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| author | Sean Christopherson <seanjc@google.com> | 2021-03-22 16:44:38 -0700 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2021-04-01 14:15:59 -0700 |
| commit | 6a3193cdd5e5b96ac65f04ee42555c216da332af (patch) | |
| tree | b61f86cf72c116c8df62e778709fa3c8037db509 /scripts | |
| parent | a5e13c6df0e41702d2b2c77c8ad41677ebb065b3 (diff) | |
| download | lwn-6a3193cdd5e5b96ac65f04ee42555c216da332af.tar.gz lwn-6a3193cdd5e5b96ac65f04ee42555c216da332af.zip | |
kbuild: lto: Merge module sections if and only if CONFIG_LTO_CLANG is enabled
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
Diffstat (limited to 'scripts')
| -rw-r--r-- | scripts/module.lds.S | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/scripts/module.lds.S b/scripts/module.lds.S index 168cd27e6122..2c52535f9b56 100644 --- a/scripts/module.lds.S +++ b/scripts/module.lds.S @@ -20,6 +20,7 @@ SECTIONS { __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. @@ -41,6 +42,7 @@ SECTIONS { } .text : { *(.text .text.[0-9a-zA-Z_]*) } +#endif } /* bring in arch-specific sections */ |