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powerpc/mm/radix: Simplify split mapping logic

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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: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Michael Ellerman
2018-08-14 22:37:32 +10:00
parent 57306c663d
commit 232aa40763
1 changed files with 10 additions and 22 deletions
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32
arch/powerpc/mm/pgtable-radix.c
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@@ -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;