Commit b757959f authored by Christophe Leroy's avatar Christophe Leroy Committed by Jason A. Donenfeld
Browse files

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



_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: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
parent 81c68960

arch/x86/entry/vdso/vma.c

+3 −0
Original line number Diff line number Diff line
@@ -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)

arch/x86/include/asm/vdso/vsyscall.h

+7 −3
Original line number Diff line number Diff line
@@ -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>

drivers/char/random.c

+3 −2
Original line number Diff line number Diff line
@@ -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);