This is a note to let you know that I've just added the patch titled
ARC: gdbserver breakage in Big-Endian configuration #1
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arc-gdbserver-breakage-in-big-endian-configuration-1.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From Vineet.Gupta1@xxxxxxxxxxxx Thu Aug 22 15:32:58 2013
From: Vineet Gupta <Vineet.Gupta1@xxxxxxxxxxxx>
Date: Tue, 20 Aug 2013 13:38:10 +0530
Subject: ARC: gdbserver breakage in Big-Endian configuration #1
To: <stable@xxxxxxxxxxxxxxx>
Cc: <gregkh@xxxxxxxxxxxxxxxxxxx>, <noamc@xxxxxxxxxx>, <Anton.Kolesov@xxxxxxxxxxxx>, <linux-kernel@xxxxxxxxxxxxxxx>, Vineet Gupta <Vineet.Gupta1@xxxxxxxxxxxx>
Message-ID: <1376986091-30241-2-git-send-email-vgupta@xxxxxxxxxxxx>
From: Vineet Gupta <Vineet.Gupta1@xxxxxxxxxxxx>
[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 <noamc@xxxxxxxxxx>
Tested-by: Anton Kolesov <akolesov@xxxxxxxxxxxx>
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arc/include/asm/ptrace.h | 2 ++
arch/arc/kernel/entry.S | 4 ++--
2 files changed, 4 insertions(+), 2 deletions(-)
--- 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;
};
};
--- 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]
@@ -723,7 +723,7 @@ 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)
Patches currently in stable-queue which might be from Vineet.Gupta1@xxxxxxxxxxxx are
queue-3.10/arc-gdbserver-breakage-in-big-endian-configuration-1.patch
queue-3.10/arc-gdbserver-breakage-in-big-endian-configuration-2.patch
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