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Message-ID: <20250508114328.2460610-7-ardb+git@google.com>
Date: Thu,  8 May 2025 13:43:31 +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 2/3] arm64/boot: Move global CPU override variables out of BSS

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

Accessing BSS will no longer be permitted from the startup code in
arch/arm64/kernel/pi, as some of it executes before BSS is cleared.
Clearing BSS earlier would involve managing cache coherency explicitly
in software, which is a hassle we prefer to avoid.

So move some variables that are assigned by the startup code out of BSS
and into .data.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/arm64/kernel/cpufeature.c | 22 ++++++++++----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 4c46d80aa64b..2cac5e5ca94d 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -765,17 +765,17 @@ static const struct arm64_ftr_bits ftr_raz[] = {
 #define ARM64_FTR_REG(id, table)		\
 	__ARM64_FTR_REG_OVERRIDE(#id, id, table, &no_override)
 
-struct arm64_ftr_override id_aa64mmfr0_override;
-struct arm64_ftr_override id_aa64mmfr1_override;
-struct arm64_ftr_override id_aa64mmfr2_override;
-struct arm64_ftr_override id_aa64pfr0_override;
-struct arm64_ftr_override id_aa64pfr1_override;
-struct arm64_ftr_override id_aa64zfr0_override;
-struct arm64_ftr_override id_aa64smfr0_override;
-struct arm64_ftr_override id_aa64isar1_override;
-struct arm64_ftr_override id_aa64isar2_override;
-
-struct arm64_ftr_override arm64_sw_feature_override;
+struct arm64_ftr_override __read_mostly id_aa64mmfr0_override;
+struct arm64_ftr_override __read_mostly id_aa64mmfr1_override;
+struct arm64_ftr_override __read_mostly id_aa64mmfr2_override;
+struct arm64_ftr_override __read_mostly id_aa64pfr0_override;
+struct arm64_ftr_override __read_mostly id_aa64pfr1_override;
+struct arm64_ftr_override __read_mostly id_aa64zfr0_override;
+struct arm64_ftr_override __read_mostly id_aa64smfr0_override;
+struct arm64_ftr_override __read_mostly id_aa64isar1_override;
+struct arm64_ftr_override __read_mostly id_aa64isar2_override;
+
+struct arm64_ftr_override __read_mostly arm64_sw_feature_override;
 
 static const struct __ftr_reg_entry {
 	u32			sys_id;
-- 
2.49.0.987.g0cc8ee98dc-goog


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