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Commit 232aa407 authored by Michael Ellerman's avatar Michael Ellerman
Browse files

powerpc/mm/radix: Simplify split mapping logic 



If we look closely at the logic in create_physical_mapping(), when
we're doing STRICT_KERNEL_RWX, we do the following steps:
  - determine the gap from where we are to the end of the range
  - choose an appropriate mapping_size based on the gap
  - check if that mapping_size would overlap the __init_begin
    boundary, and if not choose an appropriate mapping_size

We can simplify the logic by taking the __init_begin boundary into
account when we calculate the initial gap.

So add a next_boundary() function which tells us what the next
boundary is, either the __init_begin boundary or end. In future we can
add more boundaries.

Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 57306c66

arch/powerpc/mm/pgtable-radix.c

+10 −22
Original line number Diff line number Diff line
@@ -255,17 +255,21 @@ static inline void __meminit print_mapping(unsigned long start, 
	pr_info("Mapped 0x%016lx-0x%016lx with %s pages\n", start, end, buf);

}



static unsigned long next_boundary(unsigned long addr, unsigned long end)

{

#ifdef CONFIG_STRICT_KERNEL_RWX

	if (addr < __pa_symbol(__init_begin))

		return __pa_symbol(__init_begin);

#endif

	return end;

}



static int __meminit create_physical_mapping(unsigned long start,

					     unsigned long end,

					     int nid)

{

	unsigned long vaddr, addr, mapping_size = 0;

	pgprot_t prot;

#ifdef CONFIG_STRICT_KERNEL_RWX

	int split_text_mapping = 1;

#else

	int split_text_mapping = 0;

#endif

	int psize;



	start = _ALIGN_UP(start, PAGE_SIZE);
@@ -273,7 +277,7 @@ static int __meminit create_physical_mapping(unsigned long start, 
		unsigned long gap, previous_size;

		int rc;



		gap = end - addr;

		gap = next_boundary(addr, end) - addr;

		previous_size = mapping_size;



		if (IS_ALIGNED(addr, PUD_SIZE) && gap >= PUD_SIZE &&
@@ -289,22 +293,6 @@ static int __meminit create_physical_mapping(unsigned long start, 
			psize = mmu_virtual_psize;

		}



		if (split_text_mapping && (mapping_size == PUD_SIZE) &&

			(addr < __pa_symbol(__init_begin)) &&

			(addr + mapping_size) > __pa_symbol(__init_begin)) {

			if (mmu_psize_defs[MMU_PAGE_2M].shift)

				mapping_size = PMD_SIZE;

			else

				mapping_size = PAGE_SIZE;

		}



		if (split_text_mapping && (mapping_size == PMD_SIZE) &&

		    (addr < __pa_symbol(__init_begin)) &&

		    (addr + mapping_size) > __pa_symbol(__init_begin)) {

			mapping_size = PAGE_SIZE;

			psize = mmu_virtual_psize;

		}



		if (mapping_size != previous_size) {

			print_mapping(start, addr, previous_size);

			start = addr;