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D50414.id155683.diff
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diff --git a/sys/amd64/amd64/cpu_switch.S b/sys/amd64/amd64/cpu_switch.S
--- a/sys/amd64/amd64/cpu_switch.S
+++ b/sys/amd64/amd64/cpu_switch.S
@@ -91,14 +91,8 @@
jnz 2f
testb $CPUID_STDEXT_FSGSBASE,cpu_stdext_feature(%rip)
jz 2f
- movl %fs,%eax
- cmpl $KUF32SEL,%eax
- jne 1f
rdfsbase %rax
movq %rax,PCB_FSBASE(%r8)
-1: movl %gs,%eax
- cmpl $KUG32SEL,%eax
- jne 2f
movq %rdx,%r12
movl $MSR_KGSBASE,%ecx /* Read user gs base */
rdmsr
diff --git a/sys/amd64/amd64/exception.S b/sys/amd64/amd64/exception.S
--- a/sys/amd64/amd64/exception.S
+++ b/sys/amd64/amd64/exception.S
@@ -479,22 +479,14 @@
jz 6f /* already running with kernel GS.base */
testb $CPUID_STDEXT_FSGSBASE,cpu_stdext_feature(%rip)
jz 2f
- cmpw $KUF32SEL,TF_FS(%rsp)
- jne 1f
rdfsbase %rax
-1: cmpw $KUG32SEL,TF_GS(%rsp)
- jne 2f
rdgsbase %rdx
2: swapgs
lfence
movq PCPU(CURPCB),%rdi
testb $CPUID_STDEXT_FSGSBASE,cpu_stdext_feature(%rip)
jz 4f
- cmpw $KUF32SEL,TF_FS(%rsp)
- jne 3f
movq %rax,PCB_FSBASE(%rdi)
-3: cmpw $KUG32SEL,TF_GS(%rsp)
- jne 4f
movq %rdx,PCB_GSBASE(%rdi)
orl $PCB_FULL_IRET,PCB_FLAGS(%rdi) /* full iret from user #gp */
4: call handle_ibrs_entry
@@ -730,12 +722,8 @@
orl $PCB_FULL_IRET,PCB_FLAGS(%rdi)
testb $CPUID_STDEXT_FSGSBASE,cpu_stdext_feature(%rip)
jz 3f
- cmpw $KUF32SEL,TF_FS(%rsp)
- jne 2f
rdfsbase %rax
movq %rax,PCB_FSBASE(%rdi)
-2: cmpw $KUG32SEL,TF_GS(%rsp)
- jne 3f
movl $MSR_KGSBASE,%ecx
rdmsr
shlq $32,%rdx
@@ -842,12 +830,8 @@
orl $PCB_FULL_IRET,PCB_FLAGS(%rdi)
testb $CPUID_STDEXT_FSGSBASE,cpu_stdext_feature(%rip)
jz 3f
- cmpw $KUF32SEL,TF_FS(%rsp)
- jne 2f
rdfsbase %rax
movq %rax,PCB_FSBASE(%rdi)
-2: cmpw $KUG32SEL,TF_GS(%rsp)
- jne 3f
movl $MSR_KGSBASE,%ecx
rdmsr
shlq $32,%rdx
@@ -1177,8 +1161,6 @@
.globl ld_fs
ld_fs:
movw %ax,%fs
- cmpw $KUF32SEL,%ax
- jne 1f
movl $MSR_FSBASE,%ecx
movl PCB_FSBASE(%r8),%eax
movl PCB_FSBASE+4(%r8),%edx
@@ -1212,8 +1194,6 @@
* from the previously saved msr read.
*/
movl $MSR_KGSBASE,%ecx
- cmpw $KUG32SEL,%si
- jne 1f
movl PCB_GSBASE(%r8),%eax
movl PCB_GSBASE+4(%r8),%edx
jmp ld_gsbase
diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -1797,10 +1797,8 @@
(pcb->pcb_flags & PCB_FULL_IRET) == 0) {
r = intr_disable();
if ((pcb->pcb_flags & PCB_FULL_IRET) == 0) {
- if (rfs() == _ufssel)
- pcb->pcb_fsbase = rdfsbase();
- if (rgs() == _ugssel)
- pcb->pcb_gsbase = rdmsr(MSR_KGSBASE);
+ pcb->pcb_fsbase = rdfsbase();
+ pcb->pcb_gsbase = rdmsr(MSR_KGSBASE);
}
set_pcb_flags_raw(pcb, flags);
intr_restore(r);

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