[PATCH v7 21/33] arm64: head: Run feature override detection before mapping the kernel

[Ard Biesheuvel]

To permit the feature overrides to be taken into account before the
KASLR init code runs and the kernel mapping is created, move the
detection code to an earlier stage in the boot.

In a subsequent patch, this will be taken advantage of by merging the
preliminary and permanent mappings of the kernel text and data into a
single one that gets created and relocated before start_kernel() is
called.

Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
---
 arch/arm64/kernel/head.S              | 13 +++++++------
 arch/arm64/kernel/pi/idreg-override.c |  2 +-
 arch/arm64/kernel/vmlinux.lds.S       |  4 +---
 3 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 0e7aaa65ea174efc..9ea7f4e355ef5849 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -439,9 +439,6 @@ SYM_FUNC_START_LOCAL(__primary_switched)
 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
 	bl	kasan_early_init
 #endif
-	mov	x0, x20				// pass the full boot status
-	mov	x1, x22				// pass the low FDT mapping
-	bl	__pi_init_feature_override	// Parse cpu feature overrides
 #ifdef CONFIG_UNWIND_PATCH_PAC_INTO_SCS
 	bl	scs_patch_vmlinux
 #endif
@@ -698,12 +695,16 @@ SYM_FUNC_START_LOCAL(__primary_switch)
 	bl	__pi_memset
 	dsb	ishst				// Make zero page visible to PTW
 
-#ifdef CONFIG_RELOCATABLE
-	adrp	x23, KERNEL_START
-	and	x23, x23, MIN_KIMG_ALIGN - 1
 	adrp	x1, early_init_stack
 	mov	sp, x1
 	mov	x29, xzr
+	mov	x0, x20				// pass the full boot status
+	mov	x1, x22				// pass the low FDT mapping
+	bl	__pi_init_feature_override	// Parse cpu feature overrides
+
+#ifdef CONFIG_RELOCATABLE
+	adrp	x23, KERNEL_START
+	and	x23, x23, MIN_KIMG_ALIGN - 1
 #ifdef CONFIG_RANDOMIZE_BASE
 	mov	x0, x22
 	bl	__pi_kaslr_early_init
diff --git a/arch/arm64/kernel/pi/idreg-override.c b/arch/arm64/kernel/pi/idreg-override.c
index 86d994424779bc0d..c21d1e9f43a11ba7 100644
--- a/arch/arm64/kernel/pi/idreg-override.c
+++ b/arch/arm64/kernel/pi/idreg-override.c
@@ -20,7 +20,7 @@
 #define FTR_ALIAS_NAME_LEN	30
 #define FTR_ALIAS_OPTION_LEN	116
 
-static u64 __boot_status __initdata;
+static u64 __boot_status;
 
 struct ftr_set_desc {
 	s32		override_offset; 	// must remain first
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index bebb88daf4c52039..3f86a0db2952600c 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -317,10 +317,8 @@ SECTIONS
 	init_pg_dir = .;
 	. += INIT_DIR_SIZE;
 	init_pg_end = .;
-#ifdef CONFIG_RELOCATABLE
-	. += SZ_4K;		/* stack for the early relocation code */
+	. += SZ_4K;		/* stack for the early C runtime */
 	early_init_stack = .;
-#endif
 
 	. = ALIGN(SEGMENT_ALIGN);
 	__pecoff_data_size = ABSOLUTE(. - __initdata_begin);
-- 
2.35.1