From 2ddc53f3a7516b3e2c4ab9c36854a227641a4fde Mon Sep 17 00:00:00 2001 From: Ram Pai Date: Thu, 18 Jan 2018 17:50:29 -0800 Subject: [PATCH] powerpc: implementation for arch_set_user_pkey_access() This patch provides the detailed implementation for a user to allocate a key and enable it in the hardware. It provides the plumbing, but it cannot be used till the system call is implemented. The next patch will do so. Reviewed-by: Thiago Jung Bauermann Signed-off-by: Ram Pai Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/pkeys.h | 6 ++++- arch/powerpc/mm/pkeys.c | 40 ++++++++++++++++++++++++++++++++ 2 files changed, 45 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h index 5ed52ac39bab..bf8e706dcb0f 100644 --- a/arch/powerpc/include/asm/pkeys.h +++ b/arch/powerpc/include/asm/pkeys.h @@ -128,10 +128,14 @@ static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, return 0; } +extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, + unsigned long init_val); static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, unsigned long init_val) { - return 0; + if (static_branch_likely(&pkey_disabled)) + return -EINVAL; + return __arch_set_user_pkey_access(tsk, pkey, init_val); } extern void pkey_mm_init(struct mm_struct *mm); diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c index 0cfe901594c7..b01238bd88c1 100644 --- a/arch/powerpc/mm/pkeys.c +++ b/arch/powerpc/mm/pkeys.c @@ -5,6 +5,7 @@ * Copyright 2017, Ram Pai, IBM Corporation. */ +#include #include DEFINE_STATIC_KEY_TRUE(pkey_disabled); @@ -13,6 +14,9 @@ int pkeys_total; /* Total pkeys as per device tree */ u32 initial_allocation_mask; /* Bits set for reserved keys */ #define AMR_BITS_PER_PKEY 2 +#define AMR_RD_BIT 0x1UL +#define AMR_WR_BIT 0x2UL +#define IAMR_EX_BIT 0x1UL #define PKEY_REG_BITS (sizeof(u64)*8) #define pkeyshift(pkey) (PKEY_REG_BITS - ((pkey+1) * AMR_BITS_PER_PKEY)) @@ -108,6 +112,20 @@ static inline void write_uamor(u64 value) mtspr(SPRN_UAMOR, value); } +static bool is_pkey_enabled(int pkey) +{ + u64 uamor = read_uamor(); + u64 pkey_bits = 0x3ul << pkeyshift(pkey); + u64 uamor_pkey_bits = (uamor & pkey_bits); + + /* + * Both the bits in UAMOR corresponding to the key should be set or + * reset. + */ + WARN_ON(uamor_pkey_bits && (uamor_pkey_bits != pkey_bits)); + return !!(uamor_pkey_bits); +} + static inline void init_amr(int pkey, u8 init_bits) { u64 new_amr_bits = (((u64)init_bits & 0x3UL) << pkeyshift(pkey)); @@ -150,3 +168,25 @@ void __arch_deactivate_pkey(int pkey) { pkey_status_change(pkey, false); } + +/* + * Set the access rights in AMR IAMR and UAMOR registers for @pkey to that + * specified in @init_val. + */ +int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, + unsigned long init_val) +{ + u64 new_amr_bits = 0x0ul; + + if (!is_pkey_enabled(pkey)) + return -EINVAL; + + /* Set the bits we need in AMR: */ + if (init_val & PKEY_DISABLE_ACCESS) + new_amr_bits |= AMR_RD_BIT | AMR_WR_BIT; + else if (init_val & PKEY_DISABLE_WRITE) + new_amr_bits |= AMR_WR_BIT; + + init_amr(pkey, new_amr_bits); + return 0; +}