| Message ID | 20180523195421.180248-17-thgarnie@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 05/23/2018 12:54 PM, Thomas Garnier wrote: > Provide an option to have a PROVIDE_HIDDEN (linker script) entry for > each weak symbol. This option solve an error in x86_64 where the linker solves > optimizes pie generate code to be non-pie because --emit-relocs was used generated > instead of -pie (to reduce dynamic relocations). > > Signed-off-by: Thomas Garnier <thgarnie@google.com> > --- > init/Kconfig | 7 +++++++ > scripts/link-vmlinux.sh | 14 ++++++++++++++ > 2 files changed, 21 insertions(+) > > diff --git a/init/Kconfig b/init/Kconfig > index 0fc3a58d9f2f..2866cca86b4a 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1954,6 +1954,13 @@ config ASN1 > inform it as to what tags are to be expected in a stream and what > functions to call on what tags. > > +config WEAK_PROVIDE_HIDDEN > + bool > + help > + Generate linker script PROVIDE_HIDDEN entries for all weak symbols. It > + allows to prevent non-pie code being replaced by the linker if the non-PIE > + emit-relocs option is used instead of pie (useful for x86_64 pie). PIE PIE). > +
diff --git a/init/Kconfig b/init/Kconfig index 0fc3a58d9f2f..2866cca86b4a 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1954,6 +1954,13 @@ config ASN1 inform it as to what tags are to be expected in a stream and what functions to call on what tags. +config WEAK_PROVIDE_HIDDEN + bool + help + Generate linker script PROVIDE_HIDDEN entries for all weak symbols. It + allows to prevent non-pie code being replaced by the linker if the + emit-relocs option is used instead of pie (useful for x86_64 pie). + source "kernel/Kconfig.locks" config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 4bf811c09f59..f5d31119b9d7 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -142,6 +142,17 @@ kallsyms() ${CC} ${aflags} -c -o ${2} ${afile} } +gen_weak_provide_hidden() +{ + if [ -n "${CONFIG_WEAK_PROVIDE_HIDDEN}" ]; then + local pattern="s/^\s\+ w \(\w\+\)$/PROVIDE_HIDDEN(\1 = .);/gp" + echo -e "SECTIONS {\n. = _end;" > .tmp_vmlinux_hiddenld + ${NM} ${1} | sed -n "${pattern}" >> .tmp_vmlinux_hiddenld + echo "}" >> .tmp_vmlinux_hiddenld + LDFLAGS_vmlinux="${LDFLAGS_vmlinux} -T .tmp_vmlinux_hiddenld" + fi +} + # Create map file with all symbols from ${1} # See mksymap for additional details mksysmap() @@ -226,6 +237,9 @@ modpost_link vmlinux.o # modpost vmlinux.o to check for section mismatches ${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o +# Generate weak linker script +gen_weak_provide_hidden vmlinux.o + kallsymso="" kallsyms_vmlinux="" if [ -n "${CONFIG_KALLSYMS}" ]; then
Provide an option to have a PROVIDE_HIDDEN (linker script) entry for each weak symbol. This option solve an error in x86_64 where the linker optimizes pie generate code to be non-pie because --emit-relocs was used instead of -pie (to reduce dynamic relocations). Signed-off-by: Thomas Garnier <thgarnie@google.com> --- init/Kconfig | 7 +++++++ scripts/link-vmlinux.sh | 14 ++++++++++++++ 2 files changed, 21 insertions(+)