| /* Atomic operations. ARM/Linux version. |
| Copyright (C) 2002-2014 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/bits/atomic.h> |
