[PATCH V4 12/14] LoongArch: Adjust VDSO/VSYSCALL for 32BIT/64BIT

Huacai Chen
2025-11-27T15:57:23Z

Adjust VDSO/VSYSCALL because read_cpu_id() for 32BIT/64BIT are
different, and LoongArch32 doesn't support GENERIC_GETTIMEOFDAY now
(will be supported in future).

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
arch/loongarch/include/asm/vdso/gettimeofday.h | 4 ++++
arch/loongarch/kernel/time.c | 2 ++
arch/loongarch/vdso/Makefile | 7 ++++++-
arch/loongarch/vdso/vdso.lds.S | 4 ++--
arch/loongarch/vdso/vgetcpu.c | 8 ++++++++
5 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/arch/loongarch/include/asm/vdso/gettimeofday.h b/arch/loongarch/include/asm/vdso/gettimeofday.h
index dcafabca9bb6..bae76767c693 100644
--- a/arch/loongarch/include/asm/vdso/gettimeofday.h
+++ b/arch/loongarch/include/asm/vdso/gettimeofday.h
@@ -12,6 +12,8 @@
#include <asm/unistd.h>
#include <asm/vdso/vdso.h>

+#ifdef CONFIG_GENERIC_GETTIMEOFDAY
+
#define VDSO_HAS_CLOCK_GETRES 1

static __always_inline long gettimeofday_fallback(
@@ -89,6 +91,8 @@ static inline bool loongarch_vdso_hres_capable(void)
}
#define __arch_vdso_hres_capable loongarch_vdso_hres_capable

+#endif /* CONFIG_GENERIC_GETTIMEOFDAY */
+
#endif /* !__ASSEMBLER__ */

#endif /* __ASM_VDSO_GETTIMEOFDAY_H */
diff --git a/arch/loongarch/kernel/time.c b/arch/loongarch/kernel/time.c
index 5892f6da07a5..dbaaabcaf6f0 100644
--- a/arch/loongarch/kernel/time.c
+++ b/arch/loongarch/kernel/time.c
@@ -212,7 +212,9 @@ static struct clocksource clocksource_const = {
.read = read_const_counter,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
+#ifdef CONFIG_GENERIC_GETTIMEOFDAY
.vdso_clock_mode = VDSO_CLOCKMODE_CPU,
+#endif
};

int __init constant_clocksource_init(void)
diff --git a/arch/loongarch/vdso/Makefile b/arch/loongarch/vdso/Makefile
index d8316f993482..a8ac0e811e39 100644
--- a/arch/loongarch/vdso/Makefile
+++ b/arch/loongarch/vdso/Makefile
@@ -4,8 +4,9 @@
# Include the generic Makefile to check the built vdso.
include $(srctree)/lib/vdso/Makefile.include

-obj-vdso-y := elf.o vgetcpu.o vgettimeofday.o vgetrandom.o \
+obj-vdso-y := elf.o vgetcpu.o vgetrandom.o \
vgetrandom-chacha.o sigreturn.o
+obj-vdso-$(CONFIG_GENERIC_GETTIMEOFDAY) += vgettimeofday.o

# Common compiler flags between ABIs.
ccflags-vdso := \
@@ -16,6 +17,10 @@ ccflags-vdso := \
$(CLANG_FLAGS) \
-D__VDSO__

+ifdef CONFIG_32BIT
+ccflags-vdso += -DBUILD_VDSO32
+endif
+
cflags-vdso := $(ccflags-vdso) \
-isystem $(shell $(CC) -print-file-name=include) \
$(filter -W%,$(filter-out -Wa$(comma)%,$(KBUILD_CFLAGS))) \
diff --git a/arch/loongarch/vdso/vdso.lds.S b/arch/loongarch/vdso/vdso.lds.S
index 8ff986499947..ac537e02beb1 100644
--- a/arch/loongarch/vdso/vdso.lds.S
+++ b/arch/loongarch/vdso/vdso.lds.S
@@ -7,8 +7,6 @@
#include <generated/asm-offsets.h>
#include <vdso/datapage.h>

-OUTPUT_FORMAT("elf64-loongarch", "elf64-loongarch", "elf64-loongarch")
-
OUTPUT_ARCH(loongarch)

SECTIONS
@@ -63,9 +61,11 @@ VERSION
LINUX_5.10 {
global:
__vdso_getcpu;
+#ifdef CONFIG_GENERIC_GETTIMEOFDAY
__vdso_clock_getres;
__vdso_clock_gettime;
__vdso_gettimeofday;
+#endif
__vdso_getrandom;
__vdso_rt_sigreturn;
local: *;
diff --git a/arch/loongarch/vdso/vgetcpu.c b/arch/loongarch/vdso/vgetcpu.c
index 5301cd9d0f83..73af49242ecd 100644
--- a/arch/loongarch/vdso/vgetcpu.c
+++ b/arch/loongarch/vdso/vgetcpu.c
@@ -10,11 +10,19 @@ static __always_inline int read_cpu_id(void)
{
int cpu_id;

+#ifdef CONFIG_64BIT
__asm__ __volatile__(
" rdtime.d $zero, %0\n"
: "=r" (cpu_id)
:
: "memory");
+#else
+ __asm__ __volatile__(
+ " rdtimel.w $zero, %0\n"
+ : "=r" (cpu_id)
+ :
+ : "memory");
+#endif

return cpu_id;
}
--
2.47.3