Messages in this thread Patch in this message | | | From | Chao Fan <> | Subject | [PATCH v15 2/6] x86/boot: Introduce get_acpi_rsdp() to parse RSDP in cmdline from KEXEC | Date | Mon, 7 Jan 2019 11:22:39 +0800 |
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KASLR may randomly choose some positions which are located in movable memory regions. This will make the movable memory chosen by KASLR can't be removed.
Memory information in SRAT is necessary to fix the conflict between KASLR and memory-hotremove.
ACPI SRAT (System/Static Resource Affinity Table) shows the details about memory ranges, including ranges of memory provided by hot-added memory devices. SRAT is introduced by Root System Description Pointer(RSDP). So RSDP should be found firstly.
When booting form KEXEC/EFI/BIOS, the methods to find RSDP are different. When booting from KEXEC, 'acpi_rsdp=' may have been added to cmdline, so parse cmdline to find RSDP.
Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com> --- arch/x86/boot/compressed/acpi.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100644 arch/x86/boot/compressed/acpi.c
diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c new file mode 100644 index 000000000000..7ca5001d7639 --- /dev/null +++ b/arch/x86/boot/compressed/acpi.c @@ -0,0 +1,30 @@ +// SPDX-License-Identifier: GPL-2.0 +#define BOOT_CTYPE_H +#include "misc.h" +#include "error.h" +#include "../string.h" + +#include <linux/acpi.h> + +/* + * Max length of 64-bit hex address string is 19, prefix "0x" + 16 hex + * digits, and '\0' for termination. + */ +#define MAX_HEX_ADDRESS_STRING_LEN 19 + +static acpi_physical_address get_acpi_rsdp(void) +{ +#ifdef CONFIG_KEXEC + char val[MAX_HEX_ADDRESS_STRING_LEN]; + unsigned long long res; + int len = 0; + + len = cmdline_find_option("acpi_rsdp", val, MAX_HEX_ADDRESS_STRING_LEN); + if (len > 0) { + val[len] = '\0'; + if (!kstrtoull(val, 16, &res)) + return res; + } +#endif + return 0; +} -- 2.20.1
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