From: Stefan Kristiansson <stefan.kristians...@saunalahti.fi> Support for the futex_atomic_* operations by using the load-link/store-conditional l.lwa/l.swa instructions. Most openrisc cores provide these instructions now if not available, emulation is provided.
Cc: Peter Zijlstra <pet...@infradead.org> Signed-off-by: Stefan Kristiansson <stefan.kristians...@saunalahti.fi> [sho...@gmail.com: remove OPENRISC_HAVE_INST_LWA_SWA config suggesed by Alan Cox https://lkml.org/lkml/2014/7/23/666] Signed-off-by: Stafford Horne <sho...@gmail.com> --- arch/openrisc/include/asm/Kbuild | 1 - arch/openrisc/include/asm/futex.h | 135 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 135 insertions(+), 1 deletion(-) create mode 100644 arch/openrisc/include/asm/futex.h diff --git a/arch/openrisc/include/asm/Kbuild b/arch/openrisc/include/asm/Kbuild index 1cedd63..a669c14 100644 --- a/arch/openrisc/include/asm/Kbuild +++ b/arch/openrisc/include/asm/Kbuild @@ -20,7 +20,6 @@ generic-y += exec.h generic-y += fb.h generic-y += fcntl.h generic-y += ftrace.h -generic-y += futex.h generic-y += hardirq.h generic-y += hw_irq.h generic-y += ioctl.h diff --git a/arch/openrisc/include/asm/futex.h b/arch/openrisc/include/asm/futex.h new file mode 100644 index 0000000..7780873 --- /dev/null +++ b/arch/openrisc/include/asm/futex.h @@ -0,0 +1,135 @@ +#ifndef __ASM_OPENRISC_FUTEX_H +#define __ASM_OPENRISC_FUTEX_H + +#ifdef __KERNEL__ + +#include <linux/futex.h> +#include <linux/uaccess.h> +#include <asm/errno.h> + +#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \ +({ \ + __asm__ __volatile__ ( \ + "1: l.lwa %0, %2 \n" \ + insn "\n" \ + "2: l.swa %2, %1 \n" \ + " l.bnf 1b \n" \ + " l.ori %1, r0, 0 \n" \ + "3: \n" \ + ".section .fixup,\"ax\" \n" \ + "4: l.j 3b \n" \ + " l.addi %1, r0, %3 \n" \ + ".previous \n" \ + ".section __ex_table,\"a\" \n" \ + ".word 1b,4b,2b,4b \n" \ + ".previous \n" \ + : "=&r" (oldval), "=&r" (ret), "+m" (*uaddr) \ + : "i" (-EFAULT), "r" (oparg) \ + : "cc", "memory" \ + ); \ +}) + +static inline int +futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr) +{ + int op = (encoded_op >> 28) & 7; + int cmp = (encoded_op >> 24) & 15; + int oparg = (encoded_op << 8) >> 20; + int cmparg = (encoded_op << 20) >> 20; + int oldval = 0, ret; + + if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) + oparg = 1 << oparg; + + if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) + return -EFAULT; + + pagefault_disable(); + + switch (op) { + case FUTEX_OP_SET: + __futex_atomic_op("l.or %1,%4,%4", ret, oldval, uaddr, oparg); + break; + case FUTEX_OP_ADD: + __futex_atomic_op("l.add %1,%0,%4", ret, oldval, uaddr, oparg); + break; + case FUTEX_OP_OR: + __futex_atomic_op("l.or %1,%0,%4", ret, oldval, uaddr, oparg); + break; + case FUTEX_OP_ANDN: + __futex_atomic_op("l.and %1,%0,%4", ret, oldval, uaddr, ~oparg); + break; + case FUTEX_OP_XOR: + __futex_atomic_op("l.xor %1,%0,%4", ret, oldval, uaddr, oparg); + break; + default: + ret = -ENOSYS; + } + + pagefault_enable(); + + if (!ret) { + switch (cmp) { + case FUTEX_OP_CMP_EQ: + ret = (oldval == cmparg); + break; + case FUTEX_OP_CMP_NE: + ret = (oldval != cmparg); + break; + case FUTEX_OP_CMP_LT: + ret = (oldval < cmparg); + break; + case FUTEX_OP_CMP_GE: + ret = (oldval >= cmparg); + break; + case FUTEX_OP_CMP_LE: + ret = (oldval <= cmparg); + break; + case FUTEX_OP_CMP_GT: + ret = (oldval > cmparg); + break; + default: + ret = -ENOSYS; + } + } + return ret; +} + +static inline int +futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, + u32 oldval, u32 newval) +{ + int ret = 0; + u32 prev; + + if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) + return -EFAULT; + + __asm__ __volatile__ ( \ + "1: l.lwa %1, %2 \n" \ + " l.sfeq %1, %3 \n" \ + " l.bnf 3f \n" \ + " l.nop \n" \ + "2: l.swa %2, %4 \n" \ + " l.bnf 1b \n" \ + " l.nop \n" \ + "3: \n" \ + ".section .fixup,\"ax\" \n" \ + "4: l.j 3b \n" \ + " l.addi %0, r0, %5 \n" \ + ".previous \n" \ + ".section __ex_table,\"a\" \n" \ + ".word 1b,4b,2b,4b \n" \ + ".previous \n" \ + : "+r" (ret), "=&r" (prev), "+m" (*uaddr) \ + : "r" (oldval), "r" (newval), "i" (-EFAULT) \ + : "cc", "memory" \ + ); + + *uval = prev; + return ret; +} + +#endif /* __KERNEL__ */ + +#endif /* __ASM_OPENRISC_FUTEX_H */ -- 2.9.3
