Keep all function symbols in the vDSO .symtab for stack trace purposes. This enables a stack tracer, such as perf, to lookup these function symbols in addition to those already exported in vDSO .dynsym.
Signed-off-by: Jens Remus <[email protected]> --- Notes (jremus): Changes in RFC v2: - Use objcopy flag "-g" instead of "-S" with the cumbersome filter "-w -K "__arch_*" -K "__cvdso_*" -K "__s390_vdso_*" to keep the function symbols, as Josh did in "x86/vdso: Enable sframe generation in VDSO": https://lore.kernel.org/all/[email protected]/ - Reword commit message. Note that unlike Josh I did not squash this into the subsequent patch "s390/vdso: Enable SFrame generation in vDSO", as this change is unrelated to enabling the use of SFrame. perf report/script do also benefit from this change when using perf record --call-graph dwarf. Note that this change does not cause the vDSO build-id to change. perf record may therefore not dump an updated copy of the vDSO to ~/.debug/[vdso]/<build-id>/vdso, so that perf report/script may use a stale copy without .symtab. Resolve by deleting ~/.debug/. arch/s390/kernel/vdso64/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/kernel/vdso64/Makefile b/arch/s390/kernel/vdso64/Makefile index d8f0df742809..8e78dc3ba025 100644 --- a/arch/s390/kernel/vdso64/Makefile +++ b/arch/s390/kernel/vdso64/Makefile @@ -53,7 +53,7 @@ $(obj)/vdso64.so.dbg: $(obj)/vdso64.lds $(obj-vdso64) $(obj-cvdso64) FORCE $(call if_changed,vdso_and_check) # strip rule for the .so file -$(obj)/%.so: OBJCOPYFLAGS := -S +$(obj)/%.so: OBJCOPYFLAGS := -g $(obj)/%.so: $(obj)/%.so.dbg FORCE $(call if_changed,objcopy) -- 2.51.0
