lkml.org 
[lkml]   [2013]   [Oct]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[ 18/50] ARC: Ignore ptrace SETREGSET request for synthetic register "stop_pc"
Date
3.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Vineet Gupta <vgupta@synopsys.com>

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 <akolesov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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;
}



\
 
 \ /
  Last update: 2013-10-16 21:41    [W:0.165 / U:1.708 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site