Messages in this thread |  | | Date | Mon, 15 Jan 2018 20:43:50 +0800 | From | Chao Fan <> | Subject | Re: [PATCH v6 1/5] kaslr: add kaslr_mem=nn[KMG]@ss[KMG] to specify extracting memory |
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On Mon, Jan 15, 2018 at 08:40:12PM +0800, Chao Fan wrote: >In current code, kaslr only has a method to avoid some memory regions, >but no method to specify the regions for kaslr to extract. So kaslr >may choose the wrong position sometimes, which will cause some other >features fail. > >Here is a problem that 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 "kaslr_mem=" to store the regions in immovable nodes, 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. > >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 <fanc.fnst@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..b071f6edd7b2 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];
Here it may should be "kaslr_mem", but there is mem_avoid in current code, so I name it as "mem_usable" to be symmetrical with "mem_avoid". We can see more in PATCH 05.
Thanks, Chao Fan
>+ >+/* 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 >
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