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authorGerald Schaefer <gerald.schaefer@de.ibm.com>2019-02-03 21:35:45 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2019-04-29 10:47:10 +0200
commit805bc0bc238f7209fca5e39c152b0d3c12046ac9 (patch)
tree97edfcee4981bc71c2e6a9dc853353010ac4fa94
parents390: enable processes for mio instructions (diff)
downloadlinux-dev-805bc0bc238f7209fca5e39c152b0d3c12046ac9.tar.xz
linux-dev-805bc0bc238f7209fca5e39c152b0d3c12046ac9.zip
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>
-rw-r--r--arch/s390/Kconfig13
-rw-r--r--arch/s390/Makefile4
-rw-r--r--arch/s390/boot/Makefile1
-rw-r--r--arch/s390/boot/compressed/decompressor.h3
-rw-r--r--arch/s390/boot/machine_kexec_reloc.c2
-rw-r--r--arch/s390/boot/startup.c27
-rw-r--r--arch/s390/include/asm/kexec.h2
-rw-r--r--arch/s390/kernel/Makefile2
-rw-r--r--arch/s390/kernel/machine_kexec_file.c44
-rw-r--r--arch/s390/kernel/machine_kexec_reloc.c53
-rw-r--r--arch/s390/kernel/vmlinux.lds.S15
11 files changed, 124 insertions, 42 deletions
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 21e851b0a989..4c99e4f5f366 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -624,6 +624,19 @@ config EXPOLINE_FULL
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"
diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index 9c079a506325..54b8a12d64e8 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -16,6 +16,10 @@ KBUILD_AFLAGS_MODULE += -fPIC
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))
diff --git a/arch/s390/boot/Makefile b/arch/s390/boot/Makefile
index c1993c57300f..4df43e83363a 100644
--- a/arch/s390/boot/Makefile
+++ b/arch/s390/boot/Makefile
@@ -32,6 +32,7 @@ obj-y := head.o als.o startup.o mem_detect.o ipl_parm.o ipl_report.o
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
diff --git a/arch/s390/boot/compressed/decompressor.h b/arch/s390/boot/compressed/decompressor.h
index 424cf524aac1..c15eb7114d83 100644
--- a/arch/s390/boot/compressed/decompressor.h
+++ b/arch/s390/boot/compressed/decompressor.h
@@ -19,6 +19,9 @@ struct vmlinux_info {
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[];
diff --git a/arch/s390/boot/machine_kexec_reloc.c b/arch/s390/boot/machine_kexec_reloc.c
new file mode 100644
index 000000000000..b7a5d0f72097
--- /dev/null
+++ b/arch/s390/boot/machine_kexec_reloc.c
@@ -0,0 +1,2 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "../kernel/machine_kexec_reloc.c"
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
index 90898976a941..b7d6a76cb5e9 100644
--- a/arch/s390/boot/startup.c
+++ b/arch/s390/boot/startup.c
@@ -1,6 +1,8 @@
// 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"
@@ -47,6 +49,29 @@ static void copy_bootdata(void)
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;
@@ -67,5 +92,7 @@ void startup_kernel(void)
memmove((void *)vmlinux.default_lma, img, vmlinux.image_size);
}
copy_bootdata();
+ if (IS_ENABLED(CONFIG_RELOCATABLE))
+ handle_relocs(0);
vmlinux.entry();
}
diff --git a/arch/s390/include/asm/kexec.h b/arch/s390/include/asm/kexec.h
index 305d3465574f..ea398a05f643 100644
--- a/arch/s390/include/asm/kexec.h
+++ b/arch/s390/include/asm/kexec.h
@@ -71,6 +71,8 @@ int s390_verify_sig(const char *kernel, unsigned long kernel_len);
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;
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index d28acd7ba81e..19425605a83d 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -51,7 +51,7 @@ obj-y += debug.o irq.o ipl.o dis.o diag.o vdso.o early_nobss.o
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
diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c
index 48cab9600ed9..42c23a5c8229 100644
--- a/arch/s390/kernel/machine_kexec_file.c
+++ b/arch/s390/kernel/machine_kexec_file.c
@@ -290,7 +290,7 @@ int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
const Elf_Shdr *symtab)
{
Elf_Rela *relas;
- int i;
+ int i, r_type;
relas = (void *)pi->ehdr + relsec->sh_offset;
@@ -324,46 +324,8 @@ int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
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;
}
diff --git a/arch/s390/kernel/machine_kexec_reloc.c b/arch/s390/kernel/machine_kexec_reloc.c
new file mode 100644
index 000000000000..1dded39239f8
--- /dev/null
+++ b/arch/s390/kernel/machine_kexec_reloc.c
@@ -0,0 +1,53 @@
+// 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;
+}
diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 6ef9c62bb01b..49d55327de0b 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -144,6 +144,18 @@ SECTIONS
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 */
@@ -165,6 +177,9 @@ SECTIONS
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. */