -static nokprobe_inline int kprobes_fault(struct pt_regs *regs) -{ - if (!kprobes_built_in()) - return 0; - if (user_mode(regs)) - return 0; - /* - * To be potentially processing a kprobe fault and to be allowed to call - * kprobe_running(), we have to be non-preemptible. - */ - if (preemptible()) - return 0; - if (!kprobe_running()) - return 0; - return kprobe_fault_handler(regs, X86_TRAP_PF); -} - /* * Prefetch quirks: * @@ -1280,7 +1263,7 @@ do_kern_addr_fault(struct pt_regs *regs, unsigned long hw_error_code, return; /* kprobes don't want to hook the spurious faults: */ - if (kprobes_fault(regs)) + if (kprobe_page_fault(regs, X86_TRAP_PF)) return; /* @@ -1311,7 +1294,7 @@ void do_user_addr_fault(struct pt_regs *regs, mm = tsk->mm; /* kprobes don't want to hook the spurious faults: */ - if (unlikely(kprobes_fault(regs))) + if (unlikely(kprobe_page_fault(regs, X86_TRAP_PF))) return; /* diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 443d980..064dd15 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -458,4 +458,20 @@ static inline bool is_kprobe_optinsn_slot(unsigned long addr) } #endif +static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, + unsigned int trap) +{ + int ret = 0; + + /* + * To be potentially processing a kprobe fault and to be allowed + * to call kprobe_running(), we have to be non-preemptible. + */ + if (kprobes_built_in() && !preemptible() && !user_mode(regs)) { + if (kprobe_running() && kprobe_fault_handler(regs, trap)) + ret = 1; + } + return ret; +} + #endif /* _LINUX_KPROBES_H */