x86-crashkernel-auto-4.14.patch

From: Brian Maly <brian.maly@oracle.com>
Date: Wed, 20 Dec 2017 04:58:08 +0000 (-0500)
Subject: x86: add support for crashkernel=auto
X-Git-Tag: v4.14.14-11~1221
X-Git-Url: http://oss.oracle.com/git/gitweb.cgi?p=linux-uek5.git;a=commitdiff_plain;h=f03174698ead1617281e7cb0b56b937731ce1790;hp=ef29b7a9e060d1034edf0b8584d5231ca96847e9

x86: add support for crashkernel=auto

This patch adds support for "crashkernel=auto" and was backported from RHEL7.

Orabug: 27234070

Signed-off-by: Brian Maly <brian.maly@oracle.com>
Signed-off-by: Guangyu Sun <guangyu.sun@oracle.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
---

Signed-off-by: Brian Maly <brian.maly@oracle.com>
Signed-off-by: Somasundaram Krishnasamy <somasundaram.krishnasamy@oracle.com>
---

diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index 5181445..245b4d2 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -150,6 +150,15 @@ System kernel config options
    analysis tools require a vmlinux with debug symbols in order to read
    and analyze a dump file.
 
+4) Enable "automatically reserve memory for kexec kernel" in
+   "Processor type and features."
+
+   CONFIG_KEXEC_AUTO_RESERVE=y
+
+   This will let you to use "crashkernel=auto", instead of specifying
+   numbers for "crashkernel=". Note, you need to have enough memory.
+   The threshold and reserved memory size are arch-dependent.
+
 Dump-capture kernel config options (Arch Independent)
 -----------------------------------------------------
 
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index af8f5ad..32a4b85 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1971,6 +1971,19 @@ config KEXEC_BZIMAGE_VERIFY_SIG
 	---help---
 	  Enable bzImage signature verification support.
 
+config KEXEC_AUTO_RESERVE
+	bool "automatically reserve memory for kexec kernel"
+	depends on KEXEC
+	default y
+	---help---
+	  Automatically reserve memory for a kexec kernel, so that you don't
+	  need to specify numbers for the "crashkernel=X@Y" boot option,
+	  instead you can use "crashkernel=auto". To make this work, you need
+	  to have more than 4G memory.
+
+	  On x86_32, 128M is reserved, on x86_64 1/32 of your memory is
+	  reserved, but it will not exceed 4G.
+
 config CRASH_DUMP
 	bool "kernel crash dumps"
 	depends on X86_64 || (X86_32 && HIGHMEM)
diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig
index e32fc1f..03a9cb2 100644
--- a/arch/x86/configs/x86_64_defconfig
+++ b/arch/x86/configs/x86_64_defconfig
@@ -53,6 +53,7 @@ CONFIG_X86_CHECK_BIOS_CORRUPTION=y
 CONFIG_EFI=y
 CONFIG_HZ_1000=y
 CONFIG_KEXEC=y
+CONFIG_KEXEC_AUTO_RESERVE=y
 CONFIG_CRASH_DUMP=y
 CONFIG_RANDOMIZE_BASE=y
 CONFIG_RANDOMIZE_MEMORY=y
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index f327236..4d3717b 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -226,3 +226,15 @@ extern void kdump_nmi_shootdown_cpus(void);
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_X86_KEXEC_H */
+
+#ifdef CONFIG_KEXEC_AUTO_RESERVE
+
+#ifndef KEXEC_AUTO_RESERVED_SIZE
+#define KEXEC_AUTO_RESERVED_SIZE (1ULL<<28) /* 256M */
+#endif
+#ifndef KEXEC_AUTO_THRESHOLD
+#define KEXEC_AUTO_THRESHOLD (1ULL<<31) /* 2G */
+#endif
+
+
+#endif /* CONFIG_KEXEC_AUTO_RESERVE */
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 2d90996..ffb0f2e 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -9,6 +9,7 @@
 #include <linux/crash_core.h>
 #include <linux/utsname.h>
 #include <linux/vmalloc.h>
+#include <linux/kexec.h>
 
 #include <asm/page.h>
 #include <asm/sections.h>
@@ -225,6 +226,44 @@ next:
 	return ck_cmdline;
 }
 
+#ifdef CONFIG_KEXEC_AUTO_RESERVE
+#ifndef arch_default_crash_size
+unsigned long long __init arch_default_crash_size(unsigned long long total_size)
+{
+	/*
+	 * BIOS usually will reserve some memory regions for it's own use.
+	 * so we will get less than actual memory in e820 usable areas.
+	 * We workaround this by round up the total size to 128M which is
+	 * enough for our current 2G kdump auto reserve threshold.
+	 */
+	if (roundup(total_size, 0x8000000) < KEXEC_AUTO_THRESHOLD) {
+		return 0;
+
+	} else {
+		/*
+		 * Filtering logic in kdump initrd requires 2bits per 4K page.
+		 * Hence reserve 2bits per 4K of RAM (or 1byte per 16K of RAM)
+		 * on top of base of 128M (KEXEC_AUTO_RESERVED_SIZE).
+		 */
+		return KEXEC_AUTO_RESERVED_SIZE +
+			roundup((total_size - KEXEC_AUTO_RESERVED_SIZE)
+				/ (1ULL<<14), 1ULL<<20);
+	}
+}
+#define arch_default_crash_size arch_default_crash_size
+#endif
+
+#ifndef arch_default_crash_base
+unsigned long long __init arch_default_crash_base(void)
+{
+	/* 0 means find the base address automatically. */
+	return 0;
+}
+#define arch_default_crash_base arch_default_crash_base
+#endif
+
+#endif /*CONFIG_KEXEC_AUTO_RESERVE*/
+
 static int __init __parse_crashkernel(char *cmdline,
 			     unsigned long long system_ram,
 			     unsigned long long *crash_size,
@@ -249,6 +288,23 @@ static int __init __parse_crashkernel(char *cmdline,
 	if (suffix)
 		return parse_crashkernel_suffix(ck_cmdline, crash_size,
 				suffix);
+
+#ifdef CONFIG_KEXEC_AUTO_RESERVE
+	if (strncmp(ck_cmdline, "auto", 4) == 0) {
+		unsigned long long size;
+
+		size = arch_default_crash_size(system_ram);
+		if (size != 0) {
+			*crash_size = size;
+			*crash_base = arch_default_crash_base();
+			return 0;
+
+		} else {
+			pr_warn("crashkernel=auto resulted in zero bytes of reserved memory.\n");
+			return -ENOMEM;
+		}
+	}
+#endif
 	/*
 	 * if the commandline contains a ':', then that's the extended
 	 * syntax -- if not, it must be the classic syntax
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 20fef1a..2687946 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -42,6 +42,7 @@
 
 #include <asm/page.h>
 #include <asm/sections.h>
+#include <asm/setup.h>
 
 #include <crypto/hash.h>
 #include <crypto/sha.h>