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[66.187.233.206]) by smtp.gmail.com with ESMTPSA id b9sm3046654qkk.61.2019.10.29.08.55.44 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 29 Oct 2019 08:55:45 -0700 (PDT) Date: Tue, 29 Oct 2019 11:55:39 -0400 From: Masayoshi Mizuma To: Baoquan He Cc: Borislav Petkov , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Masayoshi Mizuma , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 4/5] x86/mm/KASLR: Cleanup calculation for direct mapping size Message-ID: <20191029155538.qvvp6j7cqjig45oc@gabell> References: <20190830214707.1201-1-msys.mizuma@gmail.com> <20190830214707.1201-5-msys.mizuma@gmail.com> <20190905135451.GD20805@MiWiFi-R3L-srv> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190905135451.GD20805@MiWiFi-R3L-srv> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 05, 2019 at 09:54:51PM +0800, Baoquan He wrote: > On 08/30/19 at 05:47pm, Masayoshi Mizuma wrote: > > From: Masayoshi Mizuma > > > > Cleanup calculation for direct mapping size. > > > > Signed-off-by: Baoquan He > > Signed-off-by: Masayoshi Mizuma > > --- > > arch/x86/mm/kaslr.c | 50 +++++++++++++++++++++++++++++++-------------- > > 1 file changed, 35 insertions(+), 15 deletions(-) > > > > diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c > > index dc6182eec..8e5f3642e 100644 > > --- a/arch/x86/mm/kaslr.c > > +++ b/arch/x86/mm/kaslr.c > > @@ -70,15 +70,45 @@ static inline bool kaslr_memory_enabled(void) > > return kaslr_enabled() && !IS_ENABLED(CONFIG_KASAN); > > } > > > > +/* > > + * Even though a huge virtual address space is reserved for the direct > > + * mapping of physical memory, e.g in 4-level paging mode, it's 64TB, > > + * rare system can own enough physical memory to use it up, most are > > + * even less than 1TB. So with KASLR enabled, we adapt the size of > > + * direct mapping area to the size of actual physical memory plus the > > + * configured padding CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING. > > + * The left part will be taken out to join memory randomization. > > + */ > > +static inline unsigned long calc_direct_mapping_size(void) > > I think patch 4 and 5 can be merged, just keep one > calc_direct_mapping_size() to do the mapping size calculation for the > direct mapping section, it's not that complicated. Adding > phys_memmap_size() makes it a little redundent, in my opinion. Thanks, I'll merge patch 4 and 5. - Masa > > Thanks > Baoquan > > > +{ > > + unsigned long size_tb, memory_tb; > > + > > + /* > > + * Update Physical memory mapping to available and > > + * add padding if needed (especially for memory hotplug support). > > + */ > > + memory_tb = DIV_ROUND_UP(max_pfn << PAGE_SHIFT, 1UL << TB_SHIFT) + > > + CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING; > > + > > + size_tb = 1 << (MAX_PHYSMEM_BITS - TB_SHIFT); > > + > > + /* > > + * Adapt physical memory region size based on available memory > > + */ > > + if (memory_tb < size_tb) > > + size_tb = memory_tb; > > + > > + return size_tb; > > +} > > + > > /* Initialize base and padding for each memory region randomized with KASLR */ > > void __init kernel_randomize_memory(void) > > { > > - size_t i; > > - unsigned long vaddr_start, vaddr; > > - unsigned long rand, memory_tb; > > - struct rnd_state rand_state; > > + unsigned long vaddr_start, vaddr, rand; > > unsigned long remain_entropy; > > unsigned long vmemmap_size; > > + struct rnd_state rand_state; > > + size_t i; > > > > vaddr_start = pgtable_l5_enabled() ? __PAGE_OFFSET_BASE_L5 : __PAGE_OFFSET_BASE_L4; > > vaddr = vaddr_start; > > @@ -95,20 +125,10 @@ void __init kernel_randomize_memory(void) > > if (!kaslr_memory_enabled()) > > return; > > > > - kaslr_regions[0].size_tb = 1 << (MAX_PHYSMEM_BITS - TB_SHIFT); > > + kaslr_regions[0].size_tb = calc_direct_mapping_size(); > > kaslr_regions[1].size_tb = VMALLOC_SIZE_TB; > > > > - /* > > - * Update Physical memory mapping to available and > > - * add padding if needed (especially for memory hotplug support). > > - */ > > BUG_ON(kaslr_regions[0].base != &page_offset_base); > > - memory_tb = DIV_ROUND_UP(max_pfn << PAGE_SHIFT, 1UL << TB_SHIFT) + > > - CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING; > > - > > - /* Adapt phyiscal memory region size based on available memory */ > > - if (memory_tb < kaslr_regions[0].size_tb) > > - kaslr_regions[0].size_tb = memory_tb; > > > > /* > > * Calculate the vmemmap region size in TBs, aligned to a TB > > -- > > 2.18.1 > >