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(bba-86-97-172-234.alshamil.net.ae. [86.97.172.234]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-390e47960b6sm16732712f8f.17.2025.03.03.20.26.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Mar 2025 20:26:42 -0800 (PST) From: kpark3469@gmail.com To: ardb@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: catalin.marinas@arm.com, will@kernel.org, keun-o.park@katim.com Subject: [PATCH v2] arm64: kaslr: warning linear region randomization on failure Date: Tue, 4 Mar 2025 08:26:34 +0400 Message-Id: <20250304042634.591375-1-kpark3469@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Keuno Park On systems using 4KB pages and having 39 VA_BITS, linear_region_size gets 256GiB space. It was observed that some SoCs such as Qualcomm QCM8550 returns 40bits of PA range from MMFR0_EL1. This leads range value to have minus as the variable range is s64, so that all the calculations for randomizing linear address space are skipped. As a result of this, the kernel's linear region is not randomized. For hotplug memory users, kernel needs to inform that linear region is not randomized. However, if CONFIG_MEMORY_HOTPLUG is turned off, then kernel tries to fall back to the legacy way to randomize linear region. Change-Id: Ib29e45f44928937881d514fb87b4cac828b5a3f5 Fixes: 97d6786e0669 ("arm64: mm: account for hotplug memory when randomizin= g the linear region") Signed-off-by: Keuno Park --- arch/arm64/mm/init.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 9c0b8d9558fc..848790a9e75e 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -290,6 +290,17 @@ void __init arm64_memblock_init(void) s64 range =3D linear_region_size - BIT(id_aa64mmfr0_parange_to_phys_shift(parange)); =20 + if (range < 0) { + if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) { + WARN(true, "linear region is not randomized due to bigger parange\n"); + } else { + pr_warn("falling back to the range considering on-boot DRAM size\n"); + range =3D 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 physical memory can --=20 2.34.1