Changes imported from Abseil "staging" branch:

- fbff677ef850865ea67ed6771a8ed348be181e8e Modify sysinfo.cc to support GetTID on Akaros. by Abseil Team <absl-team@google.com>
  - f1c2929e08a3d4181e08cb5014c4a569306fd922 Two functions that did not refer to their arguments unles... by Abseil Team <absl-team@google.com>
  - ee43cc3bfdb4d84d40eee31fb25ecdc1aa060f47 Support Akaros (https://akaros.org) in the ABSL spinlock_... by Abseil Team <absl-team@google.com>
  - 6869c8c5253126459d6c7f0aa708d8612c8e5963 Make sure vdso_base_ is constant-intialized. by Abseil Team <absl-team@google.com>
  - d54e0366efc8d44cd5da5fd157734da966dc45e8 Add missing include for assert used by ABSL_ASSERT. by Derek Mauro <dmauro@google.com>
  - a5139775f3917bb5201e7fc838135766daa05b8d When building against GLIBC-2.16 or newer, use getauxval(... by Abseil Team <absl-team@google.com>

GitOrigin-RevId: fbff677ef850865ea67ed6771a8ed348be181e8e
Change-Id: Ie3549f6ef054783dd104304d2faf8d9800c16b83
This commit is contained in:
Abseil Team 2017-10-24 10:37:49 -07:00 committed by Jon Cohen
parent 5fcbe86e7b
commit dedb4eec6c
9 changed files with 120 additions and 34 deletions

View file

@ -284,6 +284,30 @@ pid_t GetTID() {
return syscall(SYS_gettid);
}
#elif defined(__akaros__)
pid_t GetTID() {
// Akaros has a concept of "vcore context", which is the state the program
// is forced into when we need to make a user-level scheduling decision, or
// run a signal handler. This is analogous to the interrupt context that a
// CPU might enter if it encounters some kind of exception.
//
// There is no current thread context in vcore context, but we need to give
// a reasonable answer if asked for a thread ID (e.g., in a signal handler).
// Thread 0 always exists, so if we are in vcore context, we return that.
//
// Otherwise, we know (since we are using pthreads) that the uthread struct
// current_uthread is pointing to is the first element of a
// struct pthread_tcb, so we extract and return the thread ID from that.
//
// TODO(dcross): Akaros anticipates moving the thread ID to the uthread
// structure at some point. We should modify this code to remove the cast
// when that happens.
if (in_vcore_context())
return 0;
return reinterpret_cast<struct pthread_tcb *>(current_uthread)->id;
}
#else
// Fallback implementation of GetTID using pthread_getspecific.