6569580de7
Ld knows about 2 kinds of symbols, absolute and section relative. Section relative symbols symbols change value when a section is moved and absolute symbols do not. Currently in the linker script we have several labels marking the beginning and ending of sections that are outside of sections, making them absolute symbols. Having a mixture of absolute and section relative symbols refereing to the same data is currently harmless but it is confusing. This must be done carefully as newer revs of ld do not place symbols that appear in sections without data and instead ld makes those symbols global :( My ultimate goal is to build a relocatable kernel. The safest and least intrusive technique is to generate relocation entries so the kernel can be relocated at load time. The only penalty would be an increase in the size of the kernel binary. The problem is that if absolute and relocatable symbols are not properly specified absolute symbols will be relocated or section relative symbols won't be, which is fatal. The practical motivation is that when generating kernels that will run from a reserved area for analyzing what caused a kernel panic, it is simpler if you don't need to hard code the physical memory location they will run at, especially for the distributions. [AK: and merged:] o Also put a message so that in future people can be aware of it and avoid introducing absolute symbols. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
235 lines
7.8 KiB
C
235 lines
7.8 KiB
C
#ifndef LOAD_OFFSET
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#define LOAD_OFFSET 0
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#endif
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#ifndef VMLINUX_SYMBOL
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#define VMLINUX_SYMBOL(_sym_) _sym_
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#endif
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/* Align . to a 8 byte boundary equals to maximum function alignment. */
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#define ALIGN_FUNCTION() . = ALIGN(8)
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#define RODATA \
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. = ALIGN(4096); \
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.rodata : AT(ADDR(.rodata) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start_rodata) = .; \
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*(.rodata) *(.rodata.*) \
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*(__vermagic) /* Kernel version magic */ \
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} \
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\
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.rodata1 : AT(ADDR(.rodata1) - LOAD_OFFSET) { \
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*(.rodata1) \
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} \
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\
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/* PCI quirks */ \
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.pci_fixup : AT(ADDR(.pci_fixup) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start_pci_fixups_early) = .; \
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*(.pci_fixup_early) \
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VMLINUX_SYMBOL(__end_pci_fixups_early) = .; \
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VMLINUX_SYMBOL(__start_pci_fixups_header) = .; \
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*(.pci_fixup_header) \
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VMLINUX_SYMBOL(__end_pci_fixups_header) = .; \
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VMLINUX_SYMBOL(__start_pci_fixups_final) = .; \
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*(.pci_fixup_final) \
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VMLINUX_SYMBOL(__end_pci_fixups_final) = .; \
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VMLINUX_SYMBOL(__start_pci_fixups_enable) = .; \
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*(.pci_fixup_enable) \
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VMLINUX_SYMBOL(__end_pci_fixups_enable) = .; \
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} \
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\
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/* RapidIO route ops */ \
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.rio_route : AT(ADDR(.rio_route) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start_rio_route_ops) = .; \
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*(.rio_route_ops) \
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VMLINUX_SYMBOL(__end_rio_route_ops) = .; \
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} \
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\
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/* Kernel symbol table: Normal symbols */ \
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__ksymtab : AT(ADDR(__ksymtab) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start___ksymtab) = .; \
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*(__ksymtab) \
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VMLINUX_SYMBOL(__stop___ksymtab) = .; \
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} \
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\
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/* Kernel symbol table: GPL-only symbols */ \
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__ksymtab_gpl : AT(ADDR(__ksymtab_gpl) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start___ksymtab_gpl) = .; \
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*(__ksymtab_gpl) \
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VMLINUX_SYMBOL(__stop___ksymtab_gpl) = .; \
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} \
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\
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/* Kernel symbol table: Normal unused symbols */ \
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__ksymtab_unused : AT(ADDR(__ksymtab_unused) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start___ksymtab_unused) = .; \
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*(__ksymtab_unused) \
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VMLINUX_SYMBOL(__stop___ksymtab_unused) = .; \
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} \
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\
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/* Kernel symbol table: GPL-only unused symbols */ \
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__ksymtab_unused_gpl : AT(ADDR(__ksymtab_unused_gpl) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start___ksymtab_unused_gpl) = .; \
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*(__ksymtab_unused_gpl) \
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VMLINUX_SYMBOL(__stop___ksymtab_unused_gpl) = .; \
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} \
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\
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/* Kernel symbol table: GPL-future-only symbols */ \
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__ksymtab_gpl_future : AT(ADDR(__ksymtab_gpl_future) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start___ksymtab_gpl_future) = .; \
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*(__ksymtab_gpl_future) \
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VMLINUX_SYMBOL(__stop___ksymtab_gpl_future) = .; \
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} \
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\
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/* Kernel symbol table: Normal symbols */ \
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__kcrctab : AT(ADDR(__kcrctab) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start___kcrctab) = .; \
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*(__kcrctab) \
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VMLINUX_SYMBOL(__stop___kcrctab) = .; \
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} \
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\
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/* Kernel symbol table: GPL-only symbols */ \
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__kcrctab_gpl : AT(ADDR(__kcrctab_gpl) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start___kcrctab_gpl) = .; \
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*(__kcrctab_gpl) \
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VMLINUX_SYMBOL(__stop___kcrctab_gpl) = .; \
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} \
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\
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/* Kernel symbol table: Normal unused symbols */ \
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__kcrctab_unused : AT(ADDR(__kcrctab_unused) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start___kcrctab_unused) = .; \
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*(__kcrctab_unused) \
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VMLINUX_SYMBOL(__stop___kcrctab_unused) = .; \
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} \
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\
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/* Kernel symbol table: GPL-only unused symbols */ \
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__kcrctab_unused_gpl : AT(ADDR(__kcrctab_unused_gpl) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start___kcrctab_unused_gpl) = .; \
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*(__kcrctab_unused_gpl) \
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VMLINUX_SYMBOL(__stop___kcrctab_unused_gpl) = .; \
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} \
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\
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/* Kernel symbol table: GPL-future-only symbols */ \
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__kcrctab_gpl_future : AT(ADDR(__kcrctab_gpl_future) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start___kcrctab_gpl_future) = .; \
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*(__kcrctab_gpl_future) \
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VMLINUX_SYMBOL(__stop___kcrctab_gpl_future) = .; \
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} \
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\
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/* Kernel symbol table: strings */ \
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__ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) { \
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*(__ksymtab_strings) \
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} \
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\
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/* Unwind data binary search table */ \
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EH_FRAME_HDR \
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\
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/* Built-in module parameters. */ \
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__param : AT(ADDR(__param) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start___param) = .; \
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*(__param) \
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VMLINUX_SYMBOL(__stop___param) = .; \
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VMLINUX_SYMBOL(__end_rodata) = .; \
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} \
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\
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. = ALIGN(4096);
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#define SECURITY_INIT \
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.security_initcall.init : AT(ADDR(.security_initcall.init) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__security_initcall_start) = .; \
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*(.security_initcall.init) \
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VMLINUX_SYMBOL(__security_initcall_end) = .; \
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}
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/* sched.text is aling to function alignment to secure we have same
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* address even at second ld pass when generating System.map */
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#define SCHED_TEXT \
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ALIGN_FUNCTION(); \
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VMLINUX_SYMBOL(__sched_text_start) = .; \
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*(.sched.text) \
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VMLINUX_SYMBOL(__sched_text_end) = .;
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/* spinlock.text is aling to function alignment to secure we have same
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* address even at second ld pass when generating System.map */
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#define LOCK_TEXT \
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ALIGN_FUNCTION(); \
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VMLINUX_SYMBOL(__lock_text_start) = .; \
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*(.spinlock.text) \
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VMLINUX_SYMBOL(__lock_text_end) = .;
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#define KPROBES_TEXT \
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ALIGN_FUNCTION(); \
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VMLINUX_SYMBOL(__kprobes_text_start) = .; \
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*(.kprobes.text) \
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VMLINUX_SYMBOL(__kprobes_text_end) = .;
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#ifdef CONFIG_STACK_UNWIND
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/* Unwind data binary search table */
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#define EH_FRAME_HDR \
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.eh_frame_hdr : AT(ADDR(.eh_frame_hdr) - LOAD_OFFSET) { \
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VMLINUX_SYMBOL(__start_unwind_hdr) = .; \
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*(.eh_frame_hdr) \
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VMLINUX_SYMBOL(__end_unwind_hdr) = .; \
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}
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#else
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#define EH_FRAME_HDR
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#endif
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/* DWARF debug sections.
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Symbols in the DWARF debugging sections are relative to
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the beginning of the section so we begin them at 0. */
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#define DWARF_DEBUG \
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/* DWARF 1 */ \
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.debug 0 : { *(.debug) } \
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.line 0 : { *(.line) } \
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/* GNU DWARF 1 extensions */ \
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.debug_srcinfo 0 : { *(.debug_srcinfo) } \
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.debug_sfnames 0 : { *(.debug_sfnames) } \
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/* DWARF 1.1 and DWARF 2 */ \
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.debug_aranges 0 : { *(.debug_aranges) } \
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.debug_pubnames 0 : { *(.debug_pubnames) } \
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/* DWARF 2 */ \
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.debug_info 0 : { *(.debug_info \
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.gnu.linkonce.wi.*) } \
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.debug_abbrev 0 : { *(.debug_abbrev) } \
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.debug_line 0 : { *(.debug_line) } \
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.debug_frame 0 : { *(.debug_frame) } \
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.debug_str 0 : { *(.debug_str) } \
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.debug_loc 0 : { *(.debug_loc) } \
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.debug_macinfo 0 : { *(.debug_macinfo) } \
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/* SGI/MIPS DWARF 2 extensions */ \
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.debug_weaknames 0 : { *(.debug_weaknames) } \
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.debug_funcnames 0 : { *(.debug_funcnames) } \
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.debug_typenames 0 : { *(.debug_typenames) } \
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.debug_varnames 0 : { *(.debug_varnames) } \
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/* Stabs debugging sections. */
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#define STABS_DEBUG \
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.stab 0 : { *(.stab) } \
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.stabstr 0 : { *(.stabstr) } \
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.stab.excl 0 : { *(.stab.excl) } \
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.stab.exclstr 0 : { *(.stab.exclstr) } \
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.stab.index 0 : { *(.stab.index) } \
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.stab.indexstr 0 : { *(.stab.indexstr) } \
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.comment 0 : { *(.comment) }
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#define NOTES \
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.notes : { *(.note.*) } :note
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#define INITCALLS \
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*(.initcall0.init) \
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*(.initcall0s.init) \
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*(.initcall1.init) \
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*(.initcall1s.init) \
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*(.initcall2.init) \
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*(.initcall2s.init) \
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*(.initcall3.init) \
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*(.initcall3s.init) \
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*(.initcall4.init) \
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*(.initcall4s.init) \
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*(.initcall5.init) \
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*(.initcall5s.init) \
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*(.initcall6.init) \
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*(.initcall6s.init) \
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*(.initcall7.init) \
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*(.initcall7s.init)
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