From be9e8d9541a95bdfac1c13d112cc032ea7fc745f Mon Sep 17 00:00:00 2001 From: Arvind Sankar Date: Tue, 28 Jul 2020 18:57:13 -0400 Subject: x86/kaslr: Simplify process_gb_huge_pages() Replace the loop to determine the number of 1Gb pages with arithmetic. Signed-off-by: Arvind Sankar Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200728225722.67457-13-nivedita@alum.mit.edu --- arch/x86/boot/compressed/kaslr.c | 47 ++++++++++++++++++---------------------- 1 file changed, 21 insertions(+), 26 deletions(-) diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 3727e9708690..00ef84b689f6 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -547,49 +547,44 @@ static void store_slot_info(struct mem_vector *region, unsigned long image_size) static void process_gb_huge_pages(struct mem_vector *region, unsigned long image_size) { - unsigned long addr, size = 0; + unsigned long pud_start, pud_end, gb_huge_pages; struct mem_vector tmp; - int i = 0; if (!IS_ENABLED(CONFIG_X86_64) || !max_gb_huge_pages) { store_slot_info(region, image_size); return; } - addr = ALIGN(region->start, PUD_SIZE); - /* Did we raise the address above the passed in memory entry? */ - if (addr < region->start + region->size) - size = region->size - (addr - region->start); - - /* Check how many 1GB huge pages can be filtered out: */ - while (size >= PUD_SIZE && max_gb_huge_pages) { - size -= PUD_SIZE; - max_gb_huge_pages--; - i++; - } + /* Are there any 1GB pages in the region? */ + pud_start = ALIGN(region->start, PUD_SIZE); + pud_end = ALIGN_DOWN(region->start + region->size, PUD_SIZE); /* No good 1GB huge pages found: */ - if (!i) { + if (pud_start >= pud_end) { store_slot_info(region, image_size); return; } - /* - * Skip those 'i'*1GB good huge pages, and continue checking and - * processing the remaining head or tail part of the passed region - * if available. - */ - - if (addr >= region->start + image_size) { + /* Check if the head part of the region is usable. */ + if (pud_start >= region->start + image_size) { tmp.start = region->start; - tmp.size = addr - region->start; + tmp.size = pud_start - region->start; store_slot_info(&tmp, image_size); } - size = region->size - (addr - region->start) - i * PUD_SIZE; - if (size >= image_size) { - tmp.start = addr + i * PUD_SIZE; - tmp.size = size; + /* Skip the good 1GB pages. */ + gb_huge_pages = (pud_end - pud_start) >> PUD_SHIFT; + if (gb_huge_pages > max_gb_huge_pages) { + pud_end = pud_start + (max_gb_huge_pages << PUD_SHIFT); + max_gb_huge_pages = 0; + } else { + max_gb_huge_pages -= gb_huge_pages; + } + + /* Check if the tail part of the region is usable. */ + if (region->start + region->size >= pud_end + image_size) { + tmp.start = pud_end; + tmp.size = region->start + region->size - pud_end; store_slot_info(&tmp, image_size); } } -- cgit v1.2.3-59-g8ed1b