linux-kernel - [PATCH v2 1/3] arm64/boot: Move init_pgdir[] and init_idmap_pgdir[] into __pi

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Message-ID: <20250508114328.2460610-6-ardb+git@google.com>
Date: Thu,  8 May 2025 13:43:30 +0200
From: Ard Biesheuvel <ardb+git@...gle.com>
To: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org, will@...nel.org, catalin.marinas@....com, 
	mark.rutland@....com, Ard Biesheuvel <ardb@...nel.org>, Yeoreum Yun <yeoreum.yun@....com>
Subject: [PATCH v2 1/3] arm64/boot: Move init_pgdir[] and init_idmap_pgdir[]
 into __pi_ namespace

From: Ard Biesheuvel <ardb@...nel.org>

init_pgdir[] is only referenced from the startup code, but lives after
BSS in the linker map. Before tightening the rules about accessing BSS
from startup code, move init_pgdir[] into the __pi_ namespace, so it
does not need to be exported explicitly.

For symmetry, do the same with init_idmap_pgdir[], although it lives
before BSS.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/arm64/include/asm/pgtable.h | 2 --
 arch/arm64/kernel/head.S         | 6 +++---
 arch/arm64/kernel/image-vars.h   | 4 ----
 arch/arm64/kernel/pi/pi.h        | 1 +
 arch/arm64/kernel/vmlinux.lds.S  | 8 ++++----
 5 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index d3b538be1500..6a040f0bbfe1 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -754,8 +754,6 @@ static inline bool pud_table(pud_t pud) { return true; }
 				 PUD_TYPE_TABLE)
 #endif
 
-extern pgd_t init_pg_dir[];
-extern pgd_t init_pg_end[];
 extern pgd_t swapper_pg_dir[];
 extern pgd_t idmap_pg_dir[];
 extern pgd_t tramp_pg_dir[];
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 2ce73525de2c..ca04b338cb0d 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -89,7 +89,7 @@ SYM_CODE_START(primary_entry)
 	adrp	x1, early_init_stack
 	mov	sp, x1
 	mov	x29, xzr
-	adrp	x0, init_idmap_pg_dir
+	adrp	x0, __pi_init_idmap_pg_dir
 	mov	x1, xzr
 	bl	__pi_create_init_idmap
 
@@ -101,7 +101,7 @@ SYM_CODE_START(primary_entry)
 	cbnz	x19, 0f
 	dmb     sy
 	mov	x1, x0				// end of used region
-	adrp    x0, init_idmap_pg_dir
+	adrp    x0, __pi_init_idmap_pg_dir
 	adr_l	x2, dcache_inval_poc
 	blr	x2
 	b	1f
@@ -507,7 +507,7 @@ SYM_FUNC_END(__no_granule_support)
 
 SYM_FUNC_START_LOCAL(__primary_switch)
 	adrp	x1, reserved_pg_dir
-	adrp	x2, init_idmap_pg_dir
+	adrp	x2, __pi_init_idmap_pg_dir
 	bl	__enable_mmu
 
 	adrp	x1, early_init_stack
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 5e3c4b58f279..c3b4c0479d5c 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -54,10 +54,6 @@ PROVIDE(__pi_is_midr_in_range_list	= is_midr_in_range_list);
 PROVIDE(__pi__ctype			= _ctype);
 PROVIDE(__pi_memstart_offset_seed	= memstart_offset_seed);
 
-PROVIDE(__pi_init_idmap_pg_dir		= init_idmap_pg_dir);
-PROVIDE(__pi_init_idmap_pg_end		= init_idmap_pg_end);
-PROVIDE(__pi_init_pg_dir		= init_pg_dir);
-PROVIDE(__pi_init_pg_end		= init_pg_end);
 PROVIDE(__pi_swapper_pg_dir		= swapper_pg_dir);
 
 PROVIDE(__pi__text			= _text);
diff --git a/arch/arm64/kernel/pi/pi.h b/arch/arm64/kernel/pi/pi.h
index c91e5e965cd3..1f4731a4e17e 100644
--- a/arch/arm64/kernel/pi/pi.h
+++ b/arch/arm64/kernel/pi/pi.h
@@ -22,6 +22,7 @@ static inline void *prel64_to_pointer(const prel64_t *offset)
 extern bool dynamic_scs_is_enabled;
 
 extern pgd_t init_idmap_pg_dir[], init_idmap_pg_end[];
+extern pgd_t init_pg_dir[], init_pg_end[];
 
 void init_feature_override(u64 boot_status, const void *fdt, int chosen);
 u64 kaslr_early_init(void *fdt, int chosen);
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index e73326bd3ff7..466544c47dca 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -249,9 +249,9 @@ SECTIONS
 	__inittext_end = .;
 	__initdata_begin = .;
 
-	init_idmap_pg_dir = .;
+	__pi_init_idmap_pg_dir = .;
 	. += INIT_IDMAP_DIR_SIZE;
-	init_idmap_pg_end = .;
+	__pi_init_idmap_pg_end = .;
 
 	.init.data : {
 		INIT_DATA
@@ -321,9 +321,9 @@ SECTIONS
 	BSS_SECTION(SBSS_ALIGN, 0, 0)
 
 	. = ALIGN(PAGE_SIZE);
-	init_pg_dir = .;
+	__pi_init_pg_dir = .;
 	. += INIT_DIR_SIZE;
-	init_pg_end = .;
+	__pi_init_pg_end = .;
 	/* end of zero-init region */
 
 	. += SZ_4K;		/* stack for the early C runtime */
-- 
2.49.0.987.g0cc8ee98dc-goog