target/linux/generic/hack-5.10/220-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 --- a/arch/arm/Kconfig
  14 +++ b/arch/arm/Kconfig
  15 @@ -113,6 +113,7 @@ config ARM
  16         select HAVE_UID16
  17         select HAVE_VIRT_CPU_ACCOUNTING_GEN
  18         select IRQ_FORCED_THREADING
  19 +       select HAVE_LD_DEAD_CODE_DATA_ELIMINATION
  20         select MODULES_USE_ELF_REL
  21         select NEED_DMA_MAP_STATE
  22         select OF_EARLY_FLATTREE if OF
  23 --- a/arch/arm/boot/compressed/Makefile
  24 +++ b/arch/arm/boot/compressed/Makefile
  25 @@ -98,6 +98,7 @@ $(foreach o, $(libfdt_objs) atags_to_fdt
  26  ifdef building_out_of_srctree
  27  $(shell rm -f $(addprefix $(obj)/, fdt_rw.c fdt_ro.c fdt_wip.c fdt.c))
  28  endif
  29 +KBUILD_CFLAGS_KERNEL := $(patsubst -f%-sections,,$(KBUILD_CFLAGS_KERNEL))
  30
  31  targets       := vmlinux vmlinux.lds piggy_data piggy.o \
  32                  lib1funcs.o ashldi3.o bswapsdi2.o \
  33 --- a/arch/arm/kernel/vmlinux.lds.S
  34 +++ b/arch/arm/kernel/vmlinux.lds.S
  35 @@ -100,24 +100,24 @@ SECTIONS
  36         }
  37         .init.arch.info : {
  38                 __arch_info_begin = .;
  39 -               *(.arch.info.init)
  40 +               KEEP(*(.arch.info.init))
  41                 __arch_info_end = .;
  42         }
  43         .init.tagtable : {
  44                 __tagtable_begin = .;
  45 -               *(.taglist.init)
  46 +               KEEP(*(.taglist.init))
  47                 __tagtable_end = .;
  48         }
  49  #ifdef CONFIG_SMP_ON_UP
  50         .init.smpalt : {
  51                 __smpalt_begin = .;
  52 -               *(.alt.smp.init)
  53 +               KEEP(*(.alt.smp.init))
  54                 __smpalt_end = .;
  55         }
  56  #endif
  57         .init.pv_table : {
  58                 __pv_table_begin = .;
  59 -               *(.pv_table)
  60 +               KEEP(*(.pv_table))
  61                 __pv_table_end = .;
  62         }
  63
  64 --- a/arch/arm/include/asm/vmlinux.lds.h
  65 +++ b/arch/arm/include/asm/vmlinux.lds.h
  66 @@ -23,19 +23,19 @@
  67  #define ARM_MMU_DISCARD(x)
  68  #else
  69  #define ARM_MMU_KEEP(x)
  70 -#define ARM_MMU_DISCARD(x)     x
  71 +#define ARM_MMU_DISCARD(x)     KEEP(x)
  72  #endif
  73
  74  #define PROC_INFO                                                      \
  75                 . = ALIGN(4);                                           \
  76                 __proc_info_begin = .;                                  \
  77 -               *(.proc.info.init)                                      \
  78 +               KEEP(*(.proc.info.init))                                \
  79                 __proc_info_end = .;
  80
  81  #define IDMAP_TEXT                                                     \
  82                 ALIGN_FUNCTION();                                       \
  83                 __idmap_text_start = .;                                 \
  84 -               *(.idmap.text)                                          \
  85 +               KEEP(*(.idmap.text))                                    \
  86                 __idmap_text_end = .;                                   \
  87
  88  #define ARM_DISCARD                                                    \
  89 @@ -96,12 +96,12 @@
  90         . = ALIGN(8);                                                   \
  91         .ARM.unwind_idx : {                                             \
  92                 __start_unwind_idx = .;                                 \
  93 -               *(.ARM.exidx*)                                          \
  94 +               KEEP(*(.ARM.exidx*))                                    \
  95                 __stop_unwind_idx = .;                                  \
  96         }                                                               \
  97         .ARM.unwind_tab : {                                             \
  98                 __start_unwind_tab = .;                                 \
  99 -               *(.ARM.extab*)                                          \
 100 +               KEEP(*(.ARM.extab*))                                    \
 101                 __stop_unwind_tab = .;                                  \
 102         }
 103
 104 @@ -112,14 +112,14 @@
 105  #define ARM_VECTORS                                                    \
 106         __vectors_start = .;                                            \
 107         .vectors 0xffff0000 : AT(__vectors_start) {                     \
 108 -               *(.vectors)                                             \
 109 +               KEEP(*(.vectors))                                       \
 110         }                                                               \
 111         . = __vectors_start + SIZEOF(.vectors);                         \
 112         __vectors_end = .;                                              \
 113                                                                         \
 114         __stubs_start = .;                                              \
 115         .stubs ADDR(.vectors) + 0x1000 : AT(__stubs_start) {            \
 116 -               *(.stubs)                                               \
 117 +               KEEP(*(.stubs))                                         \
 118         }                                                               \
 119         . = __stubs_start + SIZEOF(.stubs);                             \
 120         __stubs_end = .;                                                \