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Commit f2ed480f authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Michael Ellerman
Browse files

powerpc/mm/keys: Update documentation and remove unnecessary check 



Adds more code comments. We also remove an unnecessary pkey check
after we check for pkey error in this patch.

Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent b9ee31e1

arch/powerpc/mm/fault.c

+12 −16
Original line number Diff line number Diff line
@@ -297,7 +297,12 @@ static bool access_error(bool is_write, bool is_exec, 


	if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))

		return true;



	/*

	 * We should ideally do the vma pkey access check here. But in the

	 * fault path, handle_mm_fault() also does the same check. To avoid

	 * these multiple checks, we skip it here and handle access error due

	 * to pkeys later.

	 */

	return false;

}
@@ -518,26 +523,17 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, 


#ifdef CONFIG_PPC_MEM_KEYS

	/*

	 * if the HPTE is not hashed, hardware will not detect

	 * a key fault. Lets check if we failed because of a

	 * software detected key fault.

	 * we skipped checking for access error due to key earlier.

	 * Check that using handle_mm_fault error return.

	 */

	if (unlikely(fault & VM_FAULT_SIGSEGV) &&

		!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,

			is_exec, 0)) {

		/*

		 * The PGD-PDT...PMD-PTE tree may not have been fully setup.

		 * Hence we cannot walk the tree to locate the PTE, to locate

		 * the key. Hence let's use vma_pkey() to get the key; instead

		 * of get_mm_addr_key().

		 */

		!arch_vma_access_permitted(vma, is_write, is_exec, 0)) {



		int pkey = vma_pkey(vma);



		if (likely(pkey)) {

		up_read(&mm->mmap_sem);

		return bad_key_fault_exception(regs, address, pkey);

	}

	}

#endif /* CONFIG_PPC_MEM_KEYS */



	major |= fault & VM_FAULT_MAJOR;

arch/powerpc/mm/pkeys.c

+4 −7
Original line number Diff line number Diff line
@@ -119,18 +119,15 @@ int pkey_initialize(void) 
#else

	os_reserved = 0;

#endif

	initial_allocation_mask = ~0x0;

	pkey_amr_uamor_mask = ~0x0ul;

	pkey_iamr_mask = ~0x0ul;

	/*

	 * Bits are in LE format. NOTE: 1, 0 are reserved.

	 * key 0, 1 are reserved.

	 * key 0 is the default key, which allows read/write/execute.

	 * key 1 is recommended not to be used. PowerISA(3.0) page 1015,

	 * programming note.

	 */

	initial_allocation_mask = ~0x0;



	/* register mask is in BE format */

	pkey_amr_uamor_mask = ~0x0ul;

	pkey_iamr_mask = ~0x0ul;



	for (i = 2; i < (pkeys_total - os_reserved); i++) {

		initial_allocation_mask &= ~(0x1 << i);

		pkey_amr_uamor_mask &= ~(0x3ul << pkeyshift(i));