From: Thomas Weißschuh Date: Wed, 1 Jul 2026 09:21:22 +0000 (+0200) Subject: riscv: vdso: Do not use LTO for the vDSO X-Git-Tag: v7.2-rc4~1^2~2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ad6dcfa023762e37962f77ee48e752b7570e9440;p=thirdparty%2Fkernel%2Flinux.git riscv: vdso: Do not use LTO for the vDSO With LTO enabled the compiler assumes that the vDSO functions are not used and optimizes them away completely. Currently this happens to __vdso_clock_getres(), __vdso_clock_gettime(), __vdso_getrandom(), __vdso_gettimeofday() and __vdso_riscv_hwprobe(). Disable LTO for the vDSO, as these functions are hand-optimized anyways. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202606301855.WvkSC4kD-lkp@intel.com/ Fixes: 021d23428bdb ("RISC-V: build: Allow LTO to be selected") Cc: stable@vger.kernel.org Signed-off-by: Thomas Weißschuh Link: https://patch.msgid.link/20260701-riscv-vdso-lto-v1-1-89db0cd82077@linutronix.de Signed-off-by: Paul Walmsley --- diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile index a842dc034571..43ee881f6c6f 100644 --- a/arch/riscv/kernel/vdso/Makefile +++ b/arch/riscv/kernel/vdso/Makefile @@ -69,9 +69,9 @@ CPPFLAGS_$(vdso_lds) += -DHAS_VGETTIMEOFDAY endif # Disable -pg to prevent insert call site -CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) -CFLAGS_REMOVE_getrandom.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) -CFLAGS_REMOVE_hwprobe.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) +CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_LTO) +CFLAGS_REMOVE_getrandom.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_LTO) +CFLAGS_REMOVE_hwprobe.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_LTO) # Force dependency $(obj)/$(vdso_o): $(obj)/$(vdso_so)