From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> Arnd said: I would guess that for csky, this is a mistake, as the architecture is fairly new and should be able to implement it. Guo reply: The c610, c807, c810 don't support SMP, so futex_cmpxchg_enabled = 1 with asm-generic's implementation. For c860, there is no HAVE_FUTEX_CMPXCHG and cmpxchg_inatomic/inuser implementation, so futex_cmpxchg_enabled = 0. Thx for point it out, we'll implement cmpxchg_inatomic/inuser for C860 and still use asm-generic for non-smp CPUs. LTP test: futex_wait01 1 TPASS : futex_wait(): errno=ETIMEDOUT(110): Connection timed out futex_wait01 2 TPASS : futex_wait(): errno=EAGAIN/EWOULDBLOCK(11): Resource temporarily unavailable futex_wait01 3 TPASS : futex_wait(): errno=ETIMEDOUT(110): Connection timed out futex_wait01 4 TPASS : futex_wait(): errno=EAGAIN/EWOULDBLOCK(11): Resource temporarily unavailable futex_wait02 1 TPASS : futex_wait() woken up futex_wait03 1 TPASS : futex_wait() woken up futex_wait04 1 TPASS : futex_wait() returned -1: errno=EAGAIN/EWOULDBLOCK(11): Resource temporarily unavailable Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Paul E. McKenney <paulmck@xxxxxxxxxx> Link: https://lore.kernel.org/lkml/CAK8P3a3+WaQNyJ6Za2qfu6=0mBgU1hApnRXrdp1b1=P7wwyRUg@xxxxxxxxxxxxxx/ --- arch/csky/Kconfig | 1 + arch/csky/include/asm/futex.h | 127 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 128 insertions(+) create mode 100644 arch/csky/include/asm/futex.h diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig index 50bb8b4..e254dc2 100644 --- a/arch/csky/Kconfig +++ b/arch/csky/Kconfig @@ -49,6 +49,7 @@ config CSKY select HAVE_FUNCTION_TRACER select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_ERROR_INJECTION + select HAVE_FUTEX_CMPXCHG if FUTEX && SMP select HAVE_FTRACE_MCOUNT_RECORD select HAVE_KERNEL_GZIP select HAVE_KERNEL_LZO diff --git a/arch/csky/include/asm/futex.h b/arch/csky/include/asm/futex.h new file mode 100644 index 00000000..dbe2f99 --- /dev/null +++ b/arch/csky/include/asm/futex.h @@ -0,0 +1,127 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef __ASM_CSKY_FUTEX_H +#define __ASM_CSKY_FUTEX_H + +#ifndef CONFIG_SMP +#include <asm-generic/futex.h> +#else +#include <linux/atomic.h> +#include <linux/futex.h> +#include <linux/uaccess.h> +#include <linux/errno.h> + +#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \ +{ \ + u32 tmp; \ + \ + __atomic_pre_full_fence(); \ + \ + __asm__ __volatile__ ( \ + "1: ldex.w %[ov], %[u] \n" \ + " "insn" \n" \ + "2: stex.w %[t], %[u] \n" \ + " bez %[t], 1b \n" \ + "4: \n" \ + " .section .fixup,\"ax\" \n" \ + " .balign 4 \n" \ + "5: mov %[r], %[e] \n" \ + " jmpi 4b \n" \ + " .previous \n" \ + " .section __ex_table,\"a\" \n" \ + " .balign 4 \n" \ + " .long 1b, 5b \n" \ + " .long 2b, 5b \n" \ + " .previous \n" \ + : [r] "+r" (ret), [ov] "=&r" (oldval), \ + [u] "+m" (*uaddr), [t] "=&r" (tmp) \ + : [op] "Jr" (oparg), [e] "jr" (-EFAULT) \ + : "memory"); \ + \ + __atomic_post_full_fence(); \ +} + +static inline int +arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) +{ + int oldval = 0, ret = 0; + + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; + + switch (op) { + case FUTEX_OP_SET: + __futex_atomic_op("mov %[t], %[ov]", + ret, oldval, uaddr, oparg); + break; + case FUTEX_OP_ADD: + __futex_atomic_op("add %[t], %[ov], %[op]", + ret, oldval, uaddr, oparg); + break; + case FUTEX_OP_OR: + __futex_atomic_op("or %[t], %[ov], %[op]", + ret, oldval, uaddr, oparg); + break; + case FUTEX_OP_ANDN: + __futex_atomic_op("and %[t], %[ov], %[op]", + ret, oldval, uaddr, ~oparg); + break; + case FUTEX_OP_XOR: + __futex_atomic_op("xor %[t], %[ov], %[op]", + ret, oldval, uaddr, oparg); + break; + default: + ret = -ENOSYS; + } + + if (!ret) + *oval = oldval; + + return ret; +} + + + +static inline int +futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, + u32 oldval, u32 newval) +{ + int ret = 0; + u32 val, tmp; + + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; + + __atomic_pre_full_fence(); + + __asm__ __volatile__ ( + "1: ldex.w %[v], %[u] \n" + " cmpne %[v], %[ov] \n" + " bt 4f \n" + " mov %[t], %[nv] \n" + "2: stex.w %[t], %[u] \n" + " bez %[t], 1b \n" + "4: \n" + " .section .fixup,\"ax\" \n" + " .balign 4 \n" + "5: mov %[r], %[e] \n" + " jmpi 4b \n" + " .previous \n" + " .section __ex_table,\"a\" \n" + " .balign 4 \n" + " .long 1b, 5b \n" + " .long 2b, 5b \n" + " .previous \n" + : [r] "+r" (ret), [v] "=&r" (val), [u] "+m" (*uaddr), + [t] "=&r" (tmp) + : [ov] "Jr" (oldval), [nv] "Jr" (newval), [e] "Jr" (-EFAULT) + : "memory"); + + __atomic_post_full_fence(); + + *uval = val; + return ret; +} + +#endif /* CONFIG_SMP */ +#endif /* __ASM_CSKY_FUTEX_H */ -- 2.7.4
