forked from luck/tmp_suning_uos_patched
s390/kernel: build a relocatable kernel
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>
This commit is contained in:
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833b441ec0
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805bc0bc23
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@ -624,6 +624,19 @@ config EXPOLINE_FULL
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endchoice
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config RELOCATABLE
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bool "Build a relocatable kernel"
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select MODULE_REL_CRCS if MODVERSIONS
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default y
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help
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This builds a kernel image that retains relocation information
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so it can be loaded at an arbitrary address.
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The kernel is linked as a position-independent executable (PIE)
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and contains dynamic relocations which are processed early in the
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bootup process.
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The relocations make the kernel image about 15% larger (compressed
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10%), but are discarded at runtime.
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endmenu
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menu "Memory setup"
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@ -16,6 +16,10 @@ KBUILD_AFLAGS_MODULE += -fPIC
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KBUILD_CFLAGS_MODULE += -fPIC
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KBUILD_AFLAGS += -m64
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KBUILD_CFLAGS += -m64
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ifeq ($(CONFIG_RELOCATABLE),y)
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KBUILD_CFLAGS += -fPIE
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LDFLAGS_vmlinux := -pie
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endif
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aflags_dwarf := -Wa,-gdwarf-2
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KBUILD_AFLAGS_DECOMPRESSOR := -m64 -D__ASSEMBLY__
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KBUILD_AFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),$(aflags_dwarf))
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@ -32,6 +32,7 @@ obj-y := head.o als.o startup.o mem_detect.o ipl_parm.o ipl_report.o
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obj-y += string.o ebcdic.o sclp_early_core.o mem.o ipl_vmparm.o cmdline.o
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obj-y += ctype.o
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obj-$(CONFIG_PROTECTED_VIRTUALIZATION_GUEST) += uv.o
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obj-$(CONFIG_RELOCATABLE) += machine_kexec_reloc.o
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targets := bzImage startup.a section_cmp.boot.data section_cmp.boot.preserved.data $(obj-y)
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subdir- := compressed
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@ -19,6 +19,9 @@ struct vmlinux_info {
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unsigned long bootdata_size;
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unsigned long bootdata_preserved_off;
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unsigned long bootdata_preserved_size;
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unsigned long dynsym_start;
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unsigned long rela_dyn_start;
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unsigned long rela_dyn_end;
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};
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extern char _vmlinux_info[];
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2
arch/s390/boot/machine_kexec_reloc.c
Normal file
2
arch/s390/boot/machine_kexec_reloc.c
Normal file
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@ -0,0 +1,2 @@
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// SPDX-License-Identifier: GPL-2.0
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#include "../kernel/machine_kexec_reloc.c"
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@ -1,6 +1,8 @@
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/string.h>
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#include <linux/elf.h>
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#include <asm/setup.h>
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#include <asm/kexec.h>
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#include <asm/sclp.h>
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#include <asm/uv.h>
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#include "compressed/decompressor.h"
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@ -47,6 +49,29 @@ static void copy_bootdata(void)
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memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size);
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}
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static void handle_relocs(unsigned long offset)
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{
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Elf64_Rela *rela_start, *rela_end, *rela;
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int r_type, r_sym, rc;
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Elf64_Addr loc, val;
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Elf64_Sym *dynsym;
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rela_start = (Elf64_Rela *) vmlinux.rela_dyn_start;
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rela_end = (Elf64_Rela *) vmlinux.rela_dyn_end;
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dynsym = (Elf64_Sym *) vmlinux.dynsym_start;
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for (rela = rela_start; rela < rela_end; rela++) {
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loc = rela->r_offset + offset;
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val = rela->r_addend + offset;
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r_sym = ELF64_R_SYM(rela->r_info);
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if (r_sym)
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val += dynsym[r_sym].st_value;
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r_type = ELF64_R_TYPE(rela->r_info);
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rc = arch_kexec_do_relocs(r_type, (void *) loc, val, 0);
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if (rc)
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error("Unknown relocation type");
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}
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}
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void startup_kernel(void)
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{
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unsigned long safe_addr;
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@ -67,5 +92,7 @@ void startup_kernel(void)
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memmove((void *)vmlinux.default_lma, img, vmlinux.image_size);
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}
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copy_bootdata();
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if (IS_ENABLED(CONFIG_RELOCATABLE))
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handle_relocs(0);
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vmlinux.entry();
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}
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@ -71,6 +71,8 @@ int s390_verify_sig(const char *kernel, unsigned long kernel_len);
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void *kexec_file_add_components(struct kimage *image,
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int (*add_kernel)(struct kimage *image,
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struct s390_load_data *data));
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int arch_kexec_do_relocs(int r_type, void *loc, unsigned long val,
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unsigned long addr);
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extern const struct kexec_file_ops s390_kexec_image_ops;
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extern const struct kexec_file_ops s390_kexec_elf_ops;
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@ -51,7 +51,7 @@ obj-y += debug.o irq.o ipl.o dis.o diag.o vdso.o early_nobss.o
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obj-y += sysinfo.o lgr.o os_info.o machine_kexec.o pgm_check.o
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obj-y += runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o
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obj-y += entry.o reipl.o relocate_kernel.o kdebugfs.o alternative.o
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obj-y += nospec-branch.o ipl_vmparm.o
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obj-y += nospec-branch.o ipl_vmparm.o machine_kexec_reloc.o
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extra-y += head64.o vmlinux.lds
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@ -290,7 +290,7 @@ int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
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const Elf_Shdr *symtab)
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{
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Elf_Rela *relas;
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int i;
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int i, r_type;
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relas = (void *)pi->ehdr + relsec->sh_offset;
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@ -324,46 +324,8 @@ int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
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addr = section->sh_addr + relas[i].r_offset;
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switch (ELF64_R_TYPE(relas[i].r_info)) {
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case R_390_8: /* Direct 8 bit. */
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*(u8 *)loc = val;
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break;
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case R_390_12: /* Direct 12 bit. */
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*(u16 *)loc &= 0xf000;
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*(u16 *)loc |= val & 0xfff;
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break;
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case R_390_16: /* Direct 16 bit. */
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*(u16 *)loc = val;
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break;
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case R_390_20: /* Direct 20 bit. */
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*(u32 *)loc &= 0xf00000ff;
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*(u32 *)loc |= (val & 0xfff) << 16; /* DL */
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*(u32 *)loc |= (val & 0xff000) >> 4; /* DH */
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break;
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case R_390_32: /* Direct 32 bit. */
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*(u32 *)loc = val;
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break;
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case R_390_64: /* Direct 64 bit. */
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*(u64 *)loc = val;
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break;
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case R_390_PC16: /* PC relative 16 bit. */
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*(u16 *)loc = (val - addr);
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break;
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case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */
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*(u16 *)loc = (val - addr) >> 1;
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break;
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case R_390_PC32DBL: /* PC relative 32 bit shifted by 1. */
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*(u32 *)loc = (val - addr) >> 1;
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break;
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case R_390_PC32: /* PC relative 32 bit. */
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*(u32 *)loc = (val - addr);
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break;
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case R_390_PC64: /* PC relative 64 bit. */
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*(u64 *)loc = (val - addr);
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break;
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default:
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break;
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}
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r_type = ELF64_R_TYPE(relas[i].r_info);
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arch_kexec_do_relocs(r_type, loc, val, addr);
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}
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return 0;
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}
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53
arch/s390/kernel/machine_kexec_reloc.c
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53
arch/s390/kernel/machine_kexec_reloc.c
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/elf.h>
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int arch_kexec_do_relocs(int r_type, void *loc, unsigned long val,
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unsigned long addr)
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{
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switch (r_type) {
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case R_390_NONE:
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break;
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case R_390_8: /* Direct 8 bit. */
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*(u8 *)loc = val;
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break;
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case R_390_12: /* Direct 12 bit. */
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*(u16 *)loc &= 0xf000;
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*(u16 *)loc |= val & 0xfff;
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break;
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case R_390_16: /* Direct 16 bit. */
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*(u16 *)loc = val;
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break;
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case R_390_20: /* Direct 20 bit. */
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*(u32 *)loc &= 0xf00000ff;
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*(u32 *)loc |= (val & 0xfff) << 16; /* DL */
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*(u32 *)loc |= (val & 0xff000) >> 4; /* DH */
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break;
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case R_390_32: /* Direct 32 bit. */
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*(u32 *)loc = val;
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break;
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case R_390_64: /* Direct 64 bit. */
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*(u64 *)loc = val;
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break;
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case R_390_PC16: /* PC relative 16 bit. */
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*(u16 *)loc = (val - addr);
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break;
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case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */
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*(u16 *)loc = (val - addr) >> 1;
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break;
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case R_390_PC32DBL: /* PC relative 32 bit shifted by 1. */
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*(u32 *)loc = (val - addr) >> 1;
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break;
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case R_390_PC32: /* PC relative 32 bit. */
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*(u32 *)loc = (val - addr);
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break;
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case R_390_PC64: /* PC relative 64 bit. */
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*(u64 *)loc = (val - addr);
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break;
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case R_390_RELATIVE:
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*(unsigned long *) loc = val;
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break;
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default:
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return 1;
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}
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return 0;
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}
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@ -144,6 +144,18 @@ SECTIONS
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INIT_DATA_SECTION(0x100)
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PERCPU_SECTION(0x100)
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.dynsym ALIGN(8) : {
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__dynsym_start = .;
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*(.dynsym)
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__dynsym_end = .;
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}
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.rela.dyn ALIGN(8) : {
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__rela_dyn_start = .;
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*(.rela*)
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__rela_dyn_end = .;
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}
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. = ALIGN(PAGE_SIZE);
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__init_end = .; /* freed after init ends here */
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QUAD(__boot_data_preserved_start) /* bootdata_preserved_off */
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QUAD(__boot_data_preserved_end -
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__boot_data_preserved_start) /* bootdata_preserved_size */
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QUAD(__dynsym_start) /* dynsym_start */
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QUAD(__rela_dyn_start) /* rela_dyn_start */
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QUAD(__rela_dyn_end) /* rela_dyn_end */
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} :NONE
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/* Debugging sections. */
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