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runtime/cgo: raise the thread-local storage slot search limit on Android

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On Android, the thread local offset is found by looping through memory
starting at the TLS base address. The search is limited to
PTHREAD_KEYS_MAX, but issue 19472 made it clear that in some cases, the
slot is located further from the TLS base.

The limit is merely a sanity check in case our assumptions about the
thread-local storage layout are wrong, so this CL raises it to 384, which
is enough for the test case in issue 19472.

Fixes #19472

Change-Id: I89d1db3e9739d3a7fff5548ae487a7483c0a278a
Reviewed-on: https://go-review.googlesource.com/38636
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Elias Naur 2017-03-25 12:55:40 +01:00
parent aa4c2ca316
commit 0476c7a7b5
2 changed files with 10 additions and 9 deletions
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13
src/runtime/cgo/gcc_android_arm.c
View File

@ -10,13 +10,6 @@
#define magic1 (0x23581321U) #define magic1 (0x23581321U)
// PTHREAD_KEYS_MAX has been added to sys/limits.h at head in bionic:
// https://android.googlesource.com/platform/bionic/+/master/libc/include/sys/limits.h
// TODO(crawshaw): remove this definition when NDK r10d is required.
#ifndef PTHREAD_KEYS_MAX
#define PTHREAD_KEYS_MAX 128
#endif
// inittls allocates a thread-local storage slot for g. // inittls allocates a thread-local storage slot for g.
// //
// It finds the first available slot using pthread_key_create and uses // It finds the first available slot using pthread_key_create and uses
@ -32,7 +25,11 @@ inittls(void **tlsg, void **tlsbase)
fatalf("pthread_key_create failed: %d", err); fatalf("pthread_key_create failed: %d", err);
} }
pthread_setspecific(k, (void*)magic1); pthread_setspecific(k, (void*)magic1);
for (i=0; i<PTHREAD_KEYS_MAX; i++) { // If thread local slots are laid out as we expect, our magic word will
// be located at some low offset from tlsbase. However, just in case something went
// wrong, the search is limited to sensible offsets. PTHREAD_KEYS_MAX was the
// original limit, but issue 19472 made a higher limit necessary.
for (i=0; i<384; i++) {
if (*(tlsbase+i) == (void*)magic1) { if (*(tlsbase+i) == (void*)magic1) {
*tlsg = (void*)(i*sizeof(void *)); *tlsg = (void*)(i*sizeof(void *));
pthread_setspecific(k, 0); pthread_setspecific(k, 0);

6
src/runtime/cgo/gcc_android_arm64.c
View File

@ -25,7 +25,11 @@ inittls(void **tlsg, void **tlsbase)
fatalf("pthread_key_create failed: %d", err); fatalf("pthread_key_create failed: %d", err);
} }
pthread_setspecific(k, (void*)magic1); pthread_setspecific(k, (void*)magic1);
for (i=0; i<PTHREAD_KEYS_MAX; i++) { // If thread local slots are laid out as we expect, our magic word will
// be located at some low offset from tlsbase. However, just in case something went
// wrong, the search is limited to sensible offsets. PTHREAD_KEYS_MAX was the
// original limit, but issue 19472 made a higher limit necessary.
for (i=0; i<384; i++) {
if (*(tlsbase+i) == (void*)magic1) { if (*(tlsbase+i) == (void*)magic1) {
*tlsg = (void*)(i*sizeof(void *)); *tlsg = (void*)(i*sizeof(void *));
pthread_setspecific(k, 0); pthread_setspecific(k, 0);