| Message ID | 20210305092707.740539-1-linux@rasmusvillemoes.dk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] kbuild: add CONFIG_VMLINUX_MAP expert option | expand |
On Fri, Mar 5, 2021 at 6:27 PM Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote: > > It can be quite useful to have ld emit a link map file, in order to > debug or verify that special sections end up where they are supposed > to, and to see what LD_DEAD_CODE_DATA_ELIMINATION manages to get rid > of. > > The only reason I'm not just adding this unconditionally is that the > .map file can be rather large (several MB), and that's a waste of > space when one isn't interested in these things. Also make it depend > on CONFIG_EXPERT. > > Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> > --- Applied to linux-kbuild. Thanks. > .gitignore | 1 + > Documentation/dontdiff | 1 + > lib/Kconfig.debug | 10 ++++++++++ > scripts/link-vmlinux.sh | 8 ++++++++ > 4 files changed, 20 insertions(+) > > diff --git a/.gitignore b/.gitignore > index 3af66272d6f1..3adea59847ce 100644 > --- a/.gitignore > +++ b/.gitignore > @@ -59,6 +59,7 @@ modules.order > /linux > /vmlinux > /vmlinux.32 > +/vmlinux.map > /vmlinux.symvers > /vmlinux-gdb.py > /vmlinuz > diff --git a/Documentation/dontdiff b/Documentation/dontdiff > index e361fc95ca29..ac42ad8d430d 100644 > --- a/Documentation/dontdiff > +++ b/Documentation/dontdiff > @@ -252,6 +252,7 @@ vmlinux-* > vmlinux.aout > vmlinux.bin.all > vmlinux.lds > +vmlinux.map > vmlinux.symvers > vmlinuz > voffset.h > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 5ea0c1773b0a..663c1cd5018c 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -412,6 +412,16 @@ config VMLINUX_VALIDATION > depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT > default y > > +config VMLINUX_MAP > + bool "Generate vmlinux.map file when linking" > + depends on EXPERT > + help > + Selecting this option will pass "-Map=vmlinux.map" to ld > + when linking vmlinux. That file can be useful for verifying > + and debugging magic section games, and for seeing which > + pieces of code get eliminated with > + CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. > + > config DEBUG_FORCE_WEAK_PER_CPU > bool "Force weak per-cpu definitions" > depends on DEBUG_KERNEL > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > index 3b261b0f74f0..855fd4e6f03e 100755 > --- a/scripts/link-vmlinux.sh > +++ b/scripts/link-vmlinux.sh > @@ -155,6 +155,7 @@ vmlinux_link() > local output=${1} > local objects > local strip_debug > + local map_option > > info LD ${output} > > @@ -166,6 +167,10 @@ vmlinux_link() > strip_debug=-Wl,--strip-debug > fi > > + if [ -n "${CONFIG_VMLINUX_MAP}" ]; then > + map_option="-Map=${output}.map" > + fi > + > if [ "${SRCARCH}" != "um" ]; then > if [ -n "${CONFIG_LTO_CLANG}" ]; then > # Use vmlinux.o instead of performing the slow LTO > @@ -187,6 +192,7 @@ vmlinux_link() > ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \ > ${strip_debug#-Wl,} \ > -o ${output} \ > + ${map_option} \ > -T ${lds} ${objects} > else > objects="-Wl,--whole-archive \ > @@ -200,6 +206,7 @@ vmlinux_link() > ${CC} ${CFLAGS_vmlinux} \ > ${strip_debug} \ > -o ${output} \ > + ${map_option:+-Wl,${map_option}} \ > -Wl,-T,${lds} \ > ${objects} \ > -lutil -lrt -lpthread > @@ -303,6 +310,7 @@ cleanup() > rm -f .tmp_vmlinux* > rm -f System.map > rm -f vmlinux > + rm -f vmlinux.map > rm -f vmlinux.o > } > > -- > 2.29.2 > -- Best Regards Masahiro Yamada
diff --git a/.gitignore b/.gitignore index 3af66272d6f1..3adea59847ce 100644 --- a/.gitignore +++ b/.gitignore @@ -59,6 +59,7 @@ modules.order /linux /vmlinux /vmlinux.32 +/vmlinux.map /vmlinux.symvers /vmlinux-gdb.py /vmlinuz diff --git a/Documentation/dontdiff b/Documentation/dontdiff index e361fc95ca29..ac42ad8d430d 100644 --- a/Documentation/dontdiff +++ b/Documentation/dontdiff @@ -252,6 +252,7 @@ vmlinux-* vmlinux.aout vmlinux.bin.all vmlinux.lds +vmlinux.map vmlinux.symvers vmlinuz voffset.h diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 5ea0c1773b0a..663c1cd5018c 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -412,6 +412,16 @@ config VMLINUX_VALIDATION depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT default y +config VMLINUX_MAP + bool "Generate vmlinux.map file when linking" + depends on EXPERT + help + Selecting this option will pass "-Map=vmlinux.map" to ld + when linking vmlinux. That file can be useful for verifying + and debugging magic section games, and for seeing which + pieces of code get eliminated with + CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. + config DEBUG_FORCE_WEAK_PER_CPU bool "Force weak per-cpu definitions" depends on DEBUG_KERNEL diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 3b261b0f74f0..855fd4e6f03e 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -155,6 +155,7 @@ vmlinux_link() local output=${1} local objects local strip_debug + local map_option info LD ${output} @@ -166,6 +167,10 @@ vmlinux_link() strip_debug=-Wl,--strip-debug fi + if [ -n "${CONFIG_VMLINUX_MAP}" ]; then + map_option="-Map=${output}.map" + fi + if [ "${SRCARCH}" != "um" ]; then if [ -n "${CONFIG_LTO_CLANG}" ]; then # Use vmlinux.o instead of performing the slow LTO @@ -187,6 +192,7 @@ vmlinux_link() ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \ ${strip_debug#-Wl,} \ -o ${output} \ + ${map_option} \ -T ${lds} ${objects} else objects="-Wl,--whole-archive \ @@ -200,6 +206,7 @@ vmlinux_link() ${CC} ${CFLAGS_vmlinux} \ ${strip_debug} \ -o ${output} \ + ${map_option:+-Wl,${map_option}} \ -Wl,-T,${lds} \ ${objects} \ -lutil -lrt -lpthread @@ -303,6 +310,7 @@ cleanup() rm -f .tmp_vmlinux* rm -f System.map rm -f vmlinux + rm -f vmlinux.map rm -f vmlinux.o }
It can be quite useful to have ld emit a link map file, in order to debug or verify that special sections end up where they are supposed to, and to see what LD_DEAD_CODE_DATA_ELIMINATION manages to get rid of. The only reason I'm not just adding this unconditionally is that the .map file can be rather large (several MB), and that's a waste of space when one isn't interested in these things. Also make it depend on CONFIG_EXPERT. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> --- .gitignore | 1 + Documentation/dontdiff | 1 + lib/Kconfig.debug | 10 ++++++++++ scripts/link-vmlinux.sh | 8 ++++++++ 4 files changed, 20 insertions(+)