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 <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200709032946.881753-20-aneesh.kumar@linux.ibm.com

diff --git a/arch/powerpc/include/asm/book3s/64/pkeys.h b/arch/powerpc/include/asm/book3s/64/pkeys.h
index 5b178139f3c08a00e84a9571c1919aa72c864b2c..b7d9f4267bcd0ec1ae44aa29f520947f1aaa5dd3 100644 (file)
--- a/arch/powerpc/include/asm/book3s/64/pkeys.h
+++ b/arch/powerpc/include/asm/book3s/64/pkeys.h
@@ -5,6 +5,8 @@
 
 #include <asm/book3s/64/hash-pkey.h>
 
+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 52a67835057abaa1ff9255d73a68540bab6feaab..6ac12168f1fe8e9398d86c2ab8874aa6cab2fbbc 100644 (file)
--- 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 caeb5822a8f4a6ba32f7975cf5842f01a16381b2..ac7d480cb9c1f7f5629113e363d90059ed4d4dc4 100644 (file)
--- 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 73199470c26549738ac869bd171e63d867f37e0d..8261999c7d5205d96367c47d2ac0057b29604472 100644 (file)
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -59,6 +59,7 @@
 #include <asm/asm-prototypes.h>
 #include <asm/cpu_has_feature.h>
 #include <asm/ftrace.h>
+#include <asm/kup.h>
 
 #ifdef DEBUG
 #include <asm/udbg.h>

diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
index eec6f4e5e48163c76a6f4726bc986e02bd49073a..9dfb0ceed5e32381eeed096f3c8c5c8d096dcac0 100644 (file)
--- 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 e776544a4d115fe25e555a6287f95cb3d204d814..d45864a77066b1ea425b4a271b0e73ff0476ee55 100644 (file)
--- 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 3536675dd61ec3c09cf391fade02f8f466a66f19..a8f46a6862196c2a691f3f103e11d68afffd5c7c 100644 (file)
--- 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();
 }