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Mon, 11 May 2026 03:46:39 -0700 (PDT) From: WANG Rui To: Huacai Chen , Ard Biesheuvel Cc: WANG Xuerui , Ilias Apalodimas , Haiyong Sun , Lisa Robinson , loongarch@lists.linux.dev, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, WANG Rui , Huacai Chen Subject: [PATCH v5 1/3] efi/loongarch: Randomize kernel preferred address for KASLR Date: Mon, 11 May 2026 18:45:53 +0800 Message-ID: <20260511104555.196270-2-r@hev.cc> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260511104555.196270-1-r@hev.cc> References: <20260511104555.196270-1-r@hev.cc> Precedence: bulk X-Mailing-List: linux-efi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Introduce efi_get_kimg_kaslr_address() helper to compute the preferred kernel image load address dynamically when CONFIG_RANDOMIZE_BASE is enabled. The function derives a random offset by using the EFI-provided randomness combined with the timer tick 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. Note: LoongArch can't KASLR for hibernation, so set efi_nokaslr to true if "resume=" is explicitly specified in cmdline. Acked-by: Ard Biesheuvel Co-authored-by: Huacai Chen Signed-off-by: WANG Rui Signed-off-by: Huacai Chen --- arch/loongarch/include/asm/efi.h | 4 +++- drivers/firmware/efi/libstub/efi-stub-helper.c | 4 ++++ drivers/firmware/efi/libstub/loongarch.c | 16 ++++++++++++++++ 3 files changed, 23 insertions(+), 1 deletion(-) diff --git a/arch/loongarch/include/asm/efi.h b/arch/loongarch/include/asm/efi.h index eddc8e79b3fa..1ad764b18c3e 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; } -#define EFI_KIMG_PREFERRED_ADDRESS PHYSADDR(VMLINUX_LOAD_ADDRESS) +unsigned long efi_get_kimg_kaslr_address(void); + +#define EFI_KIMG_PREFERRED_ADDRESS efi_get_kimg_kaslr_address() #endif /* _ASM_LOONGARCH_EFI_H */ diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c index 7aa2f9ad2935..f27f2e1f0019 100644 --- a/drivers/firmware/efi/libstub/efi-stub-helper.c +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c @@ -79,6 +79,10 @@ efi_status_t efi_parse_options(char const *cmdline) efi_noinitrd = true; } else if (IS_ENABLED(CONFIG_X86_64) && !strcmp(param, "no5lvl")) { efi_no5lvl = true; + } else if (IS_ENABLED(CONFIG_LOONGARCH) && + IS_ENABLED(CONFIG_HIBERNATION) && + !strcmp(param, "resume") && val) { + efi_nokaslr = true; /* LoongArch can't KASLR for hibernation */ } else if (IS_ENABLED(CONFIG_ARCH_HAS_MEM_ENCRYPT) && !strcmp(param, "mem_encrypt") && val) { if (parse_option_str(val, "on")) diff --git a/drivers/firmware/efi/libstub/loongarch.c b/drivers/firmware/efi/libstub/loongarch.c index f7938d5c196a..2b0c87dc9908 100644 --- a/drivers/firmware/efi/libstub/loongarch.c +++ b/drivers/firmware/efi/libstub/loongarch.c @@ -23,6 +23,22 @@ void efi_cache_sync_image(unsigned long image_base, unsigned long alloc_size) asm volatile ("ibar 0" ::: "memory"); } +unsigned long efi_get_kimg_kaslr_address(void) +{ + unsigned int random_offset = 0; + +#ifdef CONFIG_RANDOMIZE_BASE + if (!efi_nokaslr) { + efi_get_random_bytes(sizeof(random_offset), (u8 *)&random_offset); + random_offset ^= (random_get_entropy() << 16); + random_offset &= (CONFIG_RANDOMIZE_BASE_MAX_OFFSET - 1); + random_offset = ALIGN(random_offset + SZ_64K, SZ_64K); + } +#endif + + return PHYSADDR(VMLINUX_LOAD_ADDRESS) + random_offset; +} + struct exit_boot_struct { efi_memory_desc_t *runtime_map; int runtime_entry_count; -- 2.54.0