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712676ea2b
Hook up the generic vDSO implementation to the aarch64 vDSO data page. The _vdso_rng_data required data is placed within the _vdso_data vvar page, by using a offset larger than the vdso_data. The vDSO function requires a ChaCha20 implementation that does not write to the stack, and that can do an entire ChaCha20 permutation. The one provided uses NEON on the permute operation, with a fallback to the syscall for chips that do not support AdvSIMD. This also passes the vdso_test_chacha test along with vdso_test_getrandom. The vdso_test_getrandom bench-single result on Neoverse-N1 shows: vdso: 25000000 times in 0.783884250 seconds libc: 25000000 times in 8.780275399 seconds syscall: 25000000 times in 8.786581518 seconds A small fixup to arch/arm64/include/asm/mman.h was required to avoid pulling kernel code into the vDSO, similar to what's already done in arch/arm64/include/asm/rwonce.h. Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Will Deacon <will@kernel.org> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
50 lines
1.5 KiB
C
50 lines
1.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_VDSO_GETRANDOM_H
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#define __ASM_VDSO_GETRANDOM_H
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#ifndef __ASSEMBLY__
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#include <asm/unistd.h>
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#include <asm/vdso/vsyscall.h>
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#include <vdso/datapage.h>
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/**
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* getrandom_syscall - Invoke the getrandom() syscall.
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* @buffer: Destination buffer to fill with random bytes.
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* @len: Size of @buffer in bytes.
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* @flags: Zero or more GRND_* flags.
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* Returns: The number of random bytes written to @buffer, or a negative value indicating an error.
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*/
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static __always_inline ssize_t getrandom_syscall(void *_buffer, size_t _len, unsigned int _flags)
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{
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register void *buffer asm ("x0") = _buffer;
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register size_t len asm ("x1") = _len;
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register unsigned int flags asm ("x2") = _flags;
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register long ret asm ("x0");
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register long nr asm ("x8") = __NR_getrandom;
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asm volatile(
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" svc #0\n"
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: "=r" (ret)
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: "r" (buffer), "r" (len), "r" (flags), "r" (nr)
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: "memory");
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return ret;
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}
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static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data(void)
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{
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/*
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* The RNG data is in the real VVAR data page, but if a task belongs to a time namespace
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* then VVAR_DATA_PAGE_OFFSET points to the namespace-specific VVAR page and VVAR_TIMENS_
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* PAGE_OFFSET points to the real VVAR page.
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*/
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if (IS_ENABLED(CONFIG_TIME_NS) && _vdso_data->clock_mode == VDSO_CLOCKMODE_TIMENS)
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return (void *)&_vdso_rng_data + VVAR_TIMENS_PAGE_OFFSET * (1UL << CONFIG_PAGE_SHIFT);
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return &_vdso_rng_data;
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}
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#endif /* !__ASSEMBLY__ */
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#endif /* __ASM_VDSO_GETRANDOM_H */
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