The branch stable/14 has been updated by kib:
URL:
https://cgit.FreeBSD.org/src/commit/?id=0f44d9df994b398ba4591141559da6db18fff557
commit 0f44d9df994b398ba4591141559da6db18fff557
Author: Konstantin Belousov <k...@freebsd.org>
AuthorDate: 2025-05-19 01:30:14 +0000
Commit: Konstantin Belousov <k...@freebsd.org>
CommitDate: 2025-06-12 18:02:49 +0000
amd64: do not handle fs/gs bases conditionally on the selector
(cherry picked from commit ddab534cd6f6557740c24ff2019642880ad8bef6)
---
sys/amd64/amd64/cpu_switch.S | 6 ------
sys/amd64/amd64/exception.S | 29 -----------------------------
sys/amd64/amd64/machdep.c | 6 ++----
sys/amd64/ia32/ia32_exception.S | 3 +--
4 files changed, 3 insertions(+), 41 deletions(-)
diff --git a/sys/amd64/amd64/cpu_switch.S b/sys/amd64/amd64/cpu_switch.S
index 2a3eced01ab3..2a829c7507ea 100644
--- a/sys/amd64/amd64/cpu_switch.S
+++ b/sys/amd64/amd64/cpu_switch.S
@@ -91,14 +91,8 @@ ENTRY(cpu_switch)
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
index 90f7a88f5d52..797b2fe748f3 100644
--- a/sys/amd64/amd64/exception.S
+++ b/sys/amd64/amd64/exception.S
@@ -479,22 +479,14 @@ prot_addrf:
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 @@ dbg_fromuserspace:
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 @@ nmi_fromuserspace:
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
@@ -1177,15 +1161,12 @@ do_segs:
.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
.globl ld_fsbase
ld_fsbase:
wrmsr
-1:
/* Restore %gs and gsbase */
movw TF_GS(%rsp),%si
pushfq
@@ -1198,10 +1179,6 @@ ld_fsbase:
.globl ld_gs
ld_gs:
movw %si,%gs
- /* Save user %gs base into %r14d:%r15d */
- rdmsr
- movl %eax,%r14d
- movl %edx,%r15d
/* Restore kernel %gs base */
movl %r12d,%eax
movl %r13d,%edx
@@ -1212,14 +1189,8 @@ ld_gs:
* 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
-1:
- movl %r14d,%eax
- movl %r15d,%edx
.globl ld_gsbase
ld_gsbase:
wrmsr /* May trap if non-canonical, but only for TLS. */
diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
index ea0f164b2e56..e4109b0ff791 100644
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -1786,10 +1786,8 @@ set_pcb_flags_fsgsbase(struct pcb *pcb, const u_int
flags)
(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);
diff --git a/sys/amd64/ia32/ia32_exception.S b/sys/amd64/ia32/ia32_exception.S
index 42d0ff6c638b..ef1a2c59a0af 100644
--- a/sys/amd64/ia32/ia32_exception.S
+++ b/sys/amd64/ia32/ia32_exception.S
@@ -54,10 +54,10 @@ int0x80_syscall_common:
movq %rax,TF_RAX(%rsp)
movq %rdx,TF_RDX(%rsp)
movq %rcx,TF_RCX(%rsp)
+ movq %r15,TF_R15(%rsp)
call handle_ibrs_entry
sti
movq %rsi,TF_RSI(%rsp)
- movq %r8,TF_R8(%rsp)
movq %r9,TF_R9(%rsp)
movq %rbx,TF_RBX(%rsp)
movq %rbp,TF_RBP(%rsp)
@@ -66,7 +66,6 @@ int0x80_syscall_common:
movq %r12,TF_R12(%rsp)
movq %r13,TF_R13(%rsp)
movq %r14,TF_R14(%rsp)
- movq %r15,TF_R15(%rsp)
movl $TF_HASSEGS,TF_FLAGS(%rsp)
pushfq
andq $~(PSL_D | PSL_AC),(%rsp)
