[PATCH v10 06/10] powerpc: Implement kexec_file_load.
Thiago Jung Bauermann
bauerman at linux.vnet.ibm.com
Thu Nov 10 14:27:25 AEDT 2016
Add arch-specific functions needed by the generic kexec_file code.
Signed-off-by: Josh Sklar <sklar at linux.vnet.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman at linux.vnet.ibm.com>
---
arch/powerpc/Kconfig | 14 ++
arch/powerpc/include/asm/systbl.h | 1 +
arch/powerpc/include/asm/unistd.h | 2 +-
arch/powerpc/include/uapi/asm/unistd.h | 1 +
arch/powerpc/kernel/Makefile | 1 +
arch/powerpc/kernel/machine_kexec_file_64.c | 301 ++++++++++++++++++++++++++++
6 files changed, 319 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 6cb59c6e5ba4..a5a7bcf30c05 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -455,6 +455,20 @@ config KEXEC
interface is strongly in flux, so no good recommendation can be
made.
+config KEXEC_FILE
+ bool "kexec file based system call"
+ select KEXEC_CORE
+ select HAVE_KEXEC_FILE_PIE_PURGATORY
+ select BUILD_BIN2C
+ depends on PPC64
+ depends on CRYPTO=y
+ depends on CRYPTO_SHA256=y
+ help
+ This is a new version of the kexec system call. This call is
+ file based and takes in file descriptors as system call arguments
+ for kernel and initramfs as opposed to a list of segments as is the
+ case for the older kexec call.
+
config RELOCATABLE
bool "Build a relocatable kernel"
depends on (PPC64 && !COMPILE_TEST) || (FLATMEM && (44x || FSL_BOOKE))
diff --git a/arch/powerpc/include/asm/systbl.h b/arch/powerpc/include/asm/systbl.h
index 2fc5d4db503c..4b369d83fe9c 100644
--- a/arch/powerpc/include/asm/systbl.h
+++ b/arch/powerpc/include/asm/systbl.h
@@ -386,3 +386,4 @@ SYSCALL(mlock2)
SYSCALL(copy_file_range)
COMPAT_SYS_SPU(preadv2)
COMPAT_SYS_SPU(pwritev2)
+SYSCALL(kexec_file_load)
diff --git a/arch/powerpc/include/asm/unistd.h b/arch/powerpc/include/asm/unistd.h
index cf12c580f6b2..a01e97d3f305 100644
--- a/arch/powerpc/include/asm/unistd.h
+++ b/arch/powerpc/include/asm/unistd.h
@@ -12,7 +12,7 @@
#include <uapi/asm/unistd.h>
-#define NR_syscalls 382
+#define NR_syscalls 383
#define __NR__exit __NR_exit
diff --git a/arch/powerpc/include/uapi/asm/unistd.h b/arch/powerpc/include/uapi/asm/unistd.h
index e9f5f41aa55a..2f26335a3c42 100644
--- a/arch/powerpc/include/uapi/asm/unistd.h
+++ b/arch/powerpc/include/uapi/asm/unistd.h
@@ -392,5 +392,6 @@
#define __NR_copy_file_range 379
#define __NR_preadv2 380
#define __NR_pwritev2 381
+#define __NR_kexec_file_load 382
#endif /* _UAPI_ASM_POWERPC_UNISTD_H_ */
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 22534a56c914..6de731d90bff 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -109,6 +109,7 @@ obj-$(CONFIG_PCI) += pci_$(BITS).o $(pci64-y) \
obj-$(CONFIG_PCI_MSI) += msi.o
obj-$(CONFIG_KEXEC_CORE) += machine_kexec.o crash.o \
machine_kexec_$(BITS).o
+obj-$(CONFIG_KEXEC_FILE) += machine_kexec_file_$(BITS).o
obj-$(CONFIG_AUDIT) += audit.o
obj64-$(CONFIG_AUDIT) += compat_audit.o
diff --git a/arch/powerpc/kernel/machine_kexec_file_64.c b/arch/powerpc/kernel/machine_kexec_file_64.c
new file mode 100644
index 000000000000..172f6f736987
--- /dev/null
+++ b/arch/powerpc/kernel/machine_kexec_file_64.c
@@ -0,0 +1,301 @@
+/*
+ * ppc64 code to implement the kexec_file_load syscall
+ *
+ * Copyright (C) 2004 Adam Litke (agl at us.ibm.com)
+ * Copyright (C) 2004 IBM Corp.
+ * Copyright (C) 2005 R Sharada (sharada at in.ibm.com)
+ * Copyright (C) 2006 Mohan Kumar M (mohan at in.ibm.com)
+ * Copyright (C) 2016 IBM Corporation
+ *
+ * Based on kexec-tools' kexec-elf-ppc64.c.
+ * Heavily modified for the kernel by
+ * Thiago Jung Bauermann <bauerman at linux.vnet.ibm.com>.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation (version 2 of the License).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/slab.h>
+#include <linux/kexec.h>
+#include <linux/memblock.h>
+#include <linux/libfdt.h>
+
+#define SLAVE_CODE_SIZE 256
+
+static struct kexec_file_ops *kexec_file_loaders[] = { };
+
+int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
+ unsigned long buf_len)
+{
+ int i, ret = -ENOEXEC;
+ struct kexec_file_ops *fops;
+
+ /* We don't support crash kernels yet. */
+ if (image->type == KEXEC_TYPE_CRASH)
+ return -ENOTSUPP;
+
+ for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
+ fops = kexec_file_loaders[i];
+ if (!fops || !fops->probe)
+ continue;
+
+ ret = fops->probe(buf, buf_len);
+ if (!ret) {
+ image->fops = fops;
+ return ret;
+ }
+ }
+
+ return ret;
+}
+
+void *arch_kexec_kernel_image_load(struct kimage *image)
+{
+ if (!image->fops || !image->fops->load)
+ return ERR_PTR(-ENOEXEC);
+
+ return image->fops->load(image, image->kernel_buf,
+ image->kernel_buf_len, image->initrd_buf,
+ image->initrd_buf_len, image->cmdline_buf,
+ image->cmdline_buf_len);
+}
+
+int arch_kimage_file_post_load_cleanup(struct kimage *image)
+{
+ if (!image->fops || !image->fops->cleanup)
+ return 0;
+
+ return image->fops->cleanup(image->image_loader_data);
+}
+
+/**
+ * arch_kexec_walk_mem - call func(data) for each unreserved memory block
+ * @kbuf: Context info for the search. Also passed to @func.
+ * @func: Function to call for each memory block.
+ *
+ * This function is used by kexec_add_buffer and kexec_locate_mem_hole
+ * to find unreserved memory to load kexec segments into.
+ *
+ * Return: The memory walk will stop when func returns a non-zero value
+ * and that value will be returned. If all free regions are visited without
+ * func returning non-zero, then zero will be returned.
+ */
+int arch_kexec_walk_mem(struct kexec_buf *kbuf, int (*func)(u64, u64, void *))
+{
+ int ret = 0;
+ u64 i;
+ phys_addr_t mstart, mend;
+
+ if (kbuf->top_down) {
+ for_each_free_mem_range_reverse(i, NUMA_NO_NODE, 0,
+ &mstart, &mend, NULL) {
+ /*
+ * In memblock, end points to the first byte after the
+ * range while in kexec, end points to the last byte
+ * in the range.
+ */
+ ret = func(mstart, mend - 1, kbuf);
+ if (ret)
+ break;
+ }
+ } else {
+ for_each_free_mem_range(i, NUMA_NO_NODE, 0, &mstart, &mend,
+ NULL) {
+ /*
+ * In memblock, end points to the first byte after the
+ * range while in kexec, end points to the last byte
+ * in the range.
+ */
+ ret = func(mstart, mend - 1, kbuf);
+ if (ret)
+ break;
+ }
+ }
+
+ return ret;
+}
+
+/**
+ * arch_kexec_apply_relocations_add - apply purgatory relocations
+ * @ehdr: Pointer to ELF headers.
+ * @sechdrs: Pointer to section headers.
+ * @relsec: Section index of SHT_RELA section.
+ *
+ * Elf64_Shdr.sh_offset has been modified to keep the pointer to the section
+ * contents, while Elf64_Shdr.sh_addr points to the final address of the
+ * section in memory.
+ */
+int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
+ Elf64_Shdr *sechdrs, unsigned int relsec)
+{
+ unsigned int i;
+ unsigned long reloc_type;
+ unsigned long *location;
+ unsigned long address;
+ unsigned long value;
+ const char *name;
+ Elf64_Sym *sym;
+ /* Section containing the relocation entries. */
+ Elf64_Shdr *rel_section = &sechdrs[relsec];
+ const Elf64_Rela *rela = (const Elf64_Rela *) rel_section->sh_offset;
+ /* Section to which relocations apply. */
+ Elf64_Shdr *target_section = &sechdrs[rel_section->sh_info];
+ /* Associated symbol table. */
+ Elf64_Shdr *symtabsec = &sechdrs[rel_section->sh_link];
+ void *syms_base = (void *) symtabsec->sh_offset;
+ void *loc_base = (void *) target_section->sh_offset;
+ Elf64_Addr addr_base = target_section->sh_addr;
+ Elf64_Addr orig_addr_base;
+ const Elf_Phdr *phdrs = (const void *) ehdr + ehdr->e_phoff;
+ const Elf_Phdr *phdr;
+ unsigned long sec_base;
+ unsigned long purgatory_load_addr;
+ unsigned long orig_load_addr;
+ const char *strtab;
+ const char *shstrtab;
+ const Elf_Shdr *sechdrs_c;
+
+ 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;
+ }
+
+ /*
+ * The original section header was modified by __kexec_load_purgatory
+ * so that the ->sh_addr and ->sh_offset fields point to the permanent
+ * and temporary locations of sections.
+ */
+ sechdrs_c = (const void *) ehdr + ehdr->e_shoff;
+ orig_addr_base = sechdrs_c[rel_section->sh_info].sh_addr;
+
+ /* Find the address where the purgatory was built to be loaded in. */
+ for (phdr = phdrs; phdr < phdrs + ehdr->e_phnum; phdr++) {
+ if (phdr->p_type != PT_LOAD)
+ continue;
+
+ orig_load_addr = phdr->p_paddr - phdr->p_offset;
+ break;
+ }
+
+ /*
+ * Find the address where we will load the purgatory.
+ * This is simply the reverse of the calculation done when modifying
+ * ->sh_addr in __kexec_really_load_purgatory.
+ */
+ purgatory_load_addr = addr_base - orig_addr_base + orig_load_addr;
+
+ /* String table for the associated symbol table. */
+ strtab = (const char *) sechdrs[symtabsec->sh_link].sh_offset;
+
+ /* Section header string table. */
+ shstrtab = (const char *) sechdrs[ehdr->e_shstrndx].sh_offset;
+
+ for (i = 0; i < rel_section->sh_size / sizeof(Elf64_Rela); i++) {
+ Elf64_Addr r_offset = rela[i].r_offset - orig_addr_base;
+ long addend = rela[i].r_addend;
+ Elf64_Addr orig_sec_base;
+
+ /*
+ * rels[i].r_offset contains the byte offset from the beginning
+ * of section to the storage unit affected.
+ *
+ * This is the location to update in the temporary buffer where
+ * the section is currently loaded. The section will finally
+ * be loaded to a different address later, pointed to by
+ * addr_base.
+ */
+ location = loc_base + r_offset;
+
+ /* Final address of the location. */
+ address = addr_base + r_offset;
+
+ /* This is the symbol the relocation is referring to. */
+ sym = (Elf64_Sym *) syms_base + ELF64_R_SYM(rela[i].r_info);
+ orig_sec_base = sechdrs_c[sym->st_shndx].sh_addr;
+
+ if (sym->st_name)
+ name = strtab + sym->st_name;
+ else if (sym->st_value == orig_sec_base)
+ name = &shstrtab[sechdrs[sym->st_shndx].sh_name];
+ else
+ name = "<unnamed symbol>";
+
+ reloc_type = ELF64_R_TYPE(rela[i].r_info);
+
+ pr_debug("RELOC at %p: %lu-type as %s (0x%lx) + %li\n",
+ location, reloc_type, name, (unsigned long)sym->st_value,
+ (long)rela[i].r_addend);
+
+ if ((void *) location >= loc_base + target_section->sh_size) {
+ pr_err("Location %p is %llx bytes beyond the end of the section.\n",
+ location, (void *) location - loc_base +
+ target_section->sh_size - 1);
+ return -ENOEXEC;
+ }
+
+ /*
+ * Function descriptor symbols appear as undefined but
+ * should be resolved as well, so allow them to be processed.
+ */
+ if (sym->st_shndx == SHN_UNDEF &&
+ reloc_type != R_PPC64_RELATIVE) {
+ pr_err("Undefined symbol: %s\n", name);
+ return -ENOEXEC;
+ } else if (sym->st_shndx == SHN_COMMON) {
+ pr_err("Symbol '%s' in common section.\n",
+ name);
+ return -ENOEXEC;
+ }
+
+ if (sym->st_shndx != SHN_ABS) {
+ if (sym->st_shndx >= ehdr->e_shnum) {
+ pr_err("Invalid section %d for symbol %s\n",
+ sym->st_shndx, name);
+ return -ENOEXEC;
+ }
+
+ sec_base = sechdrs[sym->st_shndx].sh_addr;
+ } else
+ sec_base = orig_sec_base = 0;
+
+ /* `Everything is relative'. */
+ value = sym->st_value - orig_sec_base + sec_base + addend;
+
+ switch (reloc_type) {
+ case R_PPC64_ADDR16_LO:
+ *(uint16_t *) location = value & 0xffff;
+ break;
+
+ case R_PPC64_ADDR16_HI:
+ *(uint16_t *) location = (value >> 16) & 0xffff;
+ break;
+
+ case R_PPC64_ADDR16_HIGHER:
+ *(uint16_t *) location = (((uint64_t) value >> 32) &
+ 0xffff);
+ break;
+
+ case R_PPC64_ADDR16_HIGHEST:
+ *(uint16_t *) location = (((uint64_t) value >> 48) &
+ 0xffff);
+ break;
+ case R_PPC64_RELATIVE:
+ *location = purgatory_load_addr + addend - orig_load_addr;
+ break;
+ default:
+ pr_err("kexec purgatory: Unknown ADD relocation: %lu\n",
+ reloc_type);
+ return -ENOEXEC;
+ }
+ }
+
+ return 0;
+}
--
2.7.4
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