kernel_optimize_test/scripts/module.lds.S
Sean Christopherson 44b81136e8 kbuild: lto: Merge module sections if and only if CONFIG_LTO_CLANG is enabled
commit 6a3193cdd5e5b96ac65f04ee42555c216da332af upstream.

Merge module sections only when using Clang LTO. With ld.bfd, merging
sections does not appear to update the symbol tables for the module,
e.g. 'readelf -s' shows the value that a symbol would have had, if
sections were not merged. ld.lld does not show this problem.

The stale symbol table breaks gdb's function disassembler, and presumably
other things, e.g.

  gdb -batch -ex "file arch/x86/kvm/kvm.ko" -ex "disassemble kvm_init"

reads the wrong bytes and dumps garbage.

Fixes: dd2776222abb ("kbuild: lto: merge module sections")
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210322234438.502582-1-seanjc@google.com
Cc: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-02-23 12:01:00 +01:00

56 lines
1.5 KiB
ArmAsm

/*
* Common module linker script, always used when linking a module.
* Archs are free to supply their own linker scripts. ld will
* combine them automatically.
*/
SECTIONS {
/DISCARD/ : {
*(.discard)
*(.discard.*)
}
__ksymtab 0 : { *(SORT(___ksymtab+*)) }
__ksymtab_gpl 0 : { *(SORT(___ksymtab_gpl+*)) }
__ksymtab_unused 0 : { *(SORT(___ksymtab_unused+*)) }
__ksymtab_unused_gpl 0 : { *(SORT(___ksymtab_unused_gpl+*)) }
__ksymtab_gpl_future 0 : { *(SORT(___ksymtab_gpl_future+*)) }
__kcrctab 0 : { *(SORT(___kcrctab+*)) }
__kcrctab_gpl 0 : { *(SORT(___kcrctab_gpl+*)) }
__kcrctab_unused 0 : { *(SORT(___kcrctab_unused+*)) }
__kcrctab_unused_gpl 0 : { *(SORT(___kcrctab_unused_gpl+*)) }
__kcrctab_gpl_future 0 : { *(SORT(___kcrctab_gpl_future+*)) }
.init_array 0 : ALIGN(8) { *(SORT(.init_array.*)) *(.init_array) }
__jump_table 0 : ALIGN(8) { KEEP(*(__jump_table)) }
__patchable_function_entries : { *(__patchable_function_entries) }
#ifdef CONFIG_LTO_CLANG
/*
* 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_]*) }
#endif
}
/* bring in arch-specific sections */
#include <asm/module.lds.h>