target/linux/generic/patches-4.9/220-gc_sections.patch

   1 From: Felix Fietkau <nbd@nbd.name>
   2
   3 use -ffunction-sections, -fdata-sections and --gc-sections
   4
   5 In combination with kernel symbol export stripping this significantly reduces
   6 the kernel image size. Used on both ARM and MIPS architectures.
   7
   8 Signed-off-by: Felix Fietkau <nbd@nbd.name>
   9 Signed-off-by: Jonas Gorski <jogo@openwrt.org>
  10 Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
  11 ---
  12
  13 --- a/arch/mips/kernel/vmlinux.lds.S
  14 +++ b/arch/mips/kernel/vmlinux.lds.S
  15 @@ -71,7 +71,7 @@ SECTIONS
  16         /* Exception table for data bus errors */
  17         __dbe_table : {
  18                 __start___dbe_table = .;
  19 -               *(__dbe_table)
  20 +               KEEP(*(__dbe_table))
  21                 __stop___dbe_table = .;
  22         }
  23
  24 @@ -121,7 +121,7 @@ SECTIONS
  25         . = ALIGN(4);
  26         .mips.machines.init : AT(ADDR(.mips.machines.init) - LOAD_OFFSET) {
  27                 __mips_machines_start = .;
  28 -               *(.mips.machines.init)
  29 +               KEEP(*(.mips.machines.init))
  30                 __mips_machines_end = .;
  31         }
  32
  33 --- a/include/asm-generic/vmlinux.lds.h
  34 +++ b/include/asm-generic/vmlinux.lds.h
  35 @@ -114,7 +114,7 @@
  36  #ifdef CONFIG_KPROBES
  37  #define KPROBE_BLACKLIST()     . = ALIGN(8);                                 \
  38                                 VMLINUX_SYMBOL(__start_kprobe_blacklist) = .; \
  39 -                               *(_kprobe_blacklist)                          \
  40 +                               KEEP(*(_kprobe_blacklist))                    \
  41                                 VMLINUX_SYMBOL(__stop_kprobe_blacklist) = .;
  42  #else
  43  #define KPROBE_BLACKLIST()
  44 @@ -123,10 +123,10 @@
  45  #ifdef CONFIG_EVENT_TRACING
  46  #define FTRACE_EVENTS()        . = ALIGN(8);                                   \
  47                         VMLINUX_SYMBOL(__start_ftrace_events) = .;      \
  48 -                       *(_ftrace_events)                               \
  49 +                       KEEP(*(_ftrace_events))                         \
  50                         VMLINUX_SYMBOL(__stop_ftrace_events) = .;       \
  51                         VMLINUX_SYMBOL(__start_ftrace_enum_maps) = .;   \
  52 -                       *(_ftrace_enum_map)                             \
  53 +                       KEEP(*(_ftrace_enum_map))                       \
  54                         VMLINUX_SYMBOL(__stop_ftrace_enum_maps) = .;
  55  #else
  56  #define FTRACE_EVENTS()
  57 @@ -147,7 +147,7 @@
  58  #ifdef CONFIG_FTRACE_SYSCALLS
  59  #define TRACE_SYSCALLS() . = ALIGN(8);                                 \
  60                          VMLINUX_SYMBOL(__start_syscalls_metadata) = .; \
  61 -                        *(__syscalls_metadata)                         \
  62 +                        KEEP(*(__syscalls_metadata))                   \
  63                          VMLINUX_SYMBOL(__stop_syscalls_metadata) = .;
  64  #else
  65  #define TRACE_SYSCALLS()
  66 @@ -156,7 +156,7 @@
  67  #ifdef CONFIG_SERIAL_EARLYCON
  68  #define EARLYCON_TABLE() STRUCT_ALIGN();                       \
  69                          VMLINUX_SYMBOL(__earlycon_table) = .;  \
  70 -                        *(__earlycon_table)                    \
  71 +                        KEEP(*(__earlycon_table))              \
  72                          VMLINUX_SYMBOL(__earlycon_table_end) = .;
  73  #else
  74  #define EARLYCON_TABLE()
  75 @@ -169,8 +169,8 @@
  76  #define _OF_TABLE_1(name)                                              \
  77         . = ALIGN(8);                                                   \
  78         VMLINUX_SYMBOL(__##name##_of_table) = .;                        \
  79 -       *(__##name##_of_table)                                          \
  80 -       *(__##name##_of_table_end)
  81 +       KEEP(*(__##name##_of_table))                                    \
  82 +       KEEP(*(__##name##_of_table_end))
  83
  84  #define CLKSRC_OF_TABLES()     OF_TABLE(CONFIG_CLKSRC_OF, clksrc)
  85  #define IRQCHIP_OF_MATCH_TABLE() OF_TABLE(CONFIG_IRQCHIP, irqchip)
  86 @@ -193,7 +193,7 @@
  87  #define KERNEL_DTB()                                                   \
  88         STRUCT_ALIGN();                                                 \
  89         VMLINUX_SYMBOL(__dtb_start) = .;                                \
  90 -       *(.dtb.init.rodata)                                             \
  91 +       KEEP(*(.dtb.init.rodata))                                       \
  92         VMLINUX_SYMBOL(__dtb_end) = .;
  93
  94  /*
  95 @@ -214,16 +214,17 @@
  96         /* implement dynamic printk debug */                            \
  97         . = ALIGN(8);                                                   \
  98         VMLINUX_SYMBOL(__start___jump_table) = .;                       \
  99 -       *(__jump_table)                                                 \
 100 +       KEEP(*(__jump_table))                                           \
 101         VMLINUX_SYMBOL(__stop___jump_table) = .;                        \
 102         . = ALIGN(8);                                                   \
 103         VMLINUX_SYMBOL(__start___verbose) = .;                          \
 104 -       *(__verbose)                                                    \
 105 +       KEEP(*(__verbose))                                              \
 106         VMLINUX_SYMBOL(__stop___verbose) = .;                           \
 107         LIKELY_PROFILE()                                                \
 108         BRANCH_PROFILE()                                                \
 109         TRACE_PRINTKS()                                                 \
 110 -       TRACEPOINT_STR()
 111 +       TRACEPOINT_STR()                                                \
 112 +       *(.data.[a-zA-Z_]*)
 113
 114  /*
 115   * Data section helpers
 116 @@ -291,35 +292,35 @@
 117         /* PCI quirks */                                                \
 118         .pci_fixup        : AT(ADDR(.pci_fixup) - LOAD_OFFSET) {        \
 119                 VMLINUX_SYMBOL(__start_pci_fixups_early) = .;           \
 120 -               *(.pci_fixup_early)                                     \
 121 +               KEEP(*(.pci_fixup_early))                               \
 122                 VMLINUX_SYMBOL(__end_pci_fixups_early) = .;             \
 123                 VMLINUX_SYMBOL(__start_pci_fixups_header) = .;          \
 124 -               *(.pci_fixup_header)                                    \
 125 +               KEEP(*(.pci_fixup_header))                              \
 126                 VMLINUX_SYMBOL(__end_pci_fixups_header) = .;            \
 127                 VMLINUX_SYMBOL(__start_pci_fixups_final) = .;           \
 128 -               *(.pci_fixup_final)                                     \
 129 +               KEEP(*(.pci_fixup_final))                               \
 130                 VMLINUX_SYMBOL(__end_pci_fixups_final) = .;             \
 131                 VMLINUX_SYMBOL(__start_pci_fixups_enable) = .;          \
 132 -               *(.pci_fixup_enable)                                    \
 133 +               KEEP(*(.pci_fixup_enable))                              \
 134                 VMLINUX_SYMBOL(__end_pci_fixups_enable) = .;            \
 135                 VMLINUX_SYMBOL(__start_pci_fixups_resume) = .;          \
 136 -               *(.pci_fixup_resume)                                    \
 137 +               KEEP(*(.pci_fixup_resume))                              \
 138                 VMLINUX_SYMBOL(__end_pci_fixups_resume) = .;            \
 139                 VMLINUX_SYMBOL(__start_pci_fixups_resume_early) = .;    \
 140 -               *(.pci_fixup_resume_early)                              \
 141 +               KEEP(*(.pci_fixup_resume_early))                        \
 142                 VMLINUX_SYMBOL(__end_pci_fixups_resume_early) = .;      \
 143                 VMLINUX_SYMBOL(__start_pci_fixups_suspend) = .;         \
 144 -               *(.pci_fixup_suspend)                                   \
 145 +               KEEP(*(.pci_fixup_suspend))                             \
 146                 VMLINUX_SYMBOL(__end_pci_fixups_suspend) = .;           \
 147                 VMLINUX_SYMBOL(__start_pci_fixups_suspend_late) = .;    \
 148 -               *(.pci_fixup_suspend_late)                              \
 149 +               KEEP(*(.pci_fixup_suspend_late))                        \
 150                 VMLINUX_SYMBOL(__end_pci_fixups_suspend_late) = .;      \
 151         }                                                               \
 152                                                                         \
 153         /* Built-in firmware blobs */                                   \
 154         .builtin_fw        : AT(ADDR(.builtin_fw) - LOAD_OFFSET) {      \
 155                 VMLINUX_SYMBOL(__start_builtin_fw) = .;                 \
 156 -               *(.builtin_fw)                                          \
 157 +               KEEP(*(.builtin_fw))                                    \
 158                 VMLINUX_SYMBOL(__end_builtin_fw) = .;                   \
 159         }                                                               \
 160                                                                         \
 161 @@ -397,7 +398,7 @@
 162                                                                         \
 163         /* Kernel symbol table: strings */                              \
 164          __ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) {        \
 165 -               KEEP(*(__ksymtab_strings))                              \
 166 +               *(__ksymtab_strings)                                    \
 167         }                                                               \
 168                                                                         \
 169         /* __*init sections */                                          \
 170 @@ -410,14 +411,14 @@
 171         /* Built-in module parameters. */                               \
 172         __param : AT(ADDR(__param) - LOAD_OFFSET) {                     \
 173                 VMLINUX_SYMBOL(__start___param) = .;                    \
 174 -               *(__param)                                              \
 175 +               KEEP(*(__param))                                        \
 176                 VMLINUX_SYMBOL(__stop___param) = .;                     \
 177         }                                                               \
 178                                                                         \
 179         /* Built-in module versions. */                                 \
 180         __modver : AT(ADDR(__modver) - LOAD_OFFSET) {                   \
 181                 VMLINUX_SYMBOL(__start___modver) = .;                   \
 182 -               *(__modver)                                             \
 183 +               KEEP(*(__modver))                                       \
 184                 VMLINUX_SYMBOL(__stop___modver) = .;                    \
 185                 . = ALIGN((align));                                     \
 186                 VMLINUX_SYMBOL(__end_rodata) = .;                       \
 187 @@ -482,7 +483,7 @@
 188  #define ENTRY_TEXT                                                     \
 189                 ALIGN_FUNCTION();                                       \
 190                 VMLINUX_SYMBOL(__entry_text_start) = .;                 \
 191 -               *(.entry.text)                                          \
 192 +               KEEP(*(.entry.text))                                    \
 193                 VMLINUX_SYMBOL(__entry_text_end) = .;
 194
 195  #if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN)
 196 @@ -520,7 +521,7 @@
 197         . = ALIGN(align);                                               \
 198         __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {               \
 199                 VMLINUX_SYMBOL(__start___ex_table) = .;                 \
 200 -               *(__ex_table)                                           \
 201 +               KEEP(*(__ex_table))                                             \
 202                 VMLINUX_SYMBOL(__stop___ex_table) = .;                  \
 203         }
 204
 205 @@ -536,9 +537,9 @@
 206  #ifdef CONFIG_CONSTRUCTORS
 207  #define KERNEL_CTORS() . = ALIGN(8);                      \
 208                         VMLINUX_SYMBOL(__ctors_start) = .; \
 209 -                       *(.ctors)                          \
 210 +                       KEEP(*(.ctors))                    \
 211                         *(SORT(.init_array.*))             \
 212 -                       *(.init_array)                     \
 213 +                       KEEP(*(.init_array))               \
 214                         VMLINUX_SYMBOL(__ctors_end) = .;
 215  #else
 216  #define KERNEL_CTORS()
 217 @@ -595,7 +596,7 @@
 218  #define SBSS(sbss_align)                                               \
 219         . = ALIGN(sbss_align);                                          \
 220         .sbss : AT(ADDR(.sbss) - LOAD_OFFSET) {                         \
 221 -               *(.sbss)                                                \
 222 +               *(.sbss .sbss.*)                                        \
 223                 *(.scommon)                                             \
 224         }
 225
 226 @@ -662,7 +663,7 @@
 227         . = ALIGN(8);                                                   \
 228         __bug_table : AT(ADDR(__bug_table) - LOAD_OFFSET) {             \
 229                 VMLINUX_SYMBOL(__start___bug_table) = .;                \
 230 -               *(__bug_table)                                          \
 231 +               KEEP(*(__bug_table))                                    \
 232                 VMLINUX_SYMBOL(__stop___bug_table) = .;                 \
 233         }
 234  #else
 235 @@ -674,7 +675,7 @@
 236         . = ALIGN(4);                                                   \
 237         .tracedata : AT(ADDR(.tracedata) - LOAD_OFFSET) {               \
 238                 VMLINUX_SYMBOL(__tracedata_start) = .;                  \
 239 -               *(.tracedata)                                           \
 240 +               KEEP(*(.tracedata))                                     \
 241                 VMLINUX_SYMBOL(__tracedata_end) = .;                    \
 242         }
 243  #else
 244 @@ -691,7 +692,7 @@
 245  #define INIT_SETUP(initsetup_align)                                    \
 246                 . = ALIGN(initsetup_align);                             \
 247                 VMLINUX_SYMBOL(__setup_start) = .;                      \
 248 -               *(.init.setup)                                          \
 249 +               KEEP(*(.init.setup))                                    \
 250                 VMLINUX_SYMBOL(__setup_end) = .;
 251
 252  #define INIT_CALLS_LEVEL(level)                                                \
 253 --- a/arch/arm/kernel/vmlinux.lds.S
 254 +++ b/arch/arm/kernel/vmlinux.lds.S
 255 @@ -17,7 +17,7 @@
 256  #define PROC_INFO                                                      \
 257         . = ALIGN(4);                                                   \
 258         VMLINUX_SYMBOL(__proc_info_begin) = .;                          \
 259 -       *(.proc.info.init)                                              \
 260 +       KEEP(*(.proc.info.init))                                        \
 261         VMLINUX_SYMBOL(__proc_info_end) = .;
 262
 263  #define HYPERVISOR_TEXT                                                        \
 264 @@ -28,11 +28,11 @@
 265  #define IDMAP_TEXT                                                     \
 266         ALIGN_FUNCTION();                                               \
 267         VMLINUX_SYMBOL(__idmap_text_start) = .;                         \
 268 -       *(.idmap.text)                                                  \
 269 +       KEEP(*(.idmap.text))                                            \
 270         VMLINUX_SYMBOL(__idmap_text_end) = .;                           \
 271         . = ALIGN(PAGE_SIZE);                                           \
 272         VMLINUX_SYMBOL(__hyp_idmap_text_start) = .;                     \
 273 -       *(.hyp.idmap.text)                                              \
 274 +       KEEP(*(.hyp.idmap.text))                                        \
 275         VMLINUX_SYMBOL(__hyp_idmap_text_end) = .;
 276
 277  #ifdef CONFIG_HOTPLUG_CPU
 278 @@ -105,7 +105,7 @@ SECTIONS
 279                 _stext = .;             /* Text and read-only data      */
 280                         IDMAP_TEXT
 281                         __exception_text_start = .;
 282 -                       *(.exception.text)
 283 +                       KEEP(*(.exception.text))
 284                         __exception_text_end = .;
 285                         IRQENTRY_TEXT
 286                         SOFTIRQENTRY_TEXT
 287 @@ -134,7 +134,7 @@ SECTIONS
 288         __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
 289                 __start___ex_table = .;
 290  #ifdef CONFIG_MMU
 291 -               *(__ex_table)
 292 +               KEEP(*(__ex_table))
 293  #endif
 294                 __stop___ex_table = .;
 295         }
 296 @@ -146,12 +146,12 @@ SECTIONS
 297         . = ALIGN(8);
 298         .ARM.unwind_idx : {
 299                 __start_unwind_idx = .;
 300 -               *(.ARM.exidx*)
 301 +               KEEP(*(.ARM.exidx*))
 302                 __stop_unwind_idx = .;
 303         }
 304         .ARM.unwind_tab : {
 305                 __start_unwind_tab = .;
 306 -               *(.ARM.extab*)
 307 +               KEEP(*(.ARM.extab*))
 308                 __stop_unwind_tab = .;
 309         }
 310  #endif
 311 @@ -171,14 +171,14 @@ SECTIONS
 312          */
 313         __vectors_start = .;
 314         .vectors 0xffff0000 : AT(__vectors_start) {
 315 -               *(.vectors)
 316 +               KEEP(*(.vectors))
 317         }
 318         . = __vectors_start + SIZEOF(.vectors);
 319         __vectors_end = .;
 320
 321         __stubs_start = .;
 322         .stubs ADDR(.vectors) + 0x1000 : AT(__stubs_start) {
 323 -               *(.stubs)
 324 +               KEEP(*(.stubs))
 325         }
 326         . = __stubs_start + SIZEOF(.stubs);
 327         __stubs_end = .;
 328 @@ -194,24 +194,24 @@ SECTIONS
 329         }
 330         .init.arch.info : {
 331                 __arch_info_begin = .;
 332 -               *(.arch.info.init)
 333 +               KEEP(*(.arch.info.init))
 334                 __arch_info_end = .;
 335         }
 336         .init.tagtable : {
 337                 __tagtable_begin = .;
 338 -               *(.taglist.init)
 339 +               KEEP(*(.taglist.init))
 340                 __tagtable_end = .;
 341         }
 342  #ifdef CONFIG_SMP_ON_UP
 343         .init.smpalt : {
 344                 __smpalt_begin = .;
 345 -               *(.alt.smp.init)
 346 +               KEEP(*(.alt.smp.init))
 347                 __smpalt_end = .;
 348         }
 349  #endif
 350         .init.pv_table : {
 351                 __pv_table_begin = .;
 352 -               *(.pv_table)
 353 +               KEEP(*(.pv_table))
 354                 __pv_table_end = .;
 355         }
 356         .init.data : {
 357 --- a/arch/arm/boot/compressed/Makefile
 358 +++ b/arch/arm/boot/compressed/Makefile
 359 @@ -102,6 +102,7 @@ ifeq ($(CONFIG_FUNCTION_TRACER),y)
 360  ORIG_CFLAGS := $(KBUILD_CFLAGS)
 361  KBUILD_CFLAGS = $(subst -pg, , $(ORIG_CFLAGS))
 362  endif
 363 +KBUILD_CFLAGS_KERNEL := $(patsubst -f%-sections,,$(KBUILD_CFLAGS_KERNEL))
 364
 365  # -fstack-protector-strong triggers protection checks in this code,
 366  # but it is being used too early to link to meaningful stack_chk logic.
 367 --- a/arch/arm/Kconfig
 368 +++ b/arch/arm/Kconfig
 369 @@ -81,6 +81,7 @@ config ARM
 370         select HAVE_UID16
 371         select HAVE_VIRT_CPU_ACCOUNTING_GEN
 372         select IRQ_FORCED_THREADING
 373 +       select LD_DEAD_CODE_DATA_ELIMINATION
 374         select MODULES_USE_ELF_REL
 375         select NO_BOOTMEM
 376         select OF_EARLY_FLATTREE if OF
 377 --- a/arch/mips/Kconfig
 378 +++ b/arch/mips/Kconfig
 379 @@ -55,6 +55,7 @@ config MIPS
 380         select CLONE_BACKWARDS
 381         select HAVE_DEBUG_STACKOVERFLOW
 382         select HAVE_CC_STACKPROTECTOR
 383 +       select LD_DEAD_CODE_DATA_ELIMINATION
 384         select CPU_PM if CPU_IDLE
 385         select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 386         select ARCH_BINFMT_ELF_STATE
 387 --- a/Makefile
 388 +++ b/Makefile
 389 @@ -409,6 +409,11 @@ KBUILD_AFLAGS_MODULE  := -DMODULE
 390  KBUILD_CFLAGS_MODULE  := -DMODULE
 391  KBUILD_LDFLAGS_MODULE = -T $(srctree)/scripts/module-common.lds $(if $(CONFIG_PROFILING),,-s)
 392
 393 +ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
 394 +KBUILD_CFLAGS_KERNEL   += $(call cc-option,-ffunction-sections,)
 395 +KBUILD_CFLAGS_KERNEL   += $(call cc-option,-fdata-sections,)
 396 +endif
 397 +
 398  # Read KERNELRELEASE from include/config/kernel.release (if it exists)
 399  KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null)
 400  KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION)
 401 @@ -630,11 +635,6 @@ include arch/$(SRCARCH)/Makefile
 402  KBUILD_CFLAGS  += $(call cc-option,-fno-delete-null-pointer-checks,)
 403  KBUILD_CFLAGS  += $(call cc-disable-warning,frame-address,)
 404
 405 -ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
 406 -KBUILD_CFLAGS  += $(call cc-option,-ffunction-sections,)
 407 -KBUILD_CFLAGS  += $(call cc-option,-fdata-sections,)
 408 -endif
 409 -
 410  ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
 411  KBUILD_CFLAGS  += -Os $(call cc-disable-warning,maybe-uninitialized,) $(EXTRA_OPTIMIZATION)
 412  else