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authorPhilipp Rudo <prudo@linux.vnet.ibm.com>2018-04-13 15:36:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-13 17:10:28 -0700
commit8aec395b8478310521031157ef5d44ef19c2c581 (patch)
treec48f8773b3c734ab3f8ebf0e51e262959948f1b9 /arch/x86
parent961d921a1b967f76e13f9e11f2b0c2bcb5741f10 (diff)
kernel/kexec_file.c: use read-only sections in arch_kexec_apply_relocations*
When the relocations are applied to the purgatory only the section the relocations are applied to is writable. The other sections, i.e. the symtab and .rel/.rela, are in read-only kexec_purgatory. Highlight this by marking the corresponding variables as 'const'. While at it also change the signatures of arch_kexec_apply_relocations* to take section pointers instead of just the index of the relocation section. This removes the second lookup and sanity check of the sections in arch code. Link: http://lkml.kernel.org/r/20180321112751.22196-6-prudo@linux.vnet.ibm.com Signed-off-by: Philipp Rudo <prudo@linux.vnet.ibm.com> Acked-by: Dave Young <dyoung@redhat.com> Cc: AKASHI Takahiro <takahiro.akashi@linaro.org> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/machine_kexec_64.c56
1 files changed, 20 insertions, 36 deletions
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index c51d2cf27d93..63dea30c8e02 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -382,52 +382,36 @@ void *arch_kexec_kernel_image_load(struct kimage *image)
/*
* Apply purgatory relocations.
*
- * ehdr: Pointer to elf headers
- * sechdrs: Pointer to section headers.
- * relsec: section index of SHT_RELA section.
+ * @pi: Purgatory to be relocated.
+ * @section: Section relocations applying to.
+ * @relsec: Section containing RELAs.
+ * @symtabsec: Corresponding symtab.
*
* 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)
+int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
+ Elf_Shdr *section, const Elf_Shdr *relsec,
+ const Elf_Shdr *symtabsec)
{
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;
+ const Elf_Shdr *sechdrs;
- /*
- * ->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;
- }
+ /* String & section header string table */
+ sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
+ strtab = (char *)pi->ehdr + sechdrs[symtabsec->sh_link].sh_offset;
+ shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;
- strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset;
+ rel = (void *)pi->ehdr + relsec->sh_offset;
- /* section header string table */
- shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset;
+ pr_debug("Applying relocate section %s to %u\n",
+ shstrtab + relsec->sh_name, relsec->sh_info);
- for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
+ for (i = 0; i < relsec->sh_size / sizeof(*rel); i++) {
/*
* rel[i].r_offset contains byte offset from beginning
@@ -450,8 +434,8 @@ int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
* 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);
+ sym = (void *)pi->ehdr + symtabsec->sh_offset;
+ sym += ELF64_R_SYM(rel[i].r_info);
if (sym->st_name)
name = strtab + sym->st_name;
@@ -474,12 +458,12 @@ int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
if (sym->st_shndx == SHN_ABS)
sec_base = 0;
- else if (sym->st_shndx >= ehdr->e_shnum) {
+ else if (sym->st_shndx >= pi->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;
+ sec_base = pi->sechdrs[sym->st_shndx].sh_addr;
value = sym->st_value;
value += sec_base;