[PATCH v2 03/17] vdso: Add __arch_get_k_vdso_rng_data()

Christophe Leroy
2024-08-22T07:13:40Z

_vdso_data is specific to x86 and __arch_get_k_vdso_data() is provided
so that all architectures can provide the requested pointer.

Do the same with _vdso_rng_data, provide __arch_get_k_vdso_rng_data()
and don't use x86 _vdso_rng_data directly.

Until now vdso/vsyscall.h was only included by time/vsyscall.c but now
it will also be included in char/random.c, leading to a duplicate
declaration of _vdso_data and _vdso_rng_data.

To fix this issue, move declaration in a C file. vma.c looks like the
most appropriate candidate. Don't need to replace the definitions in
vsyscall.h by declarations as declarations are already in asm/vvar.h

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v2: Move x86 DEFINE_VVAR(_vdso_data) and DEFINE_VVAR(_vdso_rng_data) in vma.c
---
arch/x86/entry/vdso/vma.c | 3 +++
arch/x86/include/asm/vdso/vsyscall.h | 10 +++++++---
drivers/char/random.c | 5 +++--
3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 6d83ceb7f1ba..b8fed8b8b9cc 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -38,6 +38,9 @@ struct vdso_data *arch_get_vdso_data(void *vvar_page)
}
#undef EMIT_VVAR

+DEFINE_VVAR(struct vdso_data, _vdso_data);
+DEFINE_VVAR_SINGLE(struct vdso_rng_data, _vdso_rng_data);
+
unsigned int vclocks_used __read_mostly;

#if defined(CONFIG_X86_64)
diff --git a/arch/x86/include/asm/vdso/vsyscall.h b/arch/x86/include/asm/vdso/vsyscall.h
index 972415a8be31..67fedf1698b5 100644
--- a/arch/x86/include/asm/vdso/vsyscall.h
+++ b/arch/x86/include/asm/vdso/vsyscall.h
@@ -9,9 +9,6 @@
#include <asm/vgtod.h>
#include <asm/vvar.h>

-DEFINE_VVAR(struct vdso_data, _vdso_data);
-DEFINE_VVAR_SINGLE(struct vdso_rng_data, _vdso_rng_data);
-
/*
* Update the vDSO data page to keep in sync with kernel timekeeping.
*/
@@ -22,6 +19,13 @@ struct vdso_data *__x86_get_k_vdso_data(void)
}
#define __arch_get_k_vdso_data __x86_get_k_vdso_data

+static __always_inline
+struct vdso_rng_data *__x86_get_k_vdso_rng_data(void)
+{
+ return &_vdso_rng_data;
+}
+#define __arch_get_k_vdso_rng_data __x86_get_k_vdso_rng_data
+
/* The asm-generic header needs to be included after the definitions above */
#include <asm-generic/vdso/vsyscall.h>

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 87fe61295ea1..77968309e2c2 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -59,6 +59,7 @@
#ifdef CONFIG_VDSO_GETRANDOM
#include <vdso/getrandom.h>
#include <vdso/datapage.h>
+#include <vdso/vsyscall.h>
#endif
#include <asm/archrandom.h>
#include <asm/processor.h>
@@ -282,7 +283,7 @@ static void crng_reseed(struct work_struct *work)
* is ordered with the write above to base_crng.generation. Pairs with
* the smp_rmb() before the syscall in the vDSO code.
*/
- smp_store_release(&_vdso_rng_data.generation, next_gen + 1);
+ smp_store_release(&__arch_get_k_vdso_rng_data()->generation, next_gen + 1);
#endif
if (!static_branch_likely(&crng_is_ready))
crng_init = CRNG_READY;
@@ -735,7 +736,7 @@ static void __cold _credit_init_bits(size_t bits)
queue_work(system_unbound_wq, &set_ready);
atomic_notifier_call_chain(&random_ready_notifier, 0, NULL);
#ifdef CONFIG_VDSO_GETRANDOM
- WRITE_ONCE(_vdso_rng_data.is_ready, true);
+ WRITE_ONCE(__arch_get_k_vdso_rng_data()->is_ready, true);
#endif
wake_up_interruptible(&crng_init_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);
--
2.44.0