[PATCH v6 06/14] sparc64: vdso: Replace code patching with runtime conditional

Thomas Weißschuh
2026-03-04T07:50:19Z

The patching logic is unnecessarily complicated and stands in the way of
the adoption of the generic vDSO framework.

Replace it by a simple runtime switch, similar to other architectures.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/87ecu9tfhw.ffs@tglx/
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Tested-by: Andreas Larsson <andreas@gaisler.com>
Reviewed-by: Andreas Larsson <andreas@gaisler.com>
Acked-by: Andreas Larsson <andreas@gaisler.com>
---
arch/sparc/vdso/vclock_gettime.c | 112 +-------------------
arch/sparc/vdso/vdso.lds.S | 2 -
arch/sparc/vdso/vdso32/vdso32.lds.S | 2 -
arch/sparc/vdso/vma.c | 204 ------------------------------------
4 files changed, 4 insertions(+), 316 deletions(-)

diff --git a/arch/sparc/vdso/vclock_gettime.c b/arch/sparc/vdso/vclock_gettime.c
index 79607804ea1b..643608bffe13 100644
--- a/arch/sparc/vdso/vclock_gettime.c
+++ b/arch/sparc/vdso/vclock_gettime.c
@@ -148,17 +148,11 @@ notrace static __always_inline u64 vgetsns(struct vvar_data *vvar)
u64 v;
u64 cycles;

- cycles = vread_tick();
- v = (cycles - vvar->clock.cycle_last) & vvar->clock.mask;
- return v * vvar->clock.mult;
-}
-
-notrace static __always_inline u64 vgetsns_stick(struct vvar_data *vvar)
-{
- u64 v;
- u64 cycles;
+ if (likely(vvar->vclock_mode == VCLOCK_STICK))
+ cycles = vread_tick_stick();
+ else
+ cycles = vread_tick();

- cycles = vread_tick_stick();
v = (cycles - vvar->clock.cycle_last) & vvar->clock.mask;
return v * vvar->clock.mult;
}
@@ -183,26 +177,6 @@ notrace static __always_inline int do_realtime(struct vvar_data *vvar,
return 0;
}

-notrace static __always_inline int do_realtime_stick(struct vvar_data *vvar,
- struct __kernel_old_timespec *ts)
-{
- unsigned long seq;
- u64 ns;
-
- do {
- seq = vvar_read_begin(vvar);
- ts->tv_sec = vvar->wall_time_sec;
- ns = vvar->wall_time_snsec;
- ns += vgetsns_stick(vvar);
- ns = __shr64(ns, vvar->clock.shift);
- } while (unlikely(vvar_read_retry(vvar, seq)));
-
- ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
- ts->tv_nsec = ns;
-
- return 0;
-}
-
notrace static __always_inline int do_monotonic(struct vvar_data *vvar,
struct __kernel_old_timespec *ts)
{
@@ -223,26 +197,6 @@ notrace static __always_inline int do_monotonic(struct vvar_data *vvar,
return 0;
}

-notrace static __always_inline int do_monotonic_stick(struct vvar_data *vvar,
- struct __kernel_old_timespec *ts)
-{
- unsigned long seq;
- u64 ns;
-
- do {
- seq = vvar_read_begin(vvar);
- ts->tv_sec = vvar->monotonic_time_sec;
- ns = vvar->monotonic_time_snsec;
- ns += vgetsns_stick(vvar);
- ns = __shr64(ns, vvar->clock.shift);
- } while (unlikely(vvar_read_retry(vvar, seq)));
-
- ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
- ts->tv_nsec = ns;
-
- return 0;
-}
-
notrace static int do_realtime_coarse(struct vvar_data *vvar,
struct __kernel_old_timespec *ts)
{
@@ -298,31 +252,6 @@ int
clock_gettime(clockid_t, struct __kernel_old_timespec *)
__attribute__((weak, alias("__vdso_clock_gettime")));

-notrace int
-__vdso_clock_gettime_stick(clockid_t clock, struct __kernel_old_timespec *ts)
-{
- struct vvar_data *vvd = get_vvar_data();
-
- switch (clock) {
- case CLOCK_REALTIME:
- if (unlikely(vvd->vclock_mode == VCLOCK_NONE))
- break;
- return do_realtime_stick(vvd, ts);
- case CLOCK_MONOTONIC:
- if (unlikely(vvd->vclock_mode == VCLOCK_NONE))
- break;
- return do_monotonic_stick(vvd, ts);
- case CLOCK_REALTIME_COARSE:
- return do_realtime_coarse(vvd, ts);
- case CLOCK_MONOTONIC_COARSE:
- return do_monotonic_coarse(vvd, ts);
- }
- /*
- * Unknown clock ID ? Fall back to the syscall.
- */
- return vdso_fallback_gettime(clock, ts);
-}
-
notrace int
__vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
{
@@ -358,36 +287,3 @@ __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
int
gettimeofday(struct __kernel_old_timeval *, struct timezone *)
__attribute__((weak, alias("__vdso_gettimeofday")));
-
-notrace int
-__vdso_gettimeofday_stick(struct __kernel_old_timeval *tv, struct timezone *tz)
-{
- struct vvar_data *vvd = get_vvar_data();
-
- if (likely(vvd->vclock_mode != VCLOCK_NONE)) {
- if (likely(tv != NULL)) {
- union tstv_t {
- struct __kernel_old_timespec ts;
- struct __kernel_old_timeval tv;
- } *tstv = (union tstv_t *) tv;
- do_realtime_stick(vvd, &tstv->ts);
- /*
- * Assign before dividing to ensure that the division is
- * done in the type of tv_usec, not tv_nsec.
- *
- * There cannot be > 1 billion usec in a second:
- * do_realtime() has already distributed such overflow
- * into tv_sec. So we can assign it to an int safely.
- */
- tstv->tv.tv_usec = tstv->ts.tv_nsec;
- tstv->tv.tv_usec /= 1000;
- }
- if (unlikely(tz != NULL)) {
- /* Avoid memcpy. Some old compilers fail to inline it */
- tz->tz_minuteswest = vvd->tz_minuteswest;
- tz->tz_dsttime = vvd->tz_dsttime;
- }
- return 0;
- }
- return vdso_fallback_gettimeofday(tv, tz);
-}
diff --git a/arch/sparc/vdso/vdso.lds.S b/arch/sparc/vdso/vdso.lds.S
index 629ab6900df7..f3caa29a331c 100644
--- a/arch/sparc/vdso/vdso.lds.S
+++ b/arch/sparc/vdso/vdso.lds.S
@@ -18,10 +18,8 @@ VERSION {
global:
clock_gettime;
__vdso_clock_gettime;
- __vdso_clock_gettime_stick;
gettimeofday;
__vdso_gettimeofday;
- __vdso_gettimeofday_stick;
local: *;
};
}
diff --git a/arch/sparc/vdso/vdso32/vdso32.lds.S b/arch/sparc/vdso/vdso32/vdso32.lds.S
index 218930fdff03..53575ee154c4 100644
--- a/arch/sparc/vdso/vdso32/vdso32.lds.S
+++ b/arch/sparc/vdso/vdso32/vdso32.lds.S
@@ -17,10 +17,8 @@ VERSION {
global:
clock_gettime;
__vdso_clock_gettime;
- __vdso_clock_gettime_stick;
gettimeofday;
__vdso_gettimeofday;
- __vdso_gettimeofday_stick;
local: *;
};
}
diff --git a/arch/sparc/vdso/vma.c b/arch/sparc/vdso/vma.c
index c454689ce5fa..1f47d8341e43 100644
--- a/arch/sparc/vdso/vma.c
+++ b/arch/sparc/vdso/vma.c
@@ -42,203 +42,6 @@ static struct vm_special_mapping vdso_mapping32 = {

struct vvar_data *vvar_data;

-struct vdso_elfinfo32 {
- Elf32_Ehdr *hdr;
- Elf32_Sym *dynsym;
- unsigned long dynsymsize;
- const char *dynstr;
- unsigned long text;
-};
-
-struct vdso_elfinfo64 {
- Elf64_Ehdr *hdr;
- Elf64_Sym *dynsym;
- unsigned long dynsymsize;
- const char *dynstr;
- unsigned long text;
-};
-
-struct vdso_elfinfo {
- union {
- struct vdso_elfinfo32 elf32;
- struct vdso_elfinfo64 elf64;
- } u;
-};
-
-static void *one_section64(struct vdso_elfinfo64 *e, const char *name,
- unsigned long *size)
-{
- const char *snames;
- Elf64_Shdr *shdrs;
- unsigned int i;
-
- shdrs = (void *)e->hdr + e->hdr->e_shoff;
- snames = (void *)e->hdr + shdrs[e->hdr->e_shstrndx].sh_offset;
- for (i = 1; i < e->hdr->e_shnum; i++) {
- if (!strcmp(snames+shdrs[i].sh_name, name)) {
- if (size)
- *size = shdrs[i].sh_size;
- return (void *)e->hdr + shdrs[i].sh_offset;
- }
- }
- return NULL;
-}
-
-static int find_sections64(const struct vdso_image *image, struct vdso_elfinfo *_e)
-{
- struct vdso_elfinfo64 *e = &_e->u.elf64;
-
- e->hdr = image->data;
- e->dynsym = one_section64(e, ".dynsym", &e->dynsymsize);
- e->dynstr = one_section64(e, ".dynstr", NULL);
-
- if (!e->dynsym || !e->dynstr) {
- pr_err("VDSO64: Missing symbol sections.\n");
- return -ENODEV;
- }
- return 0;
-}
-
-static Elf64_Sym *find_sym64(const struct vdso_elfinfo64 *e, const char *name)
-{
- unsigned int i;
-
- for (i = 0; i < (e->dynsymsize / sizeof(Elf64_Sym)); i++) {
- Elf64_Sym *s = &e->dynsym[i];
- if (s->st_name == 0)
- continue;
- if (!strcmp(e->dynstr + s->st_name, name))
- return s;
- }
- return NULL;
-}
-
-static int patchsym64(struct vdso_elfinfo *_e, const char *orig,
- const char *new)
-{
- struct vdso_elfinfo64 *e = &_e->u.elf64;
- Elf64_Sym *osym = find_sym64(e, orig);
- Elf64_Sym *nsym = find_sym64(e, new);
-
- if (!nsym || !osym) {
- pr_err("VDSO64: Missing symbols.\n");
- return -ENODEV;
- }
- osym->st_value = nsym->st_value;
- osym->st_size = nsym->st_size;
- osym->st_info = nsym->st_info;
- osym->st_other = nsym->st_other;
- osym->st_shndx = nsym->st_shndx;
-
- return 0;
-}
-
-static void *one_section32(struct vdso_elfinfo32 *e, const char *name,
- unsigned long *size)
-{
- const char *snames;
- Elf32_Shdr *shdrs;
- unsigned int i;
-
- shdrs = (void *)e->hdr + e->hdr->e_shoff;
- snames = (void *)e->hdr + shdrs[e->hdr->e_shstrndx].sh_offset;
- for (i = 1; i < e->hdr->e_shnum; i++) {
- if (!strcmp(snames+shdrs[i].sh_name, name)) {
- if (size)
- *size = shdrs[i].sh_size;
- return (void *)e->hdr + shdrs[i].sh_offset;
- }
- }
- return NULL;
-}
-
-static int find_sections32(const struct vdso_image *image, struct vdso_elfinfo *_e)
-{
- struct vdso_elfinfo32 *e = &_e->u.elf32;
-
- e->hdr = image->data;
- e->dynsym = one_section32(e, ".dynsym", &e->dynsymsize);
- e->dynstr = one_section32(e, ".dynstr", NULL);
-
- if (!e->dynsym || !e->dynstr) {
- pr_err("VDSO32: Missing symbol sections.\n");
- return -ENODEV;
- }
- return 0;
-}
-
-static Elf32_Sym *find_sym32(const struct vdso_elfinfo32 *e, const char *name)
-{
- unsigned int i;
-
- for (i = 0; i < (e->dynsymsize / sizeof(Elf32_Sym)); i++) {
- Elf32_Sym *s = &e->dynsym[i];
- if (s->st_name == 0)
- continue;
- if (!strcmp(e->dynstr + s->st_name, name))
- return s;
- }
- return NULL;
-}
-
-static int patchsym32(struct vdso_elfinfo *_e, const char *orig,
- const char *new)
-{
- struct vdso_elfinfo32 *e = &_e->u.elf32;
- Elf32_Sym *osym = find_sym32(e, orig);
- Elf32_Sym *nsym = find_sym32(e, new);
-
- if (!nsym || !osym) {
- pr_err("VDSO32: Missing symbols.\n");
- return -ENODEV;
- }
- osym->st_value = nsym->st_value;
- osym->st_size = nsym->st_size;
- osym->st_info = nsym->st_info;
- osym->st_other = nsym->st_other;
- osym->st_shndx = nsym->st_shndx;
-
- return 0;
-}
-
-static int find_sections(const struct vdso_image *image, struct vdso_elfinfo *e,
- bool elf64)
-{
- if (elf64)
- return find_sections64(image, e);
- else
- return find_sections32(image, e);
-}
-
-static int patch_one_symbol(struct vdso_elfinfo *e, const char *orig,
- const char *new_target, bool elf64)
-{
- if (elf64)
- return patchsym64(e, orig, new_target);
- else
- return patchsym32(e, orig, new_target);
-}
-
-static int stick_patch(const struct vdso_image *image, struct vdso_elfinfo *e, bool elf64)
-{
- int err;
-
- err = find_sections(image, e, elf64);
- if (err)
- return err;
-
- err = patch_one_symbol(e,
- "__vdso_gettimeofday",
- "__vdso_gettimeofday_stick", elf64);
- if (err)
- return err;
-
- return patch_one_symbol(e,
- "__vdso_clock_gettime",
- "__vdso_clock_gettime_stick", elf64);
- return 0;
-}
-
/*
* Allocate pages for the vdso and vvar, and copy in the vdso text from the
* kernel image.
@@ -250,15 +53,8 @@ static int __init init_vdso_image(const struct vdso_image *image,
int cnpages = (image->size) / PAGE_SIZE;
struct page *dp, **dpp = NULL;
struct page *cp, **cpp = NULL;
- struct vdso_elfinfo ei;
int i, dnpages = 0;

- if (tlb_type != spitfire) {
- int err = stick_patch(image, &ei, elf64);
- if (err)
- return err;
- }
-
/*
* First, the vdso text. This is initialied data, an integral number of
* pages long.

--
2.53.0