Author: kib
Date: Fri Jul 10 10:29:16 2009
New Revision: 195535
URL: http://svn.freebsd.org/changeset/base/195535
Log:
When amd64 CPU cannot load segment descriptor during trap return to
usermode, it generates GPF, that is mirrored to user mode as SIGSEGV.
The offending register in mcontext should contain the value loading of
which generated the GPF, and it is so on i386. On amd64, we currently
report segment descriptor in tf_err, while segment register contains the
corrected value loaded by trap handler.
Fix the issue by behaving like i386, reloading segment register in trap
frame after signal frame is pushed onto user stack.
Noted and tested by: pho
Approved by: re (kensmith)
Modified:
head/sys/amd64/amd64/exception.S
Modified: head/sys/amd64/amd64/exception.S
==============================================================================
--- head/sys/amd64/amd64/exception.S Fri Jul 10 08:18:08 2009
(r195534)
+++ head/sys/amd64/amd64/exception.S Fri Jul 10 10:29:16 2009
(r195535)
@@ -766,38 +766,38 @@ doreti_iret_fault:
.globl ds_load_fault
ds_load_fault:
movl $T_PROTFLT,TF_TRAPNO(%rsp)
- movzwl TF_DS(%rsp),%edx
- movl %edx,TF_ERR(%rsp)
+ movq %rsp, %rdi
+ call trap
movw $KUDSEL,TF_DS(%rsp)
- jmp calltrap
+ jmp doreti
ALIGN_TEXT
.globl es_load_fault
es_load_fault:
movl $T_PROTFLT,TF_TRAPNO(%rsp)
- movzwl TF_ES(%rsp),%edx
- movl %edx,TF_ERR(%rsp)
+ movq %rsp, %rdi
+ call trap
movw $KUDSEL,TF_ES(%rsp)
- jmp calltrap
+ jmp doreti
ALIGN_TEXT
.globl fs_load_fault
fs_load_fault:
movl $T_PROTFLT,TF_TRAPNO(%rsp)
- movzwl TF_FS(%rsp),%edx
- movl %edx,TF_ERR(%rsp)
+ movq %rsp, %rdi
+ call trap
movw $KUF32SEL,TF_FS(%rsp)
- jmp calltrap
+ jmp doreti
ALIGN_TEXT
.globl gs_load_fault
gs_load_fault:
popfq
movl $T_PROTFLT,TF_TRAPNO(%rsp)
- movzwl TF_GS(%rsp),%edx
- movl %edx,TF_ERR(%rsp)
+ movq %rsp, %rdi
+ call trap
movw $KUG32SEL,TF_GS(%rsp)
- jmp calltrap
+ jmp doreti
#ifdef HWPMC_HOOKS
ENTRY(end_exceptions)
#endif
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