[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>
Cc: <stable@xxxxxxxxxxxxxxx> # [3.9 and 3.10 only]
Tested-by: Anton Kolesov <akolesov@xxxxxxxxxxxx>
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
---
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
--
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