powerpc/book3s64/pkeys: Reset userspace AMR correctly on exec

On fork, we inherit from the parent and on exec, we should switch to default_amr values.

Also, avoid changing the AMR register value within the kernel. The kernel now runs with
different AMR values.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201127044424.40686-13-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 b7d9f4267bcd0ec1ae44aa29f520947f1aaa5dd3..3b8640498f5bae47709f567d79cc360ac50ce32d 100644 (file)
--- a/arch/powerpc/include/asm/book3s/64/pkeys.h
+++ b/arch/powerpc/include/asm/book3s/64/pkeys.h
@@ -6,6 +6,8 @@
 #include <asm/book3s/64/hash-pkey.h>
 
 extern u64 __ro_after_init default_uamor;
+extern u64 __ro_after_init default_amr;
+extern u64 __ro_after_init default_iamr;
 
 static inline u64 vmflag_to_pte_pkey_bits(u64 vm_flags)
 {

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 2ec907a6f9afca150057b37bb6580d2efce393c8..0538e0f1790c7b6f88312efe5db05089a70e2453 100644 (file)
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1546,6 +1546,11 @@ void arch_setup_new_exec(void)
                struct pt_regs *regs = task_stack_page(current) + THREAD_SIZE;
                current->thread.regs = regs - 1;
        }
+
+#ifdef CONFIG_PPC_MEM_KEYS
+       current->thread.regs->amr  = default_amr;
+       current->thread.regs->iamr  = default_iamr;
+#endif
 }
 
 #ifdef CONFIG_PPC64
@@ -1895,7 +1900,6 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
        current->thread.load_tm = 0;
 #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
 
-       thread_pkey_regs_init(&current->thread);
 }
 EXPORT_SYMBOL(start_thread);
 

diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c
index e434c0a2ee5d91ae9f21645e31a5a93e3defbef5..355d001fa155ac700028f8a92e144b2f9cf7a138 100644 (file)
--- a/arch/powerpc/mm/book3s64/pkeys.c
+++ b/arch/powerpc/mm/book3s64/pkeys.c
@@ -28,8 +28,8 @@ static u32 initial_allocation_mask __ro_after_init;
  * Even if we allocate keys with sys_pkey_alloc(), we need to make sure
  * other thread still find the access denied using the same keys.
  */
-static u64 default_amr = ~0x0UL;
-static u64 default_iamr = 0x5555555555555555UL;
+u64 default_amr __ro_after_init  = ~0x0UL;
+u64 default_iamr __ro_after_init = 0x5555555555555555UL;
 u64 default_uamor __ro_after_init;
 /*
  * Key used to implement PROT_EXEC mmap. Denies READ/WRITE
@@ -396,18 +396,6 @@ void thread_pkey_regs_restore(struct thread_struct *new_thread,
                write_iamr(new_thread->iamr);
 }
 
-void thread_pkey_regs_init(struct thread_struct *thread)
-{
-       if (!mmu_has_feature(MMU_FTR_PKEY))
-               return;
-
-       thread->amr   = default_amr;
-       thread->iamr  = default_iamr;
-
-       write_amr(default_amr);
-       write_iamr(default_iamr);
-}
-
 int execute_only_pkey(struct mm_struct *mm)
 {
        return mm->context.execute_only_pkey;