From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Anton Kolesov , Vineet Gupta Subject: [ 18/50] ARC: Ignore ptrace SETREGSET request for synthetic register "stop_pc" Date: Wed, 16 Oct 2013 10:45:04 -0700 Message-Id: <20131016174400.590312903@linuxfoundation.org> In-Reply-To: <20131016174358.335646140@linuxfoundation.org> References: <20131016174358.335646140@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vineet Gupta commit 5b24282846c064ee90d40fcb3a8f63b8e754fd28 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- arch/arc/kernel/ptrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/arc/kernel/ptrace.c +++ b/arch/arc/kernel/ptrace.c @@ -102,7 +102,7 @@ static int genregs_set(struct task_struc 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; }