Author: jhb
Date: Wed Nov 11 01:32:35 2015
New Revision: 290668
URL: https://svnweb.freebsd.org/changeset/base/290668
Log:
MFC 284324,290164:
Workaround debuggers that try to read the full 32-bit words holding
selectors in trapframes.
284324:
Ensure that the upper 16 bits of segment registers manually saved in
trapframes are cleared by explicitly pushing a zero and then moving
the segment register into the low 16 bits. Certain Intel processors
treat a push of a segment register as a move of the segment register
into the low 16 bits leaving the upper 16 bits of the word in the
stack unchanged.
290164:
Use movw instead of movl (or plain mov) when moving segment registers
into memory. This is a nop on clang's assembler, but some assemblers
complain if the size suffix is incorrect.
Modified:
stable/9/sys/i386/i386/exception.s
stable/9/sys/i386/include/asmacros.h
Directory Properties:
stable/9/sys/ (props changed)
Changes in other areas also in this revision:
Modified:
stable/10/sys/i386/i386/exception.s
stable/10/sys/i386/include/asmacros.h
Directory Properties:
stable/10/ (props changed)
Modified: stable/9/sys/i386/i386/exception.s
==============================================================================
--- stable/9/sys/i386/i386/exception.s Wed Nov 11 00:45:41 2015
(r290667)
+++ stable/9/sys/i386/i386/exception.s Wed Nov 11 01:32:35 2015
(r290668)
@@ -158,9 +158,12 @@ IDTVEC(xmm)
.type alltraps,@function
alltraps:
pushal
- pushl %ds
- pushl %es
- pushl %fs
+ pushl $0
+ movw %ds,(%esp)
+ pushl $0
+ movw %es,(%esp)
+ pushl $0
+ movw %fs,(%esp)
alltraps_with_regs_pushed:
SET_KERNEL_SREGS
cld
@@ -234,9 +237,12 @@ IDTVEC(lcall_syscall)
pushl $7 /* sizeof "lcall 7,0" */
subl $4,%esp /* skip over tf_trapno */
pushal
- pushl %ds
- pushl %es
- pushl %fs
+ pushl $0
+ movw %ds,(%esp)
+ pushl $0
+ movw %es,(%esp)
+ pushl $0
+ movw %fs,(%esp)
SET_KERNEL_SREGS
cld
FAKE_MCOUNT(TF_EIP(%esp))
@@ -260,9 +266,12 @@ IDTVEC(int0x80_syscall)
pushl $2 /* sizeof "int 0x80" */
subl $4,%esp /* skip over tf_trapno */
pushal
- pushl %ds
- pushl %es
- pushl %fs
+ pushl $0
+ movw %ds,(%esp)
+ pushl $0
+ movw %es,(%esp)
+ pushl $0
+ movw %fs,(%esp)
SET_KERNEL_SREGS
cld
FAKE_MCOUNT(TF_EIP(%esp))
@@ -417,13 +426,16 @@ doreti_iret:
doreti_iret_fault:
subl $8,%esp
pushal
- pushl %ds
+ pushl $0
+ movw %ds,(%esp)
.globl doreti_popl_ds_fault
doreti_popl_ds_fault:
- pushl %es
+ pushl $0
+ movw %es,(%esp)
.globl doreti_popl_es_fault
doreti_popl_es_fault:
- pushl %fs
+ pushl $0
+ movw %fs,(%esp)
.globl doreti_popl_fs_fault
doreti_popl_fs_fault:
sti
Modified: stable/9/sys/i386/include/asmacros.h
==============================================================================
--- stable/9/sys/i386/include/asmacros.h Wed Nov 11 00:45:41 2015
(r290667)
+++ stable/9/sys/i386/include/asmacros.h Wed Nov 11 01:32:35 2015
(r290668)
@@ -146,9 +146,12 @@
pushl $0 ; /* dummy error code */ \
pushl $0 ; /* dummy trap type */ \
pushal ; /* 8 ints */ \
- pushl %ds ; /* save data and extra segments ... */ \
- pushl %es ; \
- pushl %fs
+ pushl $0 ; /* save data and extra segments ... */ \
+ movw %ds,(%esp) ; \
+ pushl $0 ; \
+ movw %es,(%esp) ; \
+ pushl $0 ; \
+ movw %fs,(%esp)
#define POP_FRAME
\
popl %fs ; \
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