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| author | Jason A. Donenfeld <Jason@zx2c4.com> | 2024-09-22 03:45:29 +0200 |
|---|---|---|
| committer | Gopher Robot <gobot@golang.org> | 2024-09-28 01:07:09 +0000 |
| commit | eb6f2c24cd17c0ca1df7e343f8d9187eef7d6e13 (patch) | |
| tree | d76c58100622eb5d33e3ffc451dd726a3dd898bd /src/internal/syscall | |
| parent | 677b6cc17544e5e667d4bb67d063f5d775c69e32 (diff) | |
| download | go-eb6f2c24cd17c0ca1df7e343f8d9187eef7d6e13.tar.xz | |
runtime: use vDSO for getrandom() on linux
Linux 6.11 supports calling getrandom() from the vDSO. It operates on a
thread-local opaque state allocated with mmap using flags specified by
the vDSO.
Opaque states are allocated in chunks, ideally ncpu at a time as a hint,
rounding up to as many fit in a complete page. On first use, a state is
assigned to an m, which owns that state, until the m exits, at which
point it is given back to the pool.
Performance appears to be quite good:
│ sec/op │ sec/op vs base │
Read/4-16 222.45n ± 3% 27.13n ± 6% -87.80% (p=0.000 n=10)
│ B/s │ B/s vs base │
Read/4-16 17.15Mi ± 3% 140.61Mi ± 6% +719.82% (p=0.000 n=10)
Fixes #69577.
Change-Id: Ib6f44e8f2f3940c94d970eaada0eb566ec297dc7
Reviewed-on: https://go-review.googlesource.com/c/go/+/614835
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Auto-Submit: Jason Donenfeld <Jason@zx2c4.com>
Reviewed-by: Paul Murphy <murp@ibm.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Diffstat (limited to 'src/internal/syscall')
| -rw-r--r-- | src/internal/syscall/unix/getrandom.go | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/src/internal/syscall/unix/getrandom.go b/src/internal/syscall/unix/getrandom.go index 4270898b7e..2dbe19887c 100644 --- a/src/internal/syscall/unix/getrandom.go +++ b/src/internal/syscall/unix/getrandom.go @@ -12,6 +12,9 @@ import ( "unsafe" ) +//go:linkname vgetrandom runtime.vgetrandom +func vgetrandom(p []byte, flags uint32) (ret int, supported bool) + var getrandomUnsupported atomic.Bool // GetRandomFlag is a flag supported by the getrandom system call. @@ -19,6 +22,13 @@ type GetRandomFlag uintptr // GetRandom calls the getrandom system call. func GetRandom(p []byte, flags GetRandomFlag) (n int, err error) { + ret, supported := vgetrandom(p, uint32(flags)) + if supported { + if ret < 0 { + return 0, syscall.Errno(-ret) + } + return ret, nil + } if getrandomUnsupported.Load() { return 0, syscall.ENOSYS } |