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linux/arch/s390/kernel/vmlinux.lds.S
Alexander Gordeev 1642285e51 s390/boot: Fix KASLR base offset off by __START_KERNEL bytes
Symbol offsets to the KASLR base do not match symbol address in
the vmlinux image. That is the result of setting the KASLR base
to the beginning of .text section as result of an optimization.

Revert that optimization and allocate virtual memory for the
whole kernel image including __START_KERNEL bytes as per the
linker script. That allows keeping the semantics of the KASLR
base offset in sync with other architectures.

Rename __START_KERNEL to TEXT_OFFSET, since it represents the
offset of the .text section within the kernel image, rather than
a virtual address.

Still skip mapping TEXT_OFFSET bytes to save memory on pgtables
and provoke exceptions in case an attempt to access this area is
made, as no kernel symbol may reside there.

In case CONFIG_KASAN is enabled the location counter might exceed
the value of TEXT_OFFSET, while the decompressor linker script
forcefully resets it to TEXT_OFFSET, which leads to a sections
overlap link failure. Use MAX() expression to avoid that.

Reported-by: Omar Sandoval <osandov@osandov.com>
Closes: https://lore.kernel.org/linux-s390/ZnS8dycxhtXBZVky@telecaster.dhcp.thefacebook.com/
Fixes: 56b1069c40 ("s390/boot: Rework deployment of the kernel image")
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-08-22 19:24:13 +02:00

270 lines
5.9 KiB
ArmAsm

/* SPDX-License-Identifier: GPL-2.0 */
/* ld script to make s390 Linux kernel
* Written by Martin Schwidefsky (schwidefsky@de.ibm.com)
*/
#include <asm/thread_info.h>
#include <asm/page.h>
#include <asm/ftrace.lds.h>
/*
* Put .bss..swapper_pg_dir as the first thing in .bss. This will
* make sure it has 16k alignment.
*/
#define BSS_FIRST_SECTIONS *(.bss..swapper_pg_dir) \
*(.bss..invalid_pg_dir)
#define RO_EXCEPTION_TABLE_ALIGN 16
/* Handle ro_after_init data on our own. */
#define RO_AFTER_INIT_DATA
#define RUNTIME_DISCARD_EXIT
#define EMITS_PT_NOTE
#include <asm-generic/vmlinux.lds.h>
#include <asm/vmlinux.lds.h>
OUTPUT_FORMAT("elf64-s390", "elf64-s390", "elf64-s390")
OUTPUT_ARCH(s390:64-bit)
ENTRY(startup_continue)
jiffies = jiffies_64;
PHDRS {
text PT_LOAD FLAGS(5); /* R_E */
data PT_LOAD FLAGS(7); /* RWE */
note PT_NOTE FLAGS(0); /* ___ */
}
SECTIONS
{
. = TEXT_OFFSET;
.text : {
_stext = .; /* Start of text section */
_text = .; /* Text and read-only data */
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
FTRACE_HOTPATCH_TRAMPOLINES_TEXT
*(.text.*_indirect_*)
*(.fixup)
*(.gnu.warning)
. = ALIGN(PAGE_SIZE);
_etext = .; /* End of text section */
} :text = 0x0700
RO_DATA(PAGE_SIZE)
. = ALIGN(PAGE_SIZE);
_sdata = .; /* Start of data section */
. = ALIGN(PAGE_SIZE);
__start_ro_after_init = .;
.data..ro_after_init : {
*(.data..ro_after_init)
JUMP_TABLE_DATA
} :data
. = ALIGN(PAGE_SIZE);
__end_ro_after_init = .;
.data.rel.ro : {
*(.data.rel.ro .data.rel.ro.*)
}
.got : {
__got_start = .;
*(.got)
__got_end = .;
}
RW_DATA(0x100, PAGE_SIZE, THREAD_SIZE)
.data.rel : {
*(.data.rel*)
}
BOOT_DATA_PRESERVED
. = ALIGN(8);
.amode31.refs : {
_start_amode31_refs = .;
*(.amode31.refs)
_end_amode31_refs = .;
}
. = ALIGN(PAGE_SIZE);
_edata = .; /* End of data section */
/* will be freed after init */
. = ALIGN(PAGE_SIZE); /* Init code and data */
__init_begin = .;
. = ALIGN(PAGE_SIZE);
.init.text : AT(ADDR(.init.text) - LOAD_OFFSET) {
_sinittext = .;
INIT_TEXT
. = ALIGN(PAGE_SIZE);
_einittext = .;
}
/*
* .exit.text is discarded at runtime, not link time,
* to deal with references from __bug_table
*/
.exit.text : {
EXIT_TEXT
}
.exit.data : {
EXIT_DATA
}
/*
* struct alt_inst entries. From the header (alternative.h):
* "Alternative instructions for different CPU types or capabilities"
* Think locking instructions on spinlocks.
* Note, that it is a part of __init region.
*/
. = ALIGN(8);
.altinstructions : {
__alt_instructions = .;
*(.altinstructions)
__alt_instructions_end = .;
}
/*
* And here are the replacement instructions. The linker sticks
* them as binary blobs. The .altinstructions has enough data to
* get the address and the length of them to patch the kernel safely.
* Note, that it is a part of __init region.
*/
.altinstr_replacement : {
*(.altinstr_replacement)
}
/*
* Table with the patch locations to undo expolines
*/
. = ALIGN(4);
.nospec_call_table : {
__nospec_call_start = . ;
*(.s390_indirect*)
__nospec_call_end = . ;
}
.nospec_return_table : {
__nospec_return_start = . ;
*(.s390_return*)
__nospec_return_end = . ;
}
BOOT_DATA
/*
* .amode31 section for code, data, ex_table that need to stay
* below 2 GB, even when the kernel is relocated above 2 GB.
*/
. = ALIGN(PAGE_SIZE);
_samode31 = .;
.amode31.text : {
_stext_amode31 = .;
*(.amode31.text)
*(.amode31.text.*_indirect_*)
. = ALIGN(PAGE_SIZE);
_etext_amode31 = .;
}
. = ALIGN(16);
.amode31.ex_table : {
_start_amode31_ex_table = .;
KEEP(*(.amode31.ex_table))
_stop_amode31_ex_table = .;
}
. = ALIGN(PAGE_SIZE);
.amode31.data : {
*(.amode31.data)
}
. = _samode31 + AMODE31_SIZE;
_eamode31 = .;
/* early.c uses stsi, which requires page aligned data. */
. = ALIGN(PAGE_SIZE);
INIT_DATA_SECTION(0x100)
RUNTIME_CONST(shift, d_hash_shift)
RUNTIME_CONST(ptr, dentry_hashtable)
PERCPU_SECTION(0x100)
. = ALIGN(PAGE_SIZE);
__init_end = .; /* freed after init ends here */
BSS_SECTION(PAGE_SIZE, 4 * PAGE_SIZE, PAGE_SIZE)
. = ALIGN(PAGE_SIZE);
_end = . ;
/*
* uncompressed image info used by the decompressor
* it should match struct vmlinux_info
*/
.vmlinux.info 0 (INFO) : {
QUAD(startup_continue) /* entry */
QUAD(__bss_start - _stext) /* image_size */
QUAD(__bss_stop - __bss_start) /* bss_size */
QUAD(__boot_data_start) /* bootdata_off */
QUAD(__boot_data_end - __boot_data_start) /* bootdata_size */
QUAD(__boot_data_preserved_start) /* bootdata_preserved_off */
QUAD(__boot_data_preserved_end -
__boot_data_preserved_start) /* bootdata_preserved_size */
QUAD(__got_start) /* got_start */
QUAD(__got_end) /* got_end */
QUAD(_eamode31 - _samode31) /* amode31_size */
QUAD(init_mm)
QUAD(swapper_pg_dir)
QUAD(invalid_pg_dir)
QUAD(__alt_instructions)
QUAD(__alt_instructions_end)
#ifdef CONFIG_KASAN
QUAD(kasan_early_shadow_page)
QUAD(kasan_early_shadow_pte)
QUAD(kasan_early_shadow_pmd)
QUAD(kasan_early_shadow_pud)
QUAD(kasan_early_shadow_p4d)
#endif
} :NONE
/* Debugging sections. */
STABS_DEBUG
DWARF_DEBUG
ELF_DETAILS
/*
* Make sure that the .got.plt is either completely empty or it
* contains only the three reserved double words.
*/
.got.plt : {
*(.got.plt)
}
ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0x18, "Unexpected GOT/PLT entries detected!")
/*
* Sections that should stay zero sized, which is safer to
* explicitly check instead of blindly discarding.
*/
.plt : {
*(.plt) *(.plt.*) *(.iplt) *(.igot .igot.plt)
}
ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!")
.rela.dyn : {
*(.rela.*) *(.rela_*)
}
ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) detected!")
/* Sections to be discarded */
DISCARDS
/DISCARD/ : {
*(.eh_frame)
*(.interp)
}
}