linux-kernel - [PATCH v2 2/4] arm64/process: Make loading of 32bit processes depend on aarch32

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Date:   Mon, 23 Oct 2023 16:42:21 +0200
From:   Andrea della Porta <andrea.porta@...e.com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     nik.borisov@...e.com, arnd@...db.de, mark.rutland@....com,
        Andrea della Porta <andrea.porta@...e.com>
Subject: [PATCH v2 2/4] arm64/process: Make loading of 32bit processes depend on aarch32_enabled()

Major aspect of Aarch32 support is the ability to load 32bit
processes.
That's currently decided (among others) by compat_elf_check_arch()
and system_supports_32bit_el0().

Make the macro use aarch32_enabled() to decide if Aarch32 compat is
enabled before loading a 32bit process.

Signed-off-by: Andrea della Porta <andrea.porta@...e.com>
---
 arch/arm64/include/asm/cpufeature.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 1180d68daaff..778f2f3b2c7d 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -679,8 +679,9 @@ static inline bool system_supports_32bit_el0(void)
 {
 	u64 pfr0 = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1);
 
-	return static_branch_unlikely(&arm64_mismatched_32bit_el0) ||
-	       id_aa64pfr0_32bit_el0(pfr0);
+	return (static_branch_unlikely(&arm64_mismatched_32bit_el0) ||
+		id_aa64pfr0_32bit_el0(pfr0)) &&
+		aarch32_enabled();
 }
 
 static inline bool system_supports_4kb_granule(void)
-- 
2.35.3