Messages in this thread | | | Subject | Re: [RFC V3] mm: Generalize and rename notify_page_fault() as kprobe_page_fault() | From | Christophe Leroy <> | Date | Fri, 7 Jun 2019 17:31:01 +0200 |
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Le 07/06/2019 à 12:34, Anshuman Khandual a écrit : > 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 <akpm@linux-foundation.org> > Cc: Michal Hocko <mhocko@suse.com> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Christophe Leroy <christophe.leroy@c-s.fr> > Cc: Stephen Rothwell <sfr@canb.auug.org.au> > Cc: Andrey Konovalov <andreyknvl@google.com> > Cc: Michael Ellerman <mpe@ellerman.id.au> > Cc: Paul Mackerras <paulus@samba.org> > Cc: Russell King <linux@armlinux.org.uk> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Tony Luck <tony.luck@intel.com> > Cc: Fenghua Yu <fenghua.yu@intel.com> > Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> > Cc: Heiko Carstens <heiko.carstens@de.ibm.com> > Cc: Yoshinori Sato <ysato@users.sourceforge.jp> > Cc: "David S. Miller" <davem@davemloft.net> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Andy Lutomirski <luto@kernel.org> > Cc: Dave Hansen <dave.hansen@linux.intel.com> > > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > 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/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;
ret is pointless.
> + > + /* > + * 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))
don't need an 'if A if B', can do 'if A && B'
> + ret = 1;
can do 'return true;' directly here
> + } > + return ret;
And 'return false' here.
Christophe
> +} > + > #endif /* _LINUX_KPROBES_H */ >
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