mirror of
https://github.com/Stichting-MINIX-Research-Foundation/pkgsrc-ng.git
synced 2025-09-07 11:20:04 -04:00
98 lines
2.0 KiB
C
98 lines
2.0 KiB
C
$NetBSD: patch-xen_include_asm-arm_spinlock.h,v 1.1 2014/12/30 08:15:01 spz Exp $
|
|
|
|
from XSA-114:
|
|
switch to write-biased r/w locks
|
|
|
|
This is to improve fairness: A permanent flow of read acquires can
|
|
otherwise lock out eventual writers indefinitely.
|
|
|
|
This is XSA-114 / CVE-2014-9065.
|
|
|
|
--- xen/include/asm-arm/spinlock.h.orig 2014-09-02 06:22:57.000000000 +0000
|
|
+++ xen/include/asm-arm/spinlock.h
|
|
@@ -55,84 +55,6 @@ static always_inline int _raw_spin_trylo
|
|
}
|
|
}
|
|
|
|
-typedef struct {
|
|
- volatile unsigned int lock;
|
|
-} raw_rwlock_t;
|
|
-
|
|
-#define _RAW_RW_LOCK_UNLOCKED { 0 }
|
|
-
|
|
-static always_inline int _raw_read_trylock(raw_rwlock_t *rw)
|
|
-{
|
|
- unsigned long tmp, tmp2 = 1;
|
|
-
|
|
- __asm__ __volatile__(
|
|
-"1: ldrex %0, [%2]\n"
|
|
-" adds %0, %0, #1\n"
|
|
-" strexpl %1, %0, [%2]\n"
|
|
- : "=&r" (tmp), "+r" (tmp2)
|
|
- : "r" (&rw->lock)
|
|
- : "cc");
|
|
-
|
|
- smp_mb();
|
|
- return tmp2 == 0;
|
|
-}
|
|
-
|
|
-static always_inline int _raw_write_trylock(raw_rwlock_t *rw)
|
|
-{
|
|
- unsigned long tmp;
|
|
-
|
|
- __asm__ __volatile__(
|
|
-"1: ldrex %0, [%1]\n"
|
|
-" teq %0, #0\n"
|
|
-" strexeq %0, %2, [%1]"
|
|
- : "=&r" (tmp)
|
|
- : "r" (&rw->lock), "r" (0x80000000)
|
|
- : "cc");
|
|
-
|
|
- if (tmp == 0) {
|
|
- smp_mb();
|
|
- return 1;
|
|
- } else {
|
|
- return 0;
|
|
- }
|
|
-}
|
|
-
|
|
-static inline void _raw_read_unlock(raw_rwlock_t *rw)
|
|
-{
|
|
- unsigned long tmp, tmp2;
|
|
-
|
|
- smp_mb();
|
|
-
|
|
- __asm__ __volatile__(
|
|
-"1: ldrex %0, [%2]\n"
|
|
-" sub %0, %0, #1\n"
|
|
-" strex %1, %0, [%2]\n"
|
|
-" teq %1, #0\n"
|
|
-" bne 1b"
|
|
- : "=&r" (tmp), "=&r" (tmp2)
|
|
- : "r" (&rw->lock)
|
|
- : "cc");
|
|
-
|
|
- if (tmp == 0)
|
|
- dsb_sev();
|
|
-}
|
|
-
|
|
-static inline void _raw_write_unlock(raw_rwlock_t *rw)
|
|
-{
|
|
- smp_mb();
|
|
-
|
|
- __asm__ __volatile__(
|
|
- "str %1, [%0]\n"
|
|
- :
|
|
- : "r" (&rw->lock), "r" (0)
|
|
- : "cc");
|
|
-
|
|
- dsb_sev();
|
|
-}
|
|
-
|
|
-#define _raw_rw_is_locked(x) ((x)->lock != 0)
|
|
-#define _raw_rw_is_write_locked(x) ((x)->lock == 0x80000000)
|
|
-
|
|
#endif /* __ASM_SPINLOCK_H */
|
|
/*
|
|
* Local variables:
|