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random: vDSO: add __arch_get_k_vdso_rng_data() helper for data page access

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_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 the declaration in a C file. vma.c looks like
the most appropriate candidate. We 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>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Christophe Leroy 2024-08-22 09:13:11 +02:00 committed by Jason A. Donenfeld
parent 81c6896049
commit b757959f19
3 changed files with 13 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/entry/vdso/vma.c
View File

@ -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)

10
arch/x86/include/asm/vdso/vsyscall.h
View File

@ -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>

5
drivers/char/random.c
View File

@ -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>
@ -289,7 +290,7 @@ static void crng_reseed(struct work_struct *work)
* because the vDSO side only checks whether the value changed, without
* actually using or interpreting the value.
*/
smp_store_release((unsigned long *)&_vdso_rng_data.generation, next_gen + 1);
smp_store_release((unsigned long *)&__arch_get_k_vdso_rng_data()->generation, next_gen + 1);
#endif
if (!static_branch_likely(&crng_is_ready))
crng_init = CRNG_READY;
@ -742,7 +743,7 @@ 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);