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[PATCH] gdb/x86: Fix write out of mxcsr register for xsave targets
- From: Andrew Burgess <andrew dot burgess at embecosm dot com>
- To: gdb-patches at sourceware dot org
- Cc: Andrew Burgess <andrew dot burgess at embecosm dot com>
- Date: Fri, 11 May 2018 12:52:28 +0100
- Subject: [PATCH] gdb/x86: Fix write out of mxcsr register for xsave targets
In commit:
commit 8ee22052f690c007556b97eed59f49350ece5ca9
Author: Andrew Burgess <andrew.burgess@embecosm.com>
Date: Thu May 3 17:46:14 2018 +0100
gdb/x86: Handle kernels using compact xsave format
in two places FXSAVE_ADDR was used instead of FXSAVE_MXCSR_ADDR to get
the address of the mxcsr register within the xsave buffer. This will
mean we are potentially accessing the wrong location within the xsave
buffer.
There are no tests included with this patch. The first mistake would
only trigger an issue if/when the user tries to manually set the mxcsr
register to a value that matches the random (value off stack) value
that is in the xsave buffer, in this case the change by the user will
go unnoticed by GDB, and the default value of mxcsr will be preserved.
The second mistake only happens on the code path where all x87
registers are being written out of the register cache. I'm not sure
how to trigger that code path.
gdb/ChangeLog:
* i387-tdep.c (i387_collect_xsave): Use FXSAVE_MXCSR_ADDR not
FXSAVE_ADDR for the mxcsr register.
---
gdb/ChangeLog | 5 +++++
gdb/i387-tdep.c | 4 ++--
2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/gdb/i387-tdep.c b/gdb/i387-tdep.c
index aca70c186f9..3effc35b174 100644
--- a/gdb/i387-tdep.c
+++ b/gdb/i387-tdep.c
@@ -1490,7 +1490,7 @@ i387_collect_xsave (const struct regcache *regcache, int regnum,
require clearing. */
if ((clear_bv & (X86_XSTATE_AVX | X86_XSTATE_SSE))
== (X86_XSTATE_AVX | X86_XSTATE_SSE))
- store_unsigned_integer (FXSAVE_ADDR (tdep, regs, i), 2, byte_order,
+ store_unsigned_integer (FXSAVE_MXCSR_ADDR (regs), 2, byte_order,
I387_MXCSR_INIT_VAL);
if ((clear_bv & X86_XSTATE_X87))
@@ -1643,7 +1643,7 @@ i387_collect_xsave (const struct regcache *regcache, int regnum,
{
i = I387_MXCSR_REGNUM (tdep);
regcache_raw_collect (regcache, i, raw);
- p = FXSAVE_ADDR (tdep, regs, i);
+ p = FXSAVE_MXCSR_ADDR (regs);
if (memcmp (raw, p, 4))
{
/* Now, we need to mark one of either SSE of AVX as enabled.
--
2.14.3