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| author | jhb <jhb@FreeBSD.org> | 2015-11-11 01:32:35 +0000 |
|---|---|---|
| committer | jhb <jhb@FreeBSD.org> | 2015-11-11 01:32:35 +0000 |
| commit | 9c319c0ee46b77f68febe6ec66b2e787d91e1627 (patch) | |
| tree | e3ff827d472df36acb14e1d6e06240194ee25406 /sys/i386 | |
| parent | 5033903e2b91c8722c776318d671e7bee03179ba (diff) | |
| download | FreeBSD-src-9c319c0ee46b77f68febe6ec66b2e787d91e1627.zip FreeBSD-src-9c319c0ee46b77f68febe6ec66b2e787d91e1627.tar.gz | |
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.
Diffstat (limited to 'sys/i386')
| -rw-r--r-- | sys/i386/i386/exception.s | 36 | ||||
| -rw-r--r-- | sys/i386/include/asmacros.h | 9 |
2 files changed, 30 insertions, 15 deletions
diff --git a/sys/i386/i386/exception.s b/sys/i386/i386/exception.s index 58cd3e8..9386ada 100644 --- a/sys/i386/i386/exception.s +++ b/sys/i386/i386/exception.s @@ -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 diff --git a/sys/i386/include/asmacros.h b/sys/i386/include/asmacros.h index c1c3f64..ef08d03 100644 --- a/sys/i386/include/asmacros.h +++ b/sys/i386/include/asmacros.h @@ -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 ; \ |
