On Mon, 11 Aug 2025 22:44:31 PDT (-0700), thomas.weisssc...@linutronix.de wrote:
All the other architectures supporting LTO (x86, arm64, loongarch) do not
use it for the vDSO.
Its is problematic for some upcoming compile-time validation of the
generated object code.
The LTO object files do not contain the necessary relocation information
and -flto-fat-objects is not compatible with clang < 16.
For consistency and to enable the mentioned compile-time checks,
disable LTO for the vDSO.
The vDSO heavily uses __always_inline anyways.
Signed-off-by: Thomas Weißschuh <thomas.weisssc...@linutronix.de>
Reviewed-by: Nathan Chancellor <nat...@kernel.org>
Tested-by: Jan Stancek <jstan...@redhat.com>
---
arch/riscv/kernel/vdso/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile
index
c19c3c76f7c9f6b2f7523a59269de3b683656323..9f1bf5bae9bd473e43d9fd3022e9e1a185128b73
100644
--- a/arch/riscv/kernel/vdso/Makefile
+++ b/arch/riscv/kernel/vdso/Makefile
@@ -49,7 +49,7 @@ CPPFLAGS_vdso.lds += -DHAS_VGETTIMEOFDAY
endif
# Disable -pg to prevent insert call site
-CFLAGS_REMOVE_VDSO = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS)
+CFLAGS_REMOVE_VDSO = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_LTO)
CFLAGS_REMOVE_vgettimeofday.o = $(CFLAGS_REMOVE_VDSO)
CFLAGS_REMOVE_getrandom.o = $(CFLAGS_REMOVE_VDSO)
CFLAGS_REMOVE_hwprobe.o = $(CFLAGS_REMOVE_VDSO)
Acked-by: Palmer Dabbelt <pal...@dabbelt.com>
Also assuming this goes with the others. Thanks!
