x86/mm/KASLR: Fix physical memory calculation on KASLR memory randomization

Initialize KASLR memory randomization after max_pfn is initialized. Also
ensure the size is rounded up. It could create problems on machines
with more than 1Tb of memory on certain random addresses.

Signed-off-by: Thomas Garnier <[email protected]>
Cc: Aleksey Makarov <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Baoquan He <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dave Young <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Fabian Frederick <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Lv Zheng <[email protected]>
Cc: Mark Salter <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rafael J . Wysocki <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Toshi Kani <[email protected]>
Cc: [email protected]
Fixes: 021182e ("Enable KASLR for physical mapping memory regions")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

Author: thgarnie

arch/x86/kernel/setup.c

@@ -936,8 +936,6 @@ void __init setup_arch(char **cmdline_p)
 
 	x86_init.oem.arch_setup();
 
-	kernel_randomize_memory();
-
 	iomem_resource.end = (1ULL << boot_cpu_data.x86_phys_bits) - 1;
 	setup_memory_map();
 	parse_setup_data();
@@ -1055,6 +1053,12 @@ void __init setup_arch(char **cmdline_p)
 
 	max_possible_pfn = max_pfn;
 
+	/*
+	 * Define random base addresses for memory sections after max_pfn is
+	 * defined and before each memory section base is used.
+	 */
+	kernel_randomize_memory();
+
 #ifdef CONFIG_X86_32
 	/* max_low_pfn get updated here */
 	find_low_pfn_range();

arch/x86/mm/kaslr.c

@@ -97,7 +97,7 @@ void __init kernel_randomize_memory(void)
 	 * add padding if needed (especially for memory hotplug support).
 	 */
 	BUG_ON(kaslr_regions[0].base != &page_offset_base);
-	memory_tb = ((max_pfn << PAGE_SHIFT) >> TB_SHIFT) +
+	memory_tb = DIV_ROUND_UP(max_pfn << PAGE_SHIFT, 1UL << TB_SHIFT) +
 		CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING;
 
 	/* Adapt phyiscal memory region size based on available memory */