In current code, kaslr may choose the memory region in movable nodes to extract kernel, which will make the nodes can't be hot-removed. To solve it, we can specify the memory region in immovable node. Create immovable_mem to store the regions in immovable_mem, where should be chosen by kaslr.
Also change the "handle_mem_memmap" to "handle_mem_filter", since it will not only handle memmap parameter now. Since "immovable_mem=" only works with "movable_node", so "immovable_mem=" doesn't work alone. If specify "movable_node" without "immovable_mem=", disable KASLR. Multiple regions can be specified, comma delimited. Considering the usage of memory, only support for 4 regions. 4 regions contains 2 nodes at least, enough for kernel to extract. Signed-off-by: Chao Fan <[email protected]> --- arch/x86/boot/compressed/kaslr.c | 112 +++++++++++++++++++++++++++++++++++++-- 1 file changed, 109 insertions(+), 3 deletions(-) diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 8199a6187251..60e5aa28b510 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -108,6 +108,19 @@ enum mem_avoid_index { static struct mem_vector mem_avoid[MEM_AVOID_MAX]; +#ifdef CONFIG_MEMORY_HOTPLUG +/* Only supporting at most 4 immovable memory regions with kaslr */ +#define MAX_IMMOVABLE_MEM 4 + +static bool lack_immovable_mem; + +/* Store the memory regions in immovable node */ +static struct mem_vector immovable_mem[MAX_IMMOVABLE_MEM]; + +/* The immovable regions user specify, not more than 4 */ +static int num_immovable_region; +#endif + static bool mem_overlaps(struct mem_vector *one, struct mem_vector *two) { /* Item one is entirely before item two. */ @@ -206,15 +219,97 @@ static void mem_avoid_memmap(char *str) memmap_too_large = true; } -static int handle_mem_memmap(void) +#ifdef CONFIG_MEMORY_HOTPLUG +static int parse_immovable_mem(char *p, + unsigned long long *start, + unsigned long long *size) +{ + char *oldp; + + if (!p) + return -EINVAL; + + oldp = p; + *size = memparse(p, &p); + if (p == oldp) + return -EINVAL; + + switch (*p) { + case '@': + *start = memparse(p + 1, &p); + return 0; + default: + /* + * If w/o offset, only size specified, immovable_mem=nn[KMG] + * has the same behaviour as immovable_mem=nn[KMG]@0. It means + * the region starts from 0. + */ + *start = 0; + return 0; + } + + return -EINVAL; +} + +static void parse_immovable_mem_regions(char *str) +{ + static int i; + + while (str && (i < MAX_IMMOVABLE_MEM)) { + int rc; + unsigned long long start, size; + char *k = strchr(str, ','); + + if (k) + *k++ = 0; + + rc = parse_immovable_mem(str, &start, &size); + if (rc < 0) + break; + str = k; + + immovable_mem[i].start = start; + immovable_mem[i].size = size; + i++; + } + num_immovable_region = i; +} +#else +static inline void parse_immovable_mem_regions(char *str) +{ +} +#endif + +static int handle_mem_filter(void) { char *args = (char *)get_cmd_line_ptr(); size_t len = strlen((char *)args); + bool enable_movable_node = false; char *tmp_cmdline; char *param, *val; u64 mem_size; - if (!strstr(args, "memmap=") && !strstr(args, "mem=")) +#ifdef CONFIG_MEMORY_HOTPLUG + if (strstr(args, "movable_node")) { + /* + * Confirm "movable_node" specified, otherwise + * "immovable_mem=" doesn't work. + */ + enable_movable_node = true; + + /* + * If only specify "movable_node" without "immovable_mem=", + * disable KASLR. + */ + if (!strstr(args, "immovable_mem=")) { + lack_immovable_mem = true; + return 0; + } + } +#endif + + if (!strstr(args, "memmap=") && !strstr(args, "mem=") && + !enable_movable_node) return 0; tmp_cmdline = malloc(len + 1); @@ -239,6 +334,9 @@ static int handle_mem_memmap(void) if (!strcmp(param, "memmap")) { mem_avoid_memmap(val); + } else if (!strcmp(param, "immovable_mem=") && + enable_movable_node) { + parse_immovable_mem_regions(val); } else if (!strcmp(param, "mem")) { char *p = val; @@ -378,7 +476,7 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size, /* We don't need to set a mapping for setup_data. */ /* Mark the memmap regions we need to avoid */ - handle_mem_memmap(); + handle_mem_filter(); #ifdef CONFIG_X86_VERBOSE_BOOTUP /* Make sure video RAM can be used. */ @@ -673,6 +771,14 @@ static unsigned long find_random_phys_addr(unsigned long minimum, return 0; } +#ifdef CONFIG_MEMORY_HOTPLUG + /* Check if specify "movable_node" without "immovable_mem=". */ + if (lack_immovable_mem) { + debug_putstr("Fail KASLR when movable_node specified without immovable_mem=.\n"); + return 0; + } +#endif + /* Make sure minimum is aligned. */ minimum = ALIGN(minimum, CONFIG_PHYSICAL_ALIGN); -- 2.14.3
