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

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 <redacted>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <redacted>
Cc: Ralf Baechle <redacted>
Cc: Paul Burton <redacted>
Cc: James Hogan <jhogan@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <redacted>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Heiko Carstens <redacted>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <redacted>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <redacted>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Naveen N. Rao" <redacted>
Cc: Anil S Keshavamurthy <redacted>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Allison Randal <redacted>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Enrico Weigelt <info@metux.net>
Cc: Richard Fontana <redacted>
Cc: Kate Stewart <redacted>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: x86@kernel.org
Cc: linux-snps-arc@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-mips@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

Signed-off-by: Anshuman Khandual <redacted>
---

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.