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Mon, 27 Apr 2026 21:02:29 -0700 (PDT) From: WANG Rui To: Huacai Chen , Ard Biesheuvel Cc: WANG Xuerui , Ilias Apalodimas , Lisa Robinson , loongarch@lists.linux.dev, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, WANG Rui Subject: [PATCH v2 1/2] efi/loongarch: Randomize kernel preferred address for KASLR Date: Tue, 28 Apr 2026 12:01:58 +0800 Message-ID: <20260428040159.1065822-2-r@hev.cc> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260428040159.1065822-1-r@hev.cc> References: <20260428040159.1065822-1-r@hev.cc> 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" Introduce efi_get_kimg_kaslr_address() to compute the preferred kernel image address dynamically when CONFIG_RANDOMIZE_BASE is enabled. The function derives a random offset using EFI-provided randomness combined with the timer value, and constrains it within CONFIG_RANDOMIZE_BASE_MAX_OFFSET. Update EFI_KIMG_PREFERRED_ADDRESS to call this helper so that the EFI stub can select a randomized load address when KASLR is active, while preserving the original base address behavior when KASLR is disabled or nokaslr is specified. Signed-off-by: WANG Rui --- arch/loongarch/Kconfig | 2 +- arch/loongarch/include/asm/efi.h | 4 +++- drivers/firmware/efi/libstub/loongarch.c | 16 ++++++++++++++++ 3 files changed, 20 insertions(+), 2 deletions(-) diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index 3b042dbb2c41..a5afb70f73d9 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -730,7 +730,7 @@ config RANDOMIZE_BASE config RANDOMIZE_BASE_MAX_OFFSET hex "Maximum KASLR offset" if EXPERT depends on RANDOMIZE_BASE - range 0x0 0x10000000 + range 0x20000 0x10000000 default "0x01000000" help When KASLR is active, this provides the maximum offset that will diff --git a/arch/loongarch/include/asm/efi.h b/arch/loongarch/include/asm/= efi.h index eddc8e79b3fa..f831320efd41 100644 --- a/arch/loongarch/include/asm/efi.h +++ b/arch/loongarch/include/asm/efi.h @@ -30,6 +30,8 @@ static inline unsigned long efi_get_kimg_min_align(void) return SZ_2M; } =20 -#define EFI_KIMG_PREFERRED_ADDRESS PHYSADDR(VMLINUX_LOAD_ADDRESS) +unsigned long efi_get_kimg_kaslr_address(void); 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Mon, 27 Apr 2026 21:02:32 -0700 (PDT) Received: from localhost ([2400:8902:e002:de33:3dbd:69cf:4a22:309]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b97ac8cd29sm10131365ad.61.2026.04.27.21.02.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Apr 2026 21:02:31 -0700 (PDT) From: WANG Rui To: Huacai Chen , Ard Biesheuvel Cc: WANG Xuerui , Ilias Apalodimas , Lisa Robinson , loongarch@lists.linux.dev, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, WANG Rui Subject: [PATCH v2 2/2] LoongArch: Skip relocation-time KASLR if it has already been applied Date: Tue, 28 Apr 2026 12:01:59 +0800 Message-ID: <20260428040159.1065822-3-r@hev.cc> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260428040159.1065822-1-r@hev.cc> References: <20260428040159.1065822-1-r@hev.cc> 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" When the kernel is relocated during early boot, a randomized load address may already have been selected and applied. In this case, performing KASLR again in relocate.c is unnecessary. Signed-off-by: WANG Rui --- arch/loongarch/kernel/relocate.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/loongarch/kernel/relocate.c b/arch/loongarch/kernel/reloc= ate.c index 16f6a9b39659..c36604a81d08 100644 --- a/arch/loongarch/kernel/relocate.c +++ b/arch/loongarch/kernel/relocate.c @@ -139,6 +139,10 @@ static inline __init bool kaslr_disabled(void) char *str; const char *builtin_cmdline =3D CONFIG_CMDLINE; =20 + /* KASLR is performed during early boot. */ + if (kaslr_offset()) + return true; + str =3D strstr(builtin_cmdline, "nokaslr"); if (str =3D=3D builtin_cmdline || (str > builtin_cmdline && *(str - 1) = =3D=3D ' ')) { pr_info(KASLR_DISABLED_MESSAGE, "\'nokaslr\'", "built-in"); --=20 2.54.0