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Subject[PATCH 6/8] powerpc: Implement kexec_file_load.
Date
Adds the machinery needed by kexec_file_load, except actually loading
a kernel and initrd.

elf64_apply_relocate_add was extended to support relative symbols. This
is necessary because before relocation, the module loading mechanism
adjusts Elf64_Sym.st_value to point to the absolute memory address,
while the kexec purgatory relocation code does that during relocation.

We also add relocation types used by the purgatory.

Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
arch/powerpc/Kconfig | 13 +++
arch/powerpc/include/asm/elf_util.h | 1 +
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 | 4 +-
arch/powerpc/kernel/elf_util_64.c | 83 +++++++++++++++++++-
arch/powerpc/kernel/machine_kexec_64.c | 139 +++++++++++++++++++++++++++++++++
arch/powerpc/kernel/module_64.c | 5 +-
9 files changed, 245 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 01f7464d9fea..3ed5770b89e4 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -457,6 +457,19 @@ 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 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 CRASH_DUMP
bool "Build a kdump crash kernel"
depends on PPC64 || 6xx || FSL_BOOKE || (44x && !SMP)
diff --git a/arch/powerpc/include/asm/elf_util.h b/arch/powerpc/include/asm/elf_util.h
index 9cd24bc528b1..41a172077f9e 100644
--- a/arch/powerpc/include/asm/elf_util.h
+++ b/arch/powerpc/include/asm/elf_util.h
@@ -86,6 +86,7 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
const char *strtab, const Elf64_Rela *rela,
unsigned int num_rela, void *syms_base,
void *loc_base, Elf64_Addr addr_base,
+ bool relative_symbols, bool check_symbols,
const char *obj_name);

#endif /* _ASM_POWERPC_ELF_UTIL_H */
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 8a53fccaa053..c937b8074464 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -124,9 +124,11 @@ ifneq ($(CONFIG_PPC_INDIRECT_PIO),y)
obj-y += iomap.o
endif

-ifeq ($(CONFIG_MODULES)$(CONFIG_WORD_SIZE),y64)
+ifneq ($(CONFIG_MODULES)$(CONFIG_KEXEC_FILE),)
+ifeq ($(CONFIG_WORD_SIZE),64)
obj-y += elf_util.o elf_util_64.o
endif
+endif

obj64-$(CONFIG_PPC_TRANSACTIONAL_MEM) += tm.o

diff --git a/arch/powerpc/kernel/elf_util_64.c b/arch/powerpc/kernel/elf_util_64.c
index cde0420add9e..287d381a1a86 100644
--- a/arch/powerpc/kernel/elf_util_64.c
+++ b/arch/powerpc/kernel/elf_util_64.c
@@ -74,6 +74,8 @@ static void squash_toc_save_inst(const char *name, unsigned long addr) { }
* @syms_base: Contents of the associated symbol table.
* @loc_base: Contents of the section to which relocations apply.
* @addr_base: The address where the section will be loaded in memory.
+ * @relative_symbols: Are the symbols' st_value members relative?
+ * @check_symbols: Fail if an unexpected symbol is found?
* @obj_name: The name of the ELF binary, for information messages.
*
* Applies RELA relocations to an ELF file already at its final location
@@ -84,16 +86,19 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
const char *strtab, const Elf64_Rela *rela,
unsigned int num_rela, void *syms_base,
void *loc_base, Elf64_Addr addr_base,
+ bool relative_symbols, bool check_symbols,
const char *obj_name)
{
unsigned int i;
unsigned long *location;
unsigned long address;
+ unsigned long sec_base;
unsigned long value;
const char *name;
Elf64_Sym *sym;

for (i = 0; i < num_rela; i++) {
+
/*
* rels[i].r_offset contains the byte offset from the beginning
* of section to the storage unit affected.
@@ -121,8 +126,34 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
name, (unsigned long)sym->st_value,
(long)rela[i].r_addend);

+ if (check_symbols) {
+ /* TOC symbols appear as undefined but should be
+ * resolved as well, so allow them to be processed. */
+ if (sym->st_shndx == SHN_UNDEF &&
+ strcmp(name, ".TOC.") != 0) {
+ 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 (relative_symbols && sym->st_shndx != SHN_ABS) {
+ if (sym->st_shndx >= elf_info->ehdr->e_shnum) {
+ pr_err("Invalid section %d for symbol %s\n",
+ sym->st_shndx, name);
+ return -ENOEXEC;
+ } else {
+ struct elf_shdr *sechdrs = elf_info->sechdrs;
+
+ sec_base = sechdrs[sym->st_shndx].sh_addr;
+ }
+ } else
+ sec_base = 0;
+
/* `Everything is relative'. */
- value = sym->st_value + rela[i].r_addend;
+ value = sym->st_value + sec_base + rela[i].r_addend;

switch (ELF64_R_TYPE(rela[i].r_info)) {
case R_PPC64_ADDR32:
@@ -135,6 +166,10 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
*(unsigned long *)location = value;
break;

+ case R_PPC64_REL32:
+ *(uint32_t *)location = value - (uint32_t)(uint64_t)location;
+ break;
+
case R_PPC64_TOC:
*(unsigned long *)location = my_r2(elf_info);
break;
@@ -186,6 +221,14 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
| (value & 0xfffc);
break;

+ case R_PPC64_TOC16_HI:
+ /* Subtract TOC pointer */
+ value -= my_r2(elf_info);
+ value = value >> 16;
+ *((uint16_t *) location)
+ = (*((uint16_t *) location) & ~0xffff)
+ | (value & 0xffff);
+
case R_PPC64_TOC16_HA:
/* Subtract TOC pointer */
value -= my_r2(elf_info);
@@ -195,6 +238,21 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
| (value & 0xffff);
break;

+ case R_PPC64_REL14:
+ /* Convert value to relative */
+ value -= address;
+ if (value + 0x8000 > 0xffff || (value & 3) != 0) {
+ pr_err("%s: REL14 %li out of range!\n", obj_name,
+ (long int)value);
+ return -ENOEXEC;
+ }
+
+ /* Only replace bits 2 through 16 */
+ *(uint32_t *)location
+ = (*(uint32_t *)location & ~0xfffc)
+ | (value & 0xfffc);
+ break;
+
case R_PPC_REL24:
/* FIXME: Handle weak symbols here --RR */
if (sym->st_shndx == SHN_UNDEF) {
@@ -263,6 +321,29 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
((uint32_t *)location)[1] = 0x38420000 + PPC_LO(value);
break;

+ 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_HA:
+ *(uint16_t *)location = (((value + 0x8000) >> 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_REL16_HA:
/* Subtract location pointer */
value -= address;
diff --git a/arch/powerpc/kernel/machine_kexec_64.c b/arch/powerpc/kernel/machine_kexec_64.c
index b8c202d63ecb..a3bd8cd53776 100644
--- a/arch/powerpc/kernel/machine_kexec_64.c
+++ b/arch/powerpc/kernel/machine_kexec_64.c
@@ -9,6 +9,7 @@
* Version 2. See the file COPYING for more details.
*/

+#define pr_fmt(fmt) "kexec: " fmt

#include <linux/kexec.h>
#include <linux/smp.h>
@@ -18,6 +19,7 @@
#include <linux/kernel.h>
#include <linux/cpu.h>
#include <linux/hardirq.h>
+#include <linux/memblock.h>

#include <asm/page.h>
#include <asm/current.h>
@@ -30,6 +32,10 @@
#include <asm/smp.h>
#include <asm/hw_breakpoint.h>

+#ifdef CONFIG_KEXEC_FILE
+static struct kexec_file_ops *kexec_file_loaders[] = { };
+#endif
+
#ifdef CONFIG_PPC_BOOK3E
int default_machine_kexec_prepare(struct kimage *image)
{
@@ -426,3 +432,136 @@ static int __init export_htab_values(void)
}
late_initcall(export_htab_values);
#endif /* CONFIG_PPC_STD_MMU_64 */
+
+/* arch-dependent functionality required for implementing kexec_file_load() syscall */
+#ifdef CONFIG_KEXEC_FILE
+int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
+ unsigned long buf_len)
+{
+ int i, ret = -ENOEXEC;
+ struct kexec_file_ops *fops;
+
+ 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_walk_system_ram - call func(data) for each unreserved memory block
+ * @start: Minimum address.
+ * @end: Maximum address.
+ * @top_down: Starts from the highest address?
+ * @data: Argument to pass 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.
+ */
+int arch_walk_system_ram(unsigned long start, unsigned long end, bool top_down,
+ void *data, int (*func)(u64, u64, void *))
+{
+ int ret = -1;
+ u64 i;
+ phys_addr_t mstart, mend;
+
+ if (top_down) {
+ for_each_free_mem_range_reverse(i, NUMA_NO_NODE, 0,
+ &mstart, &mend, NULL) {
+ if (end < mstart)
+ continue;
+ else if (start > mend)
+ break;
+
+ ret = func(mstart, mend, data);
+ if (ret)
+ break;
+ }
+ } else {
+ for_each_free_mem_range(i, NUMA_NO_NODE, 0, &mstart, &mend,
+ NULL) {
+ if (end < mstart)
+ break;
+ else if (start > mend)
+ continue;
+
+ ret = func(mstart, mend, data);
+ 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 adress of the
+ * section in memory.
+ */
+int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
+ Elf64_Shdr *sechdrs, unsigned int relsec)
+{
+ /* Section containing the relocation entries. */
+ Elf64_Shdr *rel_section = &sechdrs[relsec];
+ const Elf64_Rela *rela = (const Elf64_Rela *) rel_section->sh_offset;
+ unsigned int num_rela = rel_section->sh_size / sizeof(Elf64_Rela);
+ /* 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;
+ struct elf_info elf_info;
+ const char *strtab;
+
+ 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 table for the associated symbol table. */
+ strtab = (const char *) sechdrs[symtabsec->sh_link].sh_offset;
+
+ elf_init_elf_info(ehdr, sechdrs, &elf_info);
+
+ return elf64_apply_relocate_add(&elf_info, strtab, rela, num_rela,
+ syms_base, loc_base, addr_base,
+ true, true, "kexec purgatory");
+}
+#endif /* CONFIG_KEXEC_FILE */
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index a3cb0f6e83bb..15b822867f8d 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -442,6 +442,9 @@ int restore_r2(u32 *instruction, const char *obj_name)
* When this function is called, the module is already at its final location in
* memory, so Elf64_Shdr.sh_addr can be used for accessing the section
* contents as well as the base address for relocations.
+ *
+ * Also, simplify_symbols already changed all symbols' st_value members
+ * to absolute addresses.
*/
int apply_relocate_add(Elf64_Shdr *sechdrs,
const char *strtab,
@@ -471,7 +474,7 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,

return elf64_apply_relocate_add(&me->arch.elf_info, strtab, rela,
num_rela, syms_base, (void *) addr_base,
- addr_base, me->name);
+ addr_base, false, false, me->name);
}

#ifdef CONFIG_DYNAMIC_FTRACE
--
1.9.1
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