From 81d1b54dec95209ab5e5be2cf37182885f998753 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Tue, 14 Aug 2018 21:05:20 +1000 Subject: [PATCH] powerpc/mm/radix: Fix small page at boundary when splitting 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. Currently we always use a small page at the text/data boundary, even when that's not necessary: Mapped 0x0000000000000000-0x0000000000e00000 with 2.00 MiB pages Mapped 0x0000000000e00000-0x0000000001000000 with 64.0 KiB pages Mapped 0x0000000001000000-0x0000000040000000 with 2.00 MiB pages This is because the check that the mapping crosses the __init_begin boundary is too strict, it also returns true when we map exactly up to the boundary. So fix it to check that the mapping would actually map past __init_begin, and with that we see: Mapped 0x0000000000000000-0x0000000040000000 with 2.00 MiB pages Mapped 0x0000000040000000-0x0000000100000000 with 1.00 GiB pages Signed-off-by: Michael Ellerman --- arch/powerpc/mm/pgtable-radix.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c index bb85c58b96c8..7a44ec276290 100644 --- a/arch/powerpc/mm/pgtable-radix.c +++ b/arch/powerpc/mm/pgtable-radix.c @@ -295,14 +295,14 @@ static int __meminit create_physical_mapping(unsigned long start, if (split_text_mapping && (mapping_size == PUD_SIZE) && (addr < __pa_symbol(__init_begin)) && - (addr + mapping_size) >= __pa_symbol(__init_begin)) { + (addr + mapping_size) > __pa_symbol(__init_begin)) { max_mapping_size = PMD_SIZE; goto retry; } if (split_text_mapping && (mapping_size == PMD_SIZE) && (addr < __pa_symbol(__init_begin)) && - (addr + mapping_size) >= __pa_symbol(__init_begin)) { + (addr + mapping_size) > __pa_symbol(__init_begin)) { mapping_size = PAGE_SIZE; psize = mmu_virtual_psize; } -- GitLab