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Optimize x86-64 syscall cancellation handling.
The syscall wrappers had to save and restore the syscall parameter values and return value when calling the functions to enable/disable cancellation were called. Not anymore. The called functions are special and don't modify any unexpected registers.
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Ulrich Drepper
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Aug 4, 2009
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,114 @@ | ||
| /* Copyright (C) 2009 Free Software Foundation, Inc. | ||
| This file is part of the GNU C Library. | ||
| Contributed by Ulrich Drepper <drepper@redhat.com>, 2009. | ||
| The GNU C Library is free software; you can redistribute it and/or | ||
| modify it under the terms of the GNU Lesser General Public | ||
| License as published by the Free Software Foundation; either | ||
| version 2.1 of the License, or (at your option) any later version. | ||
| The GNU C Library is distributed in the hope that it will be useful, | ||
| but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
| Lesser General Public License for more details. | ||
| You should have received a copy of the GNU Lesser General Public | ||
| License along with the GNU C Library; if not, write to the Free | ||
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | ||
| 02111-1307 USA. */ | ||
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|
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| #include <sysdep.h> | ||
| #include <tcb-offsets.h> | ||
| #include <kernel-features.h> | ||
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| #ifdef IS_IN_libpthread | ||
| # ifdef SHARED | ||
| # define __pthread_unwind __GI___pthread_unwind | ||
| # endif | ||
| #else | ||
| # ifndef SHARED | ||
| .weak __pthread_unwind | ||
| # endif | ||
| #endif | ||
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| #ifdef __ASSUME_PRIVATE_FUTEX | ||
| # define LOAD_PRIVATE_FUTEX_WAIT(reg) \ | ||
| movl $(FUTEX_WAIT | FUTEX_PRIVATE_FLAG), reg | ||
| #else | ||
| # if FUTEX_WAIT == 0 | ||
| # define LOAD_PRIVATE_FUTEX_WAIT(reg) \ | ||
| movl %fs:PRIVATE_FUTEX, reg | ||
| # else | ||
| # define LOAD_PRIVATE_FUTEX_WAIT(reg) \ | ||
| movl %fs:PRIVATE_FUTEX, reg ; \ | ||
| orl $FUTEX_WAIT, reg | ||
| # endif | ||
| #endif | ||
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| /* It is crucial that the functions in this file don't modify registers | ||
| other than %rax and %r11. The syscall wrapper code depends on this | ||
| because it doesn't explicitly save the other registers which hold | ||
| relevant values. */ | ||
| .text | ||
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| .hidden __pthread_enable_asynccancel | ||
| ENTRY(__pthread_enable_asynccancel) | ||
| movl %fs:CANCELHANDLING, %eax | ||
| 2: movl %eax, %r11d | ||
| orl $TCB_CANCELTYPE_BITMASK, %r11d | ||
| cmpl %eax, %r11d | ||
| je 1f | ||
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| lock | ||
| cmpxchgl %r11d, %fs:CANCELHANDLING | ||
| jnz 2b | ||
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| andl $(TCB_CANCELSTATE_BITMASK|TCB_CANCELTYPE_BITMASK|TCB_CANCELED_BITMASK|TCB_EXITING_BITMASK|TCB_CANCEL_RESTMASK|TCB_TERMINATED_BITMASK), %r11d | ||
| cmpl $(TCB_CANCELTYPE_BITMASK|TCB_CANCELED_BITMASK), %r11d | ||
| je 3f | ||
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| 1: ret | ||
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| 3: movq $TCB_PTHREAD_CANCELED, %fs:RESULT | ||
| lock | ||
| orl $TCB_EXITING_BITMASK, %fs:CANCELHANDLING | ||
| movq %fs:CLEANUP_JMP_BUF, %rdi | ||
| #ifdef SHARED | ||
| call __pthread_unwind@PLT | ||
| #else | ||
| call __pthread_unwind | ||
| #endif | ||
| hlt | ||
| END(__pthread_enable_asynccancel) | ||
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| .hidden __pthread_disable_asynccancel | ||
| ENTRY(__pthread_disable_asynccancel) | ||
| testl $TCB_CANCELTYPE_BITMASK, %edi | ||
| jnz 1f | ||
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| movl %fs:CANCELHANDLING, %eax | ||
| 2: movl %eax, %r11d | ||
| andl $~TCB_CANCELTYPE_BITMASK, %r11d | ||
| lock | ||
| cmpxchgl %r11d, %fs:CANCELHANDLING | ||
| jnz 2b | ||
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| 3: movl %r11d, %eax | ||
| andl $(TCB_CANCELING_BITMASK|TCB_CANCELED_BITMASK), %eax | ||
| cmpl $TCB_CANCELING_BITMASK, %eax | ||
| je 4f | ||
| 1: ret | ||
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| /* Performance doesn't matter in this loop. We will | ||
| delay until the thread is canceled. And we will unlikely | ||
| enter the loop twice. */ | ||
| 4: movq %fs:0, %rdi | ||
| movl $__NR_futex, %eax | ||
| xorq %r10, %r10 | ||
| addq $CANCELHANDLING, %rdi | ||
| LOAD_PRIVATE_FUTEX_WAIT (%esi) | ||
| syscall | ||
| jmp 3b | ||
| END(__pthread_disable_asynccancel) |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,22 @@ | ||
| /* Copyright (C) 2009 Free Software Foundation, Inc. | ||
| This file is part of the GNU C Library. | ||
| Contributed by Ulrich Drepper <drepper@redhat.com>, 2009. | ||
| The GNU C Library is free software; you can redistribute it and/or | ||
| modify it under the terms of the GNU Lesser General Public | ||
| License as published by the Free Software Foundation; either | ||
| version 2.1 of the License, or (at your option) any later version. | ||
| The GNU C Library is distributed in the hope that it will be useful, | ||
| but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
| Lesser General Public License for more details. | ||
| You should have received a copy of the GNU Lesser General Public | ||
| License along with the GNU C Library; if not, write to the Free | ||
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | ||
| 02111-1307 USA. */ | ||
|
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| #define __pthread_enable_asynccancel __libc_enable_asynccancel | ||
| #define __pthread_disable_asynccancel __libc_disable_asynccancel | ||
| #include "cancellation.S" |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,22 @@ | ||
| /* Copyright (C) 2009 Free Software Foundation, Inc. | ||
| This file is part of the GNU C Library. | ||
| Contributed by Ulrich Drepper <drepper@redhat.com>, 2009. | ||
| The GNU C Library is free software; you can redistribute it and/or | ||
| modify it under the terms of the GNU Lesser General Public | ||
| License as published by the Free Software Foundation; either | ||
| version 2.1 of the License, or (at your option) any later version. | ||
| The GNU C Library is distributed in the hope that it will be useful, | ||
| but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
| Lesser General Public License for more details. | ||
| You should have received a copy of the GNU Lesser General Public | ||
| License along with the GNU C Library; if not, write to the Free | ||
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | ||
| 02111-1307 USA. */ | ||
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| #define __pthread_enable_asynccancel __librt_enable_asynccancel | ||
| #define __pthread_disable_asynccancel __librt_disable_asynccancel | ||
| #include "cancellation.S" |
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