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Commit db7d9a4e authored by David S. Miller's avatar David S. Miller
Browse files

[SPARC64]: Move syscall success and newchild state out of thread flags. 



These two bits were accesses non-atomically from assembler
code.  So, in order to eliminate any potential races resulting
from that, move these pieces of state into two bytes elsewhere
in struct thread_info.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent cdd5186f

arch/sparc64/kernel/entry.S

+8 −9
Original line number Diff line number Diff line
@@ -1600,11 +1600,11 @@ sys_clone: flushw 
		ba,pt		%xcc, sparc_do_fork

		 add		%sp, PTREGS_OFF, %o2

ret_from_syscall:

		/* Clear SPARC_FLAG_NEWCHILD, switch_to leaves thread.flags in

		 * %o7 for us.  Check performance counter stuff too.

		/* Clear current_thread_info()->new_child, and

		 * check performance counter stuff too.

		 */

		andn		%o7, _TIF_NEWCHILD, %l0

		stx		%l0, [%g6 + TI_FLAGS]

		stb		%g0, [%g6 + TI_NEW_CHILD]

		ldx		[%g6 + TI_FLAGS], %l0

		call		schedule_tail

		 mov		%g7, %o0

		andcc		%l0, _TIF_PERFCTR, %g0
@@ -1720,12 +1720,11 @@ ret_sys_call: 
	/* Check if force_successful_syscall_return()

	 * was invoked.

	 */

	ldx		[%curptr + TI_FLAGS], %l0

	andcc		%l0, _TIF_SYSCALL_SUCCESS, %g0

	be,pt		%icc, 1f

	 andn		%l0, _TIF_SYSCALL_SUCCESS, %l0

	ldub		[%curptr + TI_SYS_NOERROR], %l0

	brz,pt		%l0, 1f

	 nop

	ba,pt		%xcc, 80f

	 stx		%l0, [%curptr + TI_FLAGS]

	 stb		%g0, [%curptr + TI_SYS_NOERROR]



1:

	cmp		%o0, -ERESTART_RESTARTBLOCK

arch/sparc64/kernel/process.c

+1 −1
Original line number Diff line number Diff line
@@ -621,8 +621,8 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long sp, 
	memcpy(child_trap_frame, (((struct sparc_stackf *)regs)-1), (TRACEREG_SZ+STACKFRAME_SZ));



	t->flags = (t->flags & ~((0xffUL << TI_FLAG_CWP_SHIFT) | (0xffUL << TI_FLAG_CURRENT_DS_SHIFT))) |

		_TIF_NEWCHILD |

		(((regs->tstate + 1) & TSTATE_CWP) << TI_FLAG_CWP_SHIFT);

	t->new_child = 1;

	t->ksp = ((unsigned long) child_trap_frame) - STACK_BIAS;

	t->kregs = (struct pt_regs *)(child_trap_frame+sizeof(struct sparc_stackf));

	t->fpsaved[0] = 0;

arch/sparc64/kernel/smp.c

+1 −1
Original line number Diff line number Diff line
@@ -137,7 +137,7 @@ void __init smp_callin(void) 
	/* Clear this or we will die instantly when we

	 * schedule back to this idler...

	 */

	clear_thread_flag(TIF_NEWCHILD);

	current_thread_info()->new_child = 0;



	/* Attach to the address space of init_task. */

	atomic_inc(&init_mm.mm_count);

arch/sparc64/kernel/traps.c

+2 −0
Original line number Diff line number Diff line
@@ -2125,6 +2125,8 @@ void __init trap_init(void) 
	    TI_PCR != offsetof(struct thread_info, pcr_reg) ||

	    TI_CEE_STUFF != offsetof(struct thread_info, cee_stuff) ||

	    TI_PRE_COUNT != offsetof(struct thread_info, preempt_count) ||

	    TI_NEW_CHILD != offsetof(struct thread_info, new_child) ||

	    TI_SYS_NOERROR != offsetof(struct thread_info, syscall_noerror) ||

	    TI_FPREGS != offsetof(struct thread_info, fpregs) ||

	    (TI_FPREGS & (64 - 1)))

		thread_info_offsets_are_bolixed_dave();

include/asm-sparc64/ptrace.h

+3 −2
Original line number Diff line number Diff line
@@ -95,7 +95,8 @@ struct sparc_trapf { 


#ifdef __KERNEL__

#define force_successful_syscall_return()	    \

	set_thread_flag(TIF_SYSCALL_SUCCESS)

do {	current_thread_info()->syscall_noerror = 1; \

} while (0)

#define user_mode(regs) (!((regs)->tstate & TSTATE_PRIV))

#define instruction_pointer(regs) ((regs)->tpc)

#ifdef CONFIG_SMP