linux-kernel - [PATCHv5 2/2] x86/boot/KASLR: skip the specified crashkernel region

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Message-Id: <1557203494-7939-3-git-send-email-kernelfans@gmail.com>
Date:   Tue,  7 May 2019 12:31:34 +0800
From:   Pingfan Liu <kernelfans@...il.com>
To:     x86@...nel.org
Cc:     Pingfan Liu <kernelfans@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, Baoquan He <bhe@...hat.com>,
        Will Deacon <will.deacon@....com>,
        Nicolas Pitre <nico@...aro.org>,
        Vivek Goyal <vgoyal@...hat.com>,
        Chao Fan <fanc.fnst@...fujitsu.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Hari Bathini <hbathini@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCHv5 2/2] x86/boot/KASLR: skip the specified crashkernel region

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@...il.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Baoquan He <bhe@...hat.com>
Cc: Will Deacon <will.deacon@....com>
Cc: Nicolas Pitre <nico@...aro.org>
Cc: Vivek Goyal <vgoyal@...hat.com>
Cc: Chao Fan <fanc.fnst@...fujitsu.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
CC: Hari Bathini <hbathini@...ux.vnet.ibm.com>
Cc: linux-kernel@...r.kernel.org
---
 arch/x86/boot/compressed/kaslr.c | 40 ++++++++++++++++++++++++++++++++++++++++
 lib/parse_crashkernel.c          | 10 ++++++++++
 2 files changed, 50 insertions(+)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 2e53c05..12f72a3 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@...set 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;
+	char *cmdline = (char *)get_cmd_line_ptr();
+	u64 total_sz = mem_ram_size();
+
+	parse_crashkernel(cmdline, total_sz, &crash_size, &crash_base);
+	if (crash_base) {
+		mem_avoid[MEM_AVOID_CRASHKERNEL].start = crash_base;
+		mem_avoid[MEM_AVOID_CRASHKERNEL].size = crash_size;
+	}
+}
+
 /*
  * In theory, KASLR can put the kernel anywhere in the range of [16M, 64T).
  * The mem_avoid array is used to store the ranges that need to be avoided
@@ -414,6 +453,7 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
 
 	/* Mark the memmap regions we need to avoid */
 	handle_mem_options();
+	handle_crashkernel_options();
 
 	/* Enumerate the immovable memory regions */
 	num_immovable_mem = count_immovable_mem_regions();
diff --git a/lib/parse_crashkernel.c b/lib/parse_crashkernel.c
index b9a8dc6..4644379 100644
--- a/lib/parse_crashkernel.c
+++ b/lib/parse_crashkernel.c
@@ -137,6 +137,7 @@ static __initdata char *suffix_tbl[] = {
 	[SUFFIX_NULL] = NULL,
 };
 
+#ifndef _BOOT_KASLR
 /*
  * That function parses "suffix"  crashkernel command lines like
  *
@@ -169,6 +170,7 @@ static int __init parse_crashkernel_suffix(char *cmdline,
 
 	return 0;
 }
+#endif
 
 static __init char *get_last_crashkernel(char *cmdline,
 			     const char *name,
@@ -232,9 +234,11 @@ static int __init __parse_crashkernel(char *cmdline,
 
 	ck_cmdline += strlen(name);
 
+#ifndef _BOOT_KASLR
 	if (suffix)
 		return parse_crashkernel_suffix(ck_cmdline, crash_size,
 				suffix);
+#endif
 	/*
 	 * if the commandline contains a ':', then that's the extended
 	 * syntax -- if not, it must be the classic syntax
@@ -261,6 +265,11 @@ int __init parse_crashkernel(char *cmdline,
 					"crashkernel=", NULL);
 }
 
+/*
+ * At boot stage, KASLR does not care about crashkernel=size,[high|low], which
+ * never specifies the offset of region.
+ */
+#ifndef _BOOT_KASLR
 int __init parse_crashkernel_high(char *cmdline,
 			     unsigned long long system_ram,
 			     unsigned long long *crash_size,
@@ -278,3 +287,4 @@ int __init parse_crashkernel_low(char *cmdline,
 	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
 				"crashkernel=", suffix_tbl[SUFFIX_LOW]);
 }
+#endif
-- 
2.7.4