kexec: load and relocate purgatory at kernel load time

Load purgatory code in RAM and relocate it based on the location.
Relocation code has been inspired by module relocation code and purgatory
relocation code in kexec-tools.

Also compute the checksums of loaded kexec segments and store them in
purgatory.

Arch independent code provides this functionality so that arch dependent
bootloaders can make use of it.

Helper functions are provided to get/set symbol values in purgatory which
are used by bootloaders later to set things like stack and entry point of
second kernel etc.

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, 33 insertions, 0 deletions

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 8e80901e466f..84f09e9eca26 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -10,6 +10,7 @@
 #include <linux/ioport.h>
 #include <linux/elfcore.h>
 #include <linux/elf.h>
+#include <linux/module.h>
 #include <asm/kexec.h>
 
 /* Verify architecture specific macros are defined */
@@ -95,6 +96,27 @@ struct compat_kexec_segment {
 };
 #endif
 
+struct kexec_sha_region {
+	unsigned long start;
+	unsigned long len;
+};
+
+struct purgatory_info {
+	/* Pointer to elf header of read only purgatory */
+	Elf_Ehdr *ehdr;
+
+	/* Pointer to purgatory sechdrs which are modifiable */
+	Elf_Shdr *sechdrs;
+	/*
+	 * Temporary buffer location where purgatory is loaded and relocated
+	 * This memory can be freed post image load
+	 */
+	void *purgatory_buf;
+
+	/* Address where purgatory is finally loaded and is executed from */
+	unsigned long purgatory_load_addr;
+};
+
 struct kimage {
 	kimage_entry_t head;
 	kimage_entry_t *entry;
@@ -143,6 +165,9 @@ struct kimage {
 
 	/* Image loader handling the kernel can store a pointer here */
 	void *image_loader_data;
+
+	/* Information for loading purgatory */
+	struct purgatory_info purgatory_info;
 };
 
 /*
@@ -189,6 +214,14 @@ extern int kexec_add_buffer(struct kimage *image, char *buffer,
 			    unsigned long *load_addr);
 extern struct page *kimage_alloc_control_pages(struct kimage *image,
 						unsigned int order);
+extern int kexec_load_purgatory(struct kimage *image, unsigned long min,
+				unsigned long max, int top_down,
+				unsigned long *load_addr);
+extern int kexec_purgatory_get_set_symbol(struct kimage *image,
+					  const char *name, void *buf,
+					  unsigned int size, bool get_value);
+extern void *kexec_purgatory_get_symbol_addr(struct kimage *image,
+					     const char *name);
 extern void crash_kexec(struct pt_regs *);
 int kexec_should_crash(struct task_struct *);
 void crash_save_cpu(struct pt_regs *regs, int cpu);