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

   1 From e3d8676f5722b7622685581e06e8f53e6138e3ab Mon Sep 17 00:00:00 2001
   2 From: Felix Fietkau <nbd@nbd.name>
   3 Date: Sat, 15 Jul 2017 23:42:36 +0200
   4 Subject: use -ffunction-sections, -fdata-sections and --gc-sections
   5
   6 In combination with kernel symbol export stripping this significantly reduces
   7 the kernel image size. Used on both ARM and MIPS architectures.
   8
   9 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  10 Signed-off-by: Jonas Gorski <jogo@openwrt.org>
  11 Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
  12 ---
  13  Makefile                          | 10 +++----
  14  arch/arm/Kconfig                  |  1 +
  15  arch/arm/boot/compressed/Makefile |  1 +
  16  arch/arm/kernel/vmlinux.lds.S     | 26 ++++++++--------
  17  arch/mips/Kconfig                 |  1 +
  18  arch/mips/kernel/vmlinux.lds.S    |  4 +--
  19  include/asm-generic/vmlinux.lds.h | 63 ++++++++++++++++++++-------------------
  20  7 files changed, 55 insertions(+), 51 deletions(-)
  21
  22 --- a/Makefile
  23 +++ b/Makefile
  24 @@ -409,6 +409,11 @@ KBUILD_AFLAGS_MODULE  := -DMODULE
  25  KBUILD_CFLAGS_MODULE  := -DMODULE
  26  KBUILD_LDFLAGS_MODULE = -T $(srctree)/scripts/module-common.lds $(if $(CONFIG_PROFILING),,-s)
  27
  28 +ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
  29 +KBUILD_CFLAGS_KERNEL   += $(call cc-option,-ffunction-sections,)
  30 +KBUILD_CFLAGS_KERNEL   += $(call cc-option,-fdata-sections,)
  31 +endif
  32 +
  33  # Read KERNELRELEASE from include/config/kernel.release (if it exists)
  34  KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null)
  35  KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION)
  36 @@ -633,11 +638,6 @@ KBUILD_CFLAGS      += $(call cc-disable-warni
  37  KBUILD_CFLAGS  += $(call cc-disable-warning, format-overflow)
  38  KBUILD_CFLAGS  += $(call cc-disable-warning, int-in-bool-context)
  39
  40 -ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
  41 -KBUILD_CFLAGS  += $(call cc-option,-ffunction-sections,)
  42 -KBUILD_CFLAGS  += $(call cc-option,-fdata-sections,)
  43 -endif
  44 -
  45  ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
  46  KBUILD_CFLAGS  += -Os $(call cc-disable-warning,maybe-uninitialized,) $(EXTRA_OPTIMIZATION)
  47  else
  48 --- a/arch/arm/Kconfig
  49 +++ b/arch/arm/Kconfig
  50 @@ -81,6 +81,7 @@ config ARM
  51         select HAVE_UID16
  52         select HAVE_VIRT_CPU_ACCOUNTING_GEN
  53         select IRQ_FORCED_THREADING
  54 +       select LD_DEAD_CODE_DATA_ELIMINATION
  55         select MODULES_USE_ELF_REL
  56         select NO_BOOTMEM
  57         select OF_EARLY_FLATTREE if OF
  58 --- a/arch/arm/boot/compressed/Makefile
  59 +++ b/arch/arm/boot/compressed/Makefile
  60 @@ -102,6 +102,7 @@ ifeq ($(CONFIG_FUNCTION_TRACER),y)
  61  ORIG_CFLAGS := $(KBUILD_CFLAGS)
  62  KBUILD_CFLAGS = $(subst -pg, , $(ORIG_CFLAGS))
  63  endif
  64 +KBUILD_CFLAGS_KERNEL := $(patsubst -f%-sections,,$(KBUILD_CFLAGS_KERNEL))
  65
  66  # -fstack-protector-strong triggers protection checks in this code,
  67  # but it is being used too early to link to meaningful stack_chk logic.
  68 --- a/arch/arm/kernel/vmlinux.lds.S
  69 +++ b/arch/arm/kernel/vmlinux.lds.S
  70 @@ -17,7 +17,7 @@
  71  #define PROC_INFO                                                      \
  72         . = ALIGN(4);                                                   \
  73         VMLINUX_SYMBOL(__proc_info_begin) = .;                          \
  74 -       *(.proc.info.init)                                              \
  75 +       KEEP(*(.proc.info.init))                                        \
  76         VMLINUX_SYMBOL(__proc_info_end) = .;
  77
  78  #define HYPERVISOR_TEXT                                                        \
  79 @@ -28,11 +28,11 @@
  80  #define IDMAP_TEXT                                                     \
  81         ALIGN_FUNCTION();                                               \
  82         VMLINUX_SYMBOL(__idmap_text_start) = .;                         \
  83 -       *(.idmap.text)                                                  \
  84 +       KEEP(*(.idmap.text))                                            \
  85         VMLINUX_SYMBOL(__idmap_text_end) = .;                           \
  86         . = ALIGN(PAGE_SIZE);                                           \
  87         VMLINUX_SYMBOL(__hyp_idmap_text_start) = .;                     \
  88 -       *(.hyp.idmap.text)                                              \
  89 +       KEEP(*(.hyp.idmap.text))                                        \
  90         VMLINUX_SYMBOL(__hyp_idmap_text_end) = .;
  91
  92  #ifdef CONFIG_HOTPLUG_CPU
  93 @@ -105,7 +105,7 @@ SECTIONS
  94                 _stext = .;             /* Text and read-only data      */
  95                         IDMAP_TEXT
  96                         __exception_text_start = .;
  97 -                       *(.exception.text)
  98 +                       KEEP(*(.exception.text))
  99                         __exception_text_end = .;
 100                         IRQENTRY_TEXT
 101                         SOFTIRQENTRY_TEXT
 102 @@ -134,7 +134,7 @@ SECTIONS
 103         __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
 104                 __start___ex_table = .;
 105  #ifdef CONFIG_MMU
 106 -               *(__ex_table)
 107 +               KEEP(*(__ex_table))
 108  #endif
 109                 __stop___ex_table = .;
 110         }
 111 @@ -146,12 +146,12 @@ SECTIONS
 112         . = ALIGN(8);
 113         .ARM.unwind_idx : {
 114                 __start_unwind_idx = .;
 115 -               *(.ARM.exidx*)
 116 +               KEEP(*(.ARM.exidx*))
 117                 __stop_unwind_idx = .;
 118         }
 119         .ARM.unwind_tab : {
 120                 __start_unwind_tab = .;
 121 -               *(.ARM.extab*)
 122 +               KEEP(*(.ARM.extab*))
 123                 __stop_unwind_tab = .;
 124         }
 125  #endif
 126 @@ -171,14 +171,14 @@ SECTIONS
 127          */
 128         __vectors_start = .;
 129         .vectors 0xffff0000 : AT(__vectors_start) {
 130 -               *(.vectors)
 131 +               KEEP(*(.vectors))
 132         }
 133         . = __vectors_start + SIZEOF(.vectors);
 134         __vectors_end = .;
 135
 136         __stubs_start = .;
 137         .stubs ADDR(.vectors) + 0x1000 : AT(__stubs_start) {
 138 -               *(.stubs)
 139 +               KEEP(*(.stubs))
 140         }
 141         . = __stubs_start + SIZEOF(.stubs);
 142         __stubs_end = .;
 143 @@ -194,24 +194,24 @@ SECTIONS
 144         }
 145         .init.arch.info : {
 146                 __arch_info_begin = .;
 147 -               *(.arch.info.init)
 148 +               KEEP(*(.arch.info.init))
 149                 __arch_info_end = .;
 150         }
 151         .init.tagtable : {
 152                 __tagtable_begin = .;
 153 -               *(.taglist.init)
 154 +               KEEP(*(.taglist.init))
 155                 __tagtable_end = .;
 156         }
 157  #ifdef CONFIG_SMP_ON_UP
 158         .init.smpalt : {
 159                 __smpalt_begin = .;
 160 -               *(.alt.smp.init)
 161 +               KEEP(*(.alt.smp.init))
 162                 __smpalt_end = .;
 163         }
 164  #endif
 165         .init.pv_table : {
 166                 __pv_table_begin = .;
 167 -               *(.pv_table)
 168 +               KEEP(*(.pv_table))
 169                 __pv_table_end = .;
 170         }
 171         .init.data : {
 172 --- a/arch/mips/Kconfig
 173 +++ b/arch/mips/Kconfig
 174 @@ -55,6 +55,7 @@ config MIPS
 175         select CLONE_BACKWARDS
 176         select HAVE_DEBUG_STACKOVERFLOW
 177         select HAVE_CC_STACKPROTECTOR
 178 +       select LD_DEAD_CODE_DATA_ELIMINATION
 179         select CPU_PM if CPU_IDLE
 180         select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 181         select ARCH_BINFMT_ELF_STATE
 182 --- a/arch/mips/kernel/vmlinux.lds.S
 183 +++ b/arch/mips/kernel/vmlinux.lds.S
 184 @@ -71,7 +71,7 @@ SECTIONS
 185         /* Exception table for data bus errors */
 186         __dbe_table : {
 187                 __start___dbe_table = .;
 188 -               *(__dbe_table)
 189 +               KEEP(*(__dbe_table))
 190                 __stop___dbe_table = .;
 191         }
 192
 193 @@ -121,7 +121,7 @@ SECTIONS
 194         . = ALIGN(4);
 195         .mips.machines.init : AT(ADDR(.mips.machines.init) - LOAD_OFFSET) {
 196                 __mips_machines_start = .;
 197 -               *(.mips.machines.init)
 198 +               KEEP(*(.mips.machines.init))
 199                 __mips_machines_end = .;
 200         }
 201
 202 --- a/include/asm-generic/vmlinux.lds.h
 203 +++ b/include/asm-generic/vmlinux.lds.h
 204 @@ -130,7 +130,7 @@
 205  #ifdef CONFIG_KPROBES
 206  #define KPROBE_BLACKLIST()     . = ALIGN(8);                                 \
 207                                 VMLINUX_SYMBOL(__start_kprobe_blacklist) = .; \
 208 -                               *(_kprobe_blacklist)                          \
 209 +                               KEEP(*(_kprobe_blacklist))                    \
 210                                 VMLINUX_SYMBOL(__stop_kprobe_blacklist) = .;
 211  #else
 212  #define KPROBE_BLACKLIST()
 213 @@ -139,10 +139,10 @@
 214  #ifdef CONFIG_EVENT_TRACING
 215  #define FTRACE_EVENTS()        . = ALIGN(8);                                   \
 216                         VMLINUX_SYMBOL(__start_ftrace_events) = .;      \
 217 -                       *(_ftrace_events)                               \
 218 +                       KEEP(*(_ftrace_events))                         \
 219                         VMLINUX_SYMBOL(__stop_ftrace_events) = .;       \
 220                         VMLINUX_SYMBOL(__start_ftrace_enum_maps) = .;   \
 221 -                       *(_ftrace_enum_map)                             \
 222 +                       KEEP(*(_ftrace_enum_map))                       \
 223                         VMLINUX_SYMBOL(__stop_ftrace_enum_maps) = .;
 224  #else
 225  #define FTRACE_EVENTS()
 226 @@ -163,7 +163,7 @@
 227  #ifdef CONFIG_FTRACE_SYSCALLS
 228  #define TRACE_SYSCALLS() . = ALIGN(8);                                 \
 229                          VMLINUX_SYMBOL(__start_syscalls_metadata) = .; \
 230 -                        *(__syscalls_metadata)                         \
 231 +                        KEEP(*(__syscalls_metadata))                   \
 232                          VMLINUX_SYMBOL(__stop_syscalls_metadata) = .;
 233  #else
 234  #define TRACE_SYSCALLS()
 235 @@ -172,7 +172,7 @@
 236  #ifdef CONFIG_SERIAL_EARLYCON
 237  #define EARLYCON_TABLE() STRUCT_ALIGN();                       \
 238                          VMLINUX_SYMBOL(__earlycon_table) = .;  \
 239 -                        *(__earlycon_table)                    \
 240 +                        KEEP(*(__earlycon_table))              \
 241                          VMLINUX_SYMBOL(__earlycon_table_end) = .;
 242  #else
 243  #define EARLYCON_TABLE()
 244 @@ -185,8 +185,8 @@
 245  #define _OF_TABLE_1(name)                                              \
 246         . = ALIGN(8);                                                   \
 247         VMLINUX_SYMBOL(__##name##_of_table) = .;                        \
 248 -       *(__##name##_of_table)                                          \
 249 -       *(__##name##_of_table_end)
 250 +       KEEP(*(__##name##_of_table))                                    \
 251 +       KEEP(*(__##name##_of_table_end))
 252
 253  #define CLKSRC_OF_TABLES()     OF_TABLE(CONFIG_CLKSRC_OF, clksrc)
 254  #define IRQCHIP_OF_MATCH_TABLE() OF_TABLE(CONFIG_IRQCHIP, irqchip)
 255 @@ -209,7 +209,7 @@
 256  #define KERNEL_DTB()                                                   \
 257         STRUCT_ALIGN();                                                 \
 258         VMLINUX_SYMBOL(__dtb_start) = .;                                \
 259 -       *(.dtb.init.rodata)                                             \
 260 +       KEEP(*(.dtb.init.rodata))                                       \
 261         VMLINUX_SYMBOL(__dtb_end) = .;
 262
 263  /*
 264 @@ -227,16 +227,17 @@
 265         /* implement dynamic printk debug */                            \
 266         . = ALIGN(8);                                                   \
 267         VMLINUX_SYMBOL(__start___jump_table) = .;                       \
 268 -       *(__jump_table)                                                 \
 269 +       KEEP(*(__jump_table))                                           \
 270         VMLINUX_SYMBOL(__stop___jump_table) = .;                        \
 271         . = ALIGN(8);                                                   \
 272         VMLINUX_SYMBOL(__start___verbose) = .;                          \
 273 -       *(__verbose)                                                    \
 274 +       KEEP(*(__verbose))                                              \
 275         VMLINUX_SYMBOL(__stop___verbose) = .;                           \
 276         LIKELY_PROFILE()                                                \
 277         BRANCH_PROFILE()                                                \
 278         TRACE_PRINTKS()                                                 \
 279 -       TRACEPOINT_STR()
 280 +       TRACEPOINT_STR()                                                \
 281 +       *(.data.[a-zA-Z_]*)
 282
 283  /*
 284   * Data section helpers
 285 @@ -304,35 +305,35 @@
 286         /* PCI quirks */                                                \
 287         .pci_fixup        : AT(ADDR(.pci_fixup) - LOAD_OFFSET) {        \
 288                 VMLINUX_SYMBOL(__start_pci_fixups_early) = .;           \
 289 -               *(.pci_fixup_early)                                     \
 290 +               KEEP(*(.pci_fixup_early))                               \
 291                 VMLINUX_SYMBOL(__end_pci_fixups_early) = .;             \
 292                 VMLINUX_SYMBOL(__start_pci_fixups_header) = .;          \
 293 -               *(.pci_fixup_header)                                    \
 294 +               KEEP(*(.pci_fixup_header))                              \
 295                 VMLINUX_SYMBOL(__end_pci_fixups_header) = .;            \
 296                 VMLINUX_SYMBOL(__start_pci_fixups_final) = .;           \
 297 -               *(.pci_fixup_final)                                     \
 298 +               KEEP(*(.pci_fixup_final))                               \
 299                 VMLINUX_SYMBOL(__end_pci_fixups_final) = .;             \
 300                 VMLINUX_SYMBOL(__start_pci_fixups_enable) = .;          \
 301 -               *(.pci_fixup_enable)                                    \
 302 +               KEEP(*(.pci_fixup_enable))                              \
 303                 VMLINUX_SYMBOL(__end_pci_fixups_enable) = .;            \
 304                 VMLINUX_SYMBOL(__start_pci_fixups_resume) = .;          \
 305 -               *(.pci_fixup_resume)                                    \
 306 +               KEEP(*(.pci_fixup_resume))                              \
 307                 VMLINUX_SYMBOL(__end_pci_fixups_resume) = .;            \
 308                 VMLINUX_SYMBOL(__start_pci_fixups_resume_early) = .;    \
 309 -               *(.pci_fixup_resume_early)                              \
 310 +               KEEP(*(.pci_fixup_resume_early))                        \
 311                 VMLINUX_SYMBOL(__end_pci_fixups_resume_early) = .;      \
 312                 VMLINUX_SYMBOL(__start_pci_fixups_suspend) = .;         \
 313 -               *(.pci_fixup_suspend)                                   \
 314 +               KEEP(*(.pci_fixup_suspend))                             \
 315                 VMLINUX_SYMBOL(__end_pci_fixups_suspend) = .;           \
 316                 VMLINUX_SYMBOL(__start_pci_fixups_suspend_late) = .;    \
 317 -               *(.pci_fixup_suspend_late)                              \
 318 +               KEEP(*(.pci_fixup_suspend_late))                        \
 319                 VMLINUX_SYMBOL(__end_pci_fixups_suspend_late) = .;      \
 320         }                                                               \
 321                                                                         \
 322         /* Built-in firmware blobs */                                   \
 323         .builtin_fw        : AT(ADDR(.builtin_fw) - LOAD_OFFSET) {      \
 324                 VMLINUX_SYMBOL(__start_builtin_fw) = .;                 \
 325 -               *(.builtin_fw)                                          \
 326 +               KEEP(*(.builtin_fw))                                    \
 327                 VMLINUX_SYMBOL(__end_builtin_fw) = .;                   \
 328         }                                                               \
 329                                                                         \
 330 @@ -410,7 +411,7 @@
 331                                                                         \
 332         /* Kernel symbol table: strings */                              \
 333          __ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) {        \
 334 -               KEEP(*(__ksymtab_strings))                              \
 335 +               *(__ksymtab_strings)                                    \
 336         }                                                               \
 337                                                                         \
 338         /* __*init sections */                                          \
 339 @@ -423,14 +424,14 @@
 340         /* Built-in module parameters. */                               \
 341         __param : AT(ADDR(__param) - LOAD_OFFSET) {                     \
 342                 VMLINUX_SYMBOL(__start___param) = .;                    \
 343 -               *(__param)                                              \
 344 +               KEEP(*(__param))                                        \
 345                 VMLINUX_SYMBOL(__stop___param) = .;                     \
 346         }                                                               \
 347                                                                         \
 348         /* Built-in module versions. */                                 \
 349         __modver : AT(ADDR(__modver) - LOAD_OFFSET) {                   \
 350                 VMLINUX_SYMBOL(__start___modver) = .;                   \
 351 -               *(__modver)                                             \
 352 +               KEEP(*(__modver))                                       \
 353                 VMLINUX_SYMBOL(__stop___modver) = .;                    \
 354                 . = ALIGN((align));                                     \
 355                 VMLINUX_SYMBOL(__end_rodata) = .;                       \
 356 @@ -496,7 +497,7 @@
 357  #define ENTRY_TEXT                                                     \
 358                 ALIGN_FUNCTION();                                       \
 359                 VMLINUX_SYMBOL(__entry_text_start) = .;                 \
 360 -               *(.entry.text)                                          \
 361 +               KEEP(*(.entry.text))                                    \
 362                 VMLINUX_SYMBOL(__entry_text_end) = .;
 363
 364  #if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN)
 365 @@ -534,7 +535,7 @@
 366         . = ALIGN(align);                                               \
 367         __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {               \
 368                 VMLINUX_SYMBOL(__start___ex_table) = .;                 \
 369 -               *(__ex_table)                                           \
 370 +               KEEP(*(__ex_table))                                             \
 371                 VMLINUX_SYMBOL(__stop___ex_table) = .;                  \
 372         }
 373
 374 @@ -550,9 +551,9 @@
 375  #ifdef CONFIG_CONSTRUCTORS
 376  #define KERNEL_CTORS() . = ALIGN(8);                      \
 377                         VMLINUX_SYMBOL(__ctors_start) = .; \
 378 -                       *(.ctors)                          \
 379 +                       KEEP(*(.ctors))                    \
 380                         *(SORT(.init_array.*))             \
 381 -                       *(.init_array)                     \
 382 +                       KEEP(*(.init_array))               \
 383                         VMLINUX_SYMBOL(__ctors_end) = .;
 384  #else
 385  #define KERNEL_CTORS()
 386 @@ -609,7 +610,7 @@
 387  #define SBSS(sbss_align)                                               \
 388         . = ALIGN(sbss_align);                                          \
 389         .sbss : AT(ADDR(.sbss) - LOAD_OFFSET) {                         \
 390 -               *(.sbss)                                                \
 391 +               *(.sbss .sbss.*)                                        \
 392                 *(.scommon)                                             \
 393         }
 394
 395 @@ -676,7 +677,7 @@
 396         . = ALIGN(8);                                                   \
 397         __bug_table : AT(ADDR(__bug_table) - LOAD_OFFSET) {             \
 398                 VMLINUX_SYMBOL(__start___bug_table) = .;                \
 399 -               *(__bug_table)                                          \
 400 +               KEEP(*(__bug_table))                                    \
 401                 VMLINUX_SYMBOL(__stop___bug_table) = .;                 \
 402         }
 403  #else
 404 @@ -688,7 +689,7 @@
 405         . = ALIGN(4);                                                   \
 406         .tracedata : AT(ADDR(.tracedata) - LOAD_OFFSET) {               \
 407                 VMLINUX_SYMBOL(__tracedata_start) = .;                  \
 408 -               *(.tracedata)                                           \
 409 +               KEEP(*(.tracedata))                                     \
 410                 VMLINUX_SYMBOL(__tracedata_end) = .;                    \
 411         }
 412  #else
 413 @@ -705,7 +706,7 @@
 414  #define INIT_SETUP(initsetup_align)                                    \
 415                 . = ALIGN(initsetup_align);                             \
 416                 VMLINUX_SYMBOL(__setup_start) = .;                      \
 417 -               *(.init.setup)                                          \
 418 +               KEEP(*(.init.setup))                                    \
 419                 VMLINUX_SYMBOL(__setup_end) = .;
 420
 421  #define INIT_CALLS_LEVEL(level)                                                \