ARM: kdump: Add LPAE support

hulk inclusion
category: bugfix
Bugzilla: 47259
CVE: N/A

----------------------------------------

With CONFIG_ARM_LPAE=y, memory in 32-bit ARM systems can exceed
4G. So if we use kdump in such systems. The capture kernel
should parse 64-bit elf header(parse_crash_elf64_headers).

And this process can not pass because ARM linux does not
supply related check function.

This patch adds check functions related of elf64 header.
Signed-off-by: NLiu Hua <sdu.liu@huawei.com>
Signed-off-by: NYufen Wang <wangyufen@huawei.com>
Reviewed-by: NLi Bin <huawei.libin@huawei.com>
Signed-off-by: Nzhangyi (F) <yi.zhang@huawei.com>

Conflicts:
	arch/arm/include/asm/elf.h
Signed-off-by: NLi Huafei <lihuafei1@huawei.com>
Reviewed-by: NWang Yufen <wangyufen@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arm/include/asm/elf.h

@@ -99,11 +99,13 @@ typedef struct user_fp elf_fpregset_t;
 extern char elf_platform[];
 
 struct elf32_hdr;
+struct elf64_hdr;
 
 /*
  * This is used to ensure we don't load something for the wrong architecture.
  */
 extern int elf_check_arch(const struct elf32_hdr *);
+extern int elf_check_arch_64(const struct elf64_hdr *);
 #define elf_check_arch elf_check_arch
 
 #define ELFOSABI_ARM_FDPIC  65	/* ARM FDPIC platform */
@@ -111,7 +113,7 @@ extern int elf_check_arch(const struct elf32_hdr *);
 #define elf_check_const_displacement(x)  ((x)->e_flags & EF_ARM_PIC)
 #define ELF_FDPIC_CORE_EFLAGS  0
 
-#define vmcore_elf64_check_arch(x) (0)
+#define vmcore_elf64_check_arch(x) (elf_check_arch_64(x) || vmcore_elf_check_arch_cross(x))
 
 extern int arm_elf_read_implies_exec(int);
 #define elf_read_implies_exec(ex,stk) arm_elf_read_implies_exec(stk)

arch/arm/kernel/elf.c

@@ -40,6 +40,39 @@ int elf_check_arch(const struct elf32_hdr *x)
 }
 EXPORT_SYMBOL(elf_check_arch);
 
+int elf_check_arch_64(const struct elf64_hdr *x)
+{
+	unsigned int eflags;
+
+	/* Make sure it's an ARM executable */
+	if (x->e_machine != EM_ARM)
+		return 0;
+
+	/* Make sure the entry address is reasonable */
+	if (x->e_entry & 1) {
+		if (!(elf_hwcap & HWCAP_THUMB))
+			return 0;
+	} else if (x->e_entry & 3)
+		return 0;
+
+	eflags = x->e_flags;
+	if ((eflags & EF_ARM_EABI_MASK) == EF_ARM_EABI_UNKNOWN) {
+		unsigned int flt_fmt;
+
+		/* APCS26 is only allowed if the CPU supports it */
+		if ((eflags & EF_ARM_APCS_26) && !(elf_hwcap & HWCAP_26BIT))
+			return 0;
+
+		flt_fmt = eflags & (EF_ARM_VFP_FLOAT | EF_ARM_SOFT_FLOAT);
+
+		/* VFP requires the supporting code */
+		if (flt_fmt == EF_ARM_VFP_FLOAT && !(elf_hwcap & HWCAP_VFP))
+			return 0;
+	}
+	return 1;
+}
+EXPORT_SYMBOL(elf_check_arch_64);
+
 void elf_set_personality(const struct elf32_hdr *x)
 {
 	unsigned int eflags = x->e_flags;