From fc327e268fbef08e129ad51aa3a7113ee9bc6ba5 Mon Sep 17 00:00:00 2001 From: Chris Metcalf Date: Sat, 28 Apr 2012 18:51:43 -0400 Subject: arch/tile: fix up some issues in calling do_work_pending() First, we were at risk of handling thread-info flags, in particular do_signal(), when returning from kernel space. This could happen after a failed kernel_execve(), or when forking a kernel thread. The fix is to test in do_work_pending() for user_mode() and return immediately if so; we already had this test for one of the flags, so I just hoisted it to the top of the function. Second, if a ptraced process updated the callee-saved registers in the ptregs struct and then processed another thread-info flag, we would overwrite the modifications with the original callee-saved registers. To fix this, we add a register to note if we've already saved the registers once, and skip doing it on additional passes through the loop. To avoid a performance hit from the couple of extra instructions involved, I modified the GET_THREAD_INFO() macro to be guaranteed to be one instruction, then bundled it with adjacent instructions, yielding an overall net savings. Reported-By: Al Viro Signed-off-by: Chris Metcalf --- arch/tile/kernel/process.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'arch/tile/kernel/process.c') diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c index 2d5ef617bb39..54e6c64b85cc 100644 --- a/arch/tile/kernel/process.c +++ b/arch/tile/kernel/process.c @@ -567,6 +567,10 @@ struct task_struct *__sched _switch_to(struct task_struct *prev, */ int do_work_pending(struct pt_regs *regs, u32 thread_info_flags) { + /* If we enter in kernel mode, do nothing and exit the caller loop. */ + if (!user_mode(regs)) + return 0; + if (thread_info_flags & _TIF_NEED_RESCHED) { schedule(); return 1; @@ -589,8 +593,7 @@ int do_work_pending(struct pt_regs *regs, u32 thread_info_flags) return 1; } if (thread_info_flags & _TIF_SINGLESTEP) { - if ((regs->ex1 & SPR_EX_CONTEXT_1_1__PL_MASK) == 0) - single_step_once(regs); + single_step_once(regs); return 0; } panic("work_pending: bad flags %#x\n", thread_info_flags); -- cgit v1.2.3