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[PATCH] Fix length calculation in aarch64_linux_set_debug_regs
- From: Simon Marchi <simon dot marchi at ericsson dot com>
- To: <gdb-patches at sourceware dot org>
- Cc: <qiyaoltc at gmail dot com>, Simon Marchi <simon dot marchi at ericsson dot com>
- Date: Mon, 2 Nov 2015 09:48:04 -0500
- Subject: [PATCH] Fix length calculation in aarch64_linux_set_debug_regs
- Authentication-results: sourceware.org; auth=none
There is this build failure when building in C++:
In file included from build-gnulib/import/stddef.h:45:0,
from /usr/include/time.h:37,
from build-gnulib/import/time.h:41,
from build-gnulib/import/sys/stat.h:44,
from ../bfd/bfd.h:44,
from /home/simark/src/binutils-gdb/gdb/common/common-types.h:35,
from /home/simark/src/binutils-gdb/gdb/common/common-defs.h:44,
from /home/simark/src/binutils-gdb/gdb/nat/aarch64-linux-hw-point.c:19:
/home/simark/src/binutils-gdb/gdb/nat/aarch64-linux-hw-point.c: In function âvoid aarch64_linux_set_debug_regs(const aarch64_debug_reg_state*, int, int)â:
/home/simark/src/binutils-gdb/gdb/nat/aarch64-linux-hw-point.c:564:64: error: âcountâ cannot appear in a constant-expression
iov.iov_len = (offsetof (struct user_hwdebug_state, dbg_regs[count - 1])
^
I don't really understand the length computation done here.
>From what I understand, the dbg_regs array in the user_hwdebug_state structure
is 16 elements long, but we don't use all of them. We want iov_len to reflect
only the used bytes. If that's true, I don't think that the current code is
correct. Instead, it can be computed simply with:
offsetof (struct user_hwdebug_state, dbg_regs) + count * sizeof (regs.dbg_reg[0]);
Does it make sense?
gdb/ChangeLog:
* nat/aarch64-linux-hw-point.c (aarch64_linux_set_debug_regs): Fix
iov_len computation.
---
gdb/nat/aarch64-linux-hw-point.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/gdb/nat/aarch64-linux-hw-point.c b/gdb/nat/aarch64-linux-hw-point.c
index 1a5fa6a..dcbfa98 100644
--- a/gdb/nat/aarch64-linux-hw-point.c
+++ b/gdb/nat/aarch64-linux-hw-point.c
@@ -561,8 +561,8 @@ aarch64_linux_set_debug_regs (const struct aarch64_debug_reg_state *state,
ctrl = watchpoint ? state->dr_ctrl_wp : state->dr_ctrl_bp;
if (count == 0)
return;
- iov.iov_len = (offsetof (struct user_hwdebug_state, dbg_regs[count - 1])
- + sizeof (regs.dbg_regs [count - 1]));
+ iov.iov_len = (offsetof (struct user_hwdebug_state, dbg_regs)
+ + count * sizeof (regs.dbg_regs[0]));
for (i = 0; i < count; i++)
{
--
2.5.1