[PATCH 14/17] s390/kexec_file: Add kexec_file_load system call
From: Philipp Rudo
Date: Mon Feb 12 2018 - 05:08:49 EST
This patch adds the kexec_file_load system call to s390 as well as the arch
specific functions common code requires to work. Loaders for the different
file types will be added later.
Signed-off-by: Philipp Rudo <prudo@xxxxxxxxxxxxxxxxxx>
---
arch/s390/Kconfig | 4 +
arch/s390/kernel/Makefile | 1 +
arch/s390/kernel/compat_wrapper.c | 1 +
arch/s390/kernel/machine_kexec_file.c | 174 ++++++++++++++++++++++++++++++++++
arch/s390/kernel/syscalls/syscall.tbl | 1 +
5 files changed, 181 insertions(+)
create mode 100644 arch/s390/kernel/machine_kexec_file.c
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 0105ce28e246..baffd88109a5 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -51,6 +51,10 @@ config KEXEC
def_bool y
select KEXEC_CORE
+config KEXEC_FILE
+ def_bool y
+ select KEXEC_CORE
+
config AUDIT_ARCH
def_bool y
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 909bce65cb2b..496d4711c186 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -60,6 +60,7 @@ obj-y += debug.o irq.o ipl.o dis.o diag.o vdso.o als.o
obj-y += sysinfo.o jump_label.o lgr.o os_info.o machine_kexec.o pgm_check.o
obj-y += runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o
obj-y += entry.o reipl.o relocate_kernel.o kdebugfs.o alternative.o
+obj-y += machine_kexec_file.o
extra-y += head.o head64.o vmlinux.lds
diff --git a/arch/s390/kernel/compat_wrapper.c b/arch/s390/kernel/compat_wrapper.c
index 11e9d8b5c1b0..607c5e9fba3d 100644
--- a/arch/s390/kernel/compat_wrapper.c
+++ b/arch/s390/kernel/compat_wrapper.c
@@ -182,3 +182,4 @@ COMPAT_SYSCALL_WRAP6(copy_file_range, int, fd_in, loff_t __user *, off_in, int,
COMPAT_SYSCALL_WRAP2(s390_guarded_storage, int, command, struct gs_cb *, gs_cb);
COMPAT_SYSCALL_WRAP5(statx, int, dfd, const char __user *, path, unsigned, flags, unsigned, mask, struct statx __user *, buffer);
COMPAT_SYSCALL_WRAP4(s390_sthyi, unsigned long, code, void __user *, info, u64 __user *, rc, unsigned long, flags);
+COMPAT_SYSCALL_WRAP5(kexec_file_load, int, kernel_fd, int, initrd_fd, unsigned long, cmdline_len, const char __user *, cmdline_ptr, unsigned long, flags)
diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c
new file mode 100644
index 000000000000..e6928cbed524
--- /dev/null
+++ b/arch/s390/kernel/machine_kexec_file.c
@@ -0,0 +1,174 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * s390 code for kexec_file_load system call
+ *
+ * Copyright IBM Corp. 2018
+ *
+ * Author(s): Philipp Rudo <prudo@xxxxxxxxxxxxxxxxxx>
+ */
+
+#include <linux/elf.h>
+#include <linux/kexec.h>
+#include <asm/setup.h>
+
+const struct kexec_file_ops * const kexec_file_loaders[] = {
+ NULL,
+};
+
+/*
+ * The kernel is loaded to a fixed location. Turn off kexec_locate_mem_hole
+ * and provide kbuf->mem by hand.
+ */
+int arch_kexec_walk_mem(struct kexec_buf *kbuf,
+ int (*func)(struct resource *, void *))
+{
+ return 1;
+}
+
+int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
+ Elf_Shdr *section,
+ const Elf_Shdr *relsec,
+ const Elf_Shdr *symtab)
+{
+ Elf_Rela *relas;
+ int i;
+
+ relas = (void *)pi->ehdr + relsec->sh_offset;
+
+ for (i = 0; i < relsec->sh_size / sizeof(*relas); i++) {
+ const Elf_Sym *sym; /* symbol to relocate */
+ unsigned long addr; /* final location after relocation */
+ unsigned long val; /* relocated symbol value */
+ void *loc; /* tmp location to modify */
+
+ sym = (void *)pi->ehdr + symtab->sh_offset;
+ sym += ELF64_R_SYM(relas[i].r_info);
+
+ if (sym->st_shndx == SHN_UNDEF)
+ return -ENOEXEC;
+
+ if (sym->st_shndx == SHN_COMMON)
+ return -ENOEXEC;
+
+ if (sym->st_shndx >= pi->ehdr->e_shnum &&
+ sym->st_shndx != SHN_ABS)
+ return -ENOEXEC;
+
+ loc = pi->purgatory_buf;
+ loc += section->sh_offset;
+ loc += relas[i].r_offset;
+
+ val = sym->st_value;
+ if (sym->st_shndx != SHN_ABS)
+ val += pi->sechdrs[sym->st_shndx].sh_addr;
+ val += relas[i].r_addend;
+
+ addr = section->sh_addr + relas[i].r_offset;
+
+ switch (ELF64_R_TYPE(relas[i].r_info)) {
+ case R_390_8: /* Direct 8 bit. */
+ *(u8 *)loc = val;
+ break;
+ case R_390_12: /* Direct 12 bit. */
+ *(u16 *)loc &= 0xf000;
+ *(u16 *)loc |= val & 0xfff;
+ break;
+ case R_390_16: /* Direct 16 bit. */
+ *(u16 *)loc = val;
+ break;
+ case R_390_20: /* Direct 20 bit. */
+ *(u32 *)loc &= 0xf00000ff;
+ *(u32 *)loc |= (val & 0xfff) << 16; /* DL */
+ *(u32 *)loc |= (val & 0xff000) >> 4; /* DH */
+ break;
+ case R_390_32: /* Direct 32 bit. */
+ *(u32 *)loc = val;
+ break;
+ case R_390_64: /* Direct 64 bit. */
+ *(u64 *)loc = val;
+ break;
+ case R_390_PC16: /* PC relative 16 bit. */
+ *(u16 *)loc = (val - addr);
+ break;
+ case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */
+ *(u16 *)loc = (val - addr) >> 1;
+ break;
+ case R_390_PC32DBL: /* PC relative 32 bit shifted by 1. */
+ *(u32 *)loc = (val - addr) >> 1;
+ break;
+ case R_390_PC32: /* PC relative 32 bit. */
+ *(u32 *)loc = (val - addr);
+ break;
+ case R_390_PC64: /* PC relative 64 bit. */
+ *(u64 *)loc = (val - addr);
+ break;
+ default:
+ break;
+ }
+ }
+ return 0;
+}
+
+int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
+ unsigned long buf_len)
+{
+ struct kexec_file_ops *fops;
+ int i, ret;
+
+ /* A kernel must be at least large enough to contain head.S. During
+ * load memory in head.S will be accessed, e.g. to register the next
+ * command line. If the next kernel were smaller the current kernel
+ * will panic at load.
+ *
+ * 0x11000 = sizeof(head.S)
+ */
+ if (buf_len < 0x11000)
+ return -ENOEXEC;
+
+ 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 -ENOEXEC;
+}
+
+void *arch_kexec_kernel_image_load(struct kimage *image)
+{
+ if (!image->fops || !image->fops->load)
+ return ERR_PTR(-ENOEXEC);
+
+ if (image->cmdline_buf_len >= ARCH_COMMAND_LINE_SIZE)
+ return ERR_PTR(-EINVAL);
+
+ 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);
+}
+
+#ifdef CONFIG_KEXEC_VERIFY_SIG
+int arch_kexec_kernel_verify_sig(struct kimage *image, void *kernel,
+ unsigned long kernel_len)
+{
+ if (!image->fops || !image->fops->verify_sig)
+ return -EKEYREJECTED;
+
+ return image->fops->verify_sig(kernel, kernel_len);
+}
+#endif /* CONFIG_KEXEC_VERIFY_SIG */
diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl
index b38d48464368..8b210ead7956 100644
--- a/arch/s390/kernel/syscalls/syscall.tbl
+++ b/arch/s390/kernel/syscalls/syscall.tbl
@@ -388,3 +388,4 @@
378 common s390_guarded_storage sys_s390_guarded_storage compat_sys_s390_guarded_storage
379 common statx sys_statx compat_sys_statx
380 common s390_sthyi sys_s390_sthyi compat_sys_s390_sthyi
+381 common kexec_file_load sys_kexec_file_load compat_sys_kexec_file_load
--
2.13.5