Make KUAP/KUEP key a variable and also check whether the platform
limit the max key such that we can't use the key for KUAP/KEUP.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
---
.../powerpc/include/asm/book3s/64/hash-pkey.h | 22 +-------
arch/powerpc/include/asm/book3s/64/pkeys.h | 1 +
arch/powerpc/mm/book3s64/pkeys.c | 53 ++++++++++++++++---
3 files changed, 49 insertions(+), 27 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/64/hash-pkey.h b/arch/powerpc/include/asm/book3s/64/hash-pkey.h
index 9f44e208f036..ff9907c72ee3 100644
--- a/arch/powerpc/include/asm/book3s/64/hash-pkey.h
+++ b/arch/powerpc/include/asm/book3s/64/hash-pkey.h
@@ -2,9 +2,7 @@
#ifndef _ASM_POWERPC_BOOK3S_64_HASH_PKEY_H
#define _ASM_POWERPC_BOOK3S_64_HASH_PKEY_H
-/* We use key 3 for KERNEL */
-#define HASH_DEFAULT_KERNEL_KEY (HPTE_R_KEY_BIT0 | HPTE_R_KEY_BIT1)
-
+u64 pte_to_hpte_pkey_bits(u64 pteflags, unsigned long flags);
static inline u64 hash__vmflag_to_pte_pkey_bits(u64 vm_flags)
{
return (((vm_flags & VM_PKEY_BIT0) ? H_PTE_PKEY_BIT0 : 0x0UL) |
@@ -14,24 +12,6 @@ static inline u64 hash__vmflag_to_pte_pkey_bits(u64 vm_flags)
((vm_flags & VM_PKEY_BIT4) ? H_PTE_PKEY_BIT4 : 0x0UL));
}
-static inline u64 pte_to_hpte_pkey_bits(u64 pteflags, unsigned long flags)
-{
- unsigned long pte_pkey;
-
- pte_pkey = (((pteflags & H_PTE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL) |
- ((pteflags & H_PTE_PKEY_BIT3) ? HPTE_R_KEY_BIT3 : 0x0UL) |
- ((pteflags & H_PTE_PKEY_BIT2) ? HPTE_R_KEY_BIT2 : 0x0UL) |
- ((pteflags & H_PTE_PKEY_BIT1) ? HPTE_R_KEY_BIT1 : 0x0UL) |
- ((pteflags & H_PTE_PKEY_BIT0) ? HPTE_R_KEY_BIT0 : 0x0UL));
-
- if (mmu_has_feature(MMU_FTR_KUAP) || mmu_has_feature(MMU_FTR_KUEP)) {
- if ((pte_pkey == 0) && (flags & HPTE_USE_KERNEL_KEY))
- return HASH_DEFAULT_KERNEL_KEY;
- }
-
- return pte_pkey;
-}
-
static inline u16 hash__pte_to_pkey_bits(u64 pteflags)
{
return (((pteflags & H_PTE_PKEY_BIT4) ? 0x10 : 0x0UL) |
diff --git a/arch/powerpc/include/asm/book3s/64/pkeys.h b/arch/powerpc/include/asm/book3s/64/pkeys.h
index 3b8640498f5b..a2b6c4a7275f 100644
--- a/arch/powerpc/include/asm/book3s/64/pkeys.h
+++ b/arch/powerpc/include/asm/book3s/64/pkeys.h
@@ -8,6 +8,7 @@
extern u64 __ro_after_init default_uamor;
extern u64 __ro_after_init default_amr;
extern u64 __ro_after_init default_iamr;
+extern int kup_key;
static inline u64 vmflag_to_pte_pkey_bits(u64 vm_flags)
{
diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c
index f029e7bf5ca2..204e4598b45c 100644
--- a/arch/powerpc/mm/book3s64/pkeys.c
+++ b/arch/powerpc/mm/book3s64/pkeys.c
@@ -37,7 +37,10 @@ u64 default_uamor __ro_after_init;
*/
static int execute_only_key = 2;
static bool pkey_execute_disable_supported;
-
+/*
+ * key used to implement KUAP/KUEP with hash translation.
+ */
+int kup_key = 3;
#define AMR_BITS_PER_PKEY 2
#define AMR_RD_BIT 0x1UL
@@ -185,6 +188,25 @@ void __init pkey_early_init_devtree(void)
default_uamor &= ~(0x3ul << pkeyshift(execute_only_key));
}
+ if (unlikely(num_pkey <= kup_key)) {
+ /*
+ * Insufficient number of keys to support
+ * KUAP/KUEP feature.
+ */
+ kup_key = -1;
+ } else {
+ /* handle key which is used by kernel for KAUP */
+ reserved_allocation_mask |= (0x1 << kup_key);
+ /*
+ * Mark access for kup_key in default amr so that
+ * we continue to operate with that AMR in
+ * copy_to/from_user().
+ */
+ default_amr &= ~(0x3ul << pkeyshift(kup_key));
+ default_iamr &= ~(0x1ul << pkeyshift(kup_key));
+ default_uamor &= ~(0x3ul << pkeyshift(kup_key));
+ }
+
/*
* Allow access for only key 0. And prevent any other modification.
*/
@@ -205,9 +227,6 @@ void __init pkey_early_init_devtree(void)
reserved_allocation_mask |= (0x1 << 1);
default_uamor &= ~(0x3ul << pkeyshift(1));
- /* handle key 3 which is used by kernel for KAUP */
- reserved_allocation_mask |= (0x1 << 3);
- default_uamor &= ~(0x3ul << pkeyshift(3));
/*
* Prevent the usage of OS reserved keys. Update UAMOR
@@ -236,7 +255,7 @@ void __init pkey_early_init_devtree(void)
#ifdef CONFIG_PPC_KUEP
void __init setup_kuep(bool disabled)
{
- if (disabled)
+ if (disabled || kup_key == -1)
return;
/*
* On hash if PKEY feature is not enabled, disable KUAP too.
@@ -262,7 +281,7 @@ void __init setup_kuep(bool disabled)
#ifdef CONFIG_PPC_KUAP
void __init setup_kuap(bool disabled)
{
- if (disabled)
+ if (disabled || kup_key == -1)
return;
/*
* On hash if PKEY feature is not enabled, disable KUAP too.
@@ -458,4 +477,26 @@ void arch_dup_pkeys(struct mm_struct *oldmm, struct mm_struct *mm)
mm->context.execute_only_pkey = oldmm->context.execute_only_pkey;
}
+u64 pte_to_hpte_pkey_bits(u64 pteflags, unsigned long flags)
+{
+ unsigned long pte_pkey;
+
+ pte_pkey = (((pteflags & H_PTE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL) |
+ ((pteflags & H_PTE_PKEY_BIT3) ? HPTE_R_KEY_BIT3 : 0x0UL) |
+ ((pteflags & H_PTE_PKEY_BIT2) ? HPTE_R_KEY_BIT2 : 0x0UL) |
+ ((pteflags & H_PTE_PKEY_BIT1) ? HPTE_R_KEY_BIT1 : 0x0UL) |
+ ((pteflags & H_PTE_PKEY_BIT0) ? HPTE_R_KEY_BIT0 : 0x0UL));
+
+ if (mmu_has_feature(MMU_FTR_KUAP) || mmu_has_feature(MMU_FTR_KUEP)) {
+ if ((pte_pkey == 0) &&
+ (flags & HPTE_USE_KERNEL_KEY) && (kup_key != -1)) {
+ u64 vm_flag = pkey_to_vmflag_bits(kup_key);
+ u64 pte_flag = hash__vmflag_to_pte_pkey_bits(vm_flag);
+ return pte_to_hpte_pkey_bits(pte_flag, 0);
+ }
+ }
+
+ return pte_pkey;
+}
+
#endif /* CONFIG_PPC_MEM_KEYS */
--
2.28.0