[PATCHv2] x86/boot/KASLR: skip the specified crashkernel reserved region

[Pingfan Liu]

crashkernel=x@y option may fail to reserve the required memory region if
KASLR puts kernel into the region. To avoid this uncertainty, making KASLR
skip the required region.

Signed-off-by: Pingfan Liu <kernelf...@gmail.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Borislav Petkov <b...@alien8.de>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: Baoquan He <b...@redhat.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: Nicolas Pitre <n...@linaro.org>
Cc: Pingfan Liu <kernelf...@gmail.com>
Cc: Chao Fan <fanc.f...@cn.fujitsu.com>
Cc: "Kirill A. Shutemov" <kirill.shute...@linux.intel.com>
Cc: Ard Biesheuvel <ard.biesheu...@linaro.org>
Cc: linux-kernel@vger.kernel.org
---
v1 -> v2: fix some trival format

 arch/x86/boot/compressed/kaslr.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 9ed9709..e185318 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -109,6 +109,7 @@ 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_CRASHKERNEL,
        MEM_AVOID_MAX,
 };
 
@@ -240,6 +241,25 @@ static void parse_gb_huge_pages(char *param, char *val)
        }
 }
 
+/* parse crashkernel=x@y option */
+static void mem_avoid_crashkernel_simple(char *option)
+{
+       unsigned long long crash_size, crash_base;
+       char *cur = option;
+
+       crash_size = memparse(option, &cur);
+       if (option == cur)
+               return;
+
+       if (*cur == '@') {
+               option = cur + 1;
+               crash_base = memparse(option, &cur);
+               if (option == cur)
+                       return;
+               mem_avoid[MEM_AVOID_CRASHKERNEL].start = crash_base;
+               mem_avoid[MEM_AVOID_CRASHKERNEL].size = crash_size;
+       }
+}
 
 static void handle_mem_options(void)
 {
@@ -250,7 +270,7 @@ static void handle_mem_options(void)
        u64 mem_size;
 
        if (!strstr(args, "memmap=") && !strstr(args, "mem=") &&
-               !strstr(args, "hugepages"))
+               !strstr(args, "hugepages") && !strstr(args, "crashkernel="))
                return;
 
        tmp_cmdline = malloc(len + 1);
@@ -286,6 +306,8 @@ static void handle_mem_options(void)
                                goto out;
 
                        mem_limit = mem_size;
+               } else if (strstr(param, "crashkernel")) {
+                       mem_avoid_crashkernel_simple(val);
                }
        }
 
@@ -414,7 +436,7 @@ 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 */
+       /* Mark the regions we need to avoid */
        handle_mem_options();
 
 #ifdef CONFIG_X86_VERBOSE_BOOTUP
-- 
2.7.4