random: vDSO: add a __vdso_getrandom prototype for all architectures

Without a prototype, we'll have to add a prototype for each architecture
implementing vDSO getrandom. As most architectures will likely have the
vDSO getrandom implemented in a near future, and we'd like to keep the
declarations compatible everywhere (to ease the libc implementor work),
we should really just have one copy of the prototype.

This also is what's already done inside of include/vdso/gettime.h for
those vDSO functions, so this continues that convention.

Suggested-by: Huacai Chen <chenhuacai@kernel.org>
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Acked-by: Huacai Chen <chenhuacai@kernel.org>
[Jason: rewrite docbook comment for prototype.]
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

diff --git a/arch/x86/entry/vdso/vgetrandom.c b/arch/x86/entry/vdso/vgetrandom.c
index 52d3c7faae2e3c1a43313a6386af6b7187a751b3..430862b8977c788bb45724cd466d53ceee081df4 100644 (file)
--- a/arch/x86/entry/vdso/vgetrandom.c
+++ b/arch/x86/entry/vdso/vgetrandom.c
@@ -6,8 +6,6 @@
 
 #include "../../../../lib/vdso/getrandom.c"
 
-ssize_t __vdso_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state, size_t opaque_len);
-
 ssize_t __vdso_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state, size_t opaque_len)
 {
        return __cvdso_getrandom(buffer, len, flags, opaque_state, opaque_len);

diff --git a/include/vdso/getrandom.h b/include/vdso/getrandom.h
index 4cf02e678f5e1b6d6688bfb39c54714cdaf3c28c..6ca4d6de9e4688921fbdbe4f3f6fb790130da968 100644 (file)
--- a/include/vdso/getrandom.h
+++ b/include/vdso/getrandom.h
@@ -56,4 +56,19 @@ struct vgetrandom_state {
  */
 extern void __arch_chacha20_blocks_nostack(u8 *dst_bytes, const u32 *key, u32 *counter, size_t nblocks);
 
+/**
+ * __vdso_getrandom - Architecture-specific vDSO implementation of getrandom() syscall.
+ * @buffer:            Passed to __cvdso_getrandom().
+ * @len:               Passed to __cvdso_getrandom().
+ * @flags:             Passed to __cvdso_getrandom().
+ * @opaque_state:      Passed to __cvdso_getrandom().
+ * @opaque_len:                Passed to __cvdso_getrandom();
+ *
+ * This function is implemented by making a single call to to __cvdso_getrandom(), whose
+ * documentation may be consulted for more information.
+ *
+ * Returns:    The return value of __cvdso_getrandom().
+ */
+extern ssize_t __vdso_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state, size_t opaque_len);
+
 #endif /* _VDSO_GETRANDOM_H */