On 05/16/17 at 08:56am, Dou Liyang wrote:
> Hi Baoquan,
>
> At 05/13/2017 01:46 PM, Baoquan He wrote:
> > Option mem= will limit the max address a system can use and any memory
> > region above the limit will be removed.
> >
> > Furthermore, memmap=nn[KMG] which has no offset specified has the same
> > behaviour as mem=.
> >
> > KASLR needs to consider this when choosing the random position for
> > decompressing the kernel. Do it now.
> >
> > Signed-off-by: Baoquan He <b...@redhat.com>
> > Tested-by: Masayoshi Mizuma <m.miz...@jp.fujitsu.com>
> > ---
> > arch/x86/boot/compressed/kaslr.c | 68
> > +++++++++++++++++++++++++++++-----------
> > 1 file changed, 50 insertions(+), 18 deletions(-)
> >
> > diff --git a/arch/x86/boot/compressed/kaslr.c
> > b/arch/x86/boot/compressed/kaslr.c
> > index 106e13b..e0eba12 100644
> > --- a/arch/x86/boot/compressed/kaslr.c
> > +++ b/arch/x86/boot/compressed/kaslr.c
> > @@ -88,6 +88,10 @@ struct mem_vector {
> > static bool memmap_too_large;
> >
> >
> > +/* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */
> > +unsigned long long mem_limit = ULLONG_MAX;
> > +
> > +
> > enum mem_avoid_index {
> > MEM_AVOID_ZO_RANGE = 0,
> > MEM_AVOID_INITRD,
> > @@ -138,16 +142,23 @@ parse_memmap(char *p, unsigned long long *start,
> > unsigned long long *size)
> > return -EINVAL;
> >
> > switch (*p) {
> > - case '@':
> > - /* Skip this region, usable */
> > - *start = 0;
> > - *size = 0;
> > - return 0;
> > case '#':
> > case '$':
> > case '!':
> > *start = memparse(p + 1, &p);
> > return 0;
> > + case '@':
> > + /* memmap=nn@ss specifies usable region, should be skipped */
> > + *size = 0;
> > + /* Fall through */
> > + default:
> > + /*
> > + * If w/o offset, only size specified, memmap=nn[KMG] has the
> > + * same behaviour as mem=nn[KMG]. It limits the max address
> > + * system can use. Region above the limit should be avoided.
> > + */
> > + *start = 0;
> > + return 0;
> > }
> >
> > return -EINVAL;
> > @@ -173,9 +184,14 @@ static void mem_avoid_memmap(char *str)
> > if (rc < 0)
> > break;
> > str = k;
> > - /* A usable region that should not be skipped */
> > - if (size == 0)
> > +
> > + if (start == 0) {
> > + /* Store the specified memory limit if size > 0 */
> > + if (size > 0)
> > + mem_limit = size;
>
> Baoquan,
>
> I am not sure about setting the value of mem_limit to mem_size directly.
>
> If the command line has both the "memmap" and "mem", such as
> ... mem=2G memmap=4G ...
>
> ...in that code, the mem_limit may be 4G not 2G.
No, could you tell why you want to add both "memmap=nnKMG" and "mem=" at
the same time? As you sid, what if I add "mem=4G mem=2G mem=1G"?
>
> In my opinion, How about following:
>
> mem_limit = mem_limit > mem_size ? mem_size : mem_limit;
>
> > +
> > continue;
> > + }
> >
> > mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].start = start;
> > mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].size = size;
> > @@ -187,19 +203,15 @@ static void mem_avoid_memmap(char *str)
> > memmap_too_large = true;
> > }
> >
> > -
> > -/*
> > - * handle_mem_memmap will also cover 'mem=' issue in next patch. Will
> > remove
> > - * this note later.
> > - */
> > static int handle_mem_memmap(void)
> > {
> > char *args = (char *)get_cmd_line_ptr();
> > size_t len = strlen((char *)args);
> > char *tmp_cmdline;
> > char *param, *val;
> > + u64 mem_size;
> >
> > - if (!strstr(args, "memmap="))
> > + if (!strstr(args, "memmap=") && !strstr(args, "mem="))
> > return 0;
> >
> > tmp_cmdline = malloc(len + 1);
> > @@ -222,8 +234,20 @@ static int handle_mem_memmap(void)
> > return -1;
> > }
> >
> > - if (!strcmp(param, "memmap"))
> > + if (!strcmp(param, "memmap")) {
> > mem_avoid_memmap(val);
> > + } else if (!strcmp(param, "mem")) {
> > + char *p = val;
> > +
> > + if (!strcmp(p, "nopentium"))
> > + continue;
> > + mem_size = memparse(p, &p);
> > + if (mem_size == 0) {
> > + free(tmp_cmdline);
> > + return -EINVAL;
> > + }
> > + mem_limit = mem_size;
>
> The same as above.
>
> Thanks,
> Liyang.
>
> > + }
> > }
> >
> > free(tmp_cmdline);
> > @@ -460,7 +484,8 @@ static void process_e820_entry(struct boot_e820_entry
> > *entry,
> > {
> > struct mem_vector region, overlap;
> > struct slot_area slot_area;
> > - unsigned long start_orig;
> > + unsigned long start_orig, end;
> > + struct boot_e820_entry cur_entry;
> >
> > /* Skip non-RAM entries. */
> > if (entry->type != E820_TYPE_RAM)
> > @@ -474,8 +499,15 @@ static void process_e820_entry(struct boot_e820_entry
> > *entry,
> > if (entry->addr + entry->size < minimum)
> > return;
> >
> > - region.start = entry->addr;
> > - region.size = entry->size;
> > + /* Ignore entries above memory limit */
> > + end = min(entry->size + entry->addr, mem_limit);
> > + if (entry->addr >= end)
> > + return;
> > + cur_entry.addr = entry->addr;
> > + cur_entry.size = end - entry->addr;
> > +
> > + region.start = cur_entry.addr;
> > + region.size = cur_entry.size;
> >
> > /* Give up if slot area array is full. */
> > while (slot_area_index < MAX_SLOT_AREA) {
> > @@ -489,7 +521,7 @@ static void process_e820_entry(struct boot_e820_entry
> > *entry,
> > region.start = ALIGN(region.start, CONFIG_PHYSICAL_ALIGN);
> >
> > /* Did we raise the address above this e820 region? */
> > - if (region.start > entry->addr + entry->size)
> > + if (region.start > cur_entry.addr + cur_entry.size)
> > return;
> >
> > /* Reduce size by any delta from the original address. */
> >
>
>
