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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Subject: [PATCH v5 15/23] powerpc/book3s64/pkeys: Don't update SPRN_AMR when in kernel mode.
Date: Thu, 27 Aug 2020 09:39:23 +0530	[thread overview]
Message-ID: <20200827040931.297759-16-aneesh.kumar@linux.ibm.com> (raw)
In-Reply-To: <20200827040931.297759-1-aneesh.kumar@linux.ibm.com>

Now that kernel correctly store/restore userspace AMR/IAMR values, avoid
manipulating AMR and IAMR from the kernel on behalf of userspace.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 arch/powerpc/include/asm/book3s/64/kup.h | 18 ++++++++
 arch/powerpc/include/asm/processor.h     |  4 --
 arch/powerpc/kernel/process.c            |  4 --
 arch/powerpc/kernel/traps.c              |  6 ---
 arch/powerpc/mm/book3s64/pkeys.c         | 57 +++++-------------------
 5 files changed, 28 insertions(+), 61 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h
index 3f5b97b2a3d8..4e1d666032f6 100644
--- a/arch/powerpc/include/asm/book3s/64/kup.h
+++ b/arch/powerpc/include/asm/book3s/64/kup.h
@@ -171,6 +171,24 @@
 #include <asm/mmu.h>
 #include <asm/ptrace.h>
 
+/*
+ * For kernel thread that doesn't have thread.regs return
+ * default AMR/IAMR values.
+ */
+static inline u64 current_thread_amr(void)
+{
+	if (current->thread.regs)
+		return current->thread.regs->kuap;
+	return AMR_KUAP_BLOCKED;
+}
+
+static inline u64 current_thread_iamr(void)
+{
+	if (current->thread.regs)
+		return current->thread.regs->kuep;
+	return AMR_KUEP_BLOCKED;
+}
+
 static inline void kuap_restore_user_amr(struct pt_regs *regs)
 {
 	if (!mmu_has_feature(MMU_FTR_PKEY))
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index ed0d633ab5aa..8adf44a7e54f 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -234,10 +234,6 @@ struct thread_struct {
 	struct thread_vr_state ckvr_state; /* Checkpointed VR state */
 	unsigned long	ckvrsave; /* Checkpointed VRSAVE */
 #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
-#ifdef CONFIG_PPC_MEM_KEYS
-	unsigned long	amr;
-	unsigned long	iamr;
-#endif
 #ifdef CONFIG_KVM_BOOK3S_32_HANDLER
 	void*		kvm_shadow_vcpu; /* KVM internal data */
 #endif /* CONFIG_KVM_BOOK3S_32_HANDLER */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 75fd30e023bd..c8f57afba3a0 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -603,7 +603,6 @@ static void save_all(struct task_struct *tsk)
 		__giveup_spe(tsk);
 
 	msr_check_and_clear(msr_all_available);
-	thread_pkey_regs_save(&tsk->thread);
 }
 
 void flush_all_to_thread(struct task_struct *tsk)
@@ -1127,8 +1126,6 @@ static inline void save_sprs(struct thread_struct *t)
 		t->tar = mfspr(SPRN_TAR);
 	}
 #endif
-
-	thread_pkey_regs_save(t);
 }
 
 static inline void restore_sprs(struct thread_struct *old_thread,
@@ -1169,7 +1166,6 @@ static inline void restore_sprs(struct thread_struct *old_thread,
 		mtspr(SPRN_TIDR, new_thread->tidr);
 #endif
 
-	thread_pkey_regs_restore(new_thread, old_thread);
 }
 
 struct task_struct *__switch_to(struct task_struct *prev,
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index d1ebe152f210..5bda54454a2d 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -347,12 +347,6 @@ static bool exception_common(int signr, struct pt_regs *regs, int code,
 
 	current->thread.trap_nr = code;
 
-	/*
-	 * Save all the pkey registers AMR/IAMR/UAMOR. Eg: Core dumps need
-	 * to capture the content, if the task gets killed.
-	 */
-	thread_pkey_regs_save(&current->thread);
-
 	return true;
 }
 
diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c
index f47d11f2743d..391230f93da2 100644
--- a/arch/powerpc/mm/book3s64/pkeys.c
+++ b/arch/powerpc/mm/book3s64/pkeys.c
@@ -273,30 +273,17 @@ void __init setup_kuap(bool disabled)
 }
 #endif
 
-static inline u64 read_amr(void)
+static inline void update_current_thread_amr(u64 value)
 {
-	return mfspr(SPRN_AMR);
+	current->thread.regs->kuap = value;
 }
 
-static inline void write_amr(u64 value)
-{
-	mtspr(SPRN_AMR, value);
-}
-
-static inline u64 read_iamr(void)
-{
-	if (!likely(pkey_execute_disable_supported))
-		return 0x0UL;
-
-	return mfspr(SPRN_IAMR);
-}
-
-static inline void write_iamr(u64 value)
+static inline void update_current_thread_iamr(u64 value)
 {
 	if (!likely(pkey_execute_disable_supported))
 		return;
 
-	mtspr(SPRN_IAMR, value);
+	current->thread.regs->kuep = value;
 }
 
 #ifdef CONFIG_PPC_MEM_KEYS
@@ -311,17 +298,17 @@ void pkey_mm_init(struct mm_struct *mm)
 static inline void init_amr(int pkey, u8 init_bits)
 {
 	u64 new_amr_bits = (((u64)init_bits & 0x3UL) << pkeyshift(pkey));
-	u64 old_amr = read_amr() & ~((u64)(0x3ul) << pkeyshift(pkey));
+	u64 old_amr = current_thread_amr() & ~((u64)(0x3ul) << pkeyshift(pkey));
 
-	write_amr(old_amr | new_amr_bits);
+	update_current_thread_amr(old_amr | new_amr_bits);
 }
 
 static inline void init_iamr(int pkey, u8 init_bits)
 {
 	u64 new_iamr_bits = (((u64)init_bits & 0x1UL) << pkeyshift(pkey));
-	u64 old_iamr = read_iamr() & ~((u64)(0x1ul) << pkeyshift(pkey));
+	u64 old_iamr = current_thread_iamr() & ~((u64)(0x1ul) << pkeyshift(pkey));
 
-	write_iamr(old_iamr | new_iamr_bits);
+	update_current_thread_iamr(old_iamr | new_iamr_bits);
 }
 
 /*
@@ -364,30 +351,6 @@ int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 	return 0;
 }
 
-void thread_pkey_regs_save(struct thread_struct *thread)
-{
-	if (!mmu_has_feature(MMU_FTR_PKEY))
-		return;
-
-	/*
-	 * TODO: Skip saving registers if @thread hasn't used any keys yet.
-	 */
-	thread->amr = read_amr();
-	thread->iamr = read_iamr();
-}
-
-void thread_pkey_regs_restore(struct thread_struct *new_thread,
-			      struct thread_struct *old_thread)
-{
-	if (!mmu_has_feature(MMU_FTR_PKEY))
-		return;
-
-	if (old_thread->amr != new_thread->amr)
-		write_amr(new_thread->amr);
-	if (old_thread->iamr != new_thread->iamr)
-		write_iamr(new_thread->iamr);
-}
-
 int execute_only_pkey(struct mm_struct *mm)
 {
 	return mm->context.execute_only_pkey;
@@ -436,9 +399,9 @@ static bool pkey_access_permitted(int pkey, bool write, bool execute)
 
 	pkey_shift = pkeyshift(pkey);
 	if (execute)
-		return !(read_iamr() & (IAMR_EX_BIT << pkey_shift));
+		return !(current_thread_iamr() & (IAMR_EX_BIT << pkey_shift));
 
-	amr = read_amr();
+	amr = current_thread_amr();
 	if (write)
 		return !(amr & (AMR_WR_BIT << pkey_shift));
 
-- 
2.26.2


  parent reply	other threads:[~2020-08-27  4:38 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-27  4:09 [PATCH v5 00/23] Kernel userspace access/execution prevention with hash translation Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 01/23] powerpc: Add new macro to handle NESTED_IFCLR Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 02/23] KVM: PPC: BOOK3S: PR: Ignore UAMOR SPR Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 03/23] powerpc/book3s64/kuap/kuep: Make KUAP and KUEP a subfeature of PPC_MEM_KEYS Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 04/23] powerpc/book3s64/kuap/kuep: Move uamor setup to pkey init Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 05/23] powerpc/book3s64/kuap: Move KUAP related function outside radix Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 06/23] powerpc/book3s64/kup: Use the correct #ifdef when including headers Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 07/23] powerpc/book3s64/kuep: Move KUEP related function outside radix Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 08/23] powerpc/book3s64/kuap: Rename MMU_FTR_RADIX_KUAP to MMU_FTR_KUAP Aneesh Kumar K.V
2020-08-27  4:57   ` Christophe Leroy
2020-08-27  4:09 ` [PATCH v5 09/23] powerpc/book3s64/kuap: Use Key 3 for kernel mapping with hash translation Aneesh Kumar K.V
2020-10-18  3:46   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 10/23] powerpc/exec: Set thread.regs early during exec Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 11/23] powerpc/book3s64/pkeys: Store/restore userspace AMR/IAMR correctly on entry and exit from kernel Aneesh Kumar K.V
2020-10-18  3:49   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 12/23] powerpc/book3s64/pkeys: Inherit correctly on fork Aneesh Kumar K.V
2020-10-18  3:50   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 13/23] powerpc/book3s64/pkeys: Reset userspace AMR correctly on exec Aneesh Kumar K.V
2020-10-18  3:50   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 14/23] powerpc/ptrace-view: Use pt_regs values instead of thread_struct based one Aneesh Kumar K.V
2020-08-27  4:09 ` Aneesh Kumar K.V [this message]
2020-10-18  3:52   ` [PATCH v5 15/23] powerpc/book3s64/pkeys: Don't update SPRN_AMR when in kernel mode Sandipan Das
2020-08-27  4:09 ` [PATCH v5 16/23] powerpc/book3s64/kuap: Restrict access to userspace based on userspace AMR Aneesh Kumar K.V
2020-10-18  4:00   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 17/23] powerpc/book3s64/kuap: Improve error reporting with KUAP Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 18/23] powerpc/book3s64/kuap: Use Key 3 to implement KUAP with hash translation Aneesh Kumar K.V
2020-10-18  4:00   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 19/23] powerpc/book3s64/kuep: Use Key 3 to implement KUEP " Aneesh Kumar K.V
2020-10-18  4:01   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 20/23] powerpc/book3s64/hash/kuap: Enable kuap on hash Aneesh Kumar K.V
2020-09-12 11:54   ` Michael Ellerman
2020-10-18  4:02   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 21/23] powerpc/book3s64/hash/kuep: Enable KUEP " Aneesh Kumar K.V
2020-10-18  4:03   ` Sandipan Das
2020-08-27  4:09 ` [PATCH v5 22/23] powerpc/book3s64/hash/kup: Don't hardcode kup key Aneesh Kumar K.V
2020-08-27  4:09 ` [PATCH v5 23/23] powerpc/book3s64/pkeys: Optimize FTR_KUAP and FTR_KUEP disabled case Aneesh Kumar K.V

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