From: Vineet Gupta Date: Thu, 10 Oct 2013 14:03:57 +0000 (+0530) Subject: ARC: Ignore ptrace SETREGSET request for synthetic register "stop_pc" X-Git-Tag: v3.12-rc5~12^2 X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=5b24282846c064ee90d40fcb3a8f63b8e754fd28;p=uclinux-h8%2Flinux.git ARC: Ignore ptrace SETREGSET request for synthetic register "stop_pc" ARCompact TRAP_S insn used for breakpoints, commits before exception is taken (updating architectural PC). So ptregs->ret contains next-PC and not the breakpoint PC itself. This is different from other restartable exceptions such as TLB Miss where ptregs->ret has exact faulting PC. gdb needs to know exact-PC hence ARC ptrace GETREGSET provides for @stop_pc which returns ptregs->ret vs. EFA depending on the situation. However, writing stop_pc (SETREGSET request), which updates ptregs->ret doesn't makes sense stop_pc doesn't always correspond to that reg as described above. This was not an issue so far since user_regs->ret / user_regs->stop_pc had same value and both writing to ptregs->ret was OK, needless, but NOT broken, hence not observed. With gdb "jump", they diverge, and user_regs->ret updating ptregs is overwritten immediately with stop_pc, which this patch fixes. Reported-by: Anton Kolesov Signed-off-by: Vineet Gupta --- diff --git a/arch/arc/kernel/ptrace.c b/arch/arc/kernel/ptrace.c index 333238564b67..5d76706139dd 100644 --- a/arch/arc/kernel/ptrace.c +++ b/arch/arc/kernel/ptrace.c @@ -102,7 +102,7 @@ static int genregs_set(struct task_struct *target, REG_IGNORE_ONE(pad2); REG_IN_CHUNK(callee, efa, cregs); /* callee_regs[r25..r13] */ REG_IGNORE_ONE(efa); /* efa update invalid */ - REG_IN_ONE(stop_pc, &ptregs->ret); /* stop_pc: PC update */ + REG_IGNORE_ONE(stop_pc); /* PC updated via @ret */ return ret; }