[PATCH v6 19/23] powerpc/book3s64/kuap: Move UAMOR setup to key init function
Aneesh Kumar K.V
aneesh.kumar at linux.ibm.com
Thu Jul 9 13:29:42 AEST 2020
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 at 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 5b178139f3c0..b7d9f4267bcd 100644
--- 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 52a67835057a..6ac12168f1fe 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 caeb5822a8f4..ac7d480cb9c1 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 73199470c265..8261999c7d52 100644
--- 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 eec6f4e5e481..9dfb0ceed5e3 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 c682eefd3fc1..480ae31fad52 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 6d814c9bb4bf..ed24ba56d78a 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -546,6 +546,10 @@ 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();
}
--
2.26.2
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