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-rw-r--r--arch/x86/entry/entry_64.S35
1 files changed, 17 insertions, 18 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index e38a4cf795d9..97b1f84bb53f 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -574,6 +574,10 @@ SYM_INNER_LABEL(swapgs_restore_regs_and_return_to_usermode, SYM_L_GLOBAL)
ud2
1:
#endif
+#ifdef CONFIG_XEN_PV
+ ALTERNATIVE "", "jmp xenpv_restore_regs_and_return_to_usermode", X86_FEATURE_XENPV
+#endif
+
POP_REGS pop_rdi=0
/*
@@ -890,6 +894,7 @@ SYM_CODE_START_LOCAL(paranoid_entry)
.Lparanoid_entry_checkgs:
/* EBX = 1 -> kernel GSBASE active, no restore required */
movl $1, %ebx
+
/*
* The kernel-enforced convention is a negative GSBASE indicates
* a kernel value. No SWAPGS needed on entry and exit.
@@ -897,21 +902,14 @@ SYM_CODE_START_LOCAL(paranoid_entry)
movl $MSR_GS_BASE, %ecx
rdmsr
testl %edx, %edx
- jns .Lparanoid_entry_swapgs
- ret
+ js .Lparanoid_kernel_gsbase
-.Lparanoid_entry_swapgs:
+ /* EBX = 0 -> SWAPGS required on exit */
+ xorl %ebx, %ebx
swapgs
+.Lparanoid_kernel_gsbase:
- /*
- * The above SAVE_AND_SWITCH_TO_KERNEL_CR3 macro doesn't do an
- * unconditional CR3 write, even in the PTI case. So do an lfence
- * to prevent GS speculation, regardless of whether PTI is enabled.
- */
FENCE_SWAPGS_KERNEL_ENTRY
-
- /* EBX = 0 -> SWAPGS required on exit */
- xorl %ebx, %ebx
ret
SYM_CODE_END(paranoid_entry)
@@ -993,11 +991,6 @@ SYM_CODE_START_LOCAL(error_entry)
pushq %r12
ret
-.Lerror_entry_done_lfence:
- FENCE_SWAPGS_KERNEL_ENTRY
-.Lerror_entry_done:
- ret
-
/*
* There are two places in the kernel that can potentially fault with
* usergs. Handle them here. B stepping K8s sometimes report a
@@ -1020,8 +1013,14 @@ SYM_CODE_START_LOCAL(error_entry)
* .Lgs_change's error handler with kernel gsbase.
*/
SWAPGS
- FENCE_SWAPGS_USER_ENTRY
- jmp .Lerror_entry_done
+
+ /*
+ * Issue an LFENCE to prevent GS speculation, regardless of whether it is a
+ * kernel or user gsbase.
+ */
+.Lerror_entry_done_lfence:
+ FENCE_SWAPGS_KERNEL_ENTRY
+ ret
.Lbstep_iret:
/* Fix truncated RIP */