[PATCH 15/28] x86: vdso: Access timens vdso data without vvar.h

From: Thomas Weißschuh
Date: Thu Oct 10 2024 - 03:27:22 EST


The vdso_data is at the start of the timens page.
Make use of this invariant to remove the usage of vvar.h.
This also matches the logic for the pvclock and hvclock pages.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
---
arch/x86/entry/vdso/vdso-layout.lds.S | 6 ------
arch/x86/include/asm/vdso/getrandom.h | 2 +-
arch/x86/include/asm/vdso/gettimeofday.h | 6 ++++--
3 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S
index bafa73f09e9285fbf29cf3f73e13b6d92df2f376..51c0cc0119748dda0f29d577197c520f272fd02f 100644
--- a/arch/x86/entry/vdso/vdso-layout.lds.S
+++ b/arch/x86/entry/vdso/vdso-layout.lds.S
@@ -28,12 +28,6 @@ SECTIONS
hvclock_page = vvar_start + 2 * PAGE_SIZE;
timens_page = vvar_start + 3 * PAGE_SIZE;

-#undef _ASM_X86_VVAR_H
- /* Place all vvars in timens too at the offsets in asm/vvar.h. */
-#define EMIT_VVAR(name, offset) timens_ ## name = timens_page + offset;
-#include <asm/vvar.h>
-#undef EMIT_VVAR
-
. = SIZEOF_HEADERS;

.hash : { *(.hash) } :text
diff --git a/arch/x86/include/asm/vdso/getrandom.h b/arch/x86/include/asm/vdso/getrandom.h
index ecdcdbcd3392533e5619d7f09403d60a9810ceab..d0713c829254cc8172c5903a1fdba168b52ff1ea 100644
--- a/arch/x86/include/asm/vdso/getrandom.h
+++ b/arch/x86/include/asm/vdso/getrandom.h
@@ -33,7 +33,7 @@ static __always_inline ssize_t getrandom_syscall(void *buffer, size_t len, unsig
static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data(void)
{
if (IS_ENABLED(CONFIG_TIME_NS) && __arch_get_vdso_data()->clock_mode == VDSO_CLOCKMODE_TIMENS)
- return (void *)&__vdso_rng_data + ((void *)&__timens_vdso_data - (void *)__arch_get_vdso_data());
+ return (void *)&__vdso_rng_data + ((void *)&timens_page - (void *)__arch_get_vdso_data());
return &__vdso_rng_data;
}

diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
index b2d2df026f6e707b8164d8842c33edea9a658466..1e6116172a65cd07ef29092dba6241d719f07448 100644
--- a/arch/x86/include/asm/vdso/gettimeofday.h
+++ b/arch/x86/include/asm/vdso/gettimeofday.h
@@ -21,7 +21,9 @@
#include <clocksource/hyperv_timer.h>

#define __vdso_data (VVAR(_vdso_data))
-#define __timens_vdso_data (TIMENS(_vdso_data))
+
+extern struct vdso_data timens_page
+ __attribute__((visibility("hidden")));

#define VDSO_HAS_TIME 1

@@ -61,7 +63,7 @@ extern struct ms_hyperv_tsc_page hvclock_page
static __always_inline
const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
{
- return __timens_vdso_data;
+ return &timens_page;
}
#endif


--
2.47.0