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
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@ -6,6 +6,8 @@
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#include <asm/book3s/64/hash-pkey.h>
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extern u64 __ro_after_init default_uamor;
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extern u64 __ro_after_init default_amr;
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extern u64 __ro_after_init default_iamr;
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static inline u64 vmflag_to_pte_pkey_bits(u64 vm_flags)
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{
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@ -1546,6 +1546,11 @@ void arch_setup_new_exec(void)
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struct pt_regs *regs = task_stack_page(current) + THREAD_SIZE;
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current->thread.regs = regs - 1;
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}
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#ifdef CONFIG_PPC_MEM_KEYS
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current->thread.regs->amr = default_amr;
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current->thread.regs->iamr = default_iamr;
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#endif
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}
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#ifdef CONFIG_PPC64
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@ -1895,7 +1900,6 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
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current->thread.load_tm = 0;
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#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
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thread_pkey_regs_init(¤t->thread);
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}
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EXPORT_SYMBOL(start_thread);
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@ -28,8 +28,8 @@ static u32 initial_allocation_mask __ro_after_init;
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* Even if we allocate keys with sys_pkey_alloc(), we need to make sure
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* other thread still find the access denied using the same keys.
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*/
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static u64 default_amr = ~0x0UL;
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static u64 default_iamr = 0x5555555555555555UL;
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u64 default_amr __ro_after_init = ~0x0UL;
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u64 default_iamr __ro_after_init = 0x5555555555555555UL;
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u64 default_uamor __ro_after_init;
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/*
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* Key used to implement PROT_EXEC mmap. Denies READ/WRITE
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@ -396,18 +396,6 @@ void thread_pkey_regs_restore(struct thread_struct *new_thread,
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write_iamr(new_thread->iamr);
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}
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void thread_pkey_regs_init(struct thread_struct *thread)
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{
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if (!mmu_has_feature(MMU_FTR_PKEY))
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return;
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thread->amr = default_amr;
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thread->iamr = default_iamr;
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write_amr(default_amr);
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write_iamr(default_iamr);
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}
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int execute_only_pkey(struct mm_struct *mm)
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{
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return mm->context.execute_only_pkey;
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