kexec: support for kexec on panic using new system call

This patch adds support for loading a kexec on panic (kdump) kernel usning
new system call.

It prepares ELF headers for memory areas to be dumped and for saved cpu
registers.  Also prepares the memory map for second kernel and limits its
boot to reserved areas only.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: WANG Chao <chaowang@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 40 insertions, 0 deletions

diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 18d0f9e0b6d..9330434da77 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -178,6 +178,38 @@ static void load_segments(void)
 		);
 }
 
+/* Update purgatory as needed after various image segments have been prepared */
+static int arch_update_purgatory(struct kimage *image)
+{
+	int ret = 0;
+
+	if (!image->file_mode)
+		return 0;
+
+	/* Setup copying of backup region */
+	if (image->type == KEXEC_TYPE_CRASH) {
+		ret = kexec_purgatory_get_set_symbol(image, "backup_dest",
+				&image->arch.backup_load_addr,
+				sizeof(image->arch.backup_load_addr), 0);
+		if (ret)
+			return ret;
+
+		ret = kexec_purgatory_get_set_symbol(image, "backup_src",
+				&image->arch.backup_src_start,
+				sizeof(image->arch.backup_src_start), 0);
+		if (ret)
+			return ret;
+
+		ret = kexec_purgatory_get_set_symbol(image, "backup_sz",
+				&image->arch.backup_src_sz,
+				sizeof(image->arch.backup_src_sz), 0);
+		if (ret)
+			return ret;
+	}
+
+	return ret;
+}
+
 int machine_kexec_prepare(struct kimage *image)
 {
 	unsigned long start_pgtable;
@@ -191,6 +223,11 @@ int machine_kexec_prepare(struct kimage *image)
 	if (result)
 		return result;
 
+	/* update purgatory as needed */
+	result = arch_update_purgatory(image);
+	if (result)
+		return result;
+
 	return 0;
 }
 
@@ -315,6 +352,9 @@ int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
 
 void *arch_kexec_kernel_image_load(struct kimage *image)
 {
+	vfree(image->arch.elf_headers);
+	image->arch.elf_headers = NULL;
+
 	if (!image->fops || !image->fops->load)
 		return ERR_PTR(-ENOEXEC);