summaryrefslogtreecommitdiffstats
path: root/arch/x86/kernel/machine_kexec_64.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/kernel/machine_kexec_64.c')
-rw-r--r--arch/x86/kernel/machine_kexec_64.c142
1 files changed, 142 insertions, 0 deletions
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index c8875b5545e1..88404c440727 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -6,6 +6,8 @@
* Version 2. See the file COPYING for more details.
*/
+#define pr_fmt(fmt) "kexec: " fmt
+
#include <linux/mm.h>
#include <linux/kexec.h>
#include <linux/string.h>
@@ -328,3 +330,143 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
return image->fops->cleanup(image);
}
+
+/*
+ * Apply purgatory relocations.
+ *
+ * ehdr: Pointer to elf headers
+ * sechdrs: Pointer to section headers.
+ * relsec: section index of SHT_RELA section.
+ *
+ * TODO: Some of the code belongs to generic code. Move that in kexec.c.
+ */
+int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
+ Elf64_Shdr *sechdrs, unsigned int relsec)
+{
+ unsigned int i;
+ Elf64_Rela *rel;
+ Elf64_Sym *sym;
+ void *location;
+ Elf64_Shdr *section, *symtabsec;
+ unsigned long address, sec_base, value;
+ const char *strtab, *name, *shstrtab;
+
+ /*
+ * ->sh_offset has been modified to keep the pointer to section
+ * contents in memory
+ */
+ rel = (void *)sechdrs[relsec].sh_offset;
+
+ /* Section to which relocations apply */
+ section = &sechdrs[sechdrs[relsec].sh_info];
+
+ pr_debug("Applying relocate section %u to %u\n", relsec,
+ sechdrs[relsec].sh_info);
+
+ /* Associated symbol table */
+ symtabsec = &sechdrs[sechdrs[relsec].sh_link];
+
+ /* String table */
+ if (symtabsec->sh_link >= ehdr->e_shnum) {
+ /* Invalid strtab section number */
+ pr_err("Invalid string table section index %d\n",
+ symtabsec->sh_link);
+ return -ENOEXEC;
+ }
+
+ strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset;
+
+ /* section header string table */
+ shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset;
+
+ for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
+
+ /*
+ * rel[i].r_offset contains byte offset from beginning
+ * of section to the storage unit affected.
+ *
+ * This is location to update (->sh_offset). This is temporary
+ * buffer where section is currently loaded. This will finally
+ * be loaded to a different address later, pointed to by
+ * ->sh_addr. kexec takes care of moving it
+ * (kexec_load_segment()).
+ */
+ location = (void *)(section->sh_offset + rel[i].r_offset);
+
+ /* Final address of the location */
+ address = section->sh_addr + rel[i].r_offset;
+
+ /*
+ * rel[i].r_info contains information about symbol table index
+ * w.r.t which relocation must be made and type of relocation
+ * to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
+ * these respectively.
+ */
+ sym = (Elf64_Sym *)symtabsec->sh_offset +
+ ELF64_R_SYM(rel[i].r_info);
+
+ if (sym->st_name)
+ name = strtab + sym->st_name;
+ else
+ name = shstrtab + sechdrs[sym->st_shndx].sh_name;
+
+ pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n",
+ name, sym->st_info, sym->st_shndx, sym->st_value,
+ sym->st_size);
+
+ if (sym->st_shndx == SHN_UNDEF) {
+ pr_err("Undefined symbol: %s\n", name);
+ return -ENOEXEC;
+ }
+
+ if (sym->st_shndx == SHN_COMMON) {
+ pr_err("symbol '%s' in common section\n", name);
+ return -ENOEXEC;
+ }
+
+ if (sym->st_shndx == SHN_ABS)
+ sec_base = 0;
+ else if (sym->st_shndx >= ehdr->e_shnum) {
+ pr_err("Invalid section %d for symbol %s\n",
+ sym->st_shndx, name);
+ return -ENOEXEC;
+ } else
+ sec_base = sechdrs[sym->st_shndx].sh_addr;
+
+ value = sym->st_value;
+ value += sec_base;
+ value += rel[i].r_addend;
+
+ switch (ELF64_R_TYPE(rel[i].r_info)) {
+ case R_X86_64_NONE:
+ break;
+ case R_X86_64_64:
+ *(u64 *)location = value;
+ break;
+ case R_X86_64_32:
+ *(u32 *)location = value;
+ if (value != *(u32 *)location)
+ goto overflow;
+ break;
+ case R_X86_64_32S:
+ *(s32 *)location = value;
+ if ((s64)value != *(s32 *)location)
+ goto overflow;
+ break;
+ case R_X86_64_PC32:
+ value -= (u64)address;
+ *(u32 *)location = value;
+ break;
+ default:
+ pr_err("Unknown rela relocation: %llu\n",
+ ELF64_R_TYPE(rel[i].r_info));
+ return -ENOEXEC;
+ }
+ }
+ return 0;
+
+overflow:
+ pr_err("Overflow in relocation type %d value 0x%lx\n",
+ (int)ELF64_R_TYPE(rel[i].r_info), value);
+ return -ENOEXEC;
+}