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| author | Michael Pratt <mpratt@google.com> | 2021-08-12 17:17:51 -0400 |
|---|---|---|
| committer | Michael Pratt <mpratt@google.com> | 2021-08-13 14:00:23 +0000 |
| commit | 20a620fd9f7bc35739c1af3602d53808d0430814 (patch) | |
| tree | 0209d2b1a64b81fba1542331355a8bcdb5bd50b1 /src/runtime | |
| parent | 4c8ffb3baaabce1aa2139ce7739fec333ab80728 (diff) | |
| download | go-20a620fd9f7bc35739c1af3602d53808d0430814.tar.gz go-20a620fd9f7bc35739c1af3602d53808d0430814.zip | |
runtime: drop SIGPROF while in ARM < 7 kernel helpers
On Linux ARMv6 and below runtime/internal/atomic.Cas calls into a kernel
cas helper at a fixed address. If a SIGPROF arrives while executing the
kernel helper, the sigprof lostAtomic logic will miss that we are
potentially in the spinlock critical section, which could cause
a deadlock when using atomics later in sigprof.
Fixes #47505
Change-Id: If8ba0d0fc47e45d4e6c68eca98fac4c6ed4e43c1
Reviewed-on: https://go-review.googlesource.com/c/go/+/341889
Trust: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Diffstat (limited to 'src/runtime')
| -rw-r--r-- | src/runtime/proc.go | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/src/runtime/proc.go b/src/runtime/proc.go index ec4be31db3..764f12769e 100644 --- a/src/runtime/proc.go +++ b/src/runtime/proc.go @@ -4619,7 +4619,7 @@ func sigprof(pc, sp, lr uintptr, gp *g, mp *m) { return } - // On mips{,le}, 64bit atomics are emulated with spinlocks, in + // On mips{,le}/arm, 64bit atomics are emulated with spinlocks, in // runtime/internal/atomic. If SIGPROF arrives while the program is inside // the critical section, it creates a deadlock (when writing the sample). // As a workaround, create a counter of SIGPROFs while in critical section @@ -4632,6 +4632,13 @@ func sigprof(pc, sp, lr uintptr, gp *g, mp *m) { return } } + if GOARCH == "arm" && goarm < 7 && GOOS == "linux" && pc&0xffff0000 == 0xffff0000 { + // runtime/internal/atomic functions call into kernel + // helpers on arm < 7. See + // runtime/internal/atomic/sys_linux_arm.s. + cpuprof.lostAtomic++ + return + } } // Profiling runs concurrently with GC, so it must not allocate. |