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[XTENSA] Fix register corruption for certain processor configurations

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For processor configurations that have optional registers
(compiler-used but non-coprocessor), user space registers
might get corrupted when there are only 4 registers in
the current window-frame, ie. register a4 belongs to the
oldest frame in the register file.

Signed-off-by: Chris Zankel <chris@zankel.net>
This commit is contained in:
Chris Zankel 2008-01-22 00:45:25 -08:00
parent 9f8fcf38e8
commit e108843062
1 changed files with 15 additions and 29 deletions
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44
arch/xtensa/kernel/entry.S
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@ -395,55 +395,49 @@ common_exception_return:
/* Jump if we are returning from kernel exceptions. */
1: l32i a3, a1, PT_PS
_bbsi.l a3, PS_UM_BIT, 2f
j kernel_exception_exit
_bbci.l a3, PS_UM_BIT, 4f
/* Specific to a user exception exit:
* We need to check some flags for signal handling and rescheduling,
* and have to restore WB and WS, extra states, and all registers
* in the register file that were in use in the user task.
*/
2: wsr a3, PS /* disable interrupts */
/* Check for signals (keep interrupts disabled while we read TI_FLAGS)
* Note: PS.INTLEVEL = 0, PS.EXCM = 1
* Note that we don't disable interrupts here.
*/
GET_THREAD_INFO(a2,a1)
l32i a4, a2, TI_FLAGS
/* Enable interrupts again.
* Note: When we get here, we certainly have handled any interrupts.
* (Hint: There is only one user exception frame on stack)
*/
movi a3, 1 << PS_WOE_BIT
_bbsi.l a4, TIF_NEED_RESCHED, 3f
_bbci.l a4, TIF_SIGPENDING, 4f
l32i a4, a1, PT_DEPC
bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 4f
/* Reenable interrupts and call do_signal() */
wsr a3, PS
/* Call do_signal() */
movi a4, do_signal # int do_signal(struct pt_regs*, sigset_t*)
mov a6, a1
movi a7, 0
callx4 a4
j 1b
3: /* Reenable interrupts and reschedule */
3: /* Reschedule */
wsr a3, PS
movi a4, schedule # void schedule (void)
callx4 a4
j 1b
/* Restore the state of the task and return from the exception. */
4: /* Restore optional registers. */
4: /* a2 holds GET_CURRENT(a2,a1) */
load_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT
wsr a3, PS /* disable interrupts */
_bbci.l a3, PS_UM_BIT, kernel_exception_exit
user_exception_exit:
/* Restore the state of the task and return from the exception. */
/* Switch to the user thread WINDOWBASE. Save SP temporarily in DEPC */
@ -509,10 +503,6 @@ common_exception_return:
kernel_exception_exit:
/* Disable interrupts (a3 holds PT_PS) */
wsr a3, PS
#ifdef PREEMPTIBLE_KERNEL
#ifdef CONFIG_PREEMPT
@ -591,10 +581,6 @@ kernel_exception_exit:
common_exception_exit:
/* Restore optional registers. */
load_xtregs_opt a1 a3 a4 a5 a6 a7 PT_XTREGS_OPT
/* Restore address registers. */
_bbsi.l a2, 1, 1f