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Re: [PATCH, MPX] MPX-specific changes in dl_runtime routines
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: "Zamyatin, Igor" <igor dot zamyatin at intel dot com>
- Cc: "libc-alpha at sourceware dot org" <libc-alpha at sourceware dot org>
- Date: Thu, 2 Jul 2015 16:41:43 -0700
- Subject: Re: [PATCH, MPX] MPX-specific changes in dl_runtime routines
- Authentication-results: sourceware.org; auth=none
- References: <0EFAB2BDD0F67E4FB6CCC8B9F87D75696A91AC38 at IRSMSX101 dot ger dot corp dot intel dot com> <CAMe9rOqq9uHZHOG8-ByX5bt4xyy77Cb9PJWccaR_kMTOnt7qDQ at mail dot gmail dot com>
On Thu, Jul 2, 2015 at 7:33 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Thu, Jul 2, 2015 at 7:03 AM, Zamyatin, Igor <igor.zamyatin@intel.com> wrote:
>> Hi!
>>
>> This patch adds necessary changes for proper work of dl_runtime routines both for 32 and 64 bits in MPX mode.
>>
>> Is it ok for trunk?
>>
>>
>> Thanks,
>> Igor
>>
>>
>> 2015-07-02 Igor Zamyatin <igor.zamyatin@intel.com>
>>
>> * sysdeps/i386/dl-trampoline.S (_dl_runtime_profile): Save
>> and restore Intel MPX return bound registers
>> * sysdeps/x86_64/dl-trampoline.h: Add PRESERVE_BND_REGS_PREFIX to
>> call, jump and ret instructions to not loose bounds.
>> * sysdeps/x86/bits/link.h (La_i86_retval): Add lrv_bnd0 and
>> lrv_bnd1.
>
> Should we add link-defines.sym, similar to x86-64, to avoid
> those magic numbers when accessing the fields in La_i86_regs
> and La_i86_retval?
>
Here is a patch to add sysdeps/i386/link-defines.sym.
I think the i386 MPX change will store values into La_i86_retval
with wrong order. You need to store bnd0/bnd1 after lrv_st1, not
before lrv_eax.
Please add an i386 audit testcase to verify that pltexit gets correct
La_i86_regs and La_i86_retval pointers and fix the i386 MPX patch.
--
H.J.
From 4d2115cf349fbc235f4ab8c9a117bd1b20b44f2d Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Thu, 2 Jul 2015 16:33:03 -0700
Subject: [PATCH] Add and use sysdeps/i386/link-defines.sym
---
sysdeps/i386/Makefile | 1 +
sysdeps/i386/dl-trampoline.S | 39 ++++++++++++++++++++++++---------------
sysdeps/i386/link-defines.sym | 11 +++++++++++
3 files changed, 36 insertions(+), 15 deletions(-)
create mode 100644 sysdeps/i386/link-defines.sym
diff --git a/sysdeps/i386/Makefile b/sysdeps/i386/Makefile
index c8af591..87b5c6f 100644
--- a/sysdeps/i386/Makefile
+++ b/sysdeps/i386/Makefile
@@ -33,6 +33,7 @@ sysdep-CFLAGS += -mpreferred-stack-boundary=4
else
ifeq ($(subdir),csu)
sysdep-CFLAGS += -mpreferred-stack-boundary=4
+gen-as-const-headers += link-defines.sym
else
# Likewise, any function which calls user callbacks
uses-callbacks += -mpreferred-stack-boundary=4
diff --git a/sysdeps/i386/dl-trampoline.S b/sysdeps/i386/dl-trampoline.S
index f11972c..b4372c9 100644
--- a/sysdeps/i386/dl-trampoline.S
+++ b/sysdeps/i386/dl-trampoline.S
@@ -17,6 +17,7 @@
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
+#include <link-defines.h>
.text
.globl _dl_runtime_resolve
@@ -161,24 +162,32 @@ _dl_runtime_profile:
+4 free
%esp free
*/
- subl $20, %esp
- cfi_adjust_cfa_offset (20)
- movl %eax, (%esp)
- movl %edx, 4(%esp)
- fstpt 8(%esp)
- fstpt 20(%esp)
+#if LONG_DOUBLE_SIZE != 12
+# error "long double size must be 12 bytes"
+#endif
+ # Allocate space for La_i86_retval and subtract 12 free bytes.
+ subl $(LRV_SIZE - 12), %esp
+ cfi_adjust_cfa_offset (LRV_SIZE - 12)
+ movl %eax, LRV_EAX_OFFSET(%esp)
+ movl %edx, LRV_EDX_OFFSET(%esp)
+ fstpt LRV_ST0_OFFSET(%esp)
+ fstpt LRV_ST1_OFFSET(%esp)
pushl %esp
cfi_adjust_cfa_offset (4)
- leal 36(%esp), %ecx
- movl 56(%esp), %eax
- movl 60(%esp), %edx
+ # Address of La_i86_regs area.
+ leal (LRV_SIZE - 12 + 4 + 12)(%esp), %ecx
+ # PLT2
+ movl (LRV_SIZE - 12 + 4 + 32)(%esp), %eax
+ # PLT1
+ movl (LRV_SIZE - 12 + 4 + 36)(%esp), %edx
call _dl_call_pltexit
- movl (%esp), %eax
- movl 4(%esp), %edx
- fldt 20(%esp)
- fldt 8(%esp)
- addl $60, %esp
- cfi_adjust_cfa_offset (-60)
+ movl LRV_EAX_OFFSET(%esp), %eax
+ movl LRV_EDX_OFFSET(%esp), %edx
+ fldt LRV_ST1_OFFSET(%esp)
+ fldt LRV_ST0_OFFSET(%esp)
+ # Restore stack before return.
+ addl $(LRV_SIZE - 12 + 4 + 36), %esp
+ cfi_adjust_cfa_offset (-(LRV_SIZE - 12 + 4 + 36))
ret
cfi_endproc
.size _dl_runtime_profile, .-_dl_runtime_profile
diff --git a/sysdeps/i386/link-defines.sym b/sysdeps/i386/link-defines.sym
new file mode 100644
index 0000000..532a916
--- /dev/null
+++ b/sysdeps/i386/link-defines.sym
@@ -0,0 +1,11 @@
+#include "link.h"
+#include <stddef.h>
+
+--
+LONG_DOUBLE_SIZE sizeof (long double)
+
+LRV_SIZE sizeof (struct La_i86_retval)
+LRV_EAX_OFFSET offsetof (struct La_i86_retval, lrv_eax)
+LRV_EDX_OFFSET offsetof (struct La_i86_retval, lrv_edx)
+LRV_ST0_OFFSET offsetof (struct La_i86_retval, lrv_st0)
+LRV_ST1_OFFSET offsetof (struct La_i86_retval, lrv_st1)
--
2.4.3