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Subject[PATCH] x86/boot/KASLR: skip the specified crashkernel reserved region
Date
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 <kernelfans@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Chao Fan <fanc.fnst@cn.fujitsu.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-kernel@vger.kernel.org
---
arch/x86/boot/compressed/kaslr.c | 26 +++++++++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 9ed9709..728bc4b 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 +241,27 @@ static void parse_gb_huge_pages(char *param, char *val)
}
}

+/* parse crashkernel=x@y option */
+static int mem_avoid_crashkernel_simple(char *option)
+{
+ char *cur = option;
+ unsigned long long crash_size, crash_base;
+
+ crash_size = memparse(option, &cur);
+ if (option == cur)
+ return -EINVAL;
+
+ if (*cur == '@') {
+ option = cur + 1;
+ crash_base = memparse(option, &cur);
+ if (option == cur)
+ return -EINVAL;
+ mem_avoid[MEM_AVOID_CRASHKERNEL].start = crash_base;
+ mem_avoid[MEM_AVOID_CRASHKERNEL].size = crash_size;
+ }
+
+ return 0;
+}

static void handle_mem_options(void)
{
@@ -250,7 +272,7 @@ 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 +308,8 @@ static void handle_mem_options(void)
goto out;

mem_limit = mem_size;
+ } else if (strstr(param, "crashkernel")) {
+ mem_avoid_crashkernel_simple(val);
}
}

--
2.7.4
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