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From: Daniel Kiss <daniel.kiss@arm.com>
To: daniel.kiss@arm.com
Cc: Catalin.Marinas@arm.com, will@kernel.org, pcc@google.com,
	Ard.Biesheuvel@arm.com, linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 2/2] arm64: Do not configure kernel's PTR_AUTH key when it not needed.
Date: Fri, 18 Dec 2020 12:56:32 +0100	[thread overview]
Message-ID: <20201218115632.59067-3-daniel.kiss@arm.com> (raw)
In-Reply-To: <20201218115632.59067-1-daniel.kiss@arm.com>

If the kernel is not compiled with CONFIG_ARM64_PTR_AUTH_KERNEL,
then no need to install dedicated key for the kernel, user's key
could be left enabled because no PACI/AUTI instructions are expected..

Signed-off-by: Daniel Kiss <daniel.kiss@arm.com>
---
 arch/arm64/include/asm/asm_pointer_auth.h | 53 +++++++++++++----------
 arch/arm64/include/asm/pointer_auth.h     | 20 ++++++---
 arch/arm64/include/asm/processor.h        |  2 +
 arch/arm64/kernel/asm-offsets.c           |  4 ++
 4 files changed, 51 insertions(+), 28 deletions(-)

diff --git a/arch/arm64/include/asm/asm_pointer_auth.h b/arch/arm64/include/asm/asm_pointer_auth.h
index 52dead2a8640..b2572a943f59 100644
--- a/arch/arm64/include/asm/asm_pointer_auth.h
+++ b/arch/arm64/include/asm/asm_pointer_auth.h
@@ -39,27 +39,6 @@ alternative_if ARM64_HAS_GENERIC_AUTH
 alternative_else_nop_endif
 	.endm
 
-	.macro __ptrauth_keys_install_kernel_nosync tsk, tmp1, tmp2, tmp3
-	mov	\tmp1, #THREAD_KEYS_KERNEL
-	add	\tmp1, \tsk, \tmp1
-	ldp	\tmp2, \tmp3, [\tmp1, #PTRAUTH_KERNEL_KEY_APIA]
-	msr_s	SYS_APIAKEYLO_EL1, \tmp2
-	msr_s	SYS_APIAKEYHI_EL1, \tmp3
-	.endm
-
-	.macro ptrauth_keys_install_kernel_nosync tsk, tmp1, tmp2, tmp3
-alternative_if ARM64_HAS_ADDRESS_AUTH
-	__ptrauth_keys_install_kernel_nosync \tsk, \tmp1, \tmp2, \tmp3
-alternative_else_nop_endif
-	.endm
-
-	.macro ptrauth_keys_install_kernel tsk, tmp1, tmp2, tmp3
-alternative_if ARM64_HAS_ADDRESS_AUTH
-	__ptrauth_keys_install_kernel_nosync \tsk, \tmp1, \tmp2, \tmp3
-	isb
-alternative_else_nop_endif
-	.endm
-
 	.macro __ptrauth_keys_init_cpu tsk, tmp1, tmp2, tmp3
 	mrs	\tmp1, id_aa64isar1_el1
 	ubfx	\tmp1, \tmp1, #ID_AA64ISAR1_APA_SHIFT, #8
@@ -69,7 +48,9 @@ alternative_else_nop_endif
 	mrs	\tmp2, sctlr_el1
 	orr	\tmp2, \tmp2, \tmp1
 	msr	sctlr_el1, \tmp2
+#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
 	__ptrauth_keys_install_kernel_nosync \tsk, \tmp1, \tmp2, \tmp3
+#endif
 	isb
 .Lno_addr_auth\@:
 	.endm
@@ -82,17 +63,43 @@ alternative_else_nop_endif
 .Lno_addr_auth\@:
 	.endm
 
-#else /* CONFIG_ARM64_PTR_AUTH */
+#else /* !CONFIG_ARM64_PTR_AUTH */
 
 	.macro ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3
 	.endm
 
+#endif /* CONFIG_ARM64_PTR_AUTH */
+
+#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
+	.macro __ptrauth_keys_install_kernel_nosync tsk, tmp1, tmp2, tmp3
+	mov	\tmp1, #THREAD_KEYS_KERNEL
+	add	\tmp1, \tsk, \tmp1
+	ldp	\tmp2, \tmp3, [\tmp1, #PTRAUTH_KERNEL_KEY_APIA]
+	msr_s	SYS_APIAKEYLO_EL1, \tmp2
+	msr_s	SYS_APIAKEYHI_EL1, \tmp3
+	.endm
+
 	.macro ptrauth_keys_install_kernel_nosync tsk, tmp1, tmp2, tmp3
+alternative_if ARM64_HAS_ADDRESS_AUTH
+	__ptrauth_keys_install_kernel_nosync \tsk, \tmp1, \tmp2, \tmp3
+alternative_else_nop_endif
 	.endm
 
 	.macro ptrauth_keys_install_kernel tsk, tmp1, tmp2, tmp3
+alternative_if ARM64_HAS_ADDRESS_AUTH
+	__ptrauth_keys_install_kernel_nosync \tsk, \tmp1, \tmp2, \tmp3
+	isb
+alternative_else_nop_endif
 	.endm
 
-#endif /* CONFIG_ARM64_PTR_AUTH */
+#else /* CONFIG_ARM64_PTR_AUTH_KERNEL */
+
+	.macro ptrauth_keys_install_kernel_nosync tsk, tmp1, tmp2, tmp3
+	.endm
+
+	.macro ptrauth_keys_install_kernel tsk, tmp1, tmp2, tmp3
+	.endm
+
+#endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
 
 #endif /* __ASM_ASM_POINTER_AUTH_H */
diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h
index c6b4f0603024..b34aebb95757 100644
--- a/arch/arm64/include/asm/pointer_auth.h
+++ b/arch/arm64/include/asm/pointer_auth.h
@@ -30,9 +30,11 @@ struct ptrauth_keys_user {
 	struct ptrauth_key apga;
 };
 
+#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
 struct ptrauth_keys_kernel {
 	struct ptrauth_key apia;
 };
+#endif
 
 static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
 {
@@ -54,6 +56,8 @@ do {								\
 	write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1);	\
 } while (0)
 
+#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
+
 static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
 {
 	if (system_supports_address_auth())
@@ -69,6 +73,8 @@ static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kerne
 	isb();
 }
 
+#endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
+
 extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
 
 static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
@@ -78,17 +84,21 @@ static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
 
 #define ptrauth_thread_init_user(tsk)					\
 	ptrauth_keys_init_user(&(tsk)->thread.keys_user)
-#define ptrauth_thread_init_kernel(tsk)					\
-	ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
-#define ptrauth_thread_switch_kernel(tsk)				\
-	ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
 
 #else /* CONFIG_ARM64_PTR_AUTH */
 #define ptrauth_prctl_reset_keys(tsk, arg)	(-EINVAL)
 #define ptrauth_strip_insn_pac(lr)	(lr)
 #define ptrauth_thread_init_user(tsk)
+#endif /* CONFIG_ARM64_PTR_AUTH */
+
+#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
+#define ptrauth_thread_init_kernel(tsk)					\
+	ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
+#define ptrauth_thread_switch_kernel(tsk)				\
+	ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
+#else
 #define ptrauth_thread_init_kernel(tsk)
 #define ptrauth_thread_switch_kernel(tsk)
-#endif /* CONFIG_ARM64_PTR_AUTH */
+#endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
 
 #endif /* __ASM_POINTER_AUTH_H */
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 9c5efcc6e7f1..c78d63be5bd1 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -153,8 +153,10 @@ struct thread_struct {
 	struct debug_info	debug;		/* debugging */
 #ifdef CONFIG_ARM64_PTR_AUTH
 	struct ptrauth_keys_user	keys_user;
+#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
 	struct ptrauth_keys_kernel	keys_kernel;
 #endif
+#endif
 #ifdef CONFIG_ARM64_MTE
 	u64			sctlr_tcf0;
 	u64			gcr_user_incl;
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 7d32fc959b1a..cb7965a9f505 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -46,7 +46,9 @@ int main(void)
   DEFINE(THREAD_CPU_CONTEXT,	offsetof(struct task_struct, thread.cpu_context));
 #ifdef CONFIG_ARM64_PTR_AUTH
   DEFINE(THREAD_KEYS_USER,	offsetof(struct task_struct, thread.keys_user));
+#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
   DEFINE(THREAD_KEYS_KERNEL,	offsetof(struct task_struct, thread.keys_kernel));
+#endif
 #endif
   BLANK();
   DEFINE(S_X0,			offsetof(struct pt_regs, regs[0]));
@@ -141,7 +143,9 @@ int main(void)
   DEFINE(PTRAUTH_USER_KEY_APDA,		offsetof(struct ptrauth_keys_user, apda));
   DEFINE(PTRAUTH_USER_KEY_APDB,		offsetof(struct ptrauth_keys_user, apdb));
   DEFINE(PTRAUTH_USER_KEY_APGA,		offsetof(struct ptrauth_keys_user, apga));
+#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
   DEFINE(PTRAUTH_KERNEL_KEY_APIA,	offsetof(struct ptrauth_keys_kernel, apia));
+#endif
   BLANK();
 #endif
   return 0;
-- 
2.29.2


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  parent reply	other threads:[~2020-12-18 11:58 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-07 22:46 arm64: split ARM64_PTR_AUTH option to userspace and kernel configs Daniel Kiss
2020-12-07 22:46 ` [PATCH 1/2] arm64: Add ARM64_PTR_AUTH_KERNEL config option Daniel Kiss
2020-12-07 22:46 ` [PATCH 2/2] arm64: Configure kernel's PTR_AUTH key when it is built with PTR_AUTH Daniel Kiss
2020-12-07 23:07   ` Peter Collingbourne
2020-12-08 11:00     ` Catalin Marinas
2020-12-08 19:33       ` Peter Collingbourne
2020-12-09 10:51         ` Will Deacon
2020-12-09 11:56           ` Daniel Kiss
2020-12-18 11:56             ` arm64: split ARM64_PTR_AUTH option to userspace and kernel Daniel Kiss
2020-12-18 11:56               ` [PATCH v2 1/2] arm64: Add ARM64_PTR_AUTH_KERNEL config option Daniel Kiss
2021-01-26 13:27                 ` Will Deacon
2021-02-08 14:39                   ` Daniel Kiss
2020-12-18 11:56               ` Daniel Kiss [this message]
2021-01-26 13:32                 ` [PATCH v2 2/2] arm64: Do not configure kernel's PTR_AUTH key when it not needed Will Deacon
2021-01-26 13:17               ` arm64: split ARM64_PTR_AUTH option to userspace and kernel Will Deacon

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