[PATCH v2 17/28] powerpc/book3s64/pkeys: Don't update SPRN_AMR when in kernel mode.
Aneesh Kumar K.V
aneesh.kumar at linux.ibm.com
Sat May 2 21:22:18 AEST 2020
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 at linux.ibm.com>
---
arch/powerpc/include/asm/book3s/64/kup.h | 23 ++++++++
arch/powerpc/include/asm/processor.h | 5 --
arch/powerpc/kernel/process.c | 4 --
arch/powerpc/kernel/traps.c | 6 --
arch/powerpc/mm/book3s64/pkeys.c | 71 ++++--------------------
5 files changed, 34 insertions(+), 75 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h
index fe1818954e51..31eb0acddea9 100644
--- a/arch/powerpc/include/asm/book3s/64/kup.h
+++ b/arch/powerpc/include/asm/book3s/64/kup.h
@@ -174,6 +174,29 @@ extern u64 default_uamor;
extern u64 default_amr;
extern u64 default_iamr;
+/*
+ * 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 u64 read_uamor(void)
+{
+ return default_uamor;
+}
+
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 a51964b4ec42..591987da44e2 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -234,11 +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;
- unsigned long uamor;
-#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 0ab9a8cf1bcb..682deeee421f 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -585,7 +585,6 @@ 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)
@@ -1097,8 +1096,6 @@ 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,
@@ -1139,7 +1136,6 @@ 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 3fca22276bb1..a47fb49b7af8 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -348,12 +348,6 @@ 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(¤t->thread);
-
return true;
}
diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c
index 5012b57af808..0f4fc2876fc8 100644
--- a/arch/powerpc/mm/book3s64/pkeys.c
+++ b/arch/powerpc/mm/book3s64/pkeys.c
@@ -264,40 +264,17 @@ void pkey_mm_init(struct mm_struct *mm)
mm->context.execute_only_pkey = execute_only_key;
}
-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 (static_branch_unlikely(&execute_pkey_disabled))
- return 0x0UL;
-
- return mfspr(SPRN_IAMR);
-}
-
-static inline void write_iamr(u64 value)
+static inline void update_current_thread_iamr(u64 value)
{
if (static_branch_unlikely(&execute_pkey_disabled))
return;
- mtspr(SPRN_IAMR, value);
-}
-
-static inline u64 read_uamor(void)
-{
- return mfspr(SPRN_UAMOR);
-}
-
-static inline void write_uamor(u64 value)
-{
- mtspr(SPRN_UAMOR, value);
+ current->thread.regs->kuep = value;
}
static bool is_pkey_enabled(int pkey)
@@ -314,20 +291,21 @@ static bool is_pkey_enabled(int pkey)
return !!(uamor_pkey_bits);
}
+/* FIXME!! what happens to other threads AMR value? */
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);
}
/*
@@ -360,33 +338,6 @@ 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();
- thread->uamor = read_uamor();
-}
-
-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);
- if (old_thread->uamor != new_thread->uamor)
- write_uamor(new_thread->uamor);
-}
-
int execute_only_pkey(struct mm_struct *mm)
{
if (static_branch_likely(&execute_pkey_disabled))
@@ -440,10 +391,10 @@ static bool pkey_access_permitted(int pkey, bool write, bool execute)
return true;
pkey_shift = pkeyshift(pkey);
- if (execute && !(read_iamr() & (IAMR_EX_BIT << pkey_shift)))
+ if (execute && !(current_thread_iamr() & (IAMR_EX_BIT << pkey_shift)))
return true;
- amr = read_amr(); /* Delay reading amr until absolutely needed */
+ amr = current_thread_amr();
return ((!write && !(amr & (AMR_RD_BIT << pkey_shift))) ||
(write && !(amr & (AMR_WR_BIT << pkey_shift))));
}
--
2.26.2
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