diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/arm/atomic-machine.h')
| -rw-r--r-- | sysdeps/unix/sysv/linux/arm/atomic-machine.h | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/arm/atomic-machine.h b/sysdeps/unix/sysv/linux/arm/atomic-machine.h new file mode 100644 index 0000000000..fb6f39d4f6 --- /dev/null +++ b/sysdeps/unix/sysv/linux/arm/atomic-machine.h @@ -0,0 +1,107 @@ +/* Atomic operations. ARM/Linux version. + Copyright (C) 2002-2016 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + 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, see + <http://www.gnu.org/licenses/>. */ + +#include <stdint.h> + +/* If the compiler doesn't provide a primitive, we'll use this macro + to get assistance from the kernel. */ +#ifdef __thumb2__ +# define __arm_assisted_full_barrier() \ + __asm__ __volatile__ \ + ("movw\tip, #0x0fa0\n\t" \ + "movt\tip, #0xffff\n\t" \ + "blx\tip" \ + : : : "ip", "lr", "cc", "memory"); +#else +# define __arm_assisted_full_barrier() \ + __asm__ __volatile__ \ + ("mov\tip, #0xffff0fff\n\t" \ + "mov\tlr, pc\n\t" \ + "add\tpc, ip, #(0xffff0fa0 - 0xffff0fff)" \ + : : : "ip", "lr", "cc", "memory"); +#endif + +/* Atomic compare and exchange. This sequence relies on the kernel to + provide a compare and exchange operation which is atomic on the + current architecture, either via cleverness on pre-ARMv6 or via + ldrex / strex on ARMv6. + + It doesn't matter what register is used for a_oldval2, but we must + specify one to work around GCC PR rtl-optimization/21223. Otherwise + it may cause a_oldval or a_tmp to be moved to a different register. + + We use the union trick rather than simply using __typeof (...) in the + declarations of A_OLDVAL et al because when NEWVAL or OLDVAL is of the + form *PTR and PTR has a 'volatile ... *' type, then __typeof (*PTR) has + a 'volatile ...' type and this triggers -Wvolatile-register-var to + complain about 'register volatile ... asm ("reg")'. */ +#ifdef __thumb2__ +/* Thumb-2 has ldrex/strex. However it does not have barrier instructions, + so we still need to use the kernel helper. */ +# define __arm_assisted_compare_and_exchange_val_32_acq(mem, newval, oldval) \ + ({ union { __typeof (oldval) a; uint32_t v; } oldval_arg = { .a = (oldval) };\ + union { __typeof (newval) a; uint32_t v; } newval_arg = { .a = (newval) };\ + register uint32_t a_oldval asm ("r0"); \ + register uint32_t a_newval asm ("r1") = newval_arg.v; \ + register __typeof (mem) a_ptr asm ("r2") = (mem); \ + register uint32_t a_tmp asm ("r3"); \ + register uint32_t a_oldval2 asm ("r4") = oldval_arg.v; \ + __asm__ __volatile__ \ + ("0:\tldr\t%[tmp],[%[ptr]]\n\t" \ + "cmp\t%[tmp], %[old2]\n\t" \ + "bne\t1f\n\t" \ + "mov\t%[old], %[old2]\n\t" \ + "movw\t%[tmp], #0x0fc0\n\t" \ + "movt\t%[tmp], #0xffff\n\t" \ + "blx\t%[tmp]\n\t" \ + "bcc\t0b\n\t" \ + "mov\t%[tmp], %[old2]\n\t" \ + "1:" \ + : [old] "=&r" (a_oldval), [tmp] "=&r" (a_tmp) \ + : [new] "r" (a_newval), [ptr] "r" (a_ptr), \ + [old2] "r" (a_oldval2) \ + : "ip", "lr", "cc", "memory"); \ + (__typeof (oldval)) a_tmp; }) +#else +# define __arm_assisted_compare_and_exchange_val_32_acq(mem, newval, oldval) \ + ({ union { __typeof (oldval) a; uint32_t v; } oldval_arg = { .a = (oldval) };\ + union { __typeof (newval) a; uint32_t v; } newval_arg = { .a = (newval) };\ + register uint32_t a_oldval asm ("r0"); \ + register uint32_t a_newval asm ("r1") = newval_arg.v; \ + register __typeof (mem) a_ptr asm ("r2") = (mem); \ + register uint32_t a_tmp asm ("r3"); \ + register uint32_t a_oldval2 asm ("r4") = oldval_arg.v; \ + __asm__ __volatile__ \ + ("0:\tldr\t%[tmp],[%[ptr]]\n\t" \ + "cmp\t%[tmp], %[old2]\n\t" \ + "bne\t1f\n\t" \ + "mov\t%[old], %[old2]\n\t" \ + "mov\t%[tmp], #0xffff0fff\n\t" \ + "mov\tlr, pc\n\t" \ + "add\tpc, %[tmp], #(0xffff0fc0 - 0xffff0fff)\n\t" \ + "bcc\t0b\n\t" \ + "mov\t%[tmp], %[old2]\n\t" \ + "1:" \ + : [old] "=&r" (a_oldval), [tmp] "=&r" (a_tmp) \ + : [new] "r" (a_newval), [ptr] "r" (a_ptr), \ + [old2] "r" (a_oldval2) \ + : "ip", "lr", "cc", "memory"); \ + (__typeof (oldval)) a_tmp; }) +#endif + +#include <sysdeps/arm/atomic-machine.h> |