[PATCH v11 3/5] x86/boot: Add get_acpi_rsdp() to parse RSDP in cmdlien from kexec

[Chao Fan]

Imitate setup_acpi_rsdp() for the early_param of 'acpi_rsdp'.
KEXEC writes the RSDP pointer to cmdline for EFI booting.
So if 'acpi_rsdp' found in cmdline, use it directely.

Since function kstrtoull() is needed, include it in
arch/x86/boot/string.h. To solve the definition conflict
problem, set BOOT_STRING tag to expose only kstrtoull() and
functions used by it. Other functions in lib/kstrtox.c will
be covered.

Signed-off-by: Chao Fan <fanc.fnst@xxxxxxxxxxxxxx>
---
 arch/x86/boot/compressed/acpitb.c | 26 ++++++++++++++++++++++++++
 arch/x86/boot/string.h            |  4 ++++
 lib/kstrtox.c                     |  4 ++++
 3 files changed, 34 insertions(+)

diff --git a/arch/x86/boot/compressed/acpitb.c b/arch/x86/boot/compressed/acpitb.c
index 50fa65cf824d..5cfb4efa5a19 100644
--- a/arch/x86/boot/compressed/acpitb.c
+++ b/arch/x86/boot/compressed/acpitb.c
@@ -8,6 +8,12 @@
 #include <linux/numa.h>
 #include <linux/acpi.h>
 
+#define STATIC
+#include <linux/decompress/mm.h>
+
+#define BOOT_STRING
+#include "../string.h"
+
 /* Search EFI table for RSDP table. */
 static void efi_get_rsdp_addr(acpi_physical_address *rsdp_addr)
 {
@@ -200,3 +206,23 @@ static void bios_get_rsdp_addr(acpi_physical_address *rsdp_addr)
 		*rsdp_addr = (acpi_physical_address)address;
 	}
 }
+
+static void get_acpi_rsdp(acpi_physical_address *rsdp_addr)
+{
+#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 == -1)
+		return;
+
+	if (len > 0) {
+		val[len] = 0;
+		*rsdp_addr = (acpi_physical_address)kstrtoull(val, 16, &res);
+	}
+#endif
+}
diff --git a/arch/x86/boot/string.h b/arch/x86/boot/string.h
index 3d78e27077f4..0ff3edb888e4 100644
--- a/arch/x86/boot/string.h
+++ b/arch/x86/boot/string.h
@@ -30,3 +30,7 @@ extern unsigned long long simple_strtoull(const char *cp, char **endp,
 					  unsigned int base);
 
 #endif /* BOOT_STRING_H */
+
+#ifdef BOOT_STRING
+#include "../../../lib/kstrtox.c"
+#endif
diff --git a/lib/kstrtox.c b/lib/kstrtox.c
index 1006bf70bf74..3804db9eed56 100644
--- a/lib/kstrtox.c
+++ b/lib/kstrtox.c
@@ -126,6 +126,8 @@ int kstrtoull(const char *s, unsigned int base, unsigned long long *res)
 }
 EXPORT_SYMBOL(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 +410,5 @@ 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
-- 
2.19.1