[PATCH] alpha: separate thread-synchronous flags

From: Al Viro
Date: Sat Oct 20 2012 - 10:52:11 EST

... and fix the race in updating unaligned control ones

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
diff --git a/arch/alpha/include/asm/thread_info.h b/arch/alpha/include/asm/thread_info.h
index 4554ecb..1f8c729 100644
--- a/arch/alpha/include/asm/thread_info.h
+++ b/arch/alpha/include/asm/thread_info.h
@@ -7,6 +7,7 @@
#include <asm/processor.h>
#include <asm/types.h>
#include <asm/hwrpb.h>
+#include <asm/sysinfo.h>
#endif

#ifndef __ASSEMBLY__
@@ -21,6 +22,7 @@ struct thread_info {
mm_segment_t addr_limit; /* thread address space */
unsigned cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ unsigned int status; /* thread-synchronous flags */

int bpt_nsaved;
unsigned long bpt_addr[2]; /* breakpoint handling */
@@ -63,8 +65,6 @@ register struct thread_info *__current_thread_info __asm__("$8");
* - these are process state flags and used from assembly
* - pending work-to-be-done flags come first and must be assigned to be
* within bits 0 to 7 to fit in and immediate operand.
- * - ALPHA_UAC_SHIFT below must be kept consistent with the unaligned
- * control flags.
*
* TIF_SYSCALL_TRACE is known to be 0 via blbs.
*/
@@ -72,18 +72,12 @@ register struct thread_info *__current_thread_info __asm__("$8");
#define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
#define TIF_SIGPENDING 2 /* signal pending */
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
-#define TIF_POLLING_NRFLAG 8 /* poll_idle is polling NEED_RESCHED */
#define TIF_DIE_IF_KERNEL 9 /* dik recursion lock */
-#define TIF_UAC_NOPRINT 10 /* ! Preserve sequence of following */
-#define TIF_UAC_NOFIX 11 /* ! flags as they match */
-#define TIF_UAC_SIGBUS 12 /* ! userspace part of 'osf_sysinfo' */
#define TIF_MEMDIE 13 /* is terminating due to OOM killer */
-#define TIF_RESTORE_SIGMASK 14 /* restore signal mask in do_signal */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
-#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)

/* Work to do on interrupt/exception return. */
@@ -94,29 +88,63 @@ register struct thread_info *__current_thread_info __asm__("$8");
#define _TIF_ALLWORK_MASK (_TIF_WORK_MASK \
| _TIF_SYSCALL_TRACE)

-#define ALPHA_UAC_SHIFT TIF_UAC_NOPRINT
-#define ALPHA_UAC_MASK (1 << TIF_UAC_NOPRINT | 1 << TIF_UAC_NOFIX | \
- 1 << TIF_UAC_SIGBUS)
+#define TS_UAC_NOPRINT 0x0001 /* ! Preserve the following three */
+#define TS_UAC_NOFIX 0x0002 /* ! flags as they match */
+#define TS_UAC_SIGBUS 0x0004 /* ! userspace part of 'osf_sysinfo' */
+#define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */
+#define TS_POLLING 0x0010 /* idle task polling need_resched,
+ skip sending interrupt */

-#define SET_UNALIGN_CTL(task,value) ({ \
- task_thread_info(task)->flags = ((task_thread_info(task)->flags & \
- ~ALPHA_UAC_MASK) \
- | (((value) << ALPHA_UAC_SHIFT) & (1<<TIF_UAC_NOPRINT))\
- | (((value) << (ALPHA_UAC_SHIFT + 1)) & (1<<TIF_UAC_SIGBUS)) \
- | (((value) << (ALPHA_UAC_SHIFT - 1)) & (1<<TIF_UAC_NOFIX)));\
+#define tsk_is_polling(t) (task_thread_info(t)->status & TS_POLLING)
+
+#ifndef __ASSEMBLY__
+#define HAVE_SET_RESTORE_SIGMASK 1
+static inline void set_restore_sigmask(void)
+{
+ struct thread_info *ti = current_thread_info();
+ ti->status |= TS_RESTORE_SIGMASK;
+ WARN_ON(!test_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags));
+}
+static inline void clear_restore_sigmask(void)
+{
+ current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
+}
+static inline bool test_restore_sigmask(void)
+{
+ return current_thread_info()->status & TS_RESTORE_SIGMASK;
+}
+static inline bool test_and_clear_restore_sigmask(void)
+{
+ struct thread_info *ti = current_thread_info();
+ if (!(ti->status & TS_RESTORE_SIGMASK))
+ return false;
+ ti->status &= ~TS_RESTORE_SIGMASK;
+ return true;
+}
+#endif
+
+#define SET_UNALIGN_CTL(task,value) ({ \
+ __u32 status = task_thread_info(task)->status & ~UAC_BITMASK; \
+ if (value & PR_UNALIGN_NOPRINT) \
+ status |= TS_UAC_NOPRINT; \
+ if (value & PR_UNALIGN_SIGBUS) \
+ status |= TS_UAC_SIGBUS; \
+ if (value & 4) /* alpha-specific */ \
+ status |= TS_UAC_NOFIX; \
+ task_thread_info(task)->status = status; \
0; })

#define GET_UNALIGN_CTL(task,value) ({ \
- put_user((task_thread_info(task)->flags & (1 << TIF_UAC_NOPRINT))\
- >> ALPHA_UAC_SHIFT \
- | (task_thread_info(task)->flags & (1 << TIF_UAC_SIGBUS))\
- >> (ALPHA_UAC_SHIFT + 1) \
- | (task_thread_info(task)->flags & (1 << TIF_UAC_NOFIX))\
- >> (ALPHA_UAC_SHIFT - 1), \
- (int __user *)(value)); \
+ __u32 status = task_thread_info(task)->status & ~UAC_BITMASK; \
+ __u32 res = 0; \
+ if (status & TS_UAC_NOPRINT) \
+ res |= PR_UNALIGN_NOPRINT; \
+ if (status & TS_UAC_SIGBUS) \
+ res |= PR_UNALIGN_SIGBUS; \
+ if (status & TS_UAC_NOFIX) \
+ res |= 4; \
+ put_user(res, (int __user *)(value)); \
})

-#define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
-
#endif /* __KERNEL__ */
#endif /* _ALPHA_THREAD_INFO_H */
diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index 9eb0905..5530911 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -793,8 +793,7 @@ SYSCALL_DEFINE5(osf_getsysinfo, unsigned long, op, void __user *, buffer,
case GSI_UACPROC:
if (nbytes < sizeof(unsigned int))
return -EINVAL;
- w = (current_thread_info()->flags >> ALPHA_UAC_SHIFT) &
- UAC_BITMASK;
+ w = current_thread_info()->status & UAC_BITMASK;
if (put_user(w, (unsigned int __user *)buffer))
return -EFAULT;
return 1;
@@ -904,24 +903,20 @@ SYSCALL_DEFINE5(osf_setsysinfo, unsigned long, op, void __user *, buffer,
break;

case SSI_NVPAIRS: {
- unsigned long v, w, i;
- unsigned int old, new;
+ unsigned __user *p = buffer;
+ unsigned i;

- for (i = 0; i < nbytes; ++i) {
+ for (i = 0, p = buffer; i < nbytes; ++i, p += 2) {
+ unsigned v, w, status;

- if (get_user(v, 2*i + (unsigned int __user *)buffer))
- return -EFAULT;
- if (get_user(w, 2*i + 1 + (unsigned int __user *)buffer))
+ if (get_user(v, p) || get_user(w, p + 1))
return -EFAULT;
switch (v) {
case SSIN_UACPROC:
- again:
- old = current_thread_info()->flags;
- new = old & ~(UAC_BITMASK << ALPHA_UAC_SHIFT);
- new = new | (w & UAC_BITMASK) << ALPHA_UAC_SHIFT;
- if (cmpxchg(&current_thread_info()->flags,
- old, new) != old)
- goto again;
+ w &= UAC_BITMASK;
+ status = current_thread_info()->status;
+ status = (status & ~UAC_BITMASK) | w;
+ current_thread_info()->status = status;
break;

default:
diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c
index 3d28a53..ad86c09 100644
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -49,7 +49,7 @@ EXPORT_SYMBOL(pm_power_off);
void
cpu_idle(void)
{
- set_thread_flag(TIF_POLLING_NRFLAG);
+ current_thread_info()->status |= TS_POLLING;

while (1) {
/* FIXME -- EV6 and LCA45 know how to power down
diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c
index 80d987c..272666d 100644
--- a/arch/alpha/kernel/traps.c
+++ b/arch/alpha/kernel/traps.c
@@ -780,17 +780,17 @@ do_entUnaUser(void __user * va, unsigned long opcode,
/* Check the UAC bits to decide what the user wants us to do
with the unaliged access. */

- if (!test_thread_flag (TIF_UAC_NOPRINT)) {
+ if (!(current_thread_info()->status & TS_UAC_NOPRINT)) {
if (__ratelimit(&ratelimit)) {
printk("%s(%d): unaligned trap at %016lx: %p %lx %ld\n",
current->comm, task_pid_nr(current),
regs->pc - 4, va, opcode, reg);
}
}
- if (test_thread_flag (TIF_UAC_SIGBUS))
+ if ((current_thread_info()->status & TS_UAC_SIGBUS))
goto give_sigbus;
/* Not sure why you'd want to use this, but... */
- if (test_thread_flag (TIF_UAC_NOFIX))
+ if ((current_thread_info()->status & TS_UAC_NOFIX))
return;

/* Don't bother reading ds in the access check since we already
--
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