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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>
15 lines
492 B
C
15 lines
492 B
C
// SPDX-License-Identifier: GPL-2.0
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#include <uapi/asm-generic/errno.h>
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typeof(__cvdso_getrandom) __kernel_getrandom;
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ssize_t __kernel_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state, size_t opaque_len)
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{
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if (alternative_has_cap_likely(ARM64_HAS_FPSIMD))
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return __cvdso_getrandom(buffer, len, flags, opaque_state, opaque_len);
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if (unlikely(opaque_len == ~0UL && !buffer && !len && !flags))
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return -ENOSYS;
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return getrandom_syscall(buffer, len, flags);
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}
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