getrandom.h

 1/* SPDX-License-Identifier: GPL-2.0 */
 2/*
 3 * Copyright (C) 2024 Christophe Leroy <christophe.leroy@csgroup.eu>, CS GROUP France
 4 */
 5#ifndef _ASM_POWERPC_VDSO_GETRANDOM_H
 6#define _ASM_POWERPC_VDSO_GETRANDOM_H
 7
 8#ifndef __ASSEMBLER__
 9
10#include <asm/vdso_datapage.h>
11
12static __always_inline int do_syscall_3(const unsigned long _r0, const unsigned long _r3,
13					const unsigned long _r4, const unsigned long _r5)
14{
15	register long r0 asm("r0") = _r0;
16	register unsigned long r3 asm("r3") = _r3;
17	register unsigned long r4 asm("r4") = _r4;
18	register unsigned long r5 asm("r5") = _r5;
19	register int ret asm ("r3");
20
21	asm volatile(
22		"       sc\n"
23		"	bns+	1f\n"
24		"	neg	%0, %0\n"
25		"1:\n"
26	: "=r" (ret), "+r" (r4), "+r" (r5), "+r" (r0)
27	: "r" (r3)
28	: "memory", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "cr0", "ctr");
29
30	return ret;
31}
32
33/**
34 * getrandom_syscall - Invoke the getrandom() syscall.
35 * @buffer:	Destination buffer to fill with random bytes.
36 * @len:	Size of @buffer in bytes.
37 * @flags:	Zero or more GRND_* flags.
38 * Returns:	The number of bytes written to @buffer, or a negative value indicating an error.
39 */
40static __always_inline ssize_t getrandom_syscall(void *buffer, size_t len, unsigned int flags)
41{
42	return do_syscall_3(__NR_getrandom, (unsigned long)buffer,
43			    (unsigned long)len, (unsigned long)flags);
44}
45
46static __always_inline const struct vdso_rng_data *__arch_get_vdso_u_rng_data(void)
47{
48	struct vdso_rng_data *data;
49
50	asm (
51		"	bcl	20, 31, .+4 ;"
52		"0:	mflr	%0 ;"
53		"	addis	%0, %0, (vdso_u_rng_data - 0b)@ha ;"
54		"	addi	%0, %0, (vdso_u_rng_data - 0b)@l  ;"
55		: "=r" (data) : : "lr"
56	);
57
58	return data;
59}
60#define __arch_get_vdso_u_rng_data __arch_get_vdso_u_rng_data
61
62ssize_t __c_kernel_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state,
63			     size_t opaque_len);
64
65#endif /* !__ASSEMBLER__ */
66
67#endif /* _ASM_POWERPC_VDSO_GETRANDOM_H */