linux-stable/arch/powerpc/kernel/vmlinux.lds.S
Nicholas Piggin 7e3a68be42 powerpc/64: vmlinux support building with PCREL addresing
PC-Relative or PCREL addressing is an extension to the ELF ABI which
uses Power ISA v3.1 PC-relative instructions to calculate addresses,
rather than the traditional TOC scheme.

Add an option to build vmlinux using pcrel addressing. Modules continue
to use TOC addressing.

- TOC address helpers and r2 are poisoned with -1 when running vmlinux.
  r2 could be used for something useful once things are ironed out.

- Assembly must call C functions with @notoc annotation, or the linker
  complains aobut a missing nop after the call. This is done with the
  CFUNC macro introduced earlier.

- Boot: with the exception of prom_init, the execution branches to the
  kernel virtual address early in boot, before any addresses are
  generated, which ensures 34-bit pcrel addressing does not miss the
  high PAGE_OFFSET bits. TOC relative addressing has a similar
  requirement. prom_init does not go to the virtual address and its
  addresses should not carry over to the post-prom kernel.

- Ftrace trampolines are converted from TOC addressing to pcrel
  addressing, including module ftrace trampolines that currently use the
  kernel TOC to find ftrace target functions.

- BPF function prologue and function calling generation are converted
  from TOC to pcrel.

- copypage_64.S has an interesting problem, prefixed instructions have
  alignment restrictions so the linker can add padding, which makes the
  assembler treat the difference between two local labels as
  non-constant even if alignment is arranged so padding is not required.
  This may need toolchain help to solve nicely, for now move the prefix
  instruction out of the alternate patch section to work around it.

This reduces kernel text size by about 6%.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230408021752.862660-6-npiggin@gmail.com
2023-04-20 12:59:21 +10:00

428 lines
9.2 KiB
ArmAsm

/* SPDX-License-Identifier: GPL-2.0 */
#ifdef CONFIG_PPC64
#define PROVIDE32(x) PROVIDE(__unused__##x)
#else
#define PROVIDE32(x) PROVIDE(x)
#endif
#define BSS_FIRST_SECTIONS *(.bss.prominit)
#define EMITS_PT_NOTE
#define RO_EXCEPTION_TABLE_ALIGN 0
#define RUNTIME_DISCARD_EXIT
#define SOFT_MASK_TABLE(align) \
. = ALIGN(align); \
__soft_mask_table : AT(ADDR(__soft_mask_table) - LOAD_OFFSET) { \
__start___soft_mask_table = .; \
KEEP(*(__soft_mask_table)) \
__stop___soft_mask_table = .; \
}
#define RESTART_TABLE(align) \
. = ALIGN(align); \
__restart_table : AT(ADDR(__restart_table) - LOAD_OFFSET) { \
__start___restart_table = .; \
KEEP(*(__restart_table)) \
__stop___restart_table = .; \
}
#include <asm/page.h>
#include <asm-generic/vmlinux.lds.h>
#include <asm/cache.h>
#include <asm/thread_info.h>
#define STRICT_ALIGN_SIZE (1 << CONFIG_DATA_SHIFT)
#if STRICT_ALIGN_SIZE < PAGE_SIZE
#error "CONFIG_DATA_SHIFT must be >= PAGE_SHIFT"
#endif
ENTRY(_stext)
PHDRS {
text PT_LOAD FLAGS(7); /* RWX */
note PT_NOTE FLAGS(0);
}
#ifdef CONFIG_PPC64
OUTPUT_ARCH(powerpc:common64)
jiffies = jiffies_64;
#else
OUTPUT_ARCH(powerpc:common)
jiffies = jiffies_64 + 4;
#endif
SECTIONS
{
. = KERNELBASE;
/*
* Text, read only data and other permanent read-only sections
*/
_text = .;
_stext = .;
/*
* Head text.
* This needs to be in its own output section to avoid ld placing
* branch trampoline stubs randomly throughout the fixed sections,
* which it will do (even if the branch comes from another section)
* in order to optimize stub generation.
*/
.head.text : AT(ADDR(.head.text) - LOAD_OFFSET) {
#ifdef CONFIG_PPC64
KEEP(*(.head.text.first_256B));
#ifdef CONFIG_PPC_BOOK3E_64
#else
KEEP(*(.head.text.real_vectors));
*(.head.text.real_trampolines);
KEEP(*(.head.text.virt_vectors));
*(.head.text.virt_trampolines);
# if defined(CONFIG_PPC_PSERIES) || defined(CONFIG_PPC_POWERNV)
KEEP(*(.head.data.fwnmi_page));
# endif
#endif
#else /* !CONFIG_PPC64 */
HEAD_TEXT
#endif
} :text
__head_end = .;
#ifdef CONFIG_PPC64
/*
* ALIGN(0) overrides the default output section alignment because
* this needs to start right after .head.text in order for fixed
* section placement to work.
*/
.text ALIGN(0) : AT(ADDR(.text) - LOAD_OFFSET) {
#ifdef CONFIG_LD_HEAD_STUB_CATCH
KEEP(*(.linker_stub_catch));
. = . ;
#endif
#else
.text : AT(ADDR(.text) - LOAD_OFFSET) {
ALIGN_FUNCTION();
#endif
/* careful! __ftr_alt_* sections need to be close to .text */
*(.text.hot .text.hot.* TEXT_MAIN .text.fixup .text.unlikely .text.unlikely.* .fixup __ftr_alt_* .ref.text);
#ifdef CONFIG_PPC64
*(.tramp.ftrace.text);
#endif
NOINSTR_TEXT
SCHED_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
SOFTIRQENTRY_TEXT
/*
* -Os builds call FP save/restore functions. The powerpc64
* linker generates those on demand in the .sfpr section.
* .sfpr gets placed at the beginning of a group of input
* sections, which can break start-of-text offset if it is
* included with the main text sections, so put it by itself.
*/
*(.sfpr);
*(.text.asan.* .text.tsan.*)
MEM_KEEP(init.text)
MEM_KEEP(exit.text)
} :text
. = ALIGN(PAGE_SIZE);
_etext = .;
PROVIDE32 (etext = .);
/* Read-only data */
RO_DATA(PAGE_SIZE)
#ifdef CONFIG_PPC32
.sdata2 : AT(ADDR(.sdata2) - LOAD_OFFSET) {
*(.sdata2)
}
#endif
.data.rel.ro : AT(ADDR(.data.rel.ro) - LOAD_OFFSET) {
*(.data.rel.ro .data.rel.ro.*)
}
.branch_lt : AT(ADDR(.branch_lt) - LOAD_OFFSET) {
*(.branch_lt)
}
#ifdef CONFIG_PPC32
.got1 : AT(ADDR(.got1) - LOAD_OFFSET) {
*(.got1)
}
.got2 : AT(ADDR(.got2) - LOAD_OFFSET) {
__got2_start = .;
*(.got2)
__got2_end = .;
}
.got : AT(ADDR(.got) - LOAD_OFFSET) {
*(.got)
*(.got.plt)
}
.plt : AT(ADDR(.plt) - LOAD_OFFSET) {
/* XXX: is .plt (and .got.plt) required? */
*(.plt)
}
#else /* CONFIG_PPC32 */
#ifndef CONFIG_PPC_KERNEL_PCREL
.toc1 : AT(ADDR(.toc1) - LOAD_OFFSET) {
*(.toc1)
}
#endif
.got : AT(ADDR(.got) - LOAD_OFFSET) ALIGN(256) {
#ifdef CONFIG_PPC_KERNEL_PCREL
*(.got)
#else
*(.got .toc)
#endif
}
SOFT_MASK_TABLE(8)
RESTART_TABLE(8)
#ifdef CONFIG_PPC64_ELF_ABI_V1
.opd : AT(ADDR(.opd) - LOAD_OFFSET) {
__start_opd = .;
KEEP(*(.opd))
__end_opd = .;
}
#endif
. = ALIGN(8);
__stf_entry_barrier_fixup : AT(ADDR(__stf_entry_barrier_fixup) - LOAD_OFFSET) {
__start___stf_entry_barrier_fixup = .;
*(__stf_entry_barrier_fixup)
__stop___stf_entry_barrier_fixup = .;
}
. = ALIGN(8);
__uaccess_flush_fixup : AT(ADDR(__uaccess_flush_fixup) - LOAD_OFFSET) {
__start___uaccess_flush_fixup = .;
*(__uaccess_flush_fixup)
__stop___uaccess_flush_fixup = .;
}
. = ALIGN(8);
__entry_flush_fixup : AT(ADDR(__entry_flush_fixup) - LOAD_OFFSET) {
__start___entry_flush_fixup = .;
*(__entry_flush_fixup)
__stop___entry_flush_fixup = .;
}
. = ALIGN(8);
__scv_entry_flush_fixup : AT(ADDR(__scv_entry_flush_fixup) - LOAD_OFFSET) {
__start___scv_entry_flush_fixup = .;
*(__scv_entry_flush_fixup)
__stop___scv_entry_flush_fixup = .;
}
. = ALIGN(8);
__stf_exit_barrier_fixup : AT(ADDR(__stf_exit_barrier_fixup) - LOAD_OFFSET) {
__start___stf_exit_barrier_fixup = .;
*(__stf_exit_barrier_fixup)
__stop___stf_exit_barrier_fixup = .;
}
. = ALIGN(8);
__rfi_flush_fixup : AT(ADDR(__rfi_flush_fixup) - LOAD_OFFSET) {
__start___rfi_flush_fixup = .;
*(__rfi_flush_fixup)
__stop___rfi_flush_fixup = .;
}
#endif /* CONFIG_PPC32 */
#ifdef CONFIG_PPC_BARRIER_NOSPEC
. = ALIGN(8);
__spec_barrier_fixup : AT(ADDR(__spec_barrier_fixup) - LOAD_OFFSET) {
__start___barrier_nospec_fixup = .;
*(__barrier_nospec_fixup)
__stop___barrier_nospec_fixup = .;
}
#endif /* CONFIG_PPC_BARRIER_NOSPEC */
#ifdef CONFIG_PPC_E500
. = ALIGN(8);
__spec_btb_flush_fixup : AT(ADDR(__spec_btb_flush_fixup) - LOAD_OFFSET) {
__start__btb_flush_fixup = .;
*(__btb_flush_fixup)
__stop__btb_flush_fixup = .;
}
#endif
/*
* Various code relies on __init_begin being at the strict RWX boundary.
*/
. = ALIGN(STRICT_ALIGN_SIZE);
__srwx_boundary = .;
__end_rodata = .;
__init_begin = .;
/*
* Init sections discarded at runtime
*/
.init.text : AT(ADDR(.init.text) - LOAD_OFFSET) {
_sinittext = .;
INIT_TEXT
/*
*.init.text might be RO so we must ensure this section ends on
* a page boundary.
*/
. = ALIGN(PAGE_SIZE);
_einittext = .;
#ifdef CONFIG_PPC64
*(.tramp.ftrace.init);
#endif
} :text
/* .exit.text is discarded at runtime, not link time,
* to deal with references from __bug_table
*/
.exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) {
EXIT_TEXT
}
. = ALIGN(PAGE_SIZE);
INIT_DATA_SECTION(16)
. = ALIGN(8);
__ftr_fixup : AT(ADDR(__ftr_fixup) - LOAD_OFFSET) {
__start___ftr_fixup = .;
KEEP(*(__ftr_fixup))
__stop___ftr_fixup = .;
}
. = ALIGN(8);
__mmu_ftr_fixup : AT(ADDR(__mmu_ftr_fixup) - LOAD_OFFSET) {
__start___mmu_ftr_fixup = .;
KEEP(*(__mmu_ftr_fixup))
__stop___mmu_ftr_fixup = .;
}
. = ALIGN(8);
__lwsync_fixup : AT(ADDR(__lwsync_fixup) - LOAD_OFFSET) {
__start___lwsync_fixup = .;
KEEP(*(__lwsync_fixup))
__stop___lwsync_fixup = .;
}
#ifdef CONFIG_PPC64
. = ALIGN(8);
__fw_ftr_fixup : AT(ADDR(__fw_ftr_fixup) - LOAD_OFFSET) {
__start___fw_ftr_fixup = .;
KEEP(*(__fw_ftr_fixup))
__stop___fw_ftr_fixup = .;
}
#endif
PERCPU_SECTION(L1_CACHE_BYTES)
. = ALIGN(8);
.machine.desc : AT(ADDR(.machine.desc) - LOAD_OFFSET) {
__machine_desc_start = . ;
KEEP(*(.machine.desc))
__machine_desc_end = . ;
}
#ifdef CONFIG_RELOCATABLE
. = ALIGN(8);
.dynsym : AT(ADDR(.dynsym) - LOAD_OFFSET)
{
__dynamic_symtab = .;
*(.dynsym)
}
.dynstr : AT(ADDR(.dynstr) - LOAD_OFFSET) { *(.dynstr) }
.dynamic : AT(ADDR(.dynamic) - LOAD_OFFSET)
{
__dynamic_start = .;
*(.dynamic)
}
.hash : AT(ADDR(.hash) - LOAD_OFFSET) { *(.hash) }
.gnu.hash : AT(ADDR(.gnu.hash) - LOAD_OFFSET) { *(.gnu.hash) }
.interp : AT(ADDR(.interp) - LOAD_OFFSET) { *(.interp) }
.rela.dyn : AT(ADDR(.rela.dyn) - LOAD_OFFSET)
{
__rela_dyn_start = .;
*(.rela*)
}
#endif
/* .exit.data is discarded at runtime, not link time,
* to deal with references from .exit.text
*/
.exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) {
EXIT_DATA
}
/* freed after init ends here */
. = ALIGN(PAGE_SIZE);
__init_end = .;
/*
* And now the various read/write data
*/
. = ALIGN(PAGE_SIZE);
_sdata = .;
.data : AT(ADDR(.data) - LOAD_OFFSET) {
DATA_DATA
*(.data.rel*)
#ifdef CONFIG_PPC32
*(SDATA_MAIN)
#endif
}
/* The initial task and kernel stack */
INIT_TASK_DATA_SECTION(THREAD_ALIGN)
.data..page_aligned : AT(ADDR(.data..page_aligned) - LOAD_OFFSET) {
PAGE_ALIGNED_DATA(PAGE_SIZE)
}
.data..cacheline_aligned : AT(ADDR(.data..cacheline_aligned) - LOAD_OFFSET) {
CACHELINE_ALIGNED_DATA(L1_CACHE_BYTES)
}
.data..read_mostly : AT(ADDR(.data..read_mostly) - LOAD_OFFSET) {
READ_MOSTLY_DATA(L1_CACHE_BYTES)
}
. = ALIGN(PAGE_SIZE);
.data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) {
NOSAVE_DATA
}
BUG_TABLE
. = ALIGN(PAGE_SIZE);
_edata = .;
PROVIDE32 (edata = .);
/*
* And finally the bss
*/
BSS_SECTION(0, 0, 0)
. = ALIGN(PAGE_SIZE);
_end = . ;
PROVIDE32 (end = .);
DWARF_DEBUG
ELF_DETAILS
DISCARDS
/DISCARD/ : {
*(*.EMB.apuinfo)
*(.glink .iplt .plt)
*(.gnu.version*)
*(.gnu.attributes)
*(.eh_frame)
#ifndef CONFIG_RELOCATABLE
*(.rela*)
#endif
}
}