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c20a84c910
Commit a0c1e9073e added code to futex.c
to detect whether futex_atomic_cmpxchg_inatomic was implemented at run
time:
+ curval = cmpxchg_futex_value_locked(NULL, 0, 0);
+ if (curval == -EFAULT)
+ futex_cmpxchg_enabled = 1;
This is bogus on parisc, since page zero in kernel virtual space is the
gateway page for syscall entry, and should not be read from the kernel.
(That, and we really don't like the kernel faulting on its own address
space...)
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
78 lines
1.7 KiB
C
78 lines
1.7 KiB
C
#ifndef _ASM_PARISC_FUTEX_H
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#define _ASM_PARISC_FUTEX_H
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#ifdef __KERNEL__
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#include <linux/futex.h>
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#include <asm/errno.h>
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#include <asm/uaccess.h>
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static inline int
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futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
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{
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int op = (encoded_op >> 28) & 7;
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int cmp = (encoded_op >> 24) & 15;
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int oparg = (encoded_op << 8) >> 20;
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int cmparg = (encoded_op << 20) >> 20;
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int oldval = 0, ret;
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if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
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oparg = 1 << oparg;
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if (! access_ok (VERIFY_WRITE, uaddr, sizeof(int)))
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return -EFAULT;
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pagefault_disable();
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switch (op) {
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case FUTEX_OP_SET:
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case FUTEX_OP_ADD:
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case FUTEX_OP_OR:
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case FUTEX_OP_ANDN:
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case FUTEX_OP_XOR:
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default:
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ret = -ENOSYS;
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}
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pagefault_enable();
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if (!ret) {
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switch (cmp) {
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case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
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case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
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case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
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case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
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case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
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case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
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default: ret = -ENOSYS;
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}
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}
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return ret;
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}
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/* Non-atomic version */
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static inline int
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futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
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{
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int err = 0;
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int uval;
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/* futex.c wants to do a cmpxchg_inatomic on kernel NULL, which is
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* our gateway page, and causes no end of trouble...
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*/
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if (segment_eq(KERNEL_DS, get_fs()) && !uaddr)
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return -EFAULT;
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if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
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return -EFAULT;
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err = get_user(uval, uaddr);
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if (err) return -EFAULT;
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if (uval == oldval)
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err = put_user(newval, uaddr);
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if (err) return -EFAULT;
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return uval;
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}
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#endif /*__KERNEL__*/
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#endif /*_ASM_PARISC_FUTEX_H*/
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