From 57306c663d53f2e4fd856950703dc6bcfc98f7cb Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Tue, 14 Aug 2018 22:01:44 +1000 Subject: powerpc/mm/radix: Remove the retry in the split mapping logic When we have CONFIG_STRICT_KERNEL_RWX enabled, we want to split the linear mapping at the text/data boundary so we can map the kernel text read only. The current logic uses a goto inside the for loop, which works, but is hard to reason about. When we hit the goto retry case we set max_mapping_size to PMD_SIZE and go back to the start. Setting max_mapping_size means we skip the PUD case and go to the PMD case. We know we will pass the alignment and gap checks because the only reason we are there is we hit the goto retry, and that is guarded by mapping_size == PUD_SIZE, which means addr is PUD aligned and gap is greater or equal to PUD_SIZE. So the only part of the check that can fail is the mmu_psize_defs check for the 2M page size. If we just duplicate that check we can avoid the goto, and we get the same result. Signed-off-by: Michael Ellerman --- arch/powerpc/mm/pgtable-radix.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) (limited to 'arch/powerpc') diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c index 7a44ec276290..030543451229 100644 --- a/arch/powerpc/mm/pgtable-radix.c +++ b/arch/powerpc/mm/pgtable-radix.c @@ -261,7 +261,6 @@ static int __meminit create_physical_mapping(unsigned long start, { unsigned long vaddr, addr, mapping_size = 0; pgprot_t prot; - unsigned long max_mapping_size; #ifdef CONFIG_STRICT_KERNEL_RWX int split_text_mapping = 1; #else @@ -276,12 +275,9 @@ static int __meminit create_physical_mapping(unsigned long start, gap = end - addr; previous_size = mapping_size; - max_mapping_size = PUD_SIZE; -retry: if (IS_ALIGNED(addr, PUD_SIZE) && gap >= PUD_SIZE && - mmu_psize_defs[MMU_PAGE_1G].shift && - PUD_SIZE <= max_mapping_size) { + mmu_psize_defs[MMU_PAGE_1G].shift) { mapping_size = PUD_SIZE; psize = MMU_PAGE_1G; } else if (IS_ALIGNED(addr, PMD_SIZE) && gap >= PMD_SIZE && @@ -296,8 +292,10 @@ retry: if (split_text_mapping && (mapping_size == PUD_SIZE) && (addr < __pa_symbol(__init_begin)) && (addr + mapping_size) > __pa_symbol(__init_begin)) { - max_mapping_size = PMD_SIZE; - goto retry; + 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) && -- cgit v1.2.3