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Tue, 12 Sep 2023 07:18:30 -0700 (PDT) Date: Tue, 12 Sep 2023 14:16:21 +0000 In-Reply-To: <20230912141549.278777-63-ardb@google.com> Mime-Version: 1.0 References: <20230912141549.278777-63-ardb@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=3177; i=ardb@kernel.org; h=from:subject; bh=3t5eK0yXAKEY06tW4A49CunV4PkgMuSeHKCOWhSWhg0=; b=owGbwMvMwCFmkMcZplerG8N4Wi2JIZWhaNsvA9953D9md5/KCVm1N8JU1OP7U8acKttHs4WvB 90tiM7vKGVhEONgkBVTZBGY/ffdztMTpWqdZ8nCzGFlAhnCwMUpABM538XIsHXGZqUExUXiDAfv rTU5ymSf+sXctMj+w6EXB6Pyulxu3mJkuPnO7Vr1OpapW2raZ3CJ60zbacllm6bit8002u3kppI wPgA= X-Mailer: git-send-email 2.42.0.283.g2d96d420d3-goog Message-ID: <20230912141549.278777-94-ardb@google.com> Subject: [PATCH v4 31/61] arm64: head: move memstart_offset_seed handling to C code From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: Ard Biesheuvel , Catalin Marinas , Will Deacon , Marc Zyngier , Mark Rutland , Ryan Roberts , Anshuman Khandual , Kees Cook , Joey Gouly X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230912_071832_897076_57C7A2DD X-CRM114-Status: GOOD ( 14.86 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Ard Biesheuvel Now that we can set BSS variables from the early code running from the ID map, we can set memstart_offset_seed directly from the C code that derives the value instead of passing it back and forth between C and asm code. Signed-off-by: Ard Biesheuvel --- arch/arm64/kernel/head.S | 7 ------- arch/arm64/kernel/image-vars.h | 1 + arch/arm64/kernel/pi/kaslr_early.c | 4 ++++ 3 files changed, 5 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index b320702032a7..aa7766dc64d9 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -82,7 +82,6 @@ * x21 primary_entry() .. start_kernel() FDT pointer passed at boot in x0 * x22 create_idmap() .. start_kernel() ID map VA of the DT blob * x23 __primary_switch() physical misalignment/KASLR offset - * x24 __primary_switch() linear map KASLR seed * x25 primary_entry() .. start_kernel() supported VA size * x28 create_idmap() callee preserved temp register */ @@ -483,11 +482,6 @@ SYM_FUNC_START_LOCAL(__primary_switched) str x25, [x8] // ... observes the correct value dc civac, x8 // Make visible to booting secondaries #endif - -#ifdef CONFIG_RANDOMIZE_BASE - adrp x5, memstart_offset_seed // Save KASLR linear map seed - strh w24, [x5, :lo12:memstart_offset_seed] -#endif #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) bl kasan_early_init #endif @@ -779,7 +773,6 @@ SYM_FUNC_START_LOCAL(__primary_switch) #ifdef CONFIG_RANDOMIZE_BASE mov x0, x22 bl __pi_kaslr_early_init - and x24, x0, #SZ_2M - 1 // capture memstart offset seed bic x0, x0, #SZ_2M - 1 orr x23, x23, x0 // record kernel offset #endif diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h index 011a9dd93bd2..f2c06f1a9e70 100644 --- a/arch/arm64/kernel/image-vars.h +++ b/arch/arm64/kernel/image-vars.h @@ -44,6 +44,7 @@ PROVIDE(__pi_id_aa64smfr0_override = id_aa64smfr0_override); PROVIDE(__pi_id_aa64zfr0_override = id_aa64zfr0_override); PROVIDE(__pi_arm64_sw_feature_override = arm64_sw_feature_override); PROVIDE(__pi__ctype = _ctype); +PROVIDE(__pi_memstart_offset_seed = memstart_offset_seed); #ifdef CONFIG_KVM diff --git a/arch/arm64/kernel/pi/kaslr_early.c b/arch/arm64/kernel/pi/kaslr_early.c index f2305e276ec3..eeecee7ffd6f 100644 --- a/arch/arm64/kernel/pi/kaslr_early.c +++ b/arch/arm64/kernel/pi/kaslr_early.c @@ -16,6 +16,8 @@ #include #include +extern u16 memstart_offset_seed; + static u64 __init get_kaslr_seed(void *fdt) { static char const chosen_str[] __initconst = "chosen"; @@ -51,6 +53,8 @@ asmlinkage u64 __init kaslr_early_init(void *fdt) return 0; } + memstart_offset_seed = seed & U16_MAX; + /* * OK, so we are proceeding with KASLR enabled. Calculate a suitable * kernel image offset from the seed. Let's place the kernel in the