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authorKonstantin Belousov <kib@FreeBSD.org>2008-08-18 08:47:27 +0000
committerKonstantin Belousov <kib@FreeBSD.org>2008-08-18 08:47:27 +0000
commit8ad85ff260e18e0bf17f67ab941663d141d248e3 (patch)
tree42ad3ba8578b6509c62721c7dec184daa649fb73 /sys
parent0f4b98311a8675e8692204a6197ab4c52b191f29 (diff)
downloadsrc-8ad85ff260e18e0bf17f67ab941663d141d248e3.tar.gz
src-8ad85ff260e18e0bf17f67ab941663d141d248e3.zip
The doreti_iret_fault code is always called with gs base MSR containing
kernel gs base, because %rip is adjusted only on kernel-mode trap caused by iretq execution. On the other hand, the stack contains (hardware part of) trap frame from the usermode. As a consequence, checking for frame mode and doing swapgs causes the kernel to enter trap() with usermode gs base. Remove the check for mode and conditional swapgs, we already have right gs base in the MSR. Submitted by: Nate Eldredge <neldredge math ucsd edu> MFC after: 3 days
Notes
Notes: svn path=/head/; revision=181823
Diffstat (limited to 'sys')
-rw-r--r--sys/amd64/amd64/exception.S9
1 files changed, 3 insertions, 6 deletions
diff --git a/sys/amd64/amd64/exception.S b/sys/amd64/amd64/exception.S
index f1cbe35d82b7..fd0a7ca9f54a 100644
--- a/sys/amd64/amd64/exception.S
+++ b/sys/amd64/amd64/exception.S
@@ -636,13 +636,10 @@ doreti_iret:
.globl doreti_iret_fault
doreti_iret_fault:
subq $TF_RIP,%rsp /* space including tf_err, tf_trapno */
- testb $SEL_RPL_MASK,TF_CS(%rsp) /* Did we come from kernel? */
- jz 1f /* already running with kernel GS.base */
- swapgs
-1: testl $PSL_I,TF_RFLAGS(%rsp)
- jz 2f
+ testl $PSL_I,TF_RFLAGS(%rsp)
+ jz 1f
sti
-2: movq %rdi,TF_RDI(%rsp)
+1: movq %rdi,TF_RDI(%rsp)
movq %rsi,TF_RSI(%rsp)
movq %rdx,TF_RDX(%rsp)
movq %rcx,TF_RCX(%rsp)