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

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

On Tue, Nov 18, 2025, at 12:27, Huacai Chen wrote:
> Adjust VDSO/VSYSCALL because read_cpu_id() for 32BIT/64BIT are
> different, and LoongArch32 doesn't support GENERIC_GETTIMEOFDAY now.
>
> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Are you planning to add vdso_clock_gettime() later, or is the
architecture missing hardware access to the timer register
on loongarch32?

It would be good to add some comments here to ensure this is
done correctly if someone adds the vdso32 support later:
There should be clock_gettime32 support, but not the old
clock_gettime(), clock_getres() or time().

       Arnd

Hi, Arnd,

On Tue, Nov 18, 2025 at 9:42 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Tue, Nov 18, 2025, at 12:27, Huacai Chen wrote:
> > Adjust VDSO/VSYSCALL because read_cpu_id() for 32BIT/64BIT are
> > different, and LoongArch32 doesn't support GENERIC_GETTIMEOFDAY now.
> >
> > Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> > Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
>
> Are you planning to add vdso_clock_gettime() later, or is the
> architecture missing hardware access to the timer register
> on loongarch32?
Hardware has no problem, vdso_clock_gettime() will be added later.

Huacai

>
> It would be good to add some comments here to ensure this is
> done correctly if someone adds the vdso32 support later:
> There should be clock_gettime32 support, but not the old
> clock_gettime(), clock_getres() or time().
>
>        Arnd
>