linux-kernel - [PATCH v2 5/6] arm64: make the per-task SCTLR2

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Message-Id: <20250811163340.1561893-6-yeoreum.yun@arm.com>
Date: Mon, 11 Aug 2025 17:33:39 +0100
From: Yeoreum Yun <yeoreum.yun@....com>
To: catalin.marinas@....com,
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Cc: linux-arm-kernel@...ts.infradead.org,
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	Yeoreum Yun <yeoreum.yun@....com>
Subject: [PATCH v2 5/6] arm64: make the per-task SCTLR2_EL1

Some of field of SCTLR2 registers should be configurable per task
not globally -- i.e) FEAT_CPA2 related field and etc.

For future usage of these fields, make the per-task SCTLR2_EL1.

Signed-off-by: Yeoreum Yun <yeoreum.yun@....com>
---
 arch/arm64/include/asm/processor.h | 5 +++++
 arch/arm64/kernel/process.c        | 9 +++++++++
 2 files changed, 14 insertions(+)

diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 61d62bfd5a7b..2c962816de70 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -184,6 +184,7 @@ struct thread_struct {
 	u64			mte_ctrl;
 #endif
 	u64			sctlr_user;
+	u64			sctlr2_user;
 	u64			svcr;
 	u64			tpidr2_el0;
 	u64			por_el0;
@@ -258,6 +259,9 @@ static inline void task_set_sve_vl_onexec(struct task_struct *task,
 	(SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | SCTLR_ELx_ENDA | SCTLR_ELx_ENDB |   \
 	 SCTLR_EL1_TCF0_MASK)
 
+#define SCTLR2_USER_MASK	\
+	(SCTLR2_EL1_EnPACM0 | SCTLR2_EL1_CPTA0 | SCTLR2_EL1_CPTM0)
+
 static inline void arch_thread_struct_whitelist(unsigned long *offset,
 						unsigned long *size)
 {
@@ -370,6 +374,7 @@ struct task_struct;
 unsigned long __get_wchan(struct task_struct *p);
 
 void update_sctlr_el1(u64 sctlr);
+void update_sctlr2_el1(u64 sctlr2);
 
 /* Thread switching */
 extern struct task_struct *cpu_switch_to(struct task_struct *prev,
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 96482a1412c6..9191180c4875 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -698,6 +698,11 @@ void update_sctlr_el1(u64 sctlr)
 	isb();
 }
 
+void update_sctlr2_el1(u64 sctlr2)
+{
+	sysreg_clear_set_s(SYS_SCTLR2_EL1, SCTLR2_USER_MASK, sctlr2);
+}
+
 /*
  * Thread switching.
  */
@@ -737,6 +742,10 @@ struct task_struct *__switch_to(struct task_struct *prev,
 	if (prev->thread.sctlr_user != next->thread.sctlr_user)
 		update_sctlr_el1(next->thread.sctlr_user);
 
+	if (alternative_has_cap_unlikely(ARM64_HAS_SCTLR2) &&
+	    prev->thread.sctlr2_user != next->thread.sctlr2_user)
+		update_sctlr2_el1(next->thread.sctlr2_user);
+
 	/* the actual thread switch */
 	last = cpu_switch_to(prev, next);
 
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}