diff options
author | Waldemar Brodkorb <wbx@uclibc-ng.org> | 2016-05-18 18:41:24 +0200 |
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committer | Waldemar Brodkorb <wbx@uclibc-ng.org> | 2016-05-18 18:41:24 +0200 |
commit | 6a8ccc95528f5e86a8770ed15ce89609b5b3dee9 (patch) | |
tree | bbd4df35b4d4a6a8b00d7a5e61fb2668b850ad62 /libpthread/linuxthreads/sysdeps/i386/pt-machine.h | |
parent | 398a27a5b323956344b4f831d892fed3bd9813c7 (diff) |
remove linuxthreads.new, rename linuxthreads.old
Linuxthreads.new isn't really useful with the existence
of NPTL/TLS for well supported architectures. There is no
reason to use LT.new for ARM/MIPS or other architectures
supporting NPTL/TLS. It is not available for noMMU architectures
like Blackfin or FR-V. To simplify the live of the few uClibc-ng
developers, LT.new is removed and LT.old is renamed to LT.
LINUXTHREADS_OLD -> UCLIBC_HAS_LINUXTHREADS
Diffstat (limited to 'libpthread/linuxthreads/sysdeps/i386/pt-machine.h')
-rw-r--r-- | libpthread/linuxthreads/sysdeps/i386/pt-machine.h | 93 |
1 files changed, 61 insertions, 32 deletions
diff --git a/libpthread/linuxthreads/sysdeps/i386/pt-machine.h b/libpthread/linuxthreads/sysdeps/i386/pt-machine.h index 82a5cf077..24c5e6c7c 100644 --- a/libpthread/linuxthreads/sysdeps/i386/pt-machine.h +++ b/libpthread/linuxthreads/sysdeps/i386/pt-machine.h @@ -18,17 +18,14 @@ License along with the GNU C Library; see the file COPYING.LIB. If not, see <http://www.gnu.org/licenses/>. */ -#if defined __pentiumpro__ || defined __pentium4__ || defined __athlon__ || \ - defined __k8__ -# include "i686/pt-machine.h" -#else - #ifndef _PT_MACHINE_H #define _PT_MACHINE_H 1 +#include <features.h> + #ifndef __ASSEMBLER__ #ifndef PT_EI -# define PT_EI __extern_always_inline +# define PT_EI __extern_always_inline __attribute__((visibility("hidden"))) #endif extern long int testandset (int *spinlock); @@ -39,6 +36,54 @@ extern int __compare_and_swap (long int *p, long int oldval, long int newval); #define CURRENT_STACK_FRAME __builtin_frame_address (0) +/* See if we can optimize for newer cpus... */ +#if defined __GNUC__ && __GNUC__ >= 2 && \ + (defined __i486__ || defined __pentium__ || defined __pentiumpro__ || defined __pentium4__ || \ + defined __athlon__ || defined __k8__) + +/* Spinlock implementation; required. */ +PT_EI long int +testandset (int *spinlock) +{ + long int ret; + + __asm__ __volatile__ ( + "xchgl %0, %1" + : "=r" (ret), "=m" (*spinlock) + : "0" (1), "m" (*spinlock) + : "memory"); + + return ret; +} + +/* Compare-and-swap for semaphores. It's always available on i686. */ +#define HAS_COMPARE_AND_SWAP + +PT_EI int +__compare_and_swap (long int *p, long int oldval, long int newval) +{ + char ret; + long int readval; + + __asm__ __volatile__ ("lock; cmpxchgl %3, %1; sete %0" + : "=q" (ret), "=m" (*p), "=a" (readval) + : "r" (newval), "m" (*p), "a" (oldval) + : "memory"); + return ret; +} + +#if defined(__ASSUME_LDT_WORKS) && __ASSUME_LDT_WORKS > 0 +#include "useldt.h" +#endif + +/* The P4 and above really want some help to prevent overheating. */ +#define BUSY_WAIT_NOP __asm__ ("rep; nop") + + +#else /* Generic i386 implementation */ + +extern int compare_and_swap_is_available (void); + /* Spinlock implementation; required. */ PT_EI long int testandset (int *spinlock) @@ -75,43 +120,27 @@ __compare_and_swap (long int *p, long int oldval, long int newval) return ret; } - -PT_EI int get_eflags (void); -PT_EI int -get_eflags (void) -{ - int res; - __asm__ __volatile__ ("pushfl; popl %0" : "=r" (res) : ); - return res; -} - - -PT_EI void set_eflags (int newflags); -PT_EI void -set_eflags (int newflags) -{ - __asm__ __volatile__ ("pushl %0; popfl" : : "r" (newflags) : "cc"); -} - - -PT_EI int compare_and_swap_is_available (void); PT_EI int compare_and_swap_is_available (void) { - int oldflags = get_eflags (); int changed; + int oldflags; + /* get EFLAGS */ + __asm__ __volatile__ ("pushfl; popl %0" : "=r" (oldflags) : ); /* Flip AC bit in EFLAGS. */ - set_eflags (oldflags ^ 0x40000); + __asm__ __volatile__ ("pushl %0; popfl" : : "r" (oldflags ^ 0x40000) : "cc"); + /* reread EFLAGS */ + __asm__ __volatile__ ("pushfl; popl %0" : "=r" (changed) : ); /* See if bit changed. */ - changed = (get_eflags () ^ oldflags) & 0x40000; + changed = (changed ^ oldflags) & 0x40000; /* Restore EFLAGS. */ - set_eflags (oldflags); + __asm__ __volatile__ ("pushl %0; popfl" : : "r" (oldflags) : "cc"); /* If the AC flag did not change, it's a 386 and it lacks cmpxchg. Otherwise, it's a 486 or above and it has cmpxchg. */ return changed != 0; } +#endif /* Generic i386 implementation */ + #endif /* __ASSEMBLER__ */ #endif /* pt-machine.h */ - -#endif |