On Tue, Jan 16, 2018 at 08:43:20AM +0800, Baoquan He wrote: >On 01/15/18 at 08:49pm, Chao Fan wrote: >> Hi Luiz, >> >> I don't know if this patch is OK for you. >> Of coure you can only use kaslr_mem=nn@ss to solve the 1G huge page >> issue. Because we know the region [0,1G] is not suitable for 1G huge >> page, so you can specify ksalr_mem=1G@0 of kaslr_mem=1G to solve >> your problem. But the regions may be too slow and is not good >> for the randomness. > >I guess you want to say: > >"Because we know the region [0,1G] is not suitable for 1G huge page, so >you can specify ksalr_mem=1G@0 or kaslr_mem=1G to solve your problem. >But the region may be too small and is not good for the randomness." > >Hi Luiz, > >For hugetlb issue, we can always suggest users adding "kaslr_mem=1G" to >kernel cmdline on KVM. Surely if users are very familiar with system >memory layout, they can specify "kaslr_mem=1G, kaslr_mem=1G@2G >kaslr_mem=1G@4G" for better kernel text KASLR. The "kaslr_mem=1G" >suggestion can be documented for redhat kvm usage. Any thought or >suggestion? > >Thanks >Baoquan >
Thanks for your explaination. Thanks, Chao Fan >> >> So as Kess said, I put the regions suitable for 1G huge page to >> mem_avoid, you can use kaslr_mem=1G!1G to solve the problem in your >> email. >> >> Thanks, >> Chao Fan >> >> On Mon, Jan 15, 2018 at 08:40:16PM +0800, Chao Fan wrote: >> >In current code, kaslr choose the only suitable memory region for 1G >> >huge page, so the no suitable region for 1G huge page. So add this >> >feature to store these regions. >> > >> >Of coure, we can use memmap= to do this job. But memmap will be handled >> >in the later code, but kaslr_mem= only works in this period. >> > >> >It can help users to avoid more memory regions, not only the 1G huge >> >huge page issue. >> > >> >Signed-off-by: Chao Fan <[email protected]> >> >--- >> > arch/x86/boot/compressed/kaslr.c | 56 >> > +++++++++++++++++++++++++++++++++++----- >> > 1 file changed, 50 insertions(+), 6 deletions(-) >> > >> >diff --git a/arch/x86/boot/compressed/kaslr.c >> >b/arch/x86/boot/compressed/kaslr.c >> >index fc531fa1f10c..c71189cf8d56 100644 >> >--- a/arch/x86/boot/compressed/kaslr.c >> >+++ b/arch/x86/boot/compressed/kaslr.c >> >@@ -95,6 +95,18 @@ static bool memmap_too_large; >> > /* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */ >> > unsigned long long mem_limit = ULLONG_MAX; >> > >> >+/* >> >+ * Only supporting at most 4 unusable memory regions for >> >+ * "kaslr_mem=nn[KMG]!ss[KMG]" >> >+ */ >> >+#define MAX_KASLR_MEM_AVOID 4 >> >+ >> >+static bool kaslr_mem_avoid_too_large; >> >+ >> >+enum kaslr_mem_type { >> >+ CMD_MEM_USABLE = 1, >> >+ CMD_MEM_AVOID, >> >+}; >> > >> > enum mem_avoid_index { >> > MEM_AVOID_ZO_RANGE = 0, >> >@@ -103,6 +115,8 @@ enum mem_avoid_index { >> > MEM_AVOID_BOOTPARAMS, >> > MEM_AVOID_MEMMAP_BEGIN, >> > MEM_AVOID_MEMMAP_END = MEM_AVOID_MEMMAP_BEGIN + MAX_MEMMAP_REGIONS - 1, >> >+ MEM_AVOID_KASLR_MEM_BEGIN, >> >+ MEM_AVOID_KASLR_MEM_END = MEM_AVOID_KASLR_MEM_BEGIN + >> >MAX_KASLR_MEM_AVOID - 1, >> > MEM_AVOID_MAX, >> > }; >> > >> >@@ -217,7 +231,8 @@ static void mem_avoid_memmap(char *str) >> > >> > static int parse_kaslr_mem(char *p, >> > unsigned long long *start, >> >- unsigned long long *size) >> >+ unsigned long long *size, >> >+ int *cmd_type) >> > { >> > char *oldp; >> > >> >@@ -230,8 +245,13 @@ static int parse_kaslr_mem(char *p, >> > return -EINVAL; >> > >> > switch (*p) { >> >+ case '!' : >> >+ *start = memparse(p + 1, &p); >> >+ *cmd_type = CMD_MEM_AVOID; >> >+ return 0; >> > case '@': >> > *start = memparse(p + 1, &p); >> >+ *cmd_type = CMD_MEM_USABLE; >> > return 0; >> > default: >> > /* >> >@@ -240,6 +260,7 @@ static int parse_kaslr_mem(char *p, >> > * the region starts from 0. >> > */ >> > *start = 0; >> >+ *cmd_type = CMD_MEM_USABLE; >> > return 0; >> > } >> > >> >@@ -248,26 +269,44 @@ static int parse_kaslr_mem(char *p, >> > >> > static void parse_kaslr_mem_regions(char *str) >> > { >> >- static int i; >> >+ static int i = 0, j = 0; >> >+ int cmd_type = 0; >> > >> > while (str && (i < MAX_KASLR_MEM_USABLE)) { >> > int rc; >> > unsigned long long start, size; >> > char *k = strchr(str, ','); >> > >> >+ if (i >= MAX_KASLR_MEM_USABLE && j >= MAX_KASLR_MEM_AVOID) >> >+ break; >> >+ >> > if (k) >> > *k++ = 0; >> > >> >- rc = parse_kaslr_mem(str, &start, &size); >> >+ rc = parse_kaslr_mem(str, &start, &size, &cmd_type); >> > if (rc < 0) >> > break; >> > str = k; >> > >> >- mem_usable[i].start = start; >> >- mem_usable[i].size = size; >> >- i++; >> >+ if (cmd_type == CMD_MEM_USABLE) { >> >+ if (i >= MAX_KASLR_MEM_USABLE) >> >+ continue; >> >+ mem_usable[i].start = start; >> >+ mem_usable[i].size = size; >> >+ i++; >> >+ } else if (cmd_type == CMD_MEM_AVOID) { >> >+ if (j >= MAX_KASLR_MEM_AVOID) >> >+ continue; >> >+ mem_avoid[MEM_AVOID_KASLR_MEM_BEGIN + j].start = start; >> >+ mem_avoid[MEM_AVOID_KASLR_MEM_BEGIN + j].size = size; >> >+ j++; >> >+ } >> > } >> > num_usable_region = i; >> >+ >> >+ /* More than 4 kaslr_mem avoid, fail kaslr */ >> >+ if ((j >= MAX_KASLR_MEM_AVOID) && str) >> >+ kaslr_mem_avoid_too_large = true; >> > } >> > >> > static int handle_mem_filter(void) >> >@@ -799,6 +838,11 @@ static unsigned long find_random_phys_addr(unsigned >> >long minimum, >> > return 0; >> > } >> > >> >+ /* Check if we had too many kaslr_mem avoid. */ >> >+ if (kaslr_mem_avoid_too_large) { >> >+ debug_putstr("Aborted memory entries scan (more than 4 >> >kaslr_mem avoid args)!\n"); >> >+ return 0; >> >+ } >> > /* Make sure minimum is aligned. */ >> > minimum = ALIGN(minimum, CONFIG_PHYSICAL_ALIGN); >> > >> >-- >> >2.14.3 >> > >> >> > >
