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SubjectRe: [PATCH v4 2/2] x86/boot/KASLR: skip the specified crashkernel region
On Mon, Apr 08, 2019 at 01:58:35PM +0800, Pingfan Liu wrote:
> crashkernel=x@y or or =range1:size1[,range2:size2,...]@offset option may
> fail to reserve the required memory region if KASLR puts kernel into the
> region. To avoid this uncertainty, asking KASLR to 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: Vivek Goyal <vgoyal@redhat.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: Hari Bathini <hbathini@linux.vnet.ibm.com>
> Cc: linux-kernel@vger.kernel.org
> ---
> arch/x86/boot/compressed/kaslr.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 40 insertions(+)
>
> diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
> index 2e53c05..765a593 100644
> --- a/arch/x86/boot/compressed/kaslr.c
> +++ b/arch/x86/boot/compressed/kaslr.c
> @@ -107,6 +107,7 @@ 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,
> };
>
> @@ -131,6 +132,11 @@ char *skip_spaces(const char *str)
> }
> #include "../../../../lib/ctype.c"
> #include "../../../../lib/cmdline.c"
> +#ifdef CONFIG_CRASH_CORE
> +#define printk
> +#define _BOOT_KASLR
> +#include "../../../../lib/parse_crashkernel.c"
> +#endif
>
> static int
> parse_memmap(char *p, unsigned long long *start, unsigned long long *size)
> @@ -292,6 +298,39 @@ static void handle_mem_options(void)
> return;
> }
>
> +static u64 mem_ram_size(void)
> +{
> + struct boot_e820_entry *entry;
> + u64 total_sz = 0;
> + int i;
> +
> + 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;
> + }
> + return total_sz;
> +}
> +
> +/*
> + * For crashkernel=size@offset or =range1:size1[,range2:size2,...]@offset
> + * options, recording mem_avoid for them.
> + */
> +static void handle_crashkernel_options(void)
> +{
> + unsigned long long crash_size, crash_base = 0;
> + char *cmdline = (char *)get_cmd_line_ptr();
> + u64 total_sz = mem_ram_size();
> +
> + parse_crashkernel(cmdline, total_sz, &crash_size, &crash_base);

That function has a return value which you could test. And then you
don't need to set crash_base to 0 above.

--
Regards/Gruss,
Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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