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openrisc: Rework signal handling

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The mainline signal handling code for OpenRISC has been buggy since day
one with respect to syscall restart.  This patch significantly reworks
the signal handling code:

i)   Move the "work pending" loop to C code (borrowed from ARM arch)

ii)  Allow a tracer to muck about with the IP and skip syscall restart
     in that case (again, borrowed from ARM)

iii) Make signal handling WRT syscall restart actually work

v)   Make the signal handling code look more like that of other
     architectures so that it's easier for others to follow

Reported-by: Anders Nystrom <anders@southpole.se>
Signed-off-by: Jonas Bonn <jonas@southpole.se>
This commit is contained in:
Jonas Bonn
2012-02-19 17:36:53 +01:00
parent d6e0a2dd12
commit 10f67dbf6a
2 changed files with 143 additions and 122 deletions
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63
arch/openrisc/kernel/entry.S
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@@ -853,38 +853,45 @@ UNHANDLED_EXCEPTION(_vector_0x1f00,0x1f00)
/* ========================================================[ return ] === */
_work_pending:
/*
* if (current_thread_info->flags & _TIF_NEED_RESCHED)
* schedule();
*/
l.lwz r5,TI_FLAGS(r10)
l.andi r3,r5,_TIF_NEED_RESCHED
l.sfnei r3,0
l.bnf _work_notifysig
l.nop
l.jal schedule
l.nop
l.j _resume_userspace
l.nop
/* Handle pending signals and notify-resume requests.
* do_notify_resume must be passed the latest pushed pt_regs, not
* necessarily the "userspace" ones. Also, pt_regs->syscallno
* must be set so that the syscall restart functionality works.
*/
_work_notifysig:
l.jal do_notify_resume
l.ori r3,r1,0 /* pt_regs */
_resume_userspace:
DISABLE_INTERRUPTS(r3,r4)
l.lwz r3,TI_FLAGS(r10)
l.andi r3,r3,_TIF_WORK_MASK
l.sfnei r3,0
l.bf _work_pending
l.lwz r4,TI_FLAGS(r10)
l.andi r13,r4,_TIF_WORK_MASK
l.sfeqi r13,0
l.bf _restore_all
l.nop
_work_pending:
l.lwz r5,PT_ORIG_GPR11(r1)
l.sfltsi r5,0
l.bnf 1f
l.nop
l.andi r5,r5,0
1:
l.jal do_work_pending
l.ori r3,r1,0 /* pt_regs */
l.sfeqi r11,0
l.bf _restore_all
l.nop
l.sfltsi r11,0
l.bnf 1f
l.nop
l.and r11,r11,r0
l.ori r11,r11,__NR_restart_syscall
l.j _syscall_check_trace_enter
l.nop
1:
l.lwz r11,PT_ORIG_GPR11(r1)
/* Restore arg registers */
l.lwz r3,PT_GPR3(r1)
l.lwz r4,PT_GPR4(r1)
l.lwz r5,PT_GPR5(r1)
l.lwz r6,PT_GPR6(r1)
l.lwz r7,PT_GPR7(r1)
l.j _syscall_check_trace_enter
l.lwz r8,PT_GPR8(r1)
_restore_all:
RESTORE_ALL
/* This returns to userspace code */