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[2001:b400:e3a7:6c70:b197:cec7:ec88:495a]) by smtp.gmail.com with ESMTPSA id 143sm62117103pge.50.2019.04.08.09.33.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 08 Apr 2019 09:33:36 -0700 (PDT) From: pierre Kuo To: will.deacon@arm.com Cc: catalin.marinas@arm.com, steven.price@arm.com, f.fainelli@gmail.com, ard.biesheuvel@linaro.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, vichy.kuo@gmail.com Subject: [PATCH v3 1/2] kaslr: shift linear region randomization ahead of memory_limit Date: Tue, 9 Apr 2019 00:33:18 +0800 Message-Id: <20190408163319.10382-1-vichy.kuo@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following is schematic diagram of the program before and after the modification. Before: if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {} --(a) if (memory_limit != PHYS_ADDR_MAX) {} --(b) if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {} --(c) if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {} --(d)* After: if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {} --(a) if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {} --(d)* if (memory_limit != PHYS_ADDR_MAX) {} --(b) if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {} --(c) After grouping modification of memstart_address by moving linear region randomization ahead of memory_init, driver can safely using macro, __phys_to_virt, in (b) or (c), if necessary. Signed-off-by: pierre Kuo --- Changes in v2: - add Fixes tag Changes in v3: - adding patch of shifting linear region randomization ahead of memory_limit arch/arm64/mm/init.c | 33 +++++++++++++++++---------------- 1 file changed, 17 insertions(+), 16 deletions(-) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 7205a9085b4d..5142020fc146 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -389,6 +389,23 @@ void __init arm64_memblock_init(void) memblock_remove(0, memstart_addr); } + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { + extern u16 memstart_offset_seed; + u64 range = linear_region_size - + (memblock_end_of_DRAM() - memblock_start_of_DRAM()); + + /* + * If the size of the linear region exceeds, by a sufficient + * margin, the size of the region that the available physical + * memory spans, randomize the linear region as well. + */ + if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) { + range /= ARM64_MEMSTART_ALIGN; + memstart_addr -= ARM64_MEMSTART_ALIGN * + ((range * memstart_offset_seed) >> 16); + } + } + /* * Apply the memory limit if it was set. Since the kernel may be loaded * high up in memory, add back the kernel region that must be accessible @@ -428,22 +445,6 @@ void __init arm64_memblock_init(void) } } - if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { - extern u16 memstart_offset_seed; - u64 range = linear_region_size - - (memblock_end_of_DRAM() - memblock_start_of_DRAM()); - - /* - * If the size of the linear region exceeds, by a sufficient - * margin, the size of the region that the available physical - * memory spans, randomize the linear region as well. - */ - if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) { - range /= ARM64_MEMSTART_ALIGN; - memstart_addr -= ARM64_MEMSTART_ALIGN * - ((range * memstart_offset_seed) >> 16); - } - } /* * Register the kernel text, kernel data, initrd, and initial -- 2.17.1