From e0d8e991be641ba0034c67785bf86f6c097869d6 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Thu, 9 Jul 2020 08:59:42 +0530 Subject: [PATCH] powerpc/book3s64/kuap: Move UAMOR setup to key init function UAMOR values are not application-specific. The kernel initializes its value based on different reserved keys. Remove the thread-specific UAMOR value and don't switch the UAMOR on context switch. Move UAMOR initialization to key initialization code and remove thread_struct.uamor because it is not used anymore. Before commit: 4a4a5e5d2aad ("powerpc/pkeys: key allocation/deallocation must not change pkey registers") we used to update uamor based on key allocation and free. Signed-off-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200709032946.881753-20-aneesh.kumar@linux.ibm.com --- arch/powerpc/include/asm/book3s/64/pkeys.h | 2 ++ arch/powerpc/include/asm/processor.h | 1 - arch/powerpc/kernel/ptrace/ptrace-view.c | 27 +++++++++++++++++++++------ arch/powerpc/kernel/smp.c | 1 + arch/powerpc/mm/book3s64/hash_utils.c | 4 ++++ arch/powerpc/mm/book3s64/pkeys.c | 29 ++++++++++++----------------- arch/powerpc/mm/book3s64/radix_pgtable.c | 4 ++++ 7 files changed, 44 insertions(+), 24 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/64/pkeys.h b/arch/powerpc/include/asm/book3s/64/pkeys.h index 5b17813..b7d9f42 100644 --- a/arch/powerpc/include/asm/book3s/64/pkeys.h +++ b/arch/powerpc/include/asm/book3s/64/pkeys.h @@ -5,6 +5,8 @@ #include +extern u64 __ro_after_init default_uamor; + static inline u64 vmflag_to_pte_pkey_bits(u64 vm_flags) { if (!mmu_has_feature(MMU_FTR_PKEY)) diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h index 52a6783..6ac1216 100644 --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -237,7 +237,6 @@ struct thread_struct { #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 */ diff --git a/arch/powerpc/kernel/ptrace/ptrace-view.c b/arch/powerpc/kernel/ptrace/ptrace-view.c index caeb582..ac7d480 100644 --- a/arch/powerpc/kernel/ptrace/ptrace-view.c +++ b/arch/powerpc/kernel/ptrace/ptrace-view.c @@ -488,14 +488,21 @@ static int pkey_active(struct task_struct *target, const struct user_regset *reg static int pkey_get(struct task_struct *target, const struct user_regset *regset, unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf) { + int ret; + BUILD_BUG_ON(TSO(amr) + sizeof(unsigned long) != TSO(iamr)); - BUILD_BUG_ON(TSO(iamr) + sizeof(unsigned long) != TSO(uamor)); if (!arch_pkeys_enabled()) return -ENODEV; - return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &target->thread.amr, - 0, ELF_NPKEY * sizeof(unsigned long)); + ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &target->thread.amr, + 0, 2 * sizeof(unsigned long)); + if (ret) + return ret; + + ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &default_uamor, + 2 * sizeof(unsigned long), 3 * sizeof(unsigned long)); + return ret; } static int pkey_set(struct task_struct *target, const struct user_regset *regset, @@ -517,9 +524,17 @@ static int pkey_set(struct task_struct *target, const struct user_regset *regset if (ret) return ret; - /* UAMOR determines which bits of the AMR can be set from userspace. */ - target->thread.amr = (new_amr & target->thread.uamor) | - (target->thread.amr & ~target->thread.uamor); + /* + * UAMOR determines which bits of the AMR can be set from userspace. + * UAMOR value 0b11 indicates that the AMR value can be modified + * from userspace. If the kernel is using a specific key, we avoid + * userspace modifying the AMR value for that key by masking them + * via UAMOR 0b00. + * + * Pick the AMR values for the keys that kernel is using. This + * will be indicated by the ~default_uamor bits. + */ + target->thread.amr = (new_amr & default_uamor) | (target->thread.amr & ~default_uamor); return 0; } diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 7319947..8261999 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -59,6 +59,7 @@ #include #include #include +#include #ifdef DEBUG #include diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c index eec6f4e..9dfb0ce 100644 --- a/arch/powerpc/mm/book3s64/hash_utils.c +++ b/arch/powerpc/mm/book3s64/hash_utils.c @@ -1110,6 +1110,10 @@ void hash__early_init_mmu_secondary(void) if (cpu_has_feature(CPU_FTR_ARCH_206) && cpu_has_feature(CPU_FTR_HVMODE)) tlbiel_all(); + +#ifdef CONFIG_PPC_MEM_KEYS + mtspr(SPRN_UAMOR, default_uamor); +#endif } #endif /* CONFIG_SMP */ diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c index e776544..d45864a 100644 --- a/arch/powerpc/mm/book3s64/pkeys.c +++ b/arch/powerpc/mm/book3s64/pkeys.c @@ -27,9 +27,7 @@ static u32 initial_allocation_mask __ro_after_init; */ static u64 default_amr = ~0x0UL; static u64 default_iamr = 0x5555555555555555UL; - -/* Allow all keys to be modified by default */ -static u64 default_uamor = ~0x0UL; +u64 default_uamor __ro_after_init; /* * Key used to implement PROT_EXEC mmap. Denies READ/WRITE * We pick key 2 because 0 is special key and 1 is reserved as per ISA. @@ -122,10 +120,11 @@ void __init pkey_early_init_devtree(void) /* scan the device tree for pkey feature */ pkeys_total = scan_pkey_feature(); - if (!pkeys_total) { - /* No support for pkey. Mark it disabled */ - return; - } + if (!pkeys_total) + goto out; + + /* Allow all keys to be modified by default */ + default_uamor = ~0x0UL; cur_cpu_spec->mmu_features |= MMU_FTR_PKEY; @@ -209,6 +208,12 @@ void __init pkey_early_init_devtree(void) initial_allocation_mask |= reserved_allocation_mask; pr_info("Enabling pkeys with max key count %d\n", num_pkey); +out: + /* + * Setup uamor on boot cpu + */ + mtspr(SPRN_UAMOR, default_uamor); + return; } @@ -251,11 +256,6 @@ static inline u64 read_uamor(void) return mfspr(SPRN_UAMOR); } -static inline void write_uamor(u64 value) -{ - mtspr(SPRN_UAMOR, value); -} - static bool is_pkey_enabled(int pkey) { u64 uamor = read_uamor(); @@ -326,7 +326,6 @@ void thread_pkey_regs_save(struct thread_struct *thread) */ thread->amr = read_amr(); thread->iamr = read_iamr(); - thread->uamor = read_uamor(); } void thread_pkey_regs_restore(struct thread_struct *new_thread, @@ -339,8 +338,6 @@ void thread_pkey_regs_restore(struct thread_struct *new_thread, 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); } void thread_pkey_regs_init(struct thread_struct *thread) @@ -350,11 +347,9 @@ void thread_pkey_regs_init(struct thread_struct *thread) thread->amr = default_amr; thread->iamr = default_iamr; - thread->uamor = default_uamor; write_amr(default_amr); write_iamr(default_iamr); - write_uamor(default_uamor); } int execute_only_pkey(struct mm_struct *mm) diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c index 3536675..a8f46a6 100644 --- a/arch/powerpc/mm/book3s64/radix_pgtable.c +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c @@ -620,6 +620,10 @@ void setup_kuap(bool disabled) /* Make sure userspace can't change the AMR */ mtspr(SPRN_UAMOR, 0); + + /* + * Set the default kernel AMR values on all cpus. + */ mtspr(SPRN_AMR, AMR_KUAP_BLOCKED); isync(); } -- 2.7.4