go/src/runtime/sys_linux_s390x.s, branch fix-runtime-test-GOMAXPROCS

runtime: correct vdsoSP on S390X

2025-07-04T01:43:56Z

It should get the caller's SP. The current code gets the address of the first parameter, which is one word above the caller's SP. There is a slot for saving the LR at 0(SP) in the caller's frame. Fixes #62086 (for s390x). Change-Id: Ie8cbfabc8161b98658c884a32e0af72df189ea56 Reviewed-on: https://go-review.googlesource.com/c/go/+/685715 Reviewed-by: David Chase LUCI-TryBot-Result: Go LUCI

runtime: fix usleep on s390x/linux

2025-02-13T19:05:31Z

The timespec argument takes the remainder in nanoseconds, not microseconds. Convert the remaining time to nsec. Fixes #71714 Change-Id: I36cbbe3a088830c5e3afcc9516ef42e96ee21268 Reviewed-on: https://go-review.googlesource.com/c/go/+/648915 TryBot-Result: Gopher Robot Reviewed-by: Mauri de Souza Meneguzzo Reviewed-by: Axel Busch Run-TryBot: Paul Murphy Reviewed-by: Cherry Mui Reviewed-by: Ian Lance Taylor LUCI-TryBot-Result: Go LUCI Reviewed-by: Vishwanatha HD

runtime: use vDSO for getrandom() on linux

2024-09-28T01:07:09Z

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 Reviewed-by: Cuong Manh Le Auto-Submit: Jason Donenfeld Reviewed-by: Paul Murphy LUCI-TryBot-Result: Go LUCI Reviewed-by: David Chase Reviewed-by: Michael Pratt

runtime: add "sigaction" to sigreturn symbol name

2023-03-24T18:53:44Z

In order to identify the sigreturn function, gdb looks for "__restore_rt". However because that symbol is sometimes missing from the symbol table, it also performs the same instruction matching as libgcc, but only in symbols containing "sigaction" (it expects sigaction to preceed __restore_rt). To match this heuristic, we add __sigaction to the sigreturn symbol name. Fixes #25218. Change-Id: I09cb231ad23f668d451f31dd5633f782355fc91d Reviewed-on: https://go-review.googlesource.com/c/go/+/479096 Auto-Submit: Michael Pratt TryBot-Result: Gopher Robot Reviewed-by: Cherry Mui Run-TryBot: Michael Pratt

runtime: always keep global reference to mp until mexit completes

2022-10-18T20:57:24Z

Ms are allocated via standard heap allocation (`new(m)`), which means we must keep them alive (i.e., reachable by the GC) until we are completely done using them. Ms are primarily reachable through runtime.allm. However, runtime.mexit drops the M from allm fairly early, long before it is done using the M structure. If that was the last reference to the M, it is now at risk of being freed by the GC and used for some other allocation, leading to memory corruption. Ms with a Go-allocated stack coincidentally already keep a reference to the M in sched.freem, so that the stack can be freed lazily. This reference has the side effect of keeping this Ms reachable. However, Ms with an OS stack skip this and are at risk of corruption. Fix this lifetime by extending sched.freem use to all Ms, with the value of mp.freeWait determining whether the stack needs to be freed or not. Fixes #56243. Change-Id: Ic0c01684775f5646970df507111c9abaac0ba52e Reviewed-on: https://go-review.googlesource.com/c/go/+/443716 TryBot-Result: Gopher Robot Run-TryBot: Michael Pratt Reviewed-by: Michael Knyszek

runtime: move epoll syscalls to runtime/internal/syscall

2022-10-07T18:28:11Z

This change moves Linux epoll's syscalls implementation to the "runtime/internal/syscall" package. The intention in this CL was to minimise behavioural changes but make the code more generalised. This also will allow adding new syscalls (like epoll_pwait2) without the need to implement assembly stubs for each arch. It also drops epoll_create as not all architectures provide this call. epoll_create1 was added to the kernel in version 2.6.27 and Go requires Linux kernel version 2.6.32 or later since Go 1.18. So it is safe to always use epoll_create1. This is a resubmit as the previous CL 421994 was reverted due to test failures after the merge with the master. The issue was fixed in CL 438615 For #53824 For #51087 Change-Id: I1bd0f23a85b4f9b80178c5dd36fd3e95ff4f9648 Reviewed-on: https://go-review.googlesource.com/c/go/+/440115 Reviewed-by: Dmitri Shuralyov TryBot-Result: Gopher Robot Auto-Submit: Michael Pratt Reviewed-by: Michael Pratt Run-TryBot: Michael Pratt

Revert "runtime: move epoll syscalls to runtime/internal/syscall"

2022-09-30T19:07:13Z

This reverts CL 421994. Reason for revert: breaks runtime.TestCheckPtr2 For #53824 For #51087 Change-Id: I044ea4d6efdffe0a4b7fb0d2bb3717d9f391fc59 Reviewed-on: https://go-review.googlesource.com/c/go/+/437295 TryBot-Result: Gopher Robot Run-TryBot: Michael Pratt Auto-Submit: Michael Pratt Reviewed-by: Bryan Mills

runtime: move epoll syscalls to runtime/internal/syscall

2022-09-30T17:35:24Z

This change moves Linux epoll's syscalls implementation to the "runtime/internal/syscall" package. The intention in this CL was to minimise behavioural changes but make the code more generalised. This also will allow adding new syscalls (like epoll_pwait2) without the need to implement assembly stubs for each arch. It also drops epoll_create as not all architectures provide this call. epoll_create1 was added to the kernel in version 2.6.27 and Go requires Linux kernel version 2.6.32 or later since Go 1.18. So it is safe to always use epoll_create1. For #53824 For #51087 Change-Id: I9a6a26b7f2075a38e041de1bab4691da0ecb94fc Reviewed-on: https://go-review.googlesource.com/c/go/+/421994 Reviewed-by: Michael Pratt TryBot-Result: Gopher Robot Reviewed-by: Dmitri Shuralyov Run-TryBot: Michael Pratt Auto-Submit: Michael Pratt

runtime: enable vDSO support for s390x architecture

2022-05-11T13:30:43Z

This change adds support for vDSO for s390x architecture. This avoids the use of system calls in nanotime and walltime and accelerates them by factor 4-5. Benchmarks: 100,000,000 x time.Now(): syscall fallback 13923ms 139.23 ns/op vDSO enabled 2640ms 26.40 ns/op Change-Id: Ic679fe31048379e59ccf83b400140f13c9d49696 GitHub-Last-Rev: 8f6e918a45cf8c5aadc5c203949a8ce4e372086f GitHub-Pull-Request: golang/go#49717 Reviewed-on: https://go-review.googlesource.com/c/go/+/365995 Run-TryBot: Paul Murphy TryBot-Result: Gopher Robot Reviewed-by: David Chase Reviewed-by: Paul Murphy Reviewed-by: Michael Knyszek Reviewed-by: Jonathan Albrecht Reviewed-by: Heschi Kreinick Reviewed-by: Bill O'Farrell

runtime: mark sigtramp as TOPFRAME

2022-04-28T16:29:07Z

Currently throw() in the signal handler results in "fatal error: unknown return pc from runtime.sigreturn ...". Marking sigtramp as TOPFRAME allows gentraceback to stop tracebacks at the end of a signal handler, since there is not much beyond sigtramp. This is just done on Linux for now, but may apply to other Unix systems as well. Change-Id: I96edcb945283f417a5bfe00ce2fb2b1a0d578692 Reviewed-on: https://go-review.googlesource.com/c/go/+/402190 Reviewed-by: Austin Clements Run-TryBot: Michael Pratt Auto-Submit: Michael Pratt TryBot-Result: Gopher Robot Reviewed-by: Cherry Mui