On 01/17/18 at 06:53pm, Chao Fan wrote:
> Introduce a new kernel parameter kaslr_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
~ remove 'into'
> extracted into those movable regions, this will make memory hotplug fail.
> With the help of 'kaslr_mem=', limit kernel in those immovable regions
> specified.
>
> Signed-off-by: Chao Fan <fanc.f...@cn.fujitsu.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 8199a6187251..b21741135673 100644
> --- a/arch/x86/boot/compressed/kaslr.c
> +++ b/arch/x86/boot/compressed/kaslr.c
> @@ -108,6 +108,15 @@ 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 name xx_usable sounds not so good, while I don't know what
is better. Otherwise this patch looks good to me.
Ack it.
Acked-by: Baoquan He <b...@redhat.com>
> +
> +/* 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. */
> @@ -206,7 +215,62 @@ static void mem_avoid_memmap(char *str)
> memmap_too_large = true;
> }
>
> -static int handle_mem_memmap(void)
> +static int parse_kaslr_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_mem=nn[KMG]
> + * has the same behaviour as kaslr_mem=nn[KMG]@0. It means
> + * the region starts from 0.
> + */
> + *start = 0;
> + return 0;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static void parse_kaslr_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_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);
> @@ -214,7 +278,8 @@ 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_mem="))
> return 0;
>
> tmp_cmdline = malloc(len + 1);
> @@ -239,6 +304,8 @@ static int handle_mem_memmap(void)
>
> if (!strcmp(param, "memmap")) {
> mem_avoid_memmap(val);
> + } else if (!strcmp(param, "kaslr_mem")) {
> + parse_kaslr_mem_regions(val);
> } else if (!strcmp(param, "mem")) {
> char *p = val;
>
> @@ -378,7 +445,7 @@ 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
>
>
>
