Messages in this thread Patch in this message | | | From | Ard Biesheuvel <> | Subject | [PATCH v3 33/60] arm64: head: move memstart_offset_seed handling to C code | Date | Tue, 7 Mar 2023 15:04:55 +0100 |
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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 <ardb@kernel.org> --- 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 70ad180eed364906..81c2dd06420992ea 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 @@ -777,7 +771,6 @@ 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 5aa914ea919a1149..b7fa7fbf8fa543a6 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 f2305e276ec36803..eeecee7ffd6fa125 100644 --- a/arch/arm64/kernel/pi/kaslr_early.c +++ b/arch/arm64/kernel/pi/kaslr_early.c @@ -16,6 +16,8 @@ #include <asm/memory.h> #include <asm/pgtable.h> +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 -- 2.39.2
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