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authorSumanth Korikkar <sumanthk@linux.ibm.com>2024-04-25 17:59:31 +0300
committerAlexander Gordeev <agordeev@linux.ibm.com>2024-04-29 18:33:30 +0300
commit00cda11d3b2ea07295490b7d67942014f1cbc5c1 (patch)
treeeb27959101e584b9ff882be1b4d5f8b09b864cb2
parent5f90003f09042b504d90ee38618cfd380ce16f4a (diff)
downloadlinux-00cda11d3b2ea07295490b7d67942014f1cbc5c1.tar.xz
s390: Compile kernel with -fPIC and link with -no-pie
When the kernel is built with CONFIG_PIE_BUILD option enabled it uses dynamic symbols, for which the linker does not allow more than 64K number of entries. This can break features like kpatch. Hence, whenever possible the kernel is built with CONFIG_PIE_BUILD option disabled. For that support of unaligned symbols generated by linker scripts in the compiler is necessary. However, older compilers might lack such support. In that case the build process resorts to CONFIG_PIE_BUILD option-enabled build. Compile object files with -fPIC option and then link the kernel binary with -no-pie linker option. As result, the dynamic symbols are not generated and not only kpatch feature succeeds, but also the whole CONFIG_PIE_BUILD option-enabled code could be dropped. [ agordeev: Reworded the commit message ] Suggested-by: Ulrich Weigand <ulrich.weigand@de.ibm.com> Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com> Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
-rw-r--r--arch/s390/Kconfig12
-rw-r--r--arch/s390/Makefile9
-rw-r--r--arch/s390/boot/Makefile7
-rw-r--r--arch/s390/boot/boot.h6
-rw-r--r--arch/s390/boot/startup.c42
-rw-r--r--arch/s390/boot/vmlinux.lds.S2
-rw-r--r--arch/s390/kernel/vmlinux.lds.S33
7 files changed, 3 insertions, 108 deletions
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index a077ded1b9e6..7e7fe89c9b25 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -593,18 +593,6 @@ config RELOCATABLE
Note: this option exists only for documentation purposes, please do
not remove it.
-config PIE_BUILD
- def_bool CC_IS_CLANG && !$(cc-option,-munaligned-symbols)
- help
- If the compiler is unable to generate code that can manage unaligned
- symbols, the kernel is linked as a position-independent executable
- (PIE) and includes dynamic relocations that are processed early
- during bootup.
-
- For kpatch functionality, it is recommended to build the kernel
- without the PIE_BUILD option. PIE_BUILD is only enabled when the
- compiler lacks proper support for handling unaligned symbols.
-
config RANDOMIZE_BASE
bool "Randomize the address of the kernel image (KASLR)"
default y
diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index 64821f54f1e0..f2b21c7a70ef 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -14,14 +14,9 @@ KBUILD_AFLAGS_MODULE += -fPIC
KBUILD_CFLAGS_MODULE += -fPIC
KBUILD_AFLAGS += -m64
KBUILD_CFLAGS += -m64
-ifdef CONFIG_PIE_BUILD
-KBUILD_CFLAGS += -fPIE
-LDFLAGS_vmlinux := -pie -z notext
-else
-KBUILD_CFLAGS += $(call cc-option,-munaligned-symbols,)
-LDFLAGS_vmlinux := --emit-relocs --discard-none
+KBUILD_CFLAGS += -fPIC
+LDFLAGS_vmlinux := -no-pie --emit-relocs --discard-none
extra_tools := relocs
-endif
aflags_dwarf := -Wa,-gdwarf-2
KBUILD_AFLAGS_DECOMPRESSOR := $(CLANG_FLAGS) -m64 -D__ASSEMBLY__
ifndef CONFIG_AS_IS_LLVM
diff --git a/arch/s390/boot/Makefile b/arch/s390/boot/Makefile
index bd5d4d37a961..070c9b2e905f 100644
--- a/arch/s390/boot/Makefile
+++ b/arch/s390/boot/Makefile
@@ -37,8 +37,7 @@ CFLAGS_sclp_early_core.o += -I$(srctree)/drivers/s390/char
obj-y := head.o als.o startup.o physmem_info.o ipl_parm.o ipl_report.o vmem.o
obj-y += string.o ebcdic.o sclp_early_core.o mem.o ipl_vmparm.o cmdline.o
-obj-y += version.o pgm_check_info.o ctype.o ipl_data.o
-obj-y += $(if $(CONFIG_PIE_BUILD),machine_kexec_reloc.o,relocs.o)
+obj-y += version.o pgm_check_info.o ctype.o ipl_data.o relocs.o
obj-$(findstring y, $(CONFIG_PROTECTED_VIRTUALIZATION_GUEST) $(CONFIG_PGSTE)) += uv.o
obj-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
obj-y += $(if $(CONFIG_KERNEL_UNCOMPRESSED),,decompressor.o) info.o
@@ -49,9 +48,7 @@ targets := bzImage section_cmp.boot.data section_cmp.boot.preserved.data $(obj-y
targets += vmlinux.lds vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2
targets += vmlinux.bin.xz vmlinux.bin.lzma vmlinux.bin.lzo vmlinux.bin.lz4
targets += vmlinux.bin.zst info.bin syms.bin vmlinux.syms $(obj-all)
-ifndef CONFIG_PIE_BUILD
targets += relocs.S
-endif
OBJECTS := $(addprefix $(obj)/,$(obj-y))
OBJECTS_ALL := $(addprefix $(obj)/,$(obj-all))
@@ -110,13 +107,11 @@ OBJCOPYFLAGS_vmlinux.bin := -O binary --remove-section=.comment --remove-section
$(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy)
-ifndef CONFIG_PIE_BUILD
CMD_RELOCS=arch/s390/tools/relocs
quiet_cmd_relocs = RELOCS $@
cmd_relocs = $(CMD_RELOCS) $< > $@
$(obj)/relocs.S: vmlinux FORCE
$(call if_changed,relocs)
-endif
suffix-$(CONFIG_KERNEL_GZIP) := .gz
suffix-$(CONFIG_KERNEL_BZIP2) := .bz2
diff --git a/arch/s390/boot/boot.h b/arch/s390/boot/boot.h
index 85da1c6cef4f..18027fdc92b0 100644
--- a/arch/s390/boot/boot.h
+++ b/arch/s390/boot/boot.h
@@ -24,14 +24,8 @@ struct vmlinux_info {
unsigned long bootdata_size;
unsigned long bootdata_preserved_off;
unsigned long bootdata_preserved_size;
-#ifdef CONFIG_PIE_BUILD
- unsigned long dynsym_start;
- unsigned long rela_dyn_start;
- unsigned long rela_dyn_end;
-#else
unsigned long got_start;
unsigned long got_end;
-#endif
unsigned long amode31_size;
unsigned long init_mm_off;
unsigned long swapper_pg_dir_off;
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
index 246d54499c20..467283b112cd 100644
--- a/arch/s390/boot/startup.c
+++ b/arch/s390/boot/startup.c
@@ -151,41 +151,6 @@ static void copy_bootdata(void)
memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size);
}
-#ifdef CONFIG_PIE_BUILD
-static void kaslr_adjust_relocs(unsigned long min_addr, unsigned long max_addr,
- unsigned long offset, unsigned long phys_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 + phys_offset - __START_KERNEL;
- val = rela->r_addend;
- r_sym = ELF64_R_SYM(rela->r_info);
- if (r_sym) {
- if (dynsym[r_sym].st_shndx != SHN_UNDEF)
- val += dynsym[r_sym].st_value + offset - __START_KERNEL;
- } else {
- /*
- * 0 == undefined symbol table index (SHN_UNDEF),
- * used for R_390_RELATIVE, only add KASLR offset
- */
- val += offset - __START_KERNEL;
- }
- 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");
- }
-}
-
-static void kaslr_adjust_got(unsigned long offset) {}
-#else
static void kaslr_adjust_relocs(unsigned long min_addr, unsigned long max_addr,
unsigned long offset, unsigned long phys_offset)
{
@@ -212,7 +177,6 @@ static void kaslr_adjust_got(unsigned long offset)
for (entry = (u64 *)vmlinux.got_start; entry < (u64 *)vmlinux.got_end; entry++)
*entry += offset - __START_KERNEL;
}
-#endif
/*
* Merge information from several sources into a single ident_map_size value.
@@ -398,14 +362,8 @@ static void kaslr_adjust_vmlinux_info(long offset)
{
vmlinux.bootdata_off += offset;
vmlinux.bootdata_preserved_off += offset;
-#ifdef CONFIG_PIE_BUILD
- vmlinux.rela_dyn_start += offset;
- vmlinux.rela_dyn_end += offset;
- vmlinux.dynsym_start += offset;
-#else
vmlinux.got_start += offset;
vmlinux.got_end += offset;
-#endif
vmlinux.init_mm_off += offset;
vmlinux.swapper_pg_dir_off += offset;
vmlinux.invalid_pg_dir_off += offset;
diff --git a/arch/s390/boot/vmlinux.lds.S b/arch/s390/boot/vmlinux.lds.S
index d6454ec01e22..1fe5a1d3ff60 100644
--- a/arch/s390/boot/vmlinux.lds.S
+++ b/arch/s390/boot/vmlinux.lds.S
@@ -99,14 +99,12 @@ SECTIONS
_decompressor_end = .;
-#ifndef CONFIG_PIE_BUILD
. = ALIGN(4);
.vmlinux.relocs : {
__vmlinux_relocs_64_start = .;
*(.vmlinux.relocs_64)
__vmlinux_relocs_64_end = .;
}
-#endif
#ifdef CONFIG_KERNEL_UNCOMPRESSED
. = ALIGN(PAGE_SIZE);
diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 163d64f300c1..a1ce3925ec71 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -192,31 +192,6 @@ SECTIONS
PERCPU_SECTION(0x100)
-#ifdef CONFIG_PIE_BUILD
- .dynsym ALIGN(8) : {
- __dynsym_start = .;
- *(.dynsym)
- __dynsym_end = .;
- }
- .rela.dyn ALIGN(8) : {
- __rela_dyn_start = .;
- *(.rela*)
- __rela_dyn_end = .;
- }
- .dynamic ALIGN(8) : {
- *(.dynamic)
- }
- .dynstr ALIGN(8) : {
- *(.dynstr)
- }
- .hash ALIGN(8) : {
- *(.hash)
- }
- .gnu.hash ALIGN(8) : {
- *(.gnu.hash)
- }
-#endif
-
. = ALIGN(PAGE_SIZE);
__init_end = .; /* freed after init ends here */
@@ -238,14 +213,8 @@ SECTIONS
QUAD(__boot_data_preserved_start) /* bootdata_preserved_off */
QUAD(__boot_data_preserved_end -
__boot_data_preserved_start) /* bootdata_preserved_size */
-#ifdef CONFIG_PIE_BUILD
- QUAD(__dynsym_start) /* dynsym_start */
- QUAD(__rela_dyn_start) /* rela_dyn_start */
- QUAD(__rela_dyn_end) /* rela_dyn_end */
-#else
QUAD(__got_start) /* got_start */
QUAD(__got_end) /* got_end */
-#endif
QUAD(_eamode31 - _samode31) /* amode31_size */
QUAD(init_mm)
QUAD(swapper_pg_dir)
@@ -281,12 +250,10 @@ SECTIONS
*(.plt) *(.plt.*) *(.iplt) *(.igot .igot.plt)
}
ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!")
-#ifndef CONFIG_PIE_BUILD
.rela.dyn : {
*(.rela.*) *(.rela_*)
}
ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) detected!")
-#endif
/* Sections to be discarded */
DISCARDS