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ARC: gdbserver breakage in Big-Endian configuration #1

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[Based on mainline commit 502a0c775c: "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@ezchip.com>
Tested-by: Anton Kolesov <akolesov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vineet Gupta
2013-08-20 13:38:10 +05:30
committed by Greg Kroah-Hartman
parent 6e4fdb8035
commit 9b2c750d8e
2 changed files with 4 additions and 2 deletions
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2
arch/arc/include/asm/ptrace.h
View File

@@ -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;
};
};

4
arch/arc/kernel/entry.S
View File

@@ -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)