Messages in this thread Patch in this message |  | | From | Chao Fan <> | Subject | [PATCH v9 1/5] x86/KASLR: Add kaslr_boot_mem=nn[KMG]@ss[KMG] | Date | Wed, 28 Feb 2018 18:51:01 +0800 |
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Introduce a new kernel parameter kaslr_boot_mem=nn[KMG]@ss[KMG] which is used by KASLR only during kernel decompression stage.
Users can use it to specify memory regions where kernel can be randomized into. E.g if movable_node specified in kernel cmdline, kernel could be extracted into those movable regions, this will make memory hotplug fail. With the help of 'kaslr_boot_mem=', limit kernel in those immovable regions specified.
Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com> Tested-by: Luiz Capitulino <lcapitulino@redhat.com> Acked-by: Baoquan He <bhe@redhat.com> --- arch/x86/boot/compressed/kaslr.c | 73 ++++++++++++++++++++++++++++++++++++++-- 1 file changed, 70 insertions(+), 3 deletions(-)
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 66e42a098d70..e33e5cbf7244 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -114,6 +114,15 @@ enum mem_avoid_index { static struct mem_vector mem_avoid[MEM_AVOID_MAX]; +/* Only support at most 4 usable memory regions specified for kaslr */ +#define MAX_KASLR_MEM_USABLE 4 + +/* Store the usable memory regions for kaslr */ +static struct mem_vector mem_usable[MAX_KASLR_MEM_USABLE]; + +/* The amount of usable regions for kaslr user specify, not more than 4 */ +static int num_usable_region; + static bool mem_overlaps(struct mem_vector *one, struct mem_vector *two) { /* Item one is entirely before item two. */ @@ -212,7 +221,62 @@ static void mem_avoid_memmap(char *str) memmap_too_large = true; } -static int handle_mem_memmap(void) +static int parse_kaslr_boot_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, kaslr_boot_mem=nn[KMG] + * has the same behaviour as kaslr_boot_mem=nn[KMG]@0. It means + * the region starts from 0. + */ + *start = 0; + return 0; + } + + return -EINVAL; +} + +static void parse_kaslr_boot_mem_regions(char *str) +{ + static int i; + + while (str && (i < MAX_KASLR_MEM_USABLE)) { + int rc; + unsigned long long start, size; + char *k = strchr(str, ','); + + if (k) + *k++ = 0; + + rc = parse_kaslr_boot_mem(str, &start, &size); + if (rc < 0) + break; + str = k; + + mem_usable[i].start = start; + mem_usable[i].size = size; + i++; + } + num_usable_region = i; +} + +static int handle_mem_filter(void) { char *args = (char *)get_cmd_line_ptr(); size_t len = strlen((char *)args); @@ -220,7 +284,8 @@ static int handle_mem_memmap(void) char *param, *val; u64 mem_size; - if (!strstr(args, "memmap=") && !strstr(args, "mem=")) + if (!strstr(args, "memmap=") && !strstr(args, "mem=") && + !strstr(args, "kaslr_boot_mem=")) return 0; tmp_cmdline = malloc(len + 1); @@ -245,6 +310,8 @@ static int handle_mem_memmap(void) if (!strcmp(param, "memmap")) { mem_avoid_memmap(val); + } else if (!strcmp(param, "kaslr_boot_mem")) { + parse_kaslr_boot_mem_regions(val); } else if (!strcmp(param, "mem")) { char *p = val; @@ -384,7 +451,7 @@ 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. */ -- 2.14.3
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