Re: [PATCH] mm/kprobes: Add generic kprobe_fault_handler() fallback definition

[Anshuman Khandual]

On 07/05/2019 11:00 AM, Anshuman Khandual wrote:
> Architectures like parisc enable CONFIG_KROBES without having a definition
> for kprobe_fault_handler() which results in a build failure. Arch needs to
> provide kprobe_fault_handler() as it is platform specific and cannot have
> a generic working alternative. But in the event when platform lacks such a
> definition there needs to be a fallback.
> 
> This adds a stub kprobe_fault_handler() definition which not only prevents
> a build failure but also makes sure that kprobe_page_fault() if called will
> always return negative in absence of a sane platform specific alternative.
> 
> While here wrap kprobe_page_fault() in CONFIG_KPROBES. This enables stud
> definitions for generic kporbe_fault_handler() and kprobes_built_in() can
> just be dropped. Only on x86 it needs to be added back locally as it gets
> used in a !CONFIG_KPROBES function do_general_protection().
> 
> Cc: Vineet Gupta <vgupta@xxxxxxxxxxxx>
> Cc: Russell King <linux@xxxxxxxxxxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> Cc: Tony Luck <tony.luck@xxxxxxxxx>
> Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> Cc: Paul Burton <paul.burton@xxxxxxxx>
> Cc: James Hogan <jhogan@xxxxxxxxxx>
> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> Cc: Paul Mackerras <paulus@xxxxxxxxx>
> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
> Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
> Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
> Cc: Rich Felker <dalias@xxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> Cc: "Naveen N. Rao" <naveen.n.rao@xxxxxxxxxxxxx>
> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx>
> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Cc: Allison Randal <allison@xxxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Enrico Weigelt <info@xxxxxxxxx>
> Cc: Richard Fontana <rfontana@xxxxxxxxxx>
> Cc: Kate Stewart <kstewart@xxxxxxxxxxxxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> Cc: x86@xxxxxxxxxx
> Cc: linux-snps-arc@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: linux-ia64@xxxxxxxxxxxxxxx
> Cc: linux-mips@xxxxxxxxxxxxxxx
> Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
> Cc: linux-s390@xxxxxxxxxxxxxxx
> Cc: linux-sh@xxxxxxxxxxxxxxx
> Cc: sparclinux@xxxxxxxxxxxxxxx
> 
> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
> ---

Any updates or suggestions on this patch ? Currently there is a build failure on
parisc architecture due to the lack of a kprobe_fault_handler() definition when
CONFIG_KPROBES is enabled and this build failure needs to be fixed.

This patch solves the build problem. But otherwise I am also happy to just define
a stub definition for kprobe_fault_handler() on parisc arch when CONFIG_KPROBES
is enabled, which will avoid the build failure. Please suggest.