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kbuild: lto: merge module sections

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LLD always splits sections with LTO, which increases module sizes. This
change adds linker script rules to merge the split sections in the final
module.

Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201211184633.3213045-6-samitolvanen@google.com
This commit is contained in:
Sami Tolvanen 2020-12-11 10:46:22 -08:00 committed by Kees Cook
parent 22d429e75f
commit dd2776222a
1 changed files with 24 additions and 0 deletions
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24
scripts/module.lds.S
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@ -23,6 +23,30 @@ SECTIONS {
.init_array 0 : ALIGN(8) { *(SORT(.init_array.*)) *(.init_array) } .init_array 0 : ALIGN(8) { *(SORT(.init_array.*)) *(.init_array) }
__jump_table 0 : ALIGN(8) { KEEP(*(__jump_table)) } __jump_table 0 : ALIGN(8) { KEEP(*(__jump_table)) }
__patchable_function_entries : { *(__patchable_function_entries) }
/*
* With CONFIG_LTO_CLANG, LLD always enables -fdata-sections and
* -ffunction-sections, which increases the size of the final module.
* Merge the split sections in the final binary.
*/
.bss : {
*(.bss .bss.[0-9a-zA-Z_]*)
*(.bss..L*)
}
.data : {
*(.data .data.[0-9a-zA-Z_]*)
*(.data..L*)
}
.rodata : {
*(.rodata .rodata.[0-9a-zA-Z_]*)
*(.rodata..L*)
}
.text : { *(.text .text.[0-9a-zA-Z_]*) }
} }
/* bring in arch-specific sections */ /* bring in arch-specific sections */