From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anshuman Khandual Date: Fri, 14 Jun 2019 05:27:44 +0000 Subject: Re: [PATCH] mm: Generalize and rename notify_page_fault() as kprobe_page_fault() Message-Id: List-Id: References: <1560420444-25737-1-git-send-email-anshuman.khandual@arm.com> <20190613130408.3091869d8e50d0524157523f@linux-foundation.org> In-Reply-To: <20190613130408.3091869d8e50d0524157523f@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Andrew Morton Cc: Mark Rutland , Michal Hocko , linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra , Catalin Marinas , Dave Hansen , Will Deacon , linux-mips@vger.kernel.org, linux-mm@kvack.org, Paul Mackerras , sparclinux@vger.kernel.org, linux-s390@vger.kernel.org, Yoshinori Sato , Michael Ellerman , x86@kernel.org, Russell King , Matthew Wilcox , Ingo Molnar , James Hogan , linux-snps-arc@lists.infradead.org, Fenghua Yu , Stephen Rothwell , Andrey Konovalov , Andy Lutomirski , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Christophe Leroy , Tony Luck , Heiko Carstens , Vineet Gupta , linux-kernel@vger.kernel.org, Ralf Baechle , Paul Burton , Martin Schwidefsky , linuxppc-dev@lists.ozlabs.org, "David S. Miller" On 06/14/2019 01:34 AM, Andrew Morton wrote: > On Thu, 13 Jun 2019 15:37:24 +0530 Anshuman Khandual wrote: > >> Architectures which support kprobes have very similar boilerplate around >> calling kprobe_fault_handler(). Use a helper function in kprobes.h to unify >> them, based on the x86 code. >> >> This changes the behaviour for other architectures when preemption is >> enabled. Previously, they would have disabled preemption while calling the >> kprobe handler. However, preemption would be disabled if this fault was >> due to a kprobe, so we know the fault was not due to a kprobe handler and >> can simply return failure. >> >> This behaviour was introduced in the commit a980c0ef9f6d ("x86/kprobes: >> Refactor kprobes_fault() like kprobe_exceptions_notify()") >> >> ... >> >> --- 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) > > Some architectures make this `static inline'. Others make it > `nokprobes_inline', others make it `static inline __kprobes'. The > latter seems weird - why try to put an inline function into > .kprobes.text? > > So.. what's the best thing to do here? You chose `static > nokprobe_inline' - is that the best approach, if so why? Does > kprobe_page_fault() actually need to be inlined? Matthew had suggested that (nokprobe_-inline) based on current x86 implementation. But every architecture already had an inlined definition which I did not want to deviate from. > > Also, some architectures had notify_page_fault returning int, others > bool. You chose bool and that seems appropriate and all callers are OK > with that. I would believe so. No one has complained yet :)