From 48a8ab4eeb8271f2a0e2ca3cf80844a59acca153 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Fri, 27 Nov 2020 10:14:16 +0530 Subject: [PATCH] powerpc/book3s64/pkeys: Don't update SPRN_AMR when in kernel mode. 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 Reviewed-by: Sandipan Das Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201127044424.40686-15-aneesh.kumar@linux.ibm.com --- arch/powerpc/include/asm/book3s/64/kup.h | 21 ++++++++++++ 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, 31 insertions(+), 61 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h index fa67139..f41f6f4 100644 --- a/arch/powerpc/include/asm/book3s/64/kup.h +++ b/arch/powerpc/include/asm/book3s/64/kup.h @@ -177,6 +177,27 @@ DECLARE_STATIC_KEY_FALSE(uaccess_flush_key); #include #include +/* + * 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->amr; + return AMR_KUAP_BLOCKED; +} + +static inline u64 current_thread_iamr(void) +{ + if (current->thread.regs) + return current->thread.regs->iamr; + return AMR_KUEP_BLOCKED; +} +#endif /* CONFIG_PPC_PKEY */ + +#ifdef CONFIG_PPC_KUAP + static inline void kuap_user_restore(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 10d659f..8acc359 100644 --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -226,10 +226,6 @@ 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 0538e0f1..96bb10d 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -589,7 +589,6 @@ 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) @@ -1160,8 +1159,6 @@ 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, @@ -1202,7 +1199,6 @@ 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 5b39baa..46419ae 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(¤t->thread); - return true; } diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c index 355d001..8d1bf2f 100644 --- a/arch/powerpc/mm/book3s64/pkeys.c +++ b/arch/powerpc/mm/book3s64/pkeys.c @@ -281,30 +281,17 @@ 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->amr = 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->iamr = value; } #ifdef CONFIG_PPC_MEM_KEYS @@ -319,17 +306,17 @@ 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); } /* @@ -372,30 +359,6 @@ 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; @@ -444,9 +407,9 @@ 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)); -- 2.7.4