Messages in this thread | | | From | Pingfan Liu <> | Date | Thu, 4 Apr 2019 17:40:26 +0800 | Subject | Re: [PATCHv3] x86/boot/KASLR: skip the specified crashkernel region |
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On Wed, Apr 3, 2019 at 11:10 AM Baoquan He <bhe@redhat.com> wrote: > > On 04/03/19 at 10:58am, Pingfan Liu wrote: > > On Tue, Apr 2, 2019 at 4:08 PM Baoquan He <bhe@redhat.com> wrote: > > > > > > > +/* handle crashkernel=x@y or =range1:size1[,range2:size2,...]@offset options */ > > > > +static void mem_avoid_specified_crashkernel_region(char *option) > > > > +{ > > > > + unsigned long long crash_size, crash_base = 0; > > > > + char *first_colon, *first_space, *cur = option; > > > > + > > > > > > Another thing which need be noticed is that you may only need to handle > > > when '@' is found. Otherwise just let it go. Right? > > > > > According to kernel's behavior, only the last "crashkernel=" option > > takes effect. Hence if no '@', then clearing mem_avoid > > Here I mean that you can search '@' at the beginning if crashkernel is > found. Maybe no need to clear mem_avoid since it's global data, has been > initialized to 0 during loading. It's in BSS, right? > Consider the following cmdline crashkernel=256M@1G crashkernel=512M. These two options are handled independently by handle_mem_options(), and the later one should overwrite the previous one. This is the behavior of current kernel's code, referring to get_last_crashkernel(). > You don't have to search first colon or first space, then parse size of > crashkernel, and finally find out that it's only crashkernel=512M-2G:64M,2G-:128M > style, no '@' specified. What do you think? > Yes, that will be better. But I plan to reuse parse_crashkernel_mem/simple().
Thanks, Pingfan > > > > > > + first_colon = strchr(option, ':'); > > > > + first_space = strchr(option, ' '); > > > > + /* if contain ":" */ > > > > + if (first_colon && (!first_space || first_colon < first_space)) { > > > > + int i; > > > > + u64 total_sz = 0; > > > > + struct boot_e820_entry *entry; > > > > + > > > > + for (i = 0; i < boot_params->e820_entries; i++) { > > > > + entry = &boot_params->e820_table[i]; > > > > + /* Skip non-RAM entries. */ > > > > + if (entry->type != E820_TYPE_RAM) > > > > + continue; > > > > + total_sz += entry->size; > > > > + } > > > > + handle_crashkernel_mem(option, total_sz, &crash_size, > > > > + &crash_base); > > > > + } else { > > > > + crash_size = memparse(option, &cur); > > > > + if (option == cur) > > > > + return; > > > > + while (*cur && *cur != ' ' && *cur != '@') > > > > + cur++; > > > > + if (*cur == '@') { > > > > + option = cur + 1; > > > > + crash_base = memparse(option, &cur); > > > > + } > > > > + } > > > > + if (crash_base) { > > > > + mem_avoid[MEM_AVOID_CRASHKERNEL].start = crash_base; > > > > + mem_avoid[MEM_AVOID_CRASHKERNEL].size = crash_size; > > > > + } else { > > > > + /* > > > > + * Clearing mem_avoid if no offset is given. This is consistent > > > > + * with kernel, which uses the last crashkernel= option. > > > > + */ > > > > + mem_avoid[MEM_AVOID_CRASHKERNEL].start = 0; > > > > + mem_avoid[MEM_AVOID_CRASHKERNEL].size = 0; > > > > + } > > > > +}
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