This patch adds support for building a relocatable kernel with -fPIE.
The kernel will be relocated to 0 early in the boot process.
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
endchoice
+config RELOCATABLE
+ bool "Build a relocatable kernel"
+ select MODULE_REL_CRCS if MODVERSIONS
+ default y
+ help
+ This builds a kernel image that retains relocation information
+ so it can be loaded at an arbitrary address.
+ The kernel is linked as a position-independent executable (PIE)
+ and contains dynamic relocations which are processed early in the
+ bootup process.
+ The relocations make the kernel image about 15% larger (compressed
+ 10%), but are discarded at runtime.
+
endmenu
menu "Memory setup"
KBUILD_CFLAGS_MODULE += -fPIC
KBUILD_AFLAGS += -m64
KBUILD_CFLAGS += -m64
+ifeq ($(CONFIG_RELOCATABLE),y)
+KBUILD_CFLAGS += -fPIE
+LDFLAGS_vmlinux := -pie
+endif
aflags_dwarf := -Wa,-gdwarf-2
KBUILD_AFLAGS_DECOMPRESSOR := -m64 -D__ASSEMBLY__
KBUILD_AFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),$(aflags_dwarf))
obj-y += string.o ebcdic.o sclp_early_core.o mem.o ipl_vmparm.o cmdline.o
obj-y += ctype.o
obj-$(CONFIG_PROTECTED_VIRTUALIZATION_GUEST) += uv.o
+obj-$(CONFIG_RELOCATABLE) += machine_kexec_reloc.o
targets := bzImage startup.a section_cmp.boot.data section_cmp.boot.preserved.data $(obj-y)
subdir- := compressed
unsigned long bootdata_size;
unsigned long bootdata_preserved_off;
unsigned long bootdata_preserved_size;
+ unsigned long dynsym_start;
+ unsigned long rela_dyn_start;
+ unsigned long rela_dyn_end;
};
extern char _vmlinux_info[];
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+#include "../kernel/machine_kexec_reloc.c"
// SPDX-License-Identifier: GPL-2.0
#include <linux/string.h>
+#include <linux/elf.h>
#include <asm/setup.h>
+#include <asm/kexec.h>
#include <asm/sclp.h>
#include <asm/uv.h>
#include "compressed/decompressor.h"
memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size);
}
+static void handle_relocs(unsigned long offset)
+{
+ Elf64_Rela *rela_start, *rela_end, *rela;
+ int r_type, r_sym, rc;
+ Elf64_Addr loc, val;
+ Elf64_Sym *dynsym;
+
+ rela_start = (Elf64_Rela *) vmlinux.rela_dyn_start;
+ rela_end = (Elf64_Rela *) vmlinux.rela_dyn_end;
+ dynsym = (Elf64_Sym *) vmlinux.dynsym_start;
+ for (rela = rela_start; rela < rela_end; rela++) {
+ loc = rela->r_offset + offset;
+ val = rela->r_addend + offset;
+ r_sym = ELF64_R_SYM(rela->r_info);
+ if (r_sym)
+ val += dynsym[r_sym].st_value;
+ r_type = ELF64_R_TYPE(rela->r_info);
+ rc = arch_kexec_do_relocs(r_type, (void *) loc, val, 0);
+ if (rc)
+ error("Unknown relocation type");
+ }
+}
+
void startup_kernel(void)
{
unsigned long safe_addr;
memmove((void *)vmlinux.default_lma, img, vmlinux.image_size);
}
copy_bootdata();
+ if (IS_ENABLED(CONFIG_RELOCATABLE))
+ handle_relocs(0);
vmlinux.entry();
}
void *kexec_file_add_components(struct kimage *image,
int (*add_kernel)(struct kimage *image,
struct s390_load_data *data));
+int arch_kexec_do_relocs(int r_type, void *loc, unsigned long val,
+ unsigned long addr);
extern const struct kexec_file_ops s390_kexec_image_ops;
extern const struct kexec_file_ops s390_kexec_elf_ops;
obj-y += sysinfo.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 += nospec-branch.o ipl_vmparm.o
+obj-y += nospec-branch.o ipl_vmparm.o machine_kexec_reloc.o
extra-y += head64.o vmlinux.lds
const Elf_Shdr *symtab)
{
Elf_Rela *relas;
- int i;
+ int i, r_type;
relas = (void *)pi->ehdr + relsec->sh_offset;
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;
- }
+ r_type = ELF64_R_TYPE(relas[i].r_info);
+ arch_kexec_do_relocs(r_type, loc, val, addr);
}
return 0;
}
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/elf.h>
+
+int arch_kexec_do_relocs(int r_type, void *loc, unsigned long val,
+ unsigned long addr)
+{
+ switch (r_type) {
+ case R_390_NONE:
+ break;
+ 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;
+ case R_390_RELATIVE:
+ *(unsigned long *) loc = val;
+ break;
+ default:
+ return 1;
+ }
+ return 0;
+}
INIT_DATA_SECTION(0x100)
PERCPU_SECTION(0x100)
+
+ .dynsym ALIGN(8) : {
+ __dynsym_start = .;
+ *(.dynsym)
+ __dynsym_end = .;
+ }
+ .rela.dyn ALIGN(8) : {
+ __rela_dyn_start = .;
+ *(.rela*)
+ __rela_dyn_end = .;
+ }
+
. = ALIGN(PAGE_SIZE);
__init_end = .; /* freed after init ends here */
QUAD(__boot_data_preserved_start) /* bootdata_preserved_off */
QUAD(__boot_data_preserved_end -
__boot_data_preserved_start) /* bootdata_preserved_size */
+ QUAD(__dynsym_start) /* dynsym_start */
+ QUAD(__rela_dyn_start) /* rela_dyn_start */
+ QUAD(__rela_dyn_end) /* rela_dyn_end */
} :NONE
/* Debugging sections. */