Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751866Ab3HTIIt (ORCPT ); Tue, 20 Aug 2013 04:08:49 -0400 Received: from hermes.synopsys.com ([198.182.44.81]:35240 "EHLO hermes.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751344Ab3HTIIp (ORCPT ); Tue, 20 Aug 2013 04:08:45 -0400 From: Vineet Gupta To: CC: , , , , Vineet Gupta Subject: [PATCH 1/2] ARC: gdbserver breakage in Big-Endian configuration #1 Date: Tue, 20 Aug 2013 13:38:10 +0530 Message-ID: <1376986091-30241-2-git-send-email-vgupta@synopsys.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1376986091-30241-1-git-send-email-vgupta@synopsys.com> References: <20130820062901.GA3758@kroah.com> <1376986091-30241-1-git-send-email-vgupta@synopsys.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.12.197.26] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2748 Lines: 78 [Based on mainline commit 502a0c775c7f0a: "ARC: pt_regs update #5"] gdbserver needs @stop_pc, served by ptrace, but fetched from pt_regs differently, based on in_brkpt_traps(), which in turn relies on additional machine state in pt_regs->event bitfield. unsigned long orig_r8:16, event:16; For big endian config, this macro was returning false, despite being in breakpoint Trap exception, causing wrong @stop_pc to be returned to gdb. Issue #1: In BE, @event above is at offset 2 in word, while a STW insn at offset 0 was used to update it. Resort to using ST insn which updates the half-word at right location. Issue #2: The union involving bitfields causes all the members to be laid out at offset 0. So with fix #1 above, ASM was now updating at offset 2, "C" code was still referencing at offset 0. Fixed by wrapping bitfield in a struct. Reported-by: Noam Camus Cc: # [3.9 and 3.10 only] Tested-by: Anton Kolesov Signed-off-by: Vineet Gupta --- arch/arc/include/asm/ptrace.h | 2 ++ arch/arc/kernel/entry.S | 4 ++-- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h index 6179de7..2046a89 100644 --- a/arch/arc/include/asm/ptrace.h +++ b/arch/arc/include/asm/ptrace.h @@ -52,12 +52,14 @@ struct pt_regs { /*to distinguish bet excp, syscall, irq */ union { + struct { #ifdef CONFIG_CPU_BIG_ENDIAN /* so that assembly code is same for LE/BE */ unsigned long orig_r8:16, event:16; #else unsigned long event:16, orig_r8:16; #endif + }; long orig_r8_word; }; }; diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S index 7b5f3ec..724de08 100644 --- a/arch/arc/kernel/entry.S +++ b/arch/arc/kernel/entry.S @@ -498,7 +498,7 @@ tracesys_exit: trap_with_param: ; stop_pc info by gdb needs this info - stw orig_r8_IS_BRKPT, [sp, PT_orig_r8] + st orig_r8_IS_BRKPT, [sp, PT_orig_r8] mov r0, r12 lr r1, [efa] @@ -727,7 +727,7 @@ not_exception: ; things to what they were, before returning from L2 context ;---------------------------------------------------------------- - ldw r9, [sp, PT_orig_r8] ; get orig_r8 to make sure it is + ld r9, [sp, PT_orig_r8] ; get orig_r8 to make sure it is brne r9, orig_r8_IS_IRQ2, 149f ; infact a L2 ISR ret path ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs) -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/