From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anshuman Khandual Date: Tue, 08 Oct 2019 08:25:22 +0000 Subject: Re: [PATCH V4 2/2] mm/pgtable/debug: Add test validating architecture page table helpers Message-Id: <881796fc-c35e-3790-a1ee-7031c6cdb38d@arm.com> List-Id: References: <1570427124-21887-1-git-send-email-anshuman.khandual@arm.com> <1570427124-21887-3-git-send-email-anshuman.khandual@arm.com> <20191007130617.GB56546@gmail.com> <20191007132607.4q537nauwfn5thol@box> <20191007135158.GA36360@gmail.com> <20191007140058.um5g44rvxyzyiref@box> In-Reply-To: <20191007140058.um5g44rvxyzyiref@box> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "Kirill A. Shutemov" , Ingo Molnar Cc: Mark Rutland , linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra , James Hogan , Tetsuo Handa , Heiko Carstens , Michal Hocko , linux-mm@kvack.org, Dave Hansen , Paul Mackerras , sparclinux@vger.kernel.org, Thomas Gleixner , linux-s390@vger.kernel.org, Michael Ellerman , x86@kernel.org, Russell King - ARM Linux , Matthew Wilcox , Steven Price , Jason Gunthorpe , Gerald Schaefer , linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Kees Cook , Masahiro Yamada , Mark Brown , Dan Williams , Vlastimil Babka , Christophe Leroy , Sri Krishna chowdary , Ard Biesheuvel , Greg Kroah-Hartman , linux-mips@vger.kernel.org, Ralf Baechle , linux-kernel@vger.kernel.org, Paul Burton , Mike Rapoport , Vineet Gupta , Martin Schwidefsky , Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" On 10/07/2019 07:30 PM, Kirill A. Shutemov wrote: > On Mon, Oct 07, 2019 at 03:51:58PM +0200, Ingo Molnar wrote: >> >> * Kirill A. Shutemov wrote: >> >>> On Mon, Oct 07, 2019 at 03:06:17PM +0200, Ingo Molnar wrote: >>>> >>>> * Anshuman Khandual wrote: >>>> >>>>> This adds a test module which will validate architecture page table helpers >>>>> and accessors regarding compliance with generic MM semantics expectations. >>>>> This will help various architectures in validating changes to the existing >>>>> page table helpers or addition of new ones. >>>>> >>>>> Test page table and memory pages creating it's entries at various level are >>>>> all allocated from system memory with required alignments. If memory pages >>>>> with required size and alignment could not be allocated, then all depending >>>>> individual tests are skipped. >>>> >>>>> diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h >>>>> index 52e5f5f2240d..b882792a3999 100644 >>>>> --- a/arch/x86/include/asm/pgtable_64_types.h >>>>> +++ b/arch/x86/include/asm/pgtable_64_types.h >>>>> @@ -40,6 +40,8 @@ static inline bool pgtable_l5_enabled(void) >>>>> #define pgtable_l5_enabled() 0 >>>>> #endif /* CONFIG_X86_5LEVEL */ >>>>> >>>>> +#define mm_p4d_folded(mm) (!pgtable_l5_enabled()) >>>>> + >>>>> extern unsigned int pgdir_shift; >>>>> extern unsigned int ptrs_per_p4d; >>>> >>>> Any deep reason this has to be a macro instead of proper C? >>> >>> It's a way to override the generic mm_p4d_folded(). It can be rewritten >>> as inline function + define. Something like: >>> >>> #define mm_p4d_folded mm_p4d_folded >>> static inline bool mm_p4d_folded(struct mm_struct *mm) >>> { >>> return !pgtable_l5_enabled(); >>> } >>> >>> But I don't see much reason to be more verbose here than needed. >> >> C type checking? Documentation? Yeah, I know it's just a one-liner, but >> the principle of the death by a thousand cuts applies here. > > Okay, if you think it worth it. Anshuman, could you fix it up for the next > submission? Sure, will do. > > >> BTW., any reason this must be in the low level pgtable_64_types.h type >> header, instead of one of the API level header files? > > I defined it next pgtable_l5_enabled(). What is more appropriate place to > you? pgtable_64.h? Yeah, it makes sense. Needs to be moved to arch/x86/include/asm/pgtable_64.h as well ?