RISC-V: vdso: Do not add missing symbols to version section in linker script

[ Upstream commit 1fcae820055dafbcfae28d06daa982a67a739667 ]

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 <nathan@kernel.org>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20221108171324.3377226-1-nathan@kernel.org/
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile
index a4ee3a0e7d20d403f72d46614d09901ff3ad93b9..c533ac869aa286f836d60f0623fb2e268643b2e3 100644 (file)
--- a/arch/riscv/kernel/vdso/Makefile
+++ b/arch/riscv/kernel/vdso/Makefile
@@ -20,6 +20,9 @@ obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
 
 obj-y += vdso.o vdso-syms.o
 CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
+ifneq ($(filter vgettimeofday, $(vdso-syms)),)
+CPPFLAGS_vdso.lds += -DHAS_VGETTIMEOFDAY
+endif
 
 # Disable gcov profiling for VDSO code
 GCOV_PROFILE := n

diff --git a/arch/riscv/kernel/vdso/vdso.lds.S b/arch/riscv/kernel/vdso/vdso.lds.S
index f66a091cb8909452a20d466a2f5316e764556d1e..4c45adf232590d09d46dc00dfa683bf2214da407 100644 (file)
--- a/arch/riscv/kernel/vdso/vdso.lds.S
+++ b/arch/riscv/kernel/vdso/vdso.lds.S
@@ -62,9 +62,11 @@ 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: *;