[PATCH v12 1/5] x86/boot: Add get_acpi_rsdp() to parse RSDP in cmdline from KEXEC

[Chao Fan]

To fix the conflict between KASLR and memory-hotremove, memory
information in SRAT table is necessary.

ACPI SRAT (System/Static Resource Affinity Table) can show the details
about memory ranges, including ranges of memory provided by hot-added
memory devices. SRAT table must be introduced by RSDP pointer (Root
System Description Pointer). So RSDP should be found firstly.

When booting form KEXEC/EFI/BIOS, the methods to find RSDP pointer
are different. When booting from KEXEC, 'acpi_rsdp' may have been
added to cmdline, so parse the cmdline and find the RSDP pointer.

Signed-off-by: Chao Fan <fanc.fnst@xxxxxxxxxxxxxx>
---
 arch/x86/boot/compressed/acpitb.c | 33 +++++++++++++++++++++++++++++++
 arch/x86/boot/compressed/misc.c   |  5 +++++
 arch/x86/boot/compressed/misc.h   |  4 ++++
 lib/kstrtox.c                     |  5 +++++
 4 files changed, 47 insertions(+)
 create mode 100644 arch/x86/boot/compressed/acpitb.c

diff --git a/arch/x86/boot/compressed/acpitb.c b/arch/x86/boot/compressed/acpitb.c
new file mode 100644
index 000000000000..614c45655cff
--- /dev/null
+++ b/arch/x86/boot/compressed/acpitb.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+#define BOOT_CTYPE_H
+#include "misc.h"
+#include "error.h"
+
+#include <linux/efi.h>
+#include <asm/efi.h>
+#include <linux/numa.h>
+#include <linux/acpi.h>
+
+#define STATIC
+#include <linux/decompress/mm.h>
+
+/* Store the immovable memory regions. */
+struct mem_vector immovable_mem[MAX_NUMNODES*2];
+#endif
+
+static acpi_physical_address get_acpi_rsdp(void)
+{
+#ifdef CONFIG_KEXEC
+	unsigned long long res;
+	int len = 0;
+	char *val;
+
+	val = malloc(19);
+	len = cmdline_find_option("acpi_rsdp", val, 19);
+	if (len > 0) {
+		val[len] = 0;
+		return (acpi_physical_address)kstrtoull(val, 16, &res);
+	}
+	return 0;
+#endif
+}
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 8dd1d5ccae58..e51713fe3add 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -12,6 +12,7 @@
  * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
  */
 
+#define BOOT_CTYPE_H
 #include "misc.h"
 #include "error.h"
 #include "pgtable.h"
@@ -426,3 +427,7 @@ void fortify_panic(const char *name)
 {
 	error("detected buffer overflow");
 }
+
+#ifdef BOOT_STRING
+#include "../../../../lib/kstrtox.c"
+#endif
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index a1d5918765f3..809c31effa4b 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -116,3 +116,7 @@ static inline void console_init(void)
 void set_sev_encryption_mask(void);
 
 #endif
+
+/* acpitb.c */
+#define BOOT_STRING
+extern int kstrtoull(const char *s, unsigned int base, unsigned long long *res);
diff --git a/lib/kstrtox.c b/lib/kstrtox.c
index 1006bf70bf74..a0ac1b2257b8 100644
--- a/lib/kstrtox.c
+++ b/lib/kstrtox.c
@@ -126,6 +126,9 @@ int kstrtoull(const char *s, unsigned int base, unsigned long long *res)
 }
 EXPORT_SYMBOL(kstrtoull);
 
+/* Make compressed period code be able to use kstrtoull(). */
+#ifndef BOOT_STRING
+
 /**
  * kstrtoll - convert a string to a long long
  * @s: The start of the string. The string must be null-terminated, and may also
@@ -408,3 +411,5 @@ kstrto_from_user(kstrtou16_from_user,	kstrtou16,	u16);
 kstrto_from_user(kstrtos16_from_user,	kstrtos16,	s16);
 kstrto_from_user(kstrtou8_from_user,	kstrtou8,	u8);
 kstrto_from_user(kstrtos8_from_user,	kstrtos8,	s8);
+
+#endif /* BOOT_STRING */
-- 
2.19.1