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linux/include/asm-generic/vmlinux.lds.h
Sami Tolvanen cf68fffb66 add support for Clang CFI 
This change adds support for Clang’s forward-edge Control Flow
Integrity (CFI) checking. With CONFIG_CFI_CLANG, the compiler
injects a runtime check before each indirect function call to ensure
the target is a valid function with the correct static type. This
restricts possible call targets and makes it more difficult for
an attacker to exploit bugs that allow the modification of stored
function pointers. For more details, see:

  https://clang.llvm.org/docs/ControlFlowIntegrity.html

Clang requires CONFIG_LTO_CLANG to be enabled with CFI to gain
visibility to possible call targets. Kernel modules are supported
with Clang’s cross-DSO CFI mode, which allows checking between
independently compiled components.

With CFI enabled, the compiler injects a __cfi_check() function into
the kernel and each module for validating local call targets. For
cross-module calls that cannot be validated locally, the compiler
calls the global __cfi_slowpath_diag() function, which determines
the target module and calls the correct __cfi_check() function. This
patch includes a slowpath implementation that uses __module_address()
to resolve call targets, and with CONFIG_CFI_CLANG_SHADOW enabled, a
shadow map that speeds up module look-ups by ~3x.

Clang implements indirect call checking using jump tables and
offers two methods of generating them. With canonical jump tables,
the compiler renames each address-taken function to <function>.cfi
and points the original symbol to a jump table entry, which passes
__cfi_check() validation. This isn’t compatible with stand-alone
assembly code, which the compiler doesn’t instrument, and would
result in indirect calls to assembly code to fail. Therefore, we
default to using non-canonical jump tables instead, where the compiler
generates a local jump table entry <function>.cfi_jt for each
address-taken function, and replaces all references to the function
with the address of the jump table entry.

Note that because non-canonical jump table addresses are local
to each component, they break cross-module function address
equality. Specifically, the address of a global function will be
different in each module, as it's replaced with the address of a local
jump table entry. If this address is passed to a different module,
it won’t match the address of the same function taken there. This
may break code that relies on comparing addresses passed from other
components.

CFI checking can be disabled in a function with the __nocfi attribute.
Additionally, CFI can be disabled for an entire compilation unit by
filtering out CC_FLAGS_CFI.

By default, CFI failures result in a kernel panic to stop a potential
exploit. CONFIG_CFI_PERMISSIVE enables a permissive mode, where the
kernel prints out a rate-limited warning instead, and allows execution
to continue. This option is helpful for locating type mismatches, but
should only be enabled during development.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210408182843.1754385-2-samitolvanen@google.com
2021-04-08 16:04:20 -07:00

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/*
* Helper macros to support writing architecture specific
* linker scripts.
*
* A minimal linker scripts has following content:
* [This is a sample, architectures may have special requiriements]
*
* OUTPUT_FORMAT(...)
* OUTPUT_ARCH(...)
* ENTRY(...)
* SECTIONS
* {
* . = START;
* __init_begin = .;
* HEAD_TEXT_SECTION
* INIT_TEXT_SECTION(PAGE_SIZE)
* INIT_DATA_SECTION(...)
* PERCPU_SECTION(CACHELINE_SIZE)
* __init_end = .;
*
* _stext = .;
* TEXT_SECTION = 0
* _etext = .;
*
* _sdata = .;
* RO_DATA(PAGE_SIZE)
* RW_DATA(...)
* _edata = .;
*
* EXCEPTION_TABLE(...)
*
* BSS_SECTION(0, 0, 0)
* _end = .;
*
* STABS_DEBUG
* DWARF_DEBUG
* ELF_DETAILS
*
* DISCARDS // must be the last
* }
*
* [__init_begin, __init_end] is the init section that may be freed after init
* // __init_begin and __init_end should be page aligned, so that we can
* // free the whole .init memory
* [_stext, _etext] is the text section
* [_sdata, _edata] is the data section
*
* Some of the included output section have their own set of constants.
* Examples are: [__initramfs_start, __initramfs_end] for initramfs and
* [__nosave_begin, __nosave_end] for the nosave data
*/
#ifndef LOAD_OFFSET
#define LOAD_OFFSET 0
#endif
/*
* Only some architectures want to have the .notes segment visible in
* a separate PT_NOTE ELF Program Header. When this happens, it needs
* to be visible in both the kernel text's PT_LOAD and the PT_NOTE
* Program Headers. In this case, though, the PT_LOAD needs to be made
* the default again so that all the following sections don't also end
* up in the PT_NOTE Program Header.
*/
#ifdef EMITS_PT_NOTE
#define NOTES_HEADERS :text :note
#define NOTES_HEADERS_RESTORE __restore_ph : { *(.__restore_ph) } :text
#else
#define NOTES_HEADERS
#define NOTES_HEADERS_RESTORE
#endif
/*
* Some architectures have non-executable read-only exception tables.
* They can be added to the RO_DATA segment by specifying their desired
* alignment.
*/
#ifdef RO_EXCEPTION_TABLE_ALIGN
#define RO_EXCEPTION_TABLE EXCEPTION_TABLE(RO_EXCEPTION_TABLE_ALIGN)
#else
#define RO_EXCEPTION_TABLE
#endif
/* Align . to a 8 byte boundary equals to maximum function alignment. */
#define ALIGN_FUNCTION() . = ALIGN(8)
/*
* LD_DEAD_CODE_DATA_ELIMINATION option enables -fdata-sections, which
* generates .data.identifier sections, which need to be pulled in with
* .data. We don't want to pull in .data..other sections, which Linux
* has defined. Same for text and bss.
*
* With LTO_CLANG, the linker also splits sections by default, so we need
* these macros to combine the sections during the final link.
*
* RODATA_MAIN is not used because existing code already defines .rodata.x
* sections to be brought in with rodata.
*/
#if defined(CONFIG_LD_DEAD_CODE_DATA_ELIMINATION) || defined(CONFIG_LTO_CLANG)
#define TEXT_MAIN .text .text.[0-9a-zA-Z_]*
#define DATA_MAIN .data .data.[0-9a-zA-Z_]* .data..L* .data..compoundliteral* .data.$__unnamed_* .data.$L*
#define SDATA_MAIN .sdata .sdata.[0-9a-zA-Z_]*
#define RODATA_MAIN .rodata .rodata.[0-9a-zA-Z_]* .rodata..L*
#define BSS_MAIN .bss .bss.[0-9a-zA-Z_]* .bss..compoundliteral*
#define SBSS_MAIN .sbss .sbss.[0-9a-zA-Z_]*
#else
#define TEXT_MAIN .text
#define DATA_MAIN .data
#define SDATA_MAIN .sdata
#define RODATA_MAIN .rodata
#define BSS_MAIN .bss
#define SBSS_MAIN .sbss
#endif
/*
* GCC 4.5 and later have a 32 bytes section alignment for structures.
* Except GCC 4.9, that feels the need to align on 64 bytes.
*/
#if __GNUC__ == 4 && __GNUC_MINOR__ == 9
#define STRUCT_ALIGNMENT 64
#else
#define STRUCT_ALIGNMENT 32
#endif
#define STRUCT_ALIGN() . = ALIGN(STRUCT_ALIGNMENT)
/*
* The order of the sched class addresses are important, as they are
* used to determine the order of the priority of each sched class in
* relation to each other.
*/
#define SCHED_DATA \
STRUCT_ALIGN(); \
__begin_sched_classes = .; \
*(__idle_sched_class) \
*(__fair_sched_class) \
*(__rt_sched_class) \
*(__dl_sched_class) \
*(__stop_sched_class) \
__end_sched_classes = .;
/* The actual configuration determine if the init/exit sections
* are handled as text/data or they can be discarded (which
* often happens at runtime)
*/
#ifdef CONFIG_HOTPLUG_CPU
#define CPU_KEEP(sec) *(.cpu##sec)
#define CPU_DISCARD(sec)
#else
#define CPU_KEEP(sec)
#define CPU_DISCARD(sec) *(.cpu##sec)
#endif
#if defined(CONFIG_MEMORY_HOTPLUG)
#define MEM_KEEP(sec) *(.mem##sec)
#define MEM_DISCARD(sec)
#else
#define MEM_KEEP(sec)
#define MEM_DISCARD(sec) *(.mem##sec)
#endif
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
/*
* The ftrace call sites are logged to a section whose name depends on the
* compiler option used. A given kernel image will only use one, AKA
* FTRACE_CALLSITE_SECTION. We capture all of them here to avoid header
* dependencies for FTRACE_CALLSITE_SECTION's definition.
*
* Need to also make ftrace_stub_graph point to ftrace_stub
* so that the same stub location may have different protocols
* and not mess up with C verifiers.
*/
#define MCOUNT_REC() . = ALIGN(8); \
__start_mcount_loc = .; \
KEEP(*(__mcount_loc)) \
KEEP(*(__patchable_function_entries)) \
__stop_mcount_loc = .; \
ftrace_stub_graph = ftrace_stub;
#else
# ifdef CONFIG_FUNCTION_TRACER
# define MCOUNT_REC() ftrace_stub_graph = ftrace_stub;
# else
# define MCOUNT_REC()
# endif
#endif
#ifdef CONFIG_TRACE_BRANCH_PROFILING
#define LIKELY_PROFILE() __start_annotated_branch_profile = .; \
KEEP(*(_ftrace_annotated_branch)) \
__stop_annotated_branch_profile = .;
#else
#define LIKELY_PROFILE()
#endif
#ifdef CONFIG_PROFILE_ALL_BRANCHES
#define BRANCH_PROFILE() __start_branch_profile = .; \
KEEP(*(_ftrace_branch)) \
__stop_branch_profile = .;
#else
#define BRANCH_PROFILE()
#endif
#ifdef CONFIG_KPROBES
#define KPROBE_BLACKLIST() . = ALIGN(8); \
__start_kprobe_blacklist = .; \
KEEP(*(_kprobe_blacklist)) \
__stop_kprobe_blacklist = .;
#else
#define KPROBE_BLACKLIST()
#endif
#ifdef CONFIG_FUNCTION_ERROR_INJECTION
#define ERROR_INJECT_WHITELIST() STRUCT_ALIGN(); \
__start_error_injection_whitelist = .; \
KEEP(*(_error_injection_whitelist)) \
__stop_error_injection_whitelist = .;
#else
#define ERROR_INJECT_WHITELIST()
#endif
#ifdef CONFIG_EVENT_TRACING
#define FTRACE_EVENTS() . = ALIGN(8); \
__start_ftrace_events = .; \
KEEP(*(_ftrace_events)) \
__stop_ftrace_events = .; \
__start_ftrace_eval_maps = .; \
KEEP(*(_ftrace_eval_map)) \
__stop_ftrace_eval_maps = .;
#else
#define FTRACE_EVENTS()
#endif
#ifdef CONFIG_TRACING
#define TRACE_PRINTKS() __start___trace_bprintk_fmt = .; \
KEEP(*(__trace_printk_fmt)) /* Trace_printk fmt' pointer */ \
__stop___trace_bprintk_fmt = .;
#define TRACEPOINT_STR() __start___tracepoint_str = .; \
KEEP(*(__tracepoint_str)) /* Trace_printk fmt' pointer */ \
__stop___tracepoint_str = .;
#else
#define TRACE_PRINTKS()
#define TRACEPOINT_STR()
#endif
#ifdef CONFIG_FTRACE_SYSCALLS
#define TRACE_SYSCALLS() . = ALIGN(8); \
__start_syscalls_metadata = .; \
KEEP(*(__syscalls_metadata)) \
__stop_syscalls_metadata = .;
#else
#define TRACE_SYSCALLS()
#endif
#ifdef CONFIG_BPF_EVENTS
#define BPF_RAW_TP() STRUCT_ALIGN(); \
__start__bpf_raw_tp = .; \
KEEP(*(__bpf_raw_tp_map)) \
__stop__bpf_raw_tp = .;
#else
#define BPF_RAW_TP()
#endif
#ifdef CONFIG_SERIAL_EARLYCON
#define EARLYCON_TABLE() . = ALIGN(8); \
__earlycon_table = .; \
KEEP(*(__earlycon_table)) \
__earlycon_table_end = .;
#else
#define EARLYCON_TABLE()
#endif
#ifdef CONFIG_SECURITY
#define LSM_TABLE() . = ALIGN(8); \
__start_lsm_info = .; \
KEEP(*(.lsm_info.init)) \
__end_lsm_info = .;
#define EARLY_LSM_TABLE() . = ALIGN(8); \
__start_early_lsm_info = .; \
KEEP(*(.early_lsm_info.init)) \
__end_early_lsm_info = .;
#else
#define LSM_TABLE()
#define EARLY_LSM_TABLE()
#endif
#define ___OF_TABLE(cfg, name) _OF_TABLE_##cfg(name)
#define __OF_TABLE(cfg, name) ___OF_TABLE(cfg, name)
#define OF_TABLE(cfg, name) __OF_TABLE(IS_ENABLED(cfg), name)
#define _OF_TABLE_0(name)
#define _OF_TABLE_1(name) \
. = ALIGN(8); \
__##name##_of_table = .; \
KEEP(*(__##name##_of_table)) \
KEEP(*(__##name##_of_table_end))
#define TIMER_OF_TABLES() OF_TABLE(CONFIG_TIMER_OF, timer)
#define IRQCHIP_OF_MATCH_TABLE() OF_TABLE(CONFIG_IRQCHIP, irqchip)
#define CLK_OF_TABLES() OF_TABLE(CONFIG_COMMON_CLK, clk)
#define RESERVEDMEM_OF_TABLES() OF_TABLE(CONFIG_OF_RESERVED_MEM, reservedmem)
#define CPU_METHOD_OF_TABLES() OF_TABLE(CONFIG_SMP, cpu_method)
#define CPUIDLE_METHOD_OF_TABLES() OF_TABLE(CONFIG_CPU_IDLE, cpuidle_method)
#ifdef CONFIG_ACPI
#define ACPI_PROBE_TABLE(name) \
. = ALIGN(8); \
__##name##_acpi_probe_table = .; \
KEEP(*(__##name##_acpi_probe_table)) \
__##name##_acpi_probe_table_end = .;
#else
#define ACPI_PROBE_TABLE(name)
#endif
#ifdef CONFIG_THERMAL
#define THERMAL_TABLE(name) \
. = ALIGN(8); \
__##name##_thermal_table = .; \
KEEP(*(__##name##_thermal_table)) \
__##name##_thermal_table_end = .;
#else
#define THERMAL_TABLE(name)
#endif
#ifdef CONFIG_DTPM
#define DTPM_TABLE() \
. = ALIGN(8); \
__dtpm_table = .; \
KEEP(*(__dtpm_table)) \
__dtpm_table_end = .;
#else
#define DTPM_TABLE()
#endif
#define KERNEL_DTB() \
STRUCT_ALIGN(); \
__dtb_start = .; \
KEEP(*(.dtb.init.rodata)) \
__dtb_end = .;
/*
* .data section
*/
#define DATA_DATA \
*(.xiptext) \
*(DATA_MAIN) \
*(.ref.data) \
*(.data..shared_aligned) /* percpu related */ \
MEM_KEEP(init.data*) \
MEM_KEEP(exit.data*) \
*(.data.unlikely) \
__start_once = .; \
*(.data.once) \
__end_once = .; \
STRUCT_ALIGN(); \
*(__tracepoints) \
/* implement dynamic printk debug */ \
. = ALIGN(8); \
__start___dyndbg = .; \
KEEP(*(__dyndbg)) \
__stop___dyndbg = .; \
LIKELY_PROFILE() \
BRANCH_PROFILE() \
TRACE_PRINTKS() \
BPF_RAW_TP() \
TRACEPOINT_STR()
/*
* Data section helpers
*/
#define NOSAVE_DATA \
. = ALIGN(PAGE_SIZE); \
__nosave_begin = .; \
*(.data..nosave) \
. = ALIGN(PAGE_SIZE); \
__nosave_end = .;
#define PAGE_ALIGNED_DATA(page_align) \
. = ALIGN(page_align); \
*(.data..page_aligned) \
. = ALIGN(page_align);
#define READ_MOSTLY_DATA(align) \
. = ALIGN(align); \
*(.data..read_mostly) \
. = ALIGN(align);
#define CACHELINE_ALIGNED_DATA(align) \
. = ALIGN(align); \
*(.data..cacheline_aligned)
#define INIT_TASK_DATA(align) \
. = ALIGN(align); \
__start_init_task = .; \
init_thread_union = .; \
init_stack = .; \
KEEP(*(.data..init_task)) \
KEEP(*(.data..init_thread_info)) \
. = __start_init_task + THREAD_SIZE; \
__end_init_task = .;
#define JUMP_TABLE_DATA \
. = ALIGN(8); \
__start___jump_table = .; \
KEEP(*(__jump_table)) \
__stop___jump_table = .;
#define STATIC_CALL_DATA \
. = ALIGN(8); \
__start_static_call_sites = .; \
KEEP(*(.static_call_sites)) \
__stop_static_call_sites = .; \
__start_static_call_tramp_key = .; \
KEEP(*(.static_call_tramp_key)) \
__stop_static_call_tramp_key = .;
/*
* Allow architectures to handle ro_after_init data on their
* own by defining an empty RO_AFTER_INIT_DATA.
*/
#ifndef RO_AFTER_INIT_DATA
#define RO_AFTER_INIT_DATA \
. = ALIGN(8); \
__start_ro_after_init = .; \
*(.data..ro_after_init) \
JUMP_TABLE_DATA \
STATIC_CALL_DATA \
__end_ro_after_init = .;
#endif
/*
* Read only Data
*/
#define RO_DATA(align) \
. = ALIGN((align)); \
.rodata : AT(ADDR(.rodata) - LOAD_OFFSET) { \
__start_rodata = .; \
*(.rodata) *(.rodata.*) \
SCHED_DATA \
RO_AFTER_INIT_DATA /* Read only after init */ \
. = ALIGN(8); \
__start___tracepoints_ptrs = .; \
KEEP(*(__tracepoints_ptrs)) /* Tracepoints: pointer array */ \
__stop___tracepoints_ptrs = .; \
*(__tracepoints_strings)/* Tracepoints: strings */ \
} \
\
.rodata1 : AT(ADDR(.rodata1) - LOAD_OFFSET) { \
*(.rodata1) \
} \
\
/* PCI quirks */ \
.pci_fixup : AT(ADDR(.pci_fixup) - LOAD_OFFSET) { \
__start_pci_fixups_early = .; \
KEEP(*(.pci_fixup_early)) \
__end_pci_fixups_early = .; \
__start_pci_fixups_header = .; \
KEEP(*(.pci_fixup_header)) \
__end_pci_fixups_header = .; \
__start_pci_fixups_final = .; \
KEEP(*(.pci_fixup_final)) \
__end_pci_fixups_final = .; \
__start_pci_fixups_enable = .; \
KEEP(*(.pci_fixup_enable)) \
__end_pci_fixups_enable = .; \
__start_pci_fixups_resume = .; \
KEEP(*(.pci_fixup_resume)) \
__end_pci_fixups_resume = .; \
__start_pci_fixups_resume_early = .; \
KEEP(*(.pci_fixup_resume_early)) \
__end_pci_fixups_resume_early = .; \
__start_pci_fixups_suspend = .; \
KEEP(*(.pci_fixup_suspend)) \
__end_pci_fixups_suspend = .; \
__start_pci_fixups_suspend_late = .; \
KEEP(*(.pci_fixup_suspend_late)) \
__end_pci_fixups_suspend_late = .; \
} \
\
/* Built-in firmware blobs */ \
.builtin_fw : AT(ADDR(.builtin_fw) - LOAD_OFFSET) ALIGN(8) { \
__start_builtin_fw = .; \
KEEP(*(.builtin_fw)) \
__end_builtin_fw = .; \
} \
\
TRACEDATA \
\
/* Kernel symbol table: Normal symbols */ \
__ksymtab : AT(ADDR(__ksymtab) - LOAD_OFFSET) { \
__start___ksymtab = .; \
KEEP(*(SORT(___ksymtab+*))) \
__stop___ksymtab = .; \
} \
\
/* Kernel symbol table: GPL-only symbols */ \
__ksymtab_gpl : AT(ADDR(__ksymtab_gpl) - LOAD_OFFSET) { \
__start___ksymtab_gpl = .; \
KEEP(*(SORT(___ksymtab_gpl+*))) \
__stop___ksymtab_gpl = .; \
} \
\
/* Kernel symbol table: Normal symbols */ \
__kcrctab : AT(ADDR(__kcrctab) - LOAD_OFFSET) { \
__start___kcrctab = .; \
KEEP(*(SORT(___kcrctab+*))) \
__stop___kcrctab = .; \
} \
\
/* Kernel symbol table: GPL-only symbols */ \
__kcrctab_gpl : AT(ADDR(__kcrctab_gpl) - LOAD_OFFSET) { \
__start___kcrctab_gpl = .; \
KEEP(*(SORT(___kcrctab_gpl+*))) \
__stop___kcrctab_gpl = .; \
} \
\
/* Kernel symbol table: strings */ \
__ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) { \
*(__ksymtab_strings) \
} \
\
/* __*init sections */ \
__init_rodata : AT(ADDR(__init_rodata) - LOAD_OFFSET) { \
*(.ref.rodata) \
MEM_KEEP(init.rodata) \
MEM_KEEP(exit.rodata) \
} \
\
/* Built-in module parameters. */ \
__param : AT(ADDR(__param) - LOAD_OFFSET) { \
__start___param = .; \
KEEP(*(__param)) \
__stop___param = .; \
} \
\
/* Built-in module versions. */ \
__modver : AT(ADDR(__modver) - LOAD_OFFSET) { \
__start___modver = .; \
KEEP(*(__modver)) \
__stop___modver = .; \
} \
\
RO_EXCEPTION_TABLE \
NOTES \
BTF \
\
. = ALIGN((align)); \
__end_rodata = .;
/*
* .text..L.cfi.jumptable.* contain Control-Flow Integrity (CFI)
* jump table entries.
*/
#ifdef CONFIG_CFI_CLANG
#define TEXT_CFI_JT \
. = ALIGN(PMD_SIZE); \
__cfi_jt_start = .; \
*(.text..L.cfi.jumptable .text..L.cfi.jumptable.*) \
. = ALIGN(PMD_SIZE); \
__cfi_jt_end = .;
#else
#define TEXT_CFI_JT
#endif
/*
* Non-instrumentable text section
*/
#define NOINSTR_TEXT \
ALIGN_FUNCTION(); \
__noinstr_text_start = .; \
*(.noinstr.text) \
__noinstr_text_end = .;
/*
* .text section. Map to function alignment to avoid address changes
* during second ld run in second ld pass when generating System.map
*
* TEXT_MAIN here will match .text.fixup and .text.unlikely if dead
* code elimination is enabled, so these sections should be converted
* to use ".." first.
*/
#define TEXT_TEXT \
ALIGN_FUNCTION(); \
*(.text.hot .text.hot.*) \
*(TEXT_MAIN .text.fixup) \
*(.text.unlikely .text.unlikely.*) \
*(.text.unknown .text.unknown.*) \
NOINSTR_TEXT \
*(.text..refcount) \
*(.ref.text) \
TEXT_CFI_JT \
MEM_KEEP(init.text*) \
MEM_KEEP(exit.text*) \
/* sched.text is aling to function alignment to secure we have same
* address even at second ld pass when generating System.map */
#define SCHED_TEXT \
ALIGN_FUNCTION(); \
__sched_text_start = .; \
*(.sched.text) \
__sched_text_end = .;
/* spinlock.text is aling to function alignment to secure we have same
* address even at second ld pass when generating System.map */
#define LOCK_TEXT \
ALIGN_FUNCTION(); \
__lock_text_start = .; \
*(.spinlock.text) \
__lock_text_end = .;
#define CPUIDLE_TEXT \
ALIGN_FUNCTION(); \
__cpuidle_text_start = .; \
*(.cpuidle.text) \
__cpuidle_text_end = .;
#define KPROBES_TEXT \
ALIGN_FUNCTION(); \
__kprobes_text_start = .; \
*(.kprobes.text) \
__kprobes_text_end = .;
#define ENTRY_TEXT \
ALIGN_FUNCTION(); \
__entry_text_start = .; \
*(.entry.text) \
__entry_text_end = .;
#define IRQENTRY_TEXT \
ALIGN_FUNCTION(); \
__irqentry_text_start = .; \
*(.irqentry.text) \
__irqentry_text_end = .;
#define SOFTIRQENTRY_TEXT \
ALIGN_FUNCTION(); \
__softirqentry_text_start = .; \
*(.softirqentry.text) \
__softirqentry_text_end = .;
#define STATIC_CALL_TEXT \
ALIGN_FUNCTION(); \
__static_call_text_start = .; \
*(.static_call.text) \
__static_call_text_end = .;
/* Section used for early init (in .S files) */
#define HEAD_TEXT KEEP(*(.head.text))
#define HEAD_TEXT_SECTION \
.head.text : AT(ADDR(.head.text) - LOAD_OFFSET) { \
HEAD_TEXT \
}
/*
* Exception table
*/
#define EXCEPTION_TABLE(align) \
. = ALIGN(align); \
__ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { \
__start___ex_table = .; \
KEEP(*(__ex_table)) \
__stop___ex_table = .; \
}
/*
* .BTF
*/
#ifdef CONFIG_DEBUG_INFO_BTF
#define BTF \
.BTF : AT(ADDR(.BTF) - LOAD_OFFSET) { \
__start_BTF = .; \
KEEP(*(.BTF)) \
__stop_BTF = .; \
} \
. = ALIGN(4); \
.BTF_ids : AT(ADDR(.BTF_ids) - LOAD_OFFSET) { \
*(.BTF_ids) \
}
#else
#define BTF
#endif
/*
* Init task
*/
#define INIT_TASK_DATA_SECTION(align) \
. = ALIGN(align); \
.data..init_task : AT(ADDR(.data..init_task) - LOAD_OFFSET) { \
INIT_TASK_DATA(align) \
}
#ifdef CONFIG_CONSTRUCTORS
#define KERNEL_CTORS() . = ALIGN(8); \
__ctors_start = .; \
KEEP(*(SORT(.ctors.*))) \
KEEP(*(.ctors)) \
KEEP(*(SORT(.init_array.*))) \
KEEP(*(.init_array)) \
__ctors_end = .;
#else
#define KERNEL_CTORS()
#endif
/* init and exit section handling */
#define INIT_DATA \
KEEP(*(SORT(___kentry+*))) \
*(.init.data init.data.*) \
MEM_DISCARD(init.data*) \
KERNEL_CTORS() \
MCOUNT_REC() \
*(.init.rodata .init.rodata.*) \
FTRACE_EVENTS() \
TRACE_SYSCALLS() \
KPROBE_BLACKLIST() \
ERROR_INJECT_WHITELIST() \
MEM_DISCARD(init.rodata) \
CLK_OF_TABLES() \
RESERVEDMEM_OF_TABLES() \
TIMER_OF_TABLES() \
CPU_METHOD_OF_TABLES() \
CPUIDLE_METHOD_OF_TABLES() \
KERNEL_DTB() \
IRQCHIP_OF_MATCH_TABLE() \
ACPI_PROBE_TABLE(irqchip) \
ACPI_PROBE_TABLE(timer) \
THERMAL_TABLE(governor) \
DTPM_TABLE() \
EARLYCON_TABLE() \
LSM_TABLE() \
EARLY_LSM_TABLE() \
KUNIT_TABLE()
#define INIT_TEXT \
*(.init.text .init.text.*) \
*(.text.startup) \
MEM_DISCARD(init.text*)
#define EXIT_DATA \
*(.exit.data .exit.data.*) \
*(.fini_array .fini_array.*) \
*(.dtors .dtors.*) \
MEM_DISCARD(exit.data*) \
MEM_DISCARD(exit.rodata*)
#define EXIT_TEXT \
*(.exit.text) \
*(.text.exit) \
MEM_DISCARD(exit.text)
#define EXIT_CALL \
*(.exitcall.exit)
/*
* bss (Block Started by Symbol) - uninitialized data
* zeroed during startup
*/
#define SBSS(sbss_align) \
. = ALIGN(sbss_align); \
.sbss : AT(ADDR(.sbss) - LOAD_OFFSET) { \
*(.dynsbss) \
*(SBSS_MAIN) \
*(.scommon) \
}
/*
* Allow archectures to redefine BSS_FIRST_SECTIONS to add extra
* sections to the front of bss.
*/
#ifndef BSS_FIRST_SECTIONS
#define BSS_FIRST_SECTIONS
#endif
#define BSS(bss_align) \
. = ALIGN(bss_align); \
.bss : AT(ADDR(.bss) - LOAD_OFFSET) { \
BSS_FIRST_SECTIONS \
. = ALIGN(PAGE_SIZE); \
*(.bss..page_aligned) \
. = ALIGN(PAGE_SIZE); \
*(.dynbss) \
*(BSS_MAIN) \
*(COMMON) \
}
/*
* DWARF debug sections.
* Symbols in the DWARF debugging sections are relative to
* the beginning of the section so we begin them at 0.
*/
#define DWARF_DEBUG \
/* DWARF 1 */ \
.debug 0 : { *(.debug) } \
.line 0 : { *(.line) } \
/* GNU DWARF 1 extensions */ \
.debug_srcinfo 0 : { *(.debug_srcinfo) } \
.debug_sfnames 0 : { *(.debug_sfnames) } \
/* DWARF 1.1 and DWARF 2 */ \
.debug_aranges 0 : { *(.debug_aranges) } \
.debug_pubnames 0 : { *(.debug_pubnames) } \
/* DWARF 2 */ \
.debug_info 0 : { *(.debug_info \
.gnu.linkonce.wi.*) } \
.debug_abbrev 0 : { *(.debug_abbrev) } \
.debug_line 0 : { *(.debug_line) } \
.debug_frame 0 : { *(.debug_frame) } \
.debug_str 0 : { *(.debug_str) } \
.debug_loc 0 : { *(.debug_loc) } \
.debug_macinfo 0 : { *(.debug_macinfo) } \
.debug_pubtypes 0 : { *(.debug_pubtypes) } \
/* DWARF 3 */ \
.debug_ranges 0 : { *(.debug_ranges) } \
/* SGI/MIPS DWARF 2 extensions */ \
.debug_weaknames 0 : { *(.debug_weaknames) } \
.debug_funcnames 0 : { *(.debug_funcnames) } \
.debug_typenames 0 : { *(.debug_typenames) } \
.debug_varnames 0 : { *(.debug_varnames) } \
/* GNU DWARF 2 extensions */ \
.debug_gnu_pubnames 0 : { *(.debug_gnu_pubnames) } \
.debug_gnu_pubtypes 0 : { *(.debug_gnu_pubtypes) } \
/* DWARF 4 */ \
.debug_types 0 : { *(.debug_types) } \
/* DWARF 5 */ \
.debug_addr 0 : { *(.debug_addr) } \
.debug_line_str 0 : { *(.debug_line_str) } \
.debug_loclists 0 : { *(.debug_loclists) } \
.debug_macro 0 : { *(.debug_macro) } \
.debug_names 0 : { *(.debug_names) } \
.debug_rnglists 0 : { *(.debug_rnglists) } \
.debug_str_offsets 0 : { *(.debug_str_offsets) }
/* Stabs debugging sections. */
#define STABS_DEBUG \
.stab 0 : { *(.stab) } \
.stabstr 0 : { *(.stabstr) } \
.stab.excl 0 : { *(.stab.excl) } \
.stab.exclstr 0 : { *(.stab.exclstr) } \
.stab.index 0 : { *(.stab.index) } \
.stab.indexstr 0 : { *(.stab.indexstr) }
/* Required sections not related to debugging. */
#define ELF_DETAILS \
.comment 0 : { *(.comment) } \
.symtab 0 : { *(.symtab) } \
.strtab 0 : { *(.strtab) } \
.shstrtab 0 : { *(.shstrtab) }
#ifdef CONFIG_GENERIC_BUG
#define BUG_TABLE \
. = ALIGN(8); \
__bug_table : AT(ADDR(__bug_table) - LOAD_OFFSET) { \
__start___bug_table = .; \
KEEP(*(__bug_table)) \
__stop___bug_table = .; \
}
#else
#define BUG_TABLE
#endif
#ifdef CONFIG_UNWINDER_ORC
#define ORC_UNWIND_TABLE \
. = ALIGN(4); \
.orc_unwind_ip : AT(ADDR(.orc_unwind_ip) - LOAD_OFFSET) { \
__start_orc_unwind_ip = .; \
KEEP(*(.orc_unwind_ip)) \
__stop_orc_unwind_ip = .; \
} \
. = ALIGN(2); \
.orc_unwind : AT(ADDR(.orc_unwind) - LOAD_OFFSET) { \
__start_orc_unwind = .; \
KEEP(*(.orc_unwind)) \
__stop_orc_unwind = .; \
} \
. = ALIGN(4); \
.orc_lookup : AT(ADDR(.orc_lookup) - LOAD_OFFSET) { \
orc_lookup = .; \
. += (((SIZEOF(.text) + LOOKUP_BLOCK_SIZE - 1) / \
LOOKUP_BLOCK_SIZE) + 1) * 4; \
orc_lookup_end = .; \
}
#else
#define ORC_UNWIND_TABLE
#endif
#ifdef CONFIG_PM_TRACE
#define TRACEDATA \
. = ALIGN(4); \
.tracedata : AT(ADDR(.tracedata) - LOAD_OFFSET) { \
__tracedata_start = .; \
KEEP(*(.tracedata)) \
__tracedata_end = .; \
}
#else
#define TRACEDATA
#endif
#define NOTES \
.notes : AT(ADDR(.notes) - LOAD_OFFSET) { \
__start_notes = .; \
KEEP(*(.note.*)) \
__stop_notes = .; \
} NOTES_HEADERS \
NOTES_HEADERS_RESTORE
#define INIT_SETUP(initsetup_align) \
. = ALIGN(initsetup_align); \
__setup_start = .; \
KEEP(*(.init.setup)) \
__setup_end = .;
#define INIT_CALLS_LEVEL(level) \
__initcall##level##_start = .; \
KEEP(*(.initcall##level##.init)) \
KEEP(*(.initcall##level##s.init)) \
#define INIT_CALLS \
__initcall_start = .; \
KEEP(*(.initcallearly.init)) \
INIT_CALLS_LEVEL(0) \
INIT_CALLS_LEVEL(1) \
INIT_CALLS_LEVEL(2) \
INIT_CALLS_LEVEL(3) \
INIT_CALLS_LEVEL(4) \
INIT_CALLS_LEVEL(5) \
INIT_CALLS_LEVEL(rootfs) \
INIT_CALLS_LEVEL(6) \
INIT_CALLS_LEVEL(7) \
__initcall_end = .;
#define CON_INITCALL \
__con_initcall_start = .; \
KEEP(*(.con_initcall.init)) \
__con_initcall_end = .;
/* Alignment must be consistent with (kunit_suite *) in include/kunit/test.h */
#define KUNIT_TABLE() \
. = ALIGN(8); \
__kunit_suites_start = .; \
KEEP(*(.kunit_test_suites)) \
__kunit_suites_end = .;
#ifdef CONFIG_BLK_DEV_INITRD
#define INIT_RAM_FS \
. = ALIGN(4); \
__initramfs_start = .; \
KEEP(*(.init.ramfs)) \
. = ALIGN(8); \
KEEP(*(.init.ramfs.info))
#else
#define INIT_RAM_FS
#endif
/*
* Memory encryption operates on a page basis. Since we need to clear
* the memory encryption mask for this section, it needs to be aligned
* on a page boundary and be a page-size multiple in length.
*
* Note: We use a separate section so that only this section gets
* decrypted to avoid exposing more than we wish.
*/
#ifdef CONFIG_AMD_MEM_ENCRYPT
#define PERCPU_DECRYPTED_SECTION \
. = ALIGN(PAGE_SIZE); \
*(.data..percpu..decrypted) \
. = ALIGN(PAGE_SIZE);
#else
#define PERCPU_DECRYPTED_SECTION
#endif
/*
* Default discarded sections.
*
* Some archs want to discard exit text/data at runtime rather than
* link time due to cross-section references such as alt instructions,
* bug table, eh_frame, etc. DISCARDS must be the last of output
* section definitions so that such archs put those in earlier section
* definitions.
*/
#ifdef RUNTIME_DISCARD_EXIT
#define EXIT_DISCARDS
#else
#define EXIT_DISCARDS \
EXIT_TEXT \
EXIT_DATA
#endif
/*
* Clang's -fprofile-arcs, -fsanitize=kernel-address, and
* -fsanitize=thread produce unwanted sections (.eh_frame
* and .init_array.*), but CONFIG_CONSTRUCTORS wants to
* keep any .init_array.* sections.
* https://bugs.llvm.org/show_bug.cgi?id=46478
*/
#if defined(CONFIG_GCOV_KERNEL) || defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KCSAN) || \
defined(CONFIG_CFI_CLANG)
# ifdef CONFIG_CONSTRUCTORS
# define SANITIZER_DISCARDS \
*(.eh_frame)
# else
# define SANITIZER_DISCARDS \
*(.init_array) *(.init_array.*) \
*(.eh_frame)
# endif
#else
# define SANITIZER_DISCARDS
#endif
#define COMMON_DISCARDS \
SANITIZER_DISCARDS \
*(.discard) \
*(.discard.*) \
*(.modinfo) \
/* ld.bfd warns about .gnu.version* even when not emitted */ \
*(.gnu.version*) \
#define DISCARDS \
/DISCARD/ : { \
EXIT_DISCARDS \
EXIT_CALL \
COMMON_DISCARDS \
}
/**
* PERCPU_INPUT - the percpu input sections
* @cacheline: cacheline size
*
* The core percpu section names and core symbols which do not rely
* directly upon load addresses.
*
* @cacheline is used to align subsections to avoid false cacheline
* sharing between subsections for different purposes.
*/
#define PERCPU_INPUT(cacheline) \
__per_cpu_start = .; \
*(.data..percpu..first) \
. = ALIGN(PAGE_SIZE); \
*(.data..percpu..page_aligned) \
. = ALIGN(cacheline); \
*(.data..percpu..read_mostly) \
. = ALIGN(cacheline); \
*(.data..percpu) \
*(.data..percpu..shared_aligned) \
PERCPU_DECRYPTED_SECTION \
__per_cpu_end = .;
/**
* PERCPU_VADDR - define output section for percpu area
* @cacheline: cacheline size
* @vaddr: explicit base address (optional)
* @phdr: destination PHDR (optional)
*
* Macro which expands to output section for percpu area.
*
* @cacheline is used to align subsections to avoid false cacheline
* sharing between subsections for different purposes.
*
* If @vaddr is not blank, it specifies explicit base address and all
* percpu symbols will be offset from the given address. If blank,
* @vaddr always equals @laddr + LOAD_OFFSET.
*
* @phdr defines the output PHDR to use if not blank. Be warned that
* output PHDR is sticky. If @phdr is specified, the next output
* section in the linker script will go there too. @phdr should have
* a leading colon.
*
* Note that this macros defines __per_cpu_load as an absolute symbol.
* If there is no need to put the percpu section at a predetermined
* address, use PERCPU_SECTION.
*/
#define PERCPU_VADDR(cacheline, vaddr, phdr) \
__per_cpu_load = .; \
.data..percpu vaddr : AT(__per_cpu_load - LOAD_OFFSET) { \
PERCPU_INPUT(cacheline) \
} phdr \
. = __per_cpu_load + SIZEOF(.data..percpu);
/**
* PERCPU_SECTION - define output section for percpu area, simple version
* @cacheline: cacheline size
*
* Align to PAGE_SIZE and outputs output section for percpu area. This
* macro doesn't manipulate @vaddr or @phdr and __per_cpu_load and
* __per_cpu_start will be identical.
*
* This macro is equivalent to ALIGN(PAGE_SIZE); PERCPU_VADDR(@cacheline,,)
* except that __per_cpu_load is defined as a relative symbol against
* .data..percpu which is required for relocatable x86_32 configuration.
*/
#define PERCPU_SECTION(cacheline) \
. = ALIGN(PAGE_SIZE); \
.data..percpu : AT(ADDR(.data..percpu) - LOAD_OFFSET) { \
__per_cpu_load = .; \
PERCPU_INPUT(cacheline) \
}
/*
* Definition of the high level *_SECTION macros
* They will fit only a subset of the architectures
*/
/*
* Writeable data.
* All sections are combined in a single .data section.
* The sections following CONSTRUCTORS are arranged so their
* typical alignment matches.
* A cacheline is typical/always less than a PAGE_SIZE so
* the sections that has this restriction (or similar)
* is located before the ones requiring PAGE_SIZE alignment.
* NOSAVE_DATA starts and ends with a PAGE_SIZE alignment which
* matches the requirement of PAGE_ALIGNED_DATA.
*
* use 0 as page_align if page_aligned data is not used */
#define RW_DATA(cacheline, pagealigned, inittask) \
. = ALIGN(PAGE_SIZE); \
.data : AT(ADDR(.data) - LOAD_OFFSET) { \
INIT_TASK_DATA(inittask) \
NOSAVE_DATA \
PAGE_ALIGNED_DATA(pagealigned) \
CACHELINE_ALIGNED_DATA(cacheline) \
READ_MOSTLY_DATA(cacheline) \
DATA_DATA \
CONSTRUCTORS \
} \
BUG_TABLE \
#define INIT_TEXT_SECTION(inittext_align) \
. = ALIGN(inittext_align); \
.init.text : AT(ADDR(.init.text) - LOAD_OFFSET) { \
_sinittext = .; \
INIT_TEXT \
_einittext = .; \
}
#define INIT_DATA_SECTION(initsetup_align) \
.init.data : AT(ADDR(.init.data) - LOAD_OFFSET) { \
INIT_DATA \
INIT_SETUP(initsetup_align) \
INIT_CALLS \
CON_INITCALL \
INIT_RAM_FS \
}
#define BSS_SECTION(sbss_align, bss_align, stop_align) \
. = ALIGN(sbss_align); \
__bss_start = .; \
SBSS(sbss_align) \
BSS(bss_align) \
. = ALIGN(stop_align); \
__bss_stop = .;
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