From 50f4dd657a0fcf90aa8da8dc2794a8100ff4c37c Mon Sep 17 00:00:00 2001 From: Jisheng Zhang Date: Tue, 1 Nov 2022 02:29:43 +0800 Subject: riscv: vdso: fix build with llvm Even after commit 89fd4a1df829 ("riscv: jump_label: mark arguments as const to satisfy asm constraints"), building with CC_OPTIMIZE_FOR_SIZE + LLVM=1 can reproduce below build error: CC arch/riscv/kernel/vdso/vgettimeofday.o In file included from :4: In file included from lib/vdso/gettimeofday.c:5: In file included from include/vdso/datapage.h:17: In file included from include/vdso/processor.h:10: In file included from arch/riscv/include/asm/vdso/processor.h:7: In file included from include/linux/jump_label.h:112: arch/riscv/include/asm/jump_label.h:42:3: error: invalid operand for inline asm constraint 'i' " .option push \n\t" ^ 1 error generated. I think the problem is when "-Os" is passed as CFLAGS, it's removed by "CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os" which is introduced in commit e05d57dcb8c7 ("riscv: Fixup __vdso_gettimeofday broke dynamic ftrace"), thus no optimization at all for vgettimeofday.c arm64 does remove "-Os" as well, but it forces "-O2" after removing "-Os". I compared the generated vgettimeofday.o with "-O2" and "-Os", I think no big performance difference. So let's tell the kbuild not to remove "-Os" rather than follow arm64 style. vdso related performance can be improved a lot when building kernel with CC_OPTIMIZE_FOR_SIZE after this commit, ("-Os" VS no optimization) Fixes: e05d57dcb8c7 ("riscv: Fixup __vdso_gettimeofday broke dynamic ftrace") Signed-off-by: Jisheng Zhang Tested-by: Conor Dooley Link: https://lore.kernel.org/r/20221031182943.2453-1-jszhang@kernel.org Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/vdso/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/riscv/kernel/vdso') diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile index f2e065671e4d..84ac0fe612e7 100644 --- a/arch/riscv/kernel/vdso/Makefile +++ b/arch/riscv/kernel/vdso/Makefile @@ -30,7 +30,7 @@ obj-y += vdso.o CPPFLAGS_vdso.lds += -P -C -U$(ARCH) # Disable -pg to prevent insert call site -CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os +CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) # Disable profiling and instrumentation for VDSO code GCOV_PROFILE := n -- cgit v1.2.3 From fcae44fd36d052e956e69a64642fc03820968d78 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Tue, 8 Nov 2022 10:13:23 -0700 Subject: RISC-V: vdso: Do not add missing symbols to version section in linker script Recently, ld.lld moved from '--undefined-version' to '--no-undefined-version' as the default, which breaks the compat vDSO build: ld.lld: error: version script assignment of 'LINUX_4.15' to symbol '__vdso_gettimeofday' failed: symbol not defined ld.lld: error: version script assignment of 'LINUX_4.15' to symbol '__vdso_clock_gettime' failed: symbol not defined ld.lld: error: version script assignment of 'LINUX_4.15' to symbol '__vdso_clock_getres' failed: symbol not defined These symbols are not present in the compat vDSO or the regular vDSO for 32-bit but they are unconditionally included in the version section of the linker script, which is prohibited with '--no-undefined-version'. Fix this issue by only including the symbols that are actually exported in the version section of the linker script. Link: https://github.com/ClangBuiltLinux/linux/issues/1756 Signed-off-by: Nathan Chancellor Tested-by: Conor Dooley Link: https://lore.kernel.org/r/20221108171324.3377226-1-nathan@kernel.org/ Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/vdso/Makefile | 3 +++ arch/riscv/kernel/vdso/vdso.lds.S | 2 ++ 2 files changed, 5 insertions(+) (limited to 'arch/riscv/kernel/vdso') diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile index 84ac0fe612e7..db6548509bb3 100644 --- a/arch/riscv/kernel/vdso/Makefile +++ b/arch/riscv/kernel/vdso/Makefile @@ -28,6 +28,9 @@ obj-vdso := $(addprefix $(obj)/, $(obj-vdso)) obj-y += vdso.o CPPFLAGS_vdso.lds += -P -C -U$(ARCH) +ifneq ($(filter vgettimeofday, $(vdso-syms)),) +CPPFLAGS_vdso.lds += -DHAS_VGETTIMEOFDAY +endif # Disable -pg to prevent insert call site CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) diff --git a/arch/riscv/kernel/vdso/vdso.lds.S b/arch/riscv/kernel/vdso/vdso.lds.S index 01d94aae5bf5..150b1a572e61 100644 --- a/arch/riscv/kernel/vdso/vdso.lds.S +++ b/arch/riscv/kernel/vdso/vdso.lds.S @@ -68,9 +68,11 @@ VERSION LINUX_4.15 { global: __vdso_rt_sigreturn; +#ifdef HAS_VGETTIMEOFDAY __vdso_gettimeofday; __vdso_clock_gettime; __vdso_clock_getres; +#endif __vdso_getcpu; __vdso_flush_icache; local: *; -- cgit v1.2.3